TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS)

Even more remarkably for petroleum and pipeline engineers, Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is the only oilfield microbiocide that simultaneously chelates and dissolves corrosive, pyrophoric Iron Sulfide (FeS) scale deposits ("black water" and oil-stabilized "schmoo" pads), converting solid FeS into a water-soluble iron-phosphonium coordination complex to restore injection-well permeability and eliminate under-deposit pitting corrosion. Beyond water and oilfield microbial control, textile and leather chemists utilize Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) as a reactive polyfunctional hydroxymethyl monomer that condenses with urea or gaseous ammonia inside cotton fibers to produce durable flame-retardant workwear fabrics capable of withstanding 50 to 100+ industrial washes, and crosslinks collagen amino groups in wet-white eco-leather tanning to achieve shrinkage temperatures above 82 to 86 °C.

Partnering with Ataman Kimya for drum or IBC deliveries of Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) guarantees full 75.0% minimum active phosphonium assay, low free formaldehyde, US EPA and EU BPR (PT 2, 6, 11, 12) / US FDA 21 CFR 173.300 regulatory alignment, and reliable global supply chain logistics. Selecting Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) empowers water-treatment engineers, oilfield operators, paper mills, and textile finishers to achieve maximum microbial and fire protection with a low environmental footprint.

CAS Number: 55566-30-8 (Phosphonium, tetrakis(hydroxymethyl)-, sulfate (2:1) (salt); Bis[tetrakis(hydroxymethyl)phosphonium] sulfate; Tetrakis(hydroxymethyl)phosphonium sulfate)
EC Number: 259-709-0 (EINECS 259-709-0; EU REACH & Biocidal Products Regulation BPR Active Substance: tetrakis(hydroxymethyl)phosphonium sulphate (2:1))
Molecular Formula: C8H24O12P2S (Condensed Ionic Structural Formula: [(HOCH2)4P]2SO4 or [P(CH2OH)4+]2 [SO4^2-]; Theoretical Elemental Composition on 100% pure salt basis: 23.65% C, 5.95% H, 47.26% O, 15.25% P, 7.89% S by weight; in 75.0% w/w aqueous solution: ~11.44% w/w elemental P)
Molecular Weight: 406.28 g/mol (Exact Monoisotopic Mass: 406.0464 g/mol; Equivalent Weight per Phosphonium Cation: 203.14 g/eq)
INCI Name: Not assigned (Industrial water-treatment and oilfield microbiocide, iron sulfide scale dissolver, textile flame-retardant crosslinking monomer, paper-mill slimicide, and chrome-free leather tanning agent; not used in cosmetics)
E Number: Not assigned (Industrial biocide and chemical intermediate; not a direct food additive, though approved by the US Food and Drug Administration under 21 CFR 173.300 / 21 CFR 176.300 as a slimicide in the manufacture of paper and paperboard that contact food at a maximum use level of 84 mg/kg in the pulp slurry)
Melting Point: -21.0 to -35.0 °C (-5.8 to -31.0 °F Freezing / Crystallization Point for commercial 75% w/w aqueous solution of Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS), NTP value -35.0 °C; pure isolated anhydrous crystalline solid melts with thermal decomposition above ~115 to 140 °C)
Boiling Point: 109.0 to 111.0 °C (228.2 to 231.8 °F at 101.3 kPa / 760 mmHg atmospheric pressure for the commercial 75% w/w aqueous solution, followed by thermal decomposition of the residue above ~140 to 180 °C; Non-flammable aqueous solution with no flash point up to boiling)
Viscosity: 30.0 to 45.0 mPa·s (cP) dynamic viscosity at 20 °C and ~26.0 to 34.0 mPa·s (cP) at 25 °C for commercial 75% w/w aqueous Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (kinematic viscosity ~22.0 to 32.0 mm2/s [cSt] at 20–25 °C)
Density: 1.375 to 1.410 g/cm3 at 20 °C (typically 1.385 to 1.395 g/cm3 at 20 °C and 1.380 g/cm3 at 25 °C per ASTM D4052 / ISO 12185 for 75% w/w aqueous solution; Bulk Weight ~11.56 lb/gal at 20 °C; Vapor Pressure: ~23 hPa at 20 °C, 42.7 hPa [32 mmHg] at 51 °C; Refractive Index n20/D of 75% solution: ~1.482 to 1.490)

Most Frequently Encountered Synonyms:
Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS)
TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS)
Phosphonium, tetrakis(hydroxymethyl)-, sulfate (2:1) (salt)
Octakis(hydroxymethyl)diphosphonium sulfate
Tetrahydroxymethylphosphonium sulfate
THPS
THPS 75%
THPS 75
THPS Biocide
THPS 75% Aqueous Solution
Berrykem THPS 75
Proban CC (Textile flame-retardant THPS/THPC-urea condensate system)
Tetrakis hidroksimetil fosfonyum sülfat (Turkish)
Tetrakis(hidroksimetil)fosfonyum sülfat (THPS %75)

WHAT IS TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS)?

Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is a water-soluble quaternary organophosphonium salt with the chemical formula [(HOCH2)4P]2SO4 (C8H24O12P2S, CAS 55566-30-8, EC 259-709-0), supplied commercially as a 75% w/w concentrated aqueous solution (THPS 75%). Within industrial chemistry, Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) occupies a unique position as a dual-industry flagship chemical:

1. In Industrial Water Treatment, Oil & Gas Production, and Pulp & Paper Manufacturing: Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is a fast-acting, non-oxidizing, non-foaming broad-spectrum microbiocide and iron sulfide (FeS) scavenger. Recognized by the US Environmental Protection Agency with the Presidential Green Chemistry Challenge Award in 1997, Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) eradicates planktonic and sessile biofilm populations of Sulfate-Reducing Bacteria (SRB), Acid-Producing Bacteria (APB), Legionella pneumophila, general aerobic bacteria, fungi, and algae at low parts-per-million dosages (15 to 150 ppm active) and then rapidly breaks down via hydrolysis, oxidation, and photolysis into environmentally benign tris(hydroxymethyl)phosphine oxide (THPO, log Kow = -2.6, non-bioaccumulative and practically non-toxic to aquatic life).

2. In Textile Flame-Retardant Finishing and Chrome-Free Leather Tanning: Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) serves as a reactive tetra-functional methylol-phosphonium building block. When reacted with urea or ammonia inside cellulosic cotton fibers and oxidized to the pentavalent phosphine oxide state, it creates an insoluble, permanent flame-retardant polymer network (containing ~2.5% to 3.5% phosphorus on fabric weight) that endures 50 to 100+ industrial boil-wash cycles without formaldehyde release during wear. In leather tanneries, Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) crosslinks hide collagen fibers to produce bright white, chrome-free, biodegradable "wet-white" automotive and footwear leather!

HISTORICAL DEVELOPMENT AND GREEN CHEMISTRY EVOLUTION OF THPS

Quaternary hydroxymethyl phosphonium salts were first synthesized by A. Hoffman in 1921 via the reaction of phosphine gas (PH3) with formaldehyde and mineral acids. In the early 1950s, Reeves and Guthrie at the USDA Southern Regional Research Laboratory discovered that Tetrakis(hydroxymethyl)phosphonium chloride (THPC, CAS 124-64-1, [(HOCH2)4P]Cl) reacted with urea, melamine, or ammonia inside cotton textiles to impart permanent, wash-fast flame retardancy (commercialized by Albright & Wilson under the Proban process).
However, in the 1970s and 1980s, researchers discovered that replacing hydrochloric acid (HCl) with sulfuric acid (H2SO4) during synthesis—producing Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (CAS 55566-30-8) instead of THPC—delivered three transformative breakthroughs:
 
Elimination of Corrosive Chloride Ions and Bis(chloromethyl) Ether (BCME) Hazard: In textile curing ovens, combining chloride ions (from THPC) with trace formaldehyde vapor posed a theoretical risk of forming toxic bis(chloromethyl) ether, and chloride ions caused severe pitting corrosion in stainless-steel oilfield pipelines and cooling towers. Sulfate-based Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is 100% chloride-free and halogen-free!

Discovery of Oilfield SRB Biocidal & Iron Sulfide (FeS) Dissolving Synergy: In the late 1980s and 1990s, North Sea and US oilfield operators searching for a greener, non-persistent alternative to glutaraldehyde, acrolein, and quaternary ammonium compounds discovered that Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) not only killed Sulfate-Reducing Bacteria in deep sour reservoirs within 1 to 2 hours, but also dissolved black Iron Sulfide (FeS) scale plugs that no other biocide could touch—earning the 1997 US EPA Presidential Green Chemistry Award.

CHEMICAL STRUCTURE, REVERSIBLE EQUILIBRIUM, AND TRIPLE MECHANISM OF ACTION

The extraordinary versatility of Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is governed by the dynamic chemistry of its [(HOCH2)4P]+ cation in aqueous solution:

 Reversible pH-Dependent Dissociation Equilibrium Between THPS and THP:
In aqueous solution, the tetrakis(hydroxymethyl)phosphonium cation ([(HOCH2)4P]+, formal phosphorus oxidation state +3 / tetrahedral phosphonium) exists in a reversible, pH-controlled equilibrium with its conjugate neutral tertiary phosphine, Tris(hydroxymethyl)phosphine ((HOCH2)3P, abbreviated THP, pKa ~ 5.5), and hydrated formaldehyde (methylene glycol, HOCH2OH):
  [(HOCH2)4P]+  +  H2O   <===[pKa ~ 5.5]===>   (HOCH2)3P (THP)  +  CH2(OH)2  +  H+
- Under Acidic Shipping Conditions (pH 3.0 to 4.5 in commercial 75% THPS): The high proton concentration (H+) drives the equilibrium > 98% to the left, keeping the molecule locked in the stable, non-volatile, non-oxidizable quaternary phosphonium salt form [(HOCH2)4P]2SO4 for 12 to 24 months of drum/IBC shelf life!
- Upon Dilution into Neutral or Slightly Alkaline Water (pH 6.0 to 9.0 in Cooling Towers, Oilfield Brines, or Paper Mills): The equilibrium shifts partially to the right, generating neutral lipophilic Tris(hydroxymethyl)phosphine (THP) molecules in situ alongside positively charged [(HOCH2)4P]+ cations!

 Mechanism 1 — Dual Biochemical Biocidal Action and Biofilm Stripping:
- Electrostatic Cell-Wall Binding & Membrane Disruption: The positively charged [(HOCH2)4P]+ cation binds electrostatically to the negatively charged teichoic acid and lipopolysaccharide (LPS) outer membranes of Gram-negative and Gram-positive bacteria, destabilizing membrane integrity and dispersing the polyanionic polysaccharide matrix of established biofilms.
- Intracellular Disulfide (-S-S-) Cleavage & Enzyme Reduction by THP: Simultaneously, uncharged Tris(hydroxymethyl)phosphine ((HOCH2)3P) diffuses rapidly across the lipid bilayer into the bacterial cytoplasm. Because trivalent phosphorus in THP is a powerful oxophilic nucleophile and reducing agent, it attacks and cleaves essential cystine disulfide bonds (-S-S-) in microbial respiratory and metabolic enzymes (reducing -S-S- to two -SH thiol groups while oxidizing THP irreversibly to inert (HOCH2)3P=O!), while the reactive hydroxymethyl (-CH2OH) arms crosslink amino groups (-NH2) in cell-wall proteins and nucleic acids. This dual reductive + crosslinking attack causes rapid ATP depletion and microbial cell death within 1 to 4 hours, preventing bacteria from developing genetic resistance!

 Mechanism 2 — Chelation and Dissolution of Pyrophoric Iron Sulfide (FeS) Scale:
In sour oil and gas wells, pipelines, and water-injection systems, Sulfate-Reducing Bacteria (SRB) generate H2S gas that reacts with carbon steel to form insoluble Iron(II) Sulfide (FeS, mackinawite, pyrrhotite, and greigite). Solid FeS particles act as Pickering stabilizers that lock crude oil and water into intractable black "schmoo" sludge emulsions and cause severe galvanic pitting corrosion. When Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is dosed into the system (especially in synergy with 5%–20% w/w ammonium chloride/sulfate or aminocarboxylate chelator), the hydroxymethyl-phosphorus ligands coordinate directly to Fe2+ ions on the FeS crystal lattice, forming a bright red, water-soluble iron-phosphonium complex ion (approximated as [Fe(H2O)2((HOCH2)3P)n]^2+ / [Fe-THPS-NH3] complex) that dissolves solid FeS scale into the water phase!

 Mechanism 3 — Polycondensation with Amines (Urea, Ammonia, and Hide Collagen) for Flame Retardancy and Tanning:
The four primary alcohol groups (-CH2OH) of Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) undergo rapid Mannich-type nucleophilic condensation with active N-H bonds in urea (-NH-CO-NH-), gaseous ammonia (NH3), melamine, and the epsilon-amino groups of lysine/hydroxylysine in animal hide collagen:
  P+-CH2-OH  +  H2N-R   --->   P+-CH2-NH-R  +  H2O
In cotton textiles, this creates a three-dimensional crosslinked poly(phosphonium-urea-amine) network inside the fiber that, after oxidation with hydrogen peroxide (H2O2) to the stable pentavalent phosphine oxide (-P(=O)(CH2-NH-)3), acts as a condensed-phase char-forming flame retardant. In leather tanning, crosslinking hide collagen fibers with Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) at pH 5.0–6.0 raises the hydrothermal shrinkage temperature (Ts) of the hide from 60 °C up to 82–86 °C without using toxic Chromium(III/VI) or glutaraldehyde!

INDUSTRIAL PRODUCTION AND MANUFACTURING PROCESSES

Commercial 75% aqueous Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) supplied by Ataman Kimya is manufactured in specialized closed-loop batch or continuous reactors:
- Stage 1 (Generation of High-Purity Phosphine Gas PH3):
  Elemental yellow phosphorus (P4) is reacted with aqueous sodium hydroxide (or steamed/acid-hydrolyzed from metal phosphides / disproportionated from phosphorous acid) in an oxygen-free reactor to generate purified Phosphine gas (PH3, CAS 7803-51-2).
- Stage 2 (Acid-Catalyzed Condensation of Phosphine, Formaldehyde, and Sulfuric Acid):
  In a glass-lined or 316L stainless-steel jacketed pressure reactor purged completely free of oxygen with nitrogen, an aqueous solution of formaldehyde (CH2O, 37%–50%, 8.0 moles per 1.0 mole of H2SO4) and sulfuric acid (H2SO4, 1.0 mole) is charged at 20 to 60 °C. High-purity phosphine gas (PH3, 2.0 moles) is metered subsurface under slight pressure (1 to 3 bar) with vigorous agitation and cooling:
  2 PH3 + 8 CH2O (Aqueous Formaldehyde) + H2SO4  --->  [(HOCH2)4P]2SO4 (THPS)
  The reaction proceeds cleanly with nearly 100% atom economy directly in the aqueous phase!
- Stage 3 (Vacuum Concentration Standardization, pH Adjustment, and Polishing Filtration):
  After complete consumption of phosphine and purging of the headspace with nitrogen, the reaction solution is adjusted under vacuum to standardize the active [(HOCH2)4P]2SO4 concentration at 75.0 +/- 1.0% w/w (specific gravity ~1.385–1.395 g/cm3 at 20 °C) and pH 3.0 to 4.5, then filtered through 1-micron cartridges into HDPE drums or IBC totes.

PHYSICAL AND CHEMICAL PROPERTIES OF TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS)

Typical physical constants and analytical specification limits for Ataman Kimya's Commercial 75% w/w Aqueous Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (CAS 55566-30-8, EC 259-709-0) include:
- Chemical Name (IUPAC): Bis[tetrakis(hydroxymethyl)phosphonium] sulfate / Tetrakis(hydroxymethyl)phosphonium sulfate (2:1)
- CAS Registry Number: 55566-30-8
- EC / EINECS Number: 259-709-0
- Molecular Formula & Weight: C8H24O12P2S / 406.28 g/mol
- Physical Appearance at 20 °C: Clear, colorless to pale yellow / straw-colored mobile liquid free from suspended matter
- Odor: Mild, characteristic slightly pungent aldehyde/phosphonium odor
- Active THPS Assay (Iodometric Titration): 75.0 +/- 1.0% w/w (minimum 75.0% w/w; typical 75.2% to 76.2% w/w)
- Elemental Phosphorus Content (in 75% Aq Solution): ~11.4% w/w (11.2% to 11.7% w/w; theoretical 15.25% P on 100% dry basis)
- Color (APHA / Pt-Co / Hazen, ASTM D1209): <= 50 to 100 APHA (typical 20 to 45 APHA)
- pH (Undiluted 75% Solution at 20 °C): 3.0 to 4.5 (Specification range: 2.5 to 5.5; pH of 1% w/w aqueous solution: ~4.0 to 5.0)
- Specific Gravity / Relative Density (20/20 °C, ASTM D4052): 1.380 to 1.405 g/cm3 (typical 1.388 g/cm3 at 20 °C; 1.380 g/cm3 at 25 °C)
- Dynamic Viscosity at 20 °C: 30.0 to 45.0 mPa·s (cP; typical 35.0 mPa·s at 20 °C, ~30.0 mPa·s at 25 °C)
- Refractive Index (n20/D): 1.4820 to 1.4900
- Freezing / Crystallization / Pour Point: -21.0 to -35.0 °C (-5.8 to -31.0 °F; NTP value -35.0 °C)
- Boiling Point (101.3 kPa / 760 mmHg): ~109.0 to 111.0 °C (228 to 232 °F)
- Flash Point: None (Non-flammable aqueous solution)
- Surface Tension (0.1% w/w Active in Water at 20 °C): ~71.5 to 72.5 mN/m (virtually identical to pure water—100% non-foaming!)
- Iron (Fe) Content: <= 10 to 20 mg/kg (ppm)
- Heavy Metals (as Pb): <= 10 mg/kg (ppm)
- Chloride (Cl-) Content: <= 0.05% w/w (100% Chloride-Free Sulfate Salt)
- Solubility: Miscible in all proportions with water (cold or hot), ethylene glycol, propylene glycol, methanol, and lower alcohols; insoluble in non-polar aliphatic/aromatic hydrocarbons (though readily emulsified or partitioned into oilfield brines)
- Octanol-Water Partition Coefficient (log Pow / log Kow): -9.8 (for ionic THPS at 20 °C; -1.8 to -2.6 for neutral THP / THPO degradation product—zero bioaccumulation potential!)

WHY EACH IMPORTANT PROPERTY OF TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS) MATTERS IN PRACTICE

 Zero Foaming (Surface Tension ~72 mN/m) and Non-Emulsifying Oilfield Behavior:
When cationic quaternary ammonium biocides ("Quats" like BKC) are injected into oilfield water-separation vessels, gas scrubbers, or cooling towers, they lower surface tension to ~32 mN/m—causing severe foaming in gas separators, stabilizing crude-oil/water rag layers, and oil-wetting sandstone/carbonate reservoir rock (reducing oil permeability). Because Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) has no long hydrophobic alkyl tail, its aqueous surface tension is ~72 mN/m: it generates ZERO foam in cooling towers and gas separators, keeps reservoir rock water-wet, and actually breaks FeS-stabilized crude-oil emulsions!

 Ultra-Low Freezing Point (-21 to -35 °C) at 75% Concentration:
Whereas 50% Glutaraldehyde freezes around -14 to -21 °C and 20% CMIT/MIT freezes at -3 to -18 °C, commercial 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) remains a mobile liquid (~35 mPa·s at 20 °C) down to -21 to -35 °C, enabling unheated winter chemical injection on offshore platforms and remote wellheads.

 Rapid Environmental Deactivation to Non-Toxic THPO (Log Kow = -2.6):
In cooling-tower blowdown and offshore produced-water discharge, persistent biocides violate environmental toxicity limits. Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) hydrolyzes and oxidizes at neutral/alkaline pH and low ppm dilutions into Tris(hydroxymethyl)phosphine oxide (THPO), which has a 96-hour Rainbow Trout LC50 > 5,000 mg/L and Daphnia EC50 > 1,000 mg/L—allowing rapid detoxification prior to discharge (or instantaneous deactivation by adding a stoichiometric dose of sodium bisulfite or hydrogen peroxide!).

WHAT PROBLEMS CAN TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS) HELP SOLVE?

 Eradicating Sulfate-Reducing Bacteria (SRB) and Biogenic H2S Reservoir Souring in Oil & Gas Fields: Dosing 50 to 200 ppm of Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (75%) into injection waters, hydraulic fracturing fluids, and produced water kills SRB (Desulfovibrio, Desulfotomaculum) within 1 to 2 hours, halting biogenic hydrogen sulfide (H2S) gas generation and Microbiologically Influenced Corrosion (MIC).

 Dissolving Black Iron Sulfide (FeS) Scale Plugs and Breaking "Schmoo" Sludge in Pipelines & Wells: Batch-squeezing or continuously injecting Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (at 100 ppm to 15% w/w in remedial acid/chelate jobs) dissolves solid FeS scale into a water-soluble red iron-phosphonium complex, restoring water-injection rates and eliminating pyrophoric FeS filter-element fires!

 Controlling Legionella pneumophila, Algae, and Slime Biofilms in Industrial Cooling Towers & Paper Mills: Shock-dosing 30 to 100 ppm of Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) strips slimy EPS biofilms from heat-exchanger tubes and paper-machine wet-end chests without foaming or corroding metallurgy.

 Imparting Permanent 100-Wash Flame Retardancy to Cotton & Cotton-Blend Workwear (Proban / THPS-Urea Process): Treating cellulosic workwear, military uniforms, children's sleepwear, and hospital draperies with Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) creates an internal crosslinked phosphorus-nitrogen polymer that chars upon flame contact and passes NFPA 2112 / EN ISO 11612 after 50 to 100+ industrial laundering cycles.

 Replacing Toxic Chromium(III/VI) and Glutaraldehyde in Eco-Friendly "Wet-White" Leather Tanning: Tanning pickled cattle hides or sheepskins with 1.5% to 3.0% w/w Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) produces bright white, plump, tight-grain chrome-free leather with a shrinkage temperature of 82 to 86 °C for automotive upholstery and baby/athletic footwear.

BENEFITS FOR THE MANUFACTURER AND END USER

- Dual Biocide + Iron Sulfide (FeS) Scale Dissolver in One Molecule: Eliminates the need for separate corrosive HCl acidizing jobs and dangerous acrolein treatments in sour oilfields.
- Ultra-Fast Kill Speed (1 to 4 Hours) and Biofilm Penetration: Penetrates deep into sessile biofilms to kill dormant SRB and Legionella cells where oxidizing biocides (bleach/bromine) are consumed at the surface.
- 100% Non-Foaming and Chloride-Free: Safe for high-shear cooling towers, vacuum deaerators, gas scrubbers, and chloride-sensitive 304/316L stainless-steel metallurgy.
- Award-Winning Green Chemistry Environmental Profile: Degrades rapidly into non-toxic, non-bioaccumulative THPO (US EPA Presidential Green Chemistry Award winner).
- Broad Regulatory Approvals: Approved under US EPA FIFRA, EU BPR (PT 2, 6, 11, 12), and US FDA 21 CFR 173.300 / 176.300 (food-contact paper slimicide up to 84 mg/kg).

APPLICATIONS OF TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS)

Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is utilized across five major industrial sectors:

Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is utilized as a high-speed non-oxidizing microbiocide, Sulfate-Reducing Bacteria (SRB) killer, and Iron Sulfide (FeS) scale dissolver in Oil & Gas Production, Hydraulic Fracturing (Fracking) Fluids, Secondary Waterflooding, Produced-Water Injection Wells, Drilling Muds, Pipeline Hydrotesting/Lay-Up, and Subsea Umbilicals.
Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is used for controlling Legionella pneumophila, sessile biofilms, algae, and slime-forming bacteria in Industrial Recirculating Cooling Towers, Closed-Loop Chilled/Hot Water Systems, Evaporative Condensers, Air Washers, and Reverse Osmosis (RO) Pre-Treatment Lines.
Also Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is utilized in the Pulp and Paper Manufacturing Industry as an FDA 21 CFR 173.300 / 176.300 compliant wet-end slimicide and starch/coating/filler preservative to prevent biological slime breaks and sulfur odors in food-contact paperboard and tissue mills.

For Durable Flame-Retardant Textile Finishing (Proban Ammonia-Cure and THPS-Urea Pad-Dry-Cure Systems), Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is used to impart permanent, 50- to 100-wash flame resistance to 100% Cotton, Cotton-Polyester, and Cellulosic Protective Workwear, Arc-Flash Garments, Military Uniforms, and Contract Upholstery.
In the Leather Tanning and Fur Dressing Industry, Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is employed as a primary chrome-free, aldehyde-free organic tanning and re-tanning crosslinker to produce biodegradable "wet-white" automotive, upholstery, and footwear leather, as well as a bactericide/fungicide in hide soaking.
Furthermore, Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is applied in Industrial Wastewater Treatment Lagoons, Geothermal Injection Brines, Metalworking Fluid Preservation, and Aquaculture / Agricultural Irrigation Biofilm Control (where permitted by local regulations).

WHICH INDUSTRIES USE TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS)?

- The Oil & Gas Exploration, Hydraulic Fracturing, Offshore Production, and Pipeline Service Industry uses Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) for simultaneous SRB microbial control and FeS scale remediation.
- The Industrial Water Treatment, Power Generation, Petrochemical Cooling Tower, and HVAC Maintenance Industry utilizes Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) for non-foaming biofilm and Legionella eradication.
- The Pulp, Paper, Packaging Board, and Tissue Mill Industry relies on Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) as a fast-acting, food-contact-approved wet-end slimicide.
- The Protective Workwear Textile, Flame-Retardant Fabric Finishing, and Technical Textile Industry employs Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) to manufacture durable flame-retardant cotton garments.
- The Leather Tanning, Automotive Upholstery Leather, and Eco-Leather Manufacturing Industry uses Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) for chrome-free wet-white collagen crosslinking.
- The Mining, Geothermal Energy, and Industrial Chemical Formulation Industry utilizes Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) for process water microbial control and iron sulfide removal.

USE OF TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS) IN OILFIELD WATER TREATMENT, FES DISSOLUTION AND COOLING TOWERS

- Oilfield Hydraulic Fracturing, Waterflooding, and Pipeline Lay-Up with Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS):
  - In Hydraulic Fracturing (Fracking) & Produced Water: Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (75%) is dosed on-the-fly into slickwater or guar/polyacrylamide fracturing fluids at 70 to 200 ppm (delivering ~50 to 150 ppm active THPS) to sterilize mix water and prevent downhole SRB reservoir souring. (Note: in cross-linked borate/zirconate guar gels or high-molecular-weight anionic polyacrylamide friction reducers, verify compatibility with the divalent SO4^2- ion and trivalent phosphorus reducing activity at high temperature, or use an oxidative breaker delay).
  - In Waterflood Injection Systems & Pipeline Hydrotesting: For continuous injection-water treatment, 15 to 50 ppm of Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (75%) is metered continuously; for intermittent slug dosing (2 to 3 times per week for 2 to 6 hours), 70 to 250 ppm of THPS 75% is injected. For long-term subsea pipeline hydrotest and wet lay-up preservation (6 to 24 months), 250 to 1,000 ppm of Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (75%) is combined with an oxygen scavenger and corrosion inhibitor.

- Remedial Iron Sulfide (FeS) Scale Dissolution & Well Stimulation with Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS): To dissolve heavy Iron Sulfide (FeS) scale deposits plugging gravel packs, downhole pumps, heat exchangers, and water-disposal wells without releasing toxic H2S gas plumes (unlike 15% HCl acid jobs, which generate massive lethal H2S gas upon contacting FeS!), operators circulate an aqueous stimulation pill containing 5.0% to 20.0% w/w Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (75%), 2.0% to 5.0% w/w Ammonium Chloride (NH4Cl, synergistic nitrogen ligand co-activator that accelerates FeS chelation by 300%!), and 0.2% to 0.5% nonionic wetting surfactant at 40 to 80 °C for 4 to 12 hours. Solid black FeS dissolves cleanly into a bright red water-soluble iron-THPS complex with minimal H2S evolution!
- Industrial Recirculating Cooling Towers & Paper Mills with Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS): In cooling towers (pH 6.8 to 8.8), shock-dose 45 to 120 ppm of Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (75%) (delivering 35 to 90 ppm active THPS) 1 to 3 times per week to eradicate Legionella, SRB, and algae. In pulp and paper mills (21 CFR 173.300), slug-dose 20 to 100 ppm of THPS 75% into the machine chest, white-water silo, or broke system (keeping pulp slurry active THPS <= 84 mg/kg for food-contact paper).

USE OF TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS) IN TEXTILE FLAME RETARDANCY AND CHROME-FREE LEATHER TANNING

- Durable Flame-Retardant Cotton Textile Finishing (THPS-Urea / Ammonia-Cure Process): To impart wash-permanent flame retardancy to 100% cotton or 88/12 cotton/nylon protective twill fabrics (200 to 350 g/m2), Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (75%) is reacted with Urea in a ~2:1 phosphonium-to-urea molar ratio at 80–95 °C to form a water-soluble THPS-Urea precondensate solution. The cotton fabric is padded through a bath containing 30% to 45% w/w THPS-Urea precondensate, wetting agent, and softener (75%–85% wet pick-up), dried gently to 8%–12% residual moisture at 100 °C, passed through an Ammonia Gas Curing Chamber (NH3 gas, which crosslinks the hydroxymethyl groups instantly inside the cotton fiber into an insoluble trivalent phosphorus polymer), and then washed through an aqueous Hydrogen Peroxide (H2O2) oxidation bath to oxidize P(III) into hyper-stable pentavalent Phosphine Oxide P(V) ([(H-N-CH2)3P=O]n). The resulting garment self-extinguishes with < 2 seconds afterflame and < 80 mm char length even after 100 industrial washes at 75 °C!
- Chrome-Free "Wet-White" Leather Tanning with Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS): In eco-leather tanning, delimed and bated pickled pelts (at pH 3.0 to 3.5 in 6%–8% NaCl brine) are drummed with 1.5% to 2.5% w/w Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (75%, calculated on limed pelt weight) for 60 to 90 minutes to allow rapid penetration through the hide cross-section. The bath pH is then gradually basified to pH 5.2 to 6.0 using sodium bicarbonate or magnesium oxide over 3 to 4 hours at 35 °C: the four hydroxymethyl groups of Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) covalently crosslink the collagen lysine amino groups, raising the leather hydrothermal shrinkage temperature (Ts) to 82–86 °C (and up to 92–95 °C when combined with vegetable tannins or aluminum/zirconium syntans)!

FORMULATION AND PROCESS CONSIDERATIONS WHEN USING TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS)

Incompatibility with Oxidizing Biocides (Chlorine / Hypochlorite / Bromine / Peroxide):
Because Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) contains phosphorus in a lower oxidation state that acts as a chemical reducing agent toward strong oxidizers, NEVER dose Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) simultaneously into a cooling tower or water line containing high residual free chlorine (NaOCl / Cl2), bromine (BCDMH / NaOBr), chlorine dioxide (ClO2), ozone, or hydrogen peroxide!
- Stoichiometric Quenching Fact: 1.0 mg/L of free chlorine or bromine will immediately oxidize ~2.0 to 3.0 mg/L of active Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) into inactive THPO (and conversely, THPS can actually be used intentionally to dechlorinate water!).
- Correct Alternating Dosing Protocol: In cooling towers that use both continuous/intermittent chlorination and periodic non-oxidizing THPS biofilm shock treatments, shut off the chlorine/bromine feed before dosing Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) so residual free halogen drops below <= 0.2 mg/L, allow THPS to circulate for 4 to 8 hours to strip biofilms and kill SRB, and then resume halogen feed.

Synergistic Combination with Ammonium Salts for Maximum Iron Sulfide (FeS) Dissolution:
Pure Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) alone dissolves Iron Sulfide (FeS) slowly; however, adding 0.2 to 0.5 parts by weight of Ammonium Chloride (NH4Cl) or Ammonium Sulfate ((NH4)2SO4) per 1.0 part of THPS 75% (at pH 4.0 to 6.5) provides ammonia/ammonium ligands that participate directly in the inner coordination sphere of the water-soluble red iron-phosphonium chelate complex—increasing both the dissolution rate and total FeS carrying capacity by 2.5- to 4-fold!

Materials of Construction for Undiluted 75% THPS Storage & Pumping:
Because undiluted 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is mildly acidic (pH 3.0 to 4.5) and chelates iron and copper, NEVER store or pump undiluted 75% THPS in unlined carbon steel, cast iron, copper, brass, bronze, aluminum, or zinc/galvanized equipment! Always use 316L or 304 stainless steel, Hastelloy C-276, titanium, high-density polyethylene (HDPE), polypropylene (PP), PVC, CPVC, PTFE (Teflon), Viton (FKM), or EPDM seals and piping.

TYPICAL USE LEVELS AND INITIAL FORMULATION APPROACHES FOR TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS)

Typical commercial dosage levels for Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (expressed as commercial 75% w/w aqueous solution, along with active ppm equivalents) include:
- Industrial Recirculating Cooling Towers & Evaporative Condensers (Shock / Slug Biofilm & Legionella Control): Dose 45 to 125 mg/L (ppm) of commercial 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (delivering ~34 to 94 ppm active THPS) 1 to 3 times per week.
- Oilfield Waterflood Injection Systems & Produced Water (Continuous vs. Slug Dosing):
  - Continuous Injection: 15 to 60 ppm of 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (11 to 45 ppm active THPS).
  - Intermittent Batch Slug Treatment (2 to 6 hours, 1 to 3 times weekly): 70 to 250 ppm of 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (52 to 188 ppm active THPS).
- Hydraulic Fracturing (Fracking) Fluids, Drilling Muds, and Workover/Completion Brines: Dose 70 to 350 ppm of 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (52 to 262 ppm active THPS) based on total fluid volume.
- Subsea Pipeline Hydrotesting and Long-Term Wet Lay-Up Preservation: Dose 250 to 1,000 ppm of 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (188 to 750 ppm active THPS).
- Remedial Oilfield Iron Sulfide (FeS) Scale Dissolution & Well Squeeze Jobs: Circulate or squeeze a 2.0% to 20.0% w/w aqueous solution of 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) paired with 1.0% to 5.0% w/w Ammonium Chloride (NH4Cl).
- Pulp & Paper Mill Wet-End Slimicide (US FDA 21 CFR 173.300 Compliant): Dose 20 to 110 g of 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) per metric ton of dry pulp/slurry (delivering 15 to 84 mg/kg active THPS in the pulp slurry).
- Durable Flame-Retardant Cotton Textile Finishing (THPS-Urea Pad Bath): Pad bath contains 30.0% to 48.0% w/w of 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) reacted with 6.0% to 10.0% w/w Urea (delivering ~2.5% to 3.5% w/w fixed phosphorus on dry fabric after ammonia/thermal cure and H2O2 oxidation).
- Chrome-Free "Wet-White" Leather Tanning: Dose 1.5% to 3.0% w/w of 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) based on fleshed/pickled pelt weight.
The four laboratory and pilot frameworks below illustrate preliminary R&D evaluation protocols for qualified technical personnel formulating with Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS).

EXAMPLE 1: SYNERGISTIC IRON SULFIDE (FES) SCALE DISSOLUTION AND SRB BIOCIDAL STIMULATION FLUID FOR SOUR OIL & GAS WELLS

Purpose: To formulate a non-corrosive, H2S-free Iron Sulfide (FeS) scale-dissolving and SRB-sterilizing well stimulation fluid using 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) and Ammonium Chloride, and evaluate gravimetric FeS dissolution capacity at 65 °C and 2-hour SRB log-kill reduction.
Initial stimulation fluid formulation (per 1,000.0 g aqueous batch, pH ~4.2 to 4.8):
- Deionized or Filtered Field Brine Water: 806.0 g (80.6% w/w)
- Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) 75% Aqueous Concentrate (CAS 55566-30-8, Ataman Kimya Oilfield Grade, active assay = 75.3% w/w, density = 1.388 g/cm3, pH = 3.6): 150.0 g (15.0% w/w of 75% product, delivering 11.25% w/w active THPS)
- Ammonium Chloride (NH4Cl, CAS 12125-02-9, synergistic nitrogen co-ligand activator for iron-phosphonium chelation): 38.0 g (3.8% w/w; weight ratio ~1:3 to active THPS)
- Nonionic Alcohol Ethoxylate / Alkyl Polyglucoside Surfactant (C9–11 8 EO or APG, schmoo-penetrating and water-wetting aid): 4.0 g (0.4% w/w)
- Quaternary Amine / Imidazoline Mild Steel Corrosion Inhibitor: 2.0 g (0.2% w/w)
Laboratory evaluation procedure:
- Stage 1 (Fluid Preparation): Dissolve the 38.0 g ammonium chloride, 4.0 g nonionic surfactant, and 2.0 g corrosion inhibitor in the 806.0 g water at 25 °C, then blend in the 150.0 g of 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) and mix for 5 minutes to obtain a clear, colorless solution (pH ~4.4).
- Stage 2 (Gravimetric Iron Sulfide FeS Dissolution Test at 65 °C): Weigh 5.00 g of finely ground synthetic or field-recovered Iron(II) Sulfide scale (FeS, 100 mesh) into a 250 mL jacketed glass reaction flask equipped with an H2S gas detector tube at the vent, add 100.0 g of the THPS/NH4Cl stimulation fluid, and stir at 65 °C for 4.0 hours. Observe the solution rapidly turn a deep crimson-red color as solid black FeS is chelated into the soluble iron-THPS-ammonium complex! Filter the solution through a pre-weighed 0.45-micron membrane filter, wash, dry, and weigh the undissolved residue, and analyze the filtrate by ICP-OES for dissolved Fe: confirm >= 82% to 90% FeS dissolution (~41 to 45 g FeS dissolved per liter of fluid, 3.5x higher than THPS without NH4Cl!) with near-zero free H2S gas evolution compared to a 15% HCl control.
- Stage 3 (SRB Time-Kill Assay per NACE TM0194): Inoculate produced brine containing 10^7 CFU/mL of mixed oilfield Sulfate-Reducing Bacteria (Desulfovibrio desulfuricans) with 100 ppm of the 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) under anaerobic conditions at 37 °C: perform serial-dilution lactate postgate-B broth bottle counts after 2.0 hours and confirm >= 5-log (99.999%) reduction in viable SRB!

EXAMPLE 2: COOLING TOWER BIOFILM & LEGIONELLA SHOCK TREATMENT AND SYNERGISTIC NON-OXIDIZING BIOCIDE BLEND

Purpose: To formulate a dual-active non-oxidizing cooling-water microbiocide concentrate combining Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) with a penetrating co-biocide/biodispersant, and evaluate sessile Pseudomonas / Legionella biofilm eradication and post-blowdown bisulfite detoxification.
Initial cooling-water biocide concentrate (per 1,000.0 g batch, delivering 50.0% w/w active THPS):
- Deionized Water: 323.0 g (32.3% w/w)
- Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) 75% Concentrate (CAS 55566-30-8, Ataman Kimya Water-Treatment Grade): 667.0 g (66.7% w/w, delivering 50.0% w/w active [(HOCH2)4P]2SO4)
- Low-Foaming Ethylene Oxide / Propylene Oxide (EO-PO) Block Copolymer Biodispersant (slime-penetrating wetting agent): 10.0 g (1.0% w/w)
Laboratory evaluation procedure:
- Blend the 667.0 g of 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) and 10.0 g EO-PO biodispersant into the 323.0 g deionized water at 20 °C to obtain a clear, low-viscosity (< 12 mPa·s) concentrate with a freezing point below -25 °C.
- Grow mature 72-hour Pseudomonas aeruginosa and Legionella pneumophila biofilms on 316L stainless-steel coupons in a CDC Biofilm Reactor using synthetic cooling water (pH 8.1, 300 ppm CaCO3 hardness, 35 °C).
- Shock-dose the reactor with 90 ppm of the 50% THPS blend (delivering 45 ppm active Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS)): confirm zero foaming in the aerated cooling tower basin, >= 4-log reduction in sessile biofilm bacteria on the stainless-steel coupons within 3.0 hours (outperforming 45 ppm active glutaraldehyde by 2.5 logs at pH 8.1!), and demonstrate rapid blowdown deactivation by adding 25 ppm Sodium Bisulfite (NaHSO3) or 15 ppm Hydrogen Peroxide to convert residual THPS quantitatively into non-toxic THPO before effluent discharge.

EXAMPLE 3: DURABLE FLAME-RETARDANT COTTON WORKWEAR FINISHING VIA THE THPS-UREA PAD-DRY-CURE-OXIDIZE PROCESS (NFPA 2112 / ISO 11612)

Purpose: To synthesize a reactive THPS-Urea flame-retardant precondensate from 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) and apply it to 100% cotton workwear twill (280 g/m2) to achieve permanent flame retardancy surviving 50+ industrial laundry cycles.
Initial pad-bath formulation (per 1,000.0 g aqueous finishing bath, targeting 80% wet pick-up on cotton fabric):
- Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) 75% Concentrate (CAS 55566-30-8, Ataman Kimya Textile Flame-Retardant Grade, Fe <= 10 ppm, color <= 35 APHA): 420.0 g (delivering 315.0 g = 31.5% w/w active THPS = 1.55 moles phosphonium cation)
- Prilled Technical Urea (NH2CONH2, CAS 57-13-6, MW 60.06 g/mol; 0.50 moles urea per 1.00 mole phosphonium cation): 46.5 g (0.775 moles)
- Sodium Acetate / Disodium Phosphate pH Buffer (to adjust pad-bath pH to 5.2–5.8): 12.0 g
- High-Density Polyethylene (HDPE) / Silicone Emulsion Fabric Softener (tear-strength & hand protector): 25.0 g (2.5% w/w)
- Nonionic Wetting Agent (rapid cotton fiber core penetrant): 3.0 g (0.3% w/w)
- Deionized Water (balance to 1,000.0 g): 493.5 g
Laboratory evaluation procedure:
- Stage 1 (THPS-Urea Precondensate Synthesis): Charge the 420.0 g of 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS), 46.5 g urea, and 150.0 g deionized water into a reflux reactor, heat to 85 to 90 °C for 60 minutes to condense ~1 to 2 hydroxymethyl arms per phosphonium ion with urea into a water-soluble oligomeric THPS-Urea precondensate, cool to 25 °C, and blend with the remaining water, buffer (pH 5.5), softener, and wetting agent.
- Stage 2 (Padding, Controlled Drying, and Ammonia / Thermal Crosslinking): Pad scoured, mercerized 100% cotton twill (280 g/m2) through the finishing bath on a two-bowl laboratory padder at 80% wet pick-up, and pre-dry in a stenter frame at 95 to 105 °C to exactly 10% residual moisture. Pass the fabric through a laboratory Ammonia Gas Curing Unit (gaseous NH3 for 45 seconds) followed by thermal curing at 140 °C for 2 minutes to lock the insoluble crosslinked poly(phosphonium-urea-amine) polymer inside the cotton fiber lumens.
- Stage 3 (Hydrogen Peroxide P(III)-to-P(V) Oxidation and Wash-Fastness Testing): Immediately wash the cured fabric through an oxidizing bath containing 15 g/L of 35% Hydrogen Peroxide (H2O2) and 5 g/L Soda Ash (Na2CO3) at 60 °C for 10 minutes to oxidize trivalent phosphorus P(III) into odorless, hydrolytically permanent pentavalent Phosphine Oxide P(V), then rinse, soap at 80 °C, and dry. Verify: fixed Phosphorus content on fabric = 3.1% w/w, Nitrogen content = 2.9% w/w, tear strength retention >= 88%, free formaldehyde on finished fabric < 75 ppm (ISO 14184-1), and Vertical Flammability Test (ASTM D6413 / ISO 15025) both initial and after 50 industrial wash/dry cycles at 75 °C (ISO 6330): Afterflame = 0.0 seconds, Afterglow <= 1.0 second, and Char Length <= 68 mm!

EXAMPLE 4: CHROME-FREE "WET-WHITE" ECO-LEATHER TANNING WITH TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS) AND SYNTAN

Purpose: To tan pickled bovine/ovine hides into bright white, chrome-free, glutaraldehyde-free "wet-white" leather using 2.0% w/w Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (75%) and evaluate hydrothermal shrinkage temperature (Ts per ISO 3380) and grain tightness.
Initial tanning drum recipe (percentages calculated on 100.0 parts fleshed/delimed pelt weight):
- Pickled Pelt (at pH 3.0 to 3.2 in 80% float of 7% w/w NaCl brine): 100.0%
- Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) 75% Concentrate (CAS 55566-30-8, Ataman Kimya Tanning Grade, pre-diluted 1:3 in water): 2.0% w/w (delivering 1.5% active THPS on pelt weight)
- Phenolic / Naphthalene Sulfonate Dispersing Syntan + Tara / Mimosa Vegetable Tannin (co-tanning partner): 6.0% w/w
- Sulfated / Sulfited Fatliquor (leather fiber lubricant): 3.0% w/w
- Sodium Bicarbonate (NaHCO3, pre-dissolved 1:10 in water for gradual basification to pH 5.6): ~1.2% to 1.6% w/w
Laboratory evaluation procedure:
- Drum the pickled pelt in the 80% brine float at pH 3.2 and 25 °C, add the 2.0% w/w Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (75%), and run the tanning drum for 90 minutes. At pH 3.2, the compact [(HOCH2)4P]+ cations penetrate rapidly and completely through the entire hide cross-section without surface over-tanning ("case hardening").
- Add the 6.0% syntan/vegetable co-tanning agent and drum for 60 minutes, then gradually feed the sodium bicarbonate solution in 4 increments over 2.5 hours while warming the float to 38 °C until bath pH reaches 5.6 to 5.8. At pH 5.6, the four hydroxymethyl groups of Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) condense covalently with the unprotonated epsilon-amino groups of collagen lysine residues!
- Add 0.2% hydrogen peroxide (35%) for 20 minutes to oxidize residual phosphonium groups to odorless phosphine oxide, fatliquor, drain, wash, and horse up for 24 hours. Measure Differential Scanning Calorimetry / ISO 3380 Hydrothermal Shrinkage Temperature (Ts): confirm Ts = 84.5 °C (up from 58 °C for raw hide!), bright white color (CIE L >= 88), zero Cr(III)/Cr(VI) content, and soft, full-grain handle suitable for automotive upholstery and shoe uppers.

COMPATIBILITY AND INCOMPATIBILITY OF TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS)

- Compatible Water-Treatment and Oilfield Co-Additives:
  - Scale & Corrosion Inhibitors: At normal use dilutions (15 to 250 ppm), Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is compatible with phosphonate scale inhibitors (HEDP, ATMP, DTPMP, PBTC), polycarboxylate/maleic/sulfonated polymers, quaternary amine and imidazoline corrosion inhibitors, ethylene/propylene/triethylene glycols, and methanol.
  - Non-Oxidizing Co-Biocides & Surfactants: Compatible and synergistic with glutaraldehyde, CMIT/MIT, bronopol, DBNPA, quaternary ammonium compounds (ADBAC / DDAC), EO-PO block copolymers, and nonionic/anionic/cationic surfactants.
- Chemical and Material Incompatibilities:
  - Strong Oxidizing Agents & Halogens (Immediate Reaction / Deactivation!): Undiluted or diluted Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) reacts exothermically and is chemically deactivated by oxidizing agents including sodium/calcium hypochlorite (bleach), chlorine gas, bromine, chlorine dioxide, hydrogen peroxide, peracetic acid, permanganates, chromates, and nitric acid. (Notice that in textile finishing and effluent detoxification, controlled H2O2 or bisulfite addition is used intentionally after curing or blowdown to oxidize P(III) to P(V) THPO!)
  - Strong Bases (NaOH / KOH at pH > 10) and Strong Reducing Hydrides: Adding concentrated caustic alkali directly to undiluted 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) drives rapid exothermic release of formaldehyde and tris(hydroxymethyl)phosphine (and above 120 °C can liberate toxic, flammable phosphine gas PH3).
  - Incompatible Metals for Undiluted 75% Concentrate: Corrosive to carbon steel, cast iron, copper, brass, bronze, zinc (galvanized steel), and aluminum; store and pump undiluted 75% THPS only in 304/316L stainless steel, HDPE, PP, PVC, CPVC, FRP, PTFE, or Viton.

TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS, CAS 55566-30-8) AND TETRAKIS HYDROXYMETHYL PHOSPHONIUM CHLORIDE (THPC, CAS 124-64-1)

THPC ([(HOCH2)4P]Cl, MW 190.56 g/mol, supplied at 80% in water) is the chloride salt analogue of Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) ([(HOCH2)4P]2SO4, supplied at 75% in water). While both contain the exact same active [(HOCH2)4P]+ cation, THPC introduces ~14.9% corrosive chloride (Cl-) ions that cause severe chloride stress-corrosion cracking and pitting in stainless-steel oilfield pipelines and cooling systems. Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is 100% chloride-free and halogen-free, dominating global water treatment and oilfield applications as well as modern chloride-free textile and leather processing.

TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS, CAS 55566-30-8) AND GLUTARALDEHYDE (50% AQ, CAS 111-30-8)

Glutaraldehyde (1,5-pentanedial) is a traditional oilfield and cooling-tower biocide, but Glutaraldehyde is a severe respiratory sensitizer (occupational asthma hazard), acts more slowly against established biofilms, becomes unstable above 60–70 °C at alkaline pH, and has ZERO ability to dissolve Iron Sulfide (FeS) scale! By contrast, Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is non-sensitizing to the respiratory tract, kills SRB faster (1 to 4 hours), remains thermally stable in hot downhole reservoirs up to 120–150 °C, dissolves FeS scale plugs, and degrades rapidly to non-toxic THPO.

TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS, CAS 55566-30-8) AND QUATERNARY AMMONIUM COMPOUNDS (ADBAC / BKC / DDAC)

Alkyl dimethyl benzyl ammonium chloride (ADBAC / BKC) and didecyl dimethyl ammonium chloride (DDAC) are surface-active cationic biocides that foam heavily in cooling towers and gas separators, oil-wet sandstone reservoir rock, precipitate with anionic scale inhibitors, and persist in aquatic sediments. Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is 100% non-foaming, keeps reservoir rock water-wet, is compatible with anionic phosphonate/polymer scale inhibitors at use dilutions, and does not bioaccumulate.

TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS, CAS 55566-30-8) AND CMIT/MIT ISOTHIAZOLINONES (CAS 55965-84-9)

Isothiazolinones (CMIT/MIT 14% or 1.5%) are slow-acting bacteriostats (requiring 12 to 24 hours for bacterial kill) that are immediately deactivated by hydrogen sulfide (H2S) and mercaptans in sour oilfields or paper mills! Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is completely immune to H2S deactivation—in fact, it thrives in sour H2S environments where it kills SRB in 1–2 hours and dissolves FeS scale.

QUALITY GRADES, QUALITY CONTROL AND PURCHASING CRITERIA FOR TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS)

Ataman Kimya supplies Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) in two high-purity commercial grades:
Standard 75% Oilfield, Cooling-Water & Paper-Mill Biocide Grade Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (Aqucar THPS 75 / Tolcide PS75 Equivalent):
Guaranteed Active [(HOCH2)4P]2SO4 Assay 75.0 +/- 1.0% w/w (minimum 75.0% w/w), Specific Gravity (20 °C) 1.380 to 1.405 g/cm3, Dynamic Viscosity (20 °C) 30 to 45 mPa·s, pH 3.0 to 4.5, Color <= 50 to 100 APHA, and Freezing Point <= -21 to -35 °C.

Low-Iron Textile Flame-Retardant & Wet-White Leather Tanning Grade Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) 75%:
Specially refined grade with Active Assay >= 75.0% w/w, ultra-low Iron (Fe <= 10 ppm max, preventing yellow/tan iron discoloration on white cotton fabrics and wet-white hides!), ultra-low Color <= 30 to 40 APHA, Free Formaldehyde <= 0.2%–0.5% w/w, and zero chloride content.
Incoming quality control verification of Active THPS Content (% w/w) is performed by standardized Iodometric Titration (where an accurately weighed diluted aliquot of THPS is buffered with sodium bicarbonate/acid and titrated with 0.1 N standard Iodine solution to a starch endpoint, oxidizing trivalent phosphorus quantitatively to pentavalent phosphine oxide) alongside 31P-NMR spectroscopy (confirming > 97% phosphorus peak at delta +26.8 ppm for [(HOCH2)4P]+).

STORAGE AND HANDLING OF TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS)

- Commercial Packaging Formats from Ataman Kimya:
  - 250 kg net high-density polyethylene (HDPE) tight-head L-ring drums (4 drums per pallet = 1,000 kg net).
  - 1,250 kg or 1,350 kg net Intermediate Bulk Containers (heavy-duty UV-stabilized HDPE IBC totes in galvanized steel cages with Viton/EPDM bottom butterfly valves, matched to THPS's 1.39 g/cm3 high density).
  - 22,000 to 25,000 kg net bulk 316L stainless-steel or HDPE-lined ISO tank containers.
- Storage Conditions and Shelf Life:
  - Store Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) in tightly sealed original HDPE drums, IBCs, or 316L stainless-steel / HDPE bulk tanks in a cool, dry, well-ventilated indoor warehouse at ambient temperatures between +5 °C and +30 °C, away from direct sunlight, heat sources (> 40 °C), strong alkalies, and oxidizing agents (hypochlorite, peroxides).
  - Keep container bungs tightly closed when not in use to prevent slow air oxidation of the phosphonium cation and maintain the stabilizing acidic pH (3.0 to 4.5).
  - Shelf Life: Minimum 12 to 24 months from date of manufacture when stored unopened in original HDPE containers below +30 °C.
- Transport Classification (ADR / RID / ADN / IMDG / IATA-DGR):
  - UN Number: UN 2810 (or UN 2922 depending on regional corrosivity/toxicity dossier classification; standard international classification for THPS 75% is UN 2810)
  - Proper Shipping Name: TOXIC LIQUID, ORGANIC, N.O.S. (contains Tetrakis(hydroxymethyl)phosphonium sulfate)
  - Transport Hazard Class: Class 6.1 (Toxic Substances)
  - Packing Group: PG III (Low/Medium Danger; Tunnel Restriction Code: (E); IMDG EmS: F-A, S-A)

FIRST AID MEASURES AND SAFETY INFORMATION FOR TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS)

Concentrated 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is an active industrial biocide that must be handled with appropriate personal protective equipment:
- GHS / EU CLP Hazard Classifications for 75% Concentrate:
  - Acute Toxicity Category 4 (Oral) — H302: Harmful if swallowed (Rat Acute Oral LD50 of 75% THPS = 333 to 575 mg/kg bw; Rabbit Acute Dermal LD50 > 2,000 mg/kg bw, not classified for dermal acute toxicity).
  - Acute Toxicity Category 3 (Inhalation of Mists/Aerosols) — H331: Toxic if inhaled as fine aerosol mist (Rat 4-Hour Aerosol LC50 = 0.59 mg/L; note that because THPS is an involatile ionic salt with vapor pressure governed by water, normal ambient liquid transfer does NOT generate toxic vapor—the inhalation hazard applies specifically to spraying or high-pressure misting!).
  - Serious Eye Damage Category 1 — H318: Causes serious eye damage / corneal injury upon direct splash contact (Danger, corrosion pictogram GHS05).
  - Skin Irritation Category 2 / Skin Sensitizer Category 1 — H315 (Causes skin irritation) & H317 (May cause an allergic skin reaction upon repeated dermal contact; non-sensitizing to the respiratory tract).
  - Aquatic Acute Category 1 & Aquatic Chronic Category 2 — H400 (Very toxic to aquatic life prior to environmental degradation: 96-h Rainbow Trout LC50 = 119 mg/L, Bluegill Sunfish LC50 = 93 mg/L, Daphnia magna 48-h EC50 = 19.4 mg/L, Skeletonema costatum algae 72-h EC50 = 0.16 to 0.65 mg/L; rapidly degrades in receiving waters to non-toxic THPO with LC50 > 5,000 mg/L).

- Workplace Exposure Limits & Engineering Controls:
  - ACGIH TLV-TWA for Tetrakis(hydroxymethyl)phosphonium salts: 2.0 mg/m3 (8-hour TWA, inhalable fraction).
  - When curing THPS-treated textiles at 130–150 °C or handling open tanks, provide local exhaust ventilation to keep airborne formaldehyde vapor below occupational exposure limits (<= 0.3 ppm).

- Personal Protective Equipment (PPE) & Spill Neutralization:
  - Wear chemical splash goggles and a full face shield (EN 166), impervious nitrile rubber, butyl rubber, neoprene, or Viton gloves (EN 374), and chemical-resistant apron/boots. If spraying or handling where aerosol mists may form, wear a half-mask or full-face respirator with combination Type ABEK-P3 / formaldehyde cartridges.
  - Spill Cleanup & Chemical Deactivation: Dike and absorb liquid spills with inert mineral absorbent (vermiculite, sand, earth). Residual traces of Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) in wash water can be chemically deactivated into non-toxic THPO by treating with dilute Sodium Bisulfite (NaHSO3) or dilute Hydrogen Peroxide under controlled conditions before disposal in accordance with local regulations.

- First Aid Measures:
  - Eye Contact: IMMEDIATELY flush eyes with copious amounts of lukewarm running water for at least 15 to 20 minutes while holding eyelids forcibly open; remove contact lenses if easy to do and transport immediately to an ophthalmologist!
  - Skin Contact: Immediately remove contaminated clothing and shoes, and wash skin thoroughly with plenty of soap and flowing water for 15 minutes; seek medical attention if redness, blistering, or irritation develops.
  - Inhalation: Move the affected person to fresh air immediately and keep at rest; seek immediate medical attention if mists or vapors were inhaled.
  - Ingestion: Rinse mouth thoroughly with water. Do NOT induce vomiting! Give 1 small glass of water to dilute if the patient is fully conscious and not convulsing, and seek immediate emergency medical care.

WHAT SHOULD BE CONSIDERED WHEN PURCHASING TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS)?

Verify Active [(HOCH2)4P]2SO4 Assay (>= 75.0% w/w) and Specific Gravity (1.380–1.405 g/cm3 at 20 °C) on the Certificate of Analysis: Ensure you are purchasing full-strength 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) rather than diluted 20%–50% field blends, and verify the active titer by iodometric titration and 31P-NMR purity.
Check pH (3.0 to 4.5), Low Color (<= 50 APHA), and Low Iron (<= 10–20 ppm): A properly buffered acidic pH (3.0–4.5) guarantees 12 to 24 months of storage stability by suppressing dissociation into THP and formaldehyde, while ultra-low iron (<= 10 ppm) is mandatory for white flame-retardant cotton textiles and chrome-free wet-white leather tanning.

Confirm Zero Chloride Content (Sulfate Salt CAS 55566-30-8 vs. Chloride Salt CAS 124-64-1): For stainless-steel oilfield pipelines, downhole tubulars, and cooling towers, ensure the specification guarantees chloride-free Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) rather than THPC.
Inspect Packaging Density Ratings (250 kg HDPE Drums / 1,250–1,350 kg Heavy-Duty IBCs): Because 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) has a high density of ~1.39 g/cm3, standard lightweight 1,000-kg-rated IBC totes are insufficient; verify that IBCs are heavy-duty UN-certified totes rated for >= 1.45 g/cm3 liquids.

TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS) SUPPLY FROM ATAMAN KİMYA

Ataman Kimya supplies high-purity 75.0% w/w Aqueous Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (CAS 55566-30-8, EC 259-709-0, active assay >= 75.0% w/w, density 1.380–1.400 g/cm3, pH 3.0–4.5, color <= 40–50 APHA, Fe <= 10–15 ppm, freezing point <= -21 to -35 °C) directly from warehouse stock in Türkiye in 250 kg HDPE drums and 1,250–1,350 kg heavy-duty IBC totes.
Every shipment of Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) from Ataman Kimya is accompanied by a batch-specific Certificate of Analysis (CoA) verifying iodometric active THPS assay, specific gravity, pH, APHA color, viscosity, and trace iron content, alongside EU REACH / BPR / CLP and Turkish KKDIK compliant Safety Data Sheets.

For oilfield service companies and industrial water-treatment formulators, Ataman Kimya offers Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) alongside complementary water-treatment and oilfield chemicals—including Glutaraldehyde 50%, CMIT/MIT 14%, Bronopol, DBNPA, ADBAC/BKC & DDAC Quats, HEDP/ATMP/DTPMP/PBTC Phosphonates, Ammonium Chloride, Sodium Bisulfite (oxygen scavenger), and Scale/Corrosion Inhibitors.
For flame-retardant textile mills and chrome-free leather tanneries, Ataman Kimya supplies low-iron Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) together with Technical Urea, Hydrogen Peroxide (35%/50%), Naphthalene Sulfonate Syntans, Formic Acid, and Sodium Bicarbonate from our integrated distribution facilities in Istanbul.
Ataman Kimya's technical specialists support R&D laboratories, oilfield operators, and plant engineers with sample evaluation quantities of Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) and UN 2810 hazardous-cargo logistics across Türkiye, Europe, the Middle East, Central Asia, and North Africa.

FREQUENTLY ASKED QUESTIONS ABOUT TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS)

 Why is Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) supplied as a 75% aqueous solution rather than a 100% dry powder?
Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is synthesized directly in water from phosphine, formaldehyde, and sulfuric acid, and pure anhydrous THPS is an extremely hygroscopic solid that absorbs moisture from the air. Supplying Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) as a standardized 75.0% w/w aqueous liquid concentrate provides maximum active concentration while remaining a low-viscosity (~35 mPa·s), non-dusty, pumpable liquid with an ultra-low freezing point of -21 to -35 °C!

 How does Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) kill Sulfate-Reducing Bacteria (SRB) and strip biofilms so quickly?
When diluted into neutral or slightly alkaline water (pH 6 to 9), Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) establishes a dynamic equilibrium between positively charged [(HOCH2)4P]+ cations and neutral lipophilic Tris(hydroxymethyl)phosphine (THP). The cations disrupt negatively charged bacterial membranes and disperse extracellular biofilm slime, while THP penetrates the cell wall and cleaves essential disulfide (-S-S-) bridges in microbial respiratory enzymes—achieving 4- to 5-log bacterial kill within 1 to 4 hours.

 How does Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) dissolve black Iron Sulfide (FeS) scale in oil and gas wells without evolving lethal H2S gas?
Whereas hydrochloric acid (15% HCl) dissolves FeS by protonation (FeS + 2 HCl -> FeCl2 + H2S gas, releasing dangerous toxic H2S plumes!), Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (especially when co-dosed with Ammonium Chloride at pH 4.0 to 6.5) chelates the Fe2+ ions of the FeS crystal lattice via its hydroxymethyl-phosphorus and ammonia ligands to form a water-soluble crimson-red iron-phosphonium coordination complex—dissolving FeS plugs and breaking oil-water "schmoo" emulsions cleanly with minimal H2S gas release!

 Why did Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) win the US EPA Presidential Green Chemistry Award?
Unlike persistent quaternary ammonium biocides or brominated/chlorinated compounds, once Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is diluted and discharged into aerobic or sunlit receiving waters, its trivalent phosphonium center rapidly oxidizes and hydrolyzes into Tris(hydroxymethyl)phosphine oxide (THPO, (HOCH2)3P=O). THPO has an octanol-water partition coefficient of log Kow = -2.6 (zero bioaccumulation) and a 96-hour fish LC50 > 5,000 mg/L (practically non-toxic to aquatic organisms).

 Can Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) be dosed at the same time as chlorine (bleach) or bromine in a cooling tower?
No! Because Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is a chemical reducing agent toward strong oxidizers, free chlorine (NaOCl) or bromine will immediately oxidize THPS into inactive THPO (and THPS will consume the chlorine residual). Always turn off the chlorine/bromine feed until free halogen drops below <= 0.2 ppm before shock-dosing Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS), allow THPS to circulate for 4 to 8 hours to strip biofilms, and then resume chlorination.

 How do you rapidly deactivate or neutralize residual Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) in cooling-tower blowdown or hydrotest water prior to environmental discharge?
Residual active Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) in effluent water can be detoxified rapidly prior to discharge by dosing either Sodium Bisulfite (NaHSO3 / metabisulfite, which forms an unreactive bisulfite adduct) or a controlled stoichiometric dose of Hydrogen Peroxide (H2O2, which oxidizes THPS immediately into non-toxic THPO).

 What is the difference between THPS (CAS 55566-30-8) and THPC (CAS 124-64-1)?
THPS is the sulfate salt ([(HOCH2)4P]2SO4, 0% chloride), whereas THPC is the chloride salt ([(HOCH2)4P]Cl, ~14.9% chloride ion). Because chloride ions cause severe pitting and stress-corrosion cracking in 304/316 stainless-steel pipelines and cooling systems (and pose chloromethyl ether risks in hot formaldehyde textile ovens), chloride-free Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is universally preferred across oilfields, water treatment, paper mills, and modern leather/textile plants.

 Is Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) approved for use in paper mills producing food-contact paperboard?
Yes. Under US FDA 21 CFR 173.300 and 21 CFR 176.300, Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) is cleared for use as a slimicide in the manufacture of paper and paperboard intended to contact food, up to a maximum concentration of 84 mg/kg (ppm) of active THPS in the pulp slurry.

 Why do 200-liter drums and 1,000-liter IBCs of 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) weigh 250 kg and 1,250–1,350 kg net?
Because a 75% w/w aqueous solution of Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) has a high specific gravity of 1.385 to 1.400 g/cm3 at 20 °C (nearly 40% heavier than water!), a standard 200-liter HDPE drum holds 250 kg net and a 1,000-liter IBC tote holds 1,250 to 1,350 kg net.

 Which tank, pipe, and pump materials are compatible with undiluted 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS)?
Always store and transfer undiluted 75% Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (pH 3.0–4.5) in 316L or 304 stainless steel, high-density polyethylene (HDPE), polypropylene (PP), PVC, CPVC, PTFE (Teflon), or Viton (FKM) equipment. Never use unlined carbon steel, cast iron, copper, brass, aluminum, or galvanized zinc for undiluted THPS.

TETRAKIS HYDROXYMETHYL PHOSPHONIUM SULFATE (THPS) – TECHNICAL SUMMARY

Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) (Tetrakis(hydroxymethyl)phosphonium sulfate (2:1), Bis[tetrakis(hydroxymethyl)phosphonium] sulfate, THPS 75%, Aqucar THPS 75, Tolcide PS75, CAS 55566-30-8, EC 259-709-0, [(HOCH2)4P]2SO4, C8H24O12P2S, MW 406.28 g/mol) is the global benchmark green-chemistry non-oxidizing quaternary phosphonium biocide, Iron Sulfide (FeS) scale dissolver, durable cotton flame-retardant monomer, and chrome-free leather tanning crosslinker. Supplied as a crystal-clear, non-foaming, chloride-free 75.0% w/w aqueous concentrate (density ~1.39 g/cm3, viscosity ~35 mPa·s, pH 3.0 to 4.5, freezing point <= -21 to -35 °C), Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS) delivers rapid 1- to 4-hour eradication of Sulfate-Reducing Bacteria (SRB), Legionella, and sessile biofilms, chelates and dissolves pyrophoric FeS scale in sour oil and gas wells, degrades rapidly into non-toxic THPO in the environment, imparts 100-wash flame resistance to cellulosic workwear, and produces bright white chrome-free leather with Ts > 82 °C. For technical data sheets, batch Certificate of Analysis verification, sample requests, or bulk 250 kg drum and 1,350 kg IBC quotations for Tetrakis Hydroxymethyl Phosphonium Sulfate (THPS), contact Ataman Kimya:

Ataman Chemicals
Phone: +90 216 577 10 10
Email: info@atamankimya.com