Quick Search
CAS no: 9003-05-8
EC / List no: 618-350-3
Chemical formula: (C3H5NO)x
Synonyms: 2-Propenamide homopolymer, Polyacrylamide, Polyacrylamide polymer, Polyamide Polymer, poly(2-prop-enamide), Acrylamide, prop-2-enamide
Anionic Polyacrylamide (APAM) is a high-performance, ultra-high molecular weight (exceeding 30 million Da) synthetic polymer engineered for superior flocculation, thickening, dispersion, drag reduction, and solid-liquid separation. Synthesized through the continuous copolymerization of acrylamide monomers with anionic acrylate salts, APAM features negatively charged carboxylate groups randomly distributed along its long, flexible linear backbone.
Operating through a synergistic "electrical neutralization and adsorption bridging" mechanism, APAM rapidly neutralizes positively charged suspended solids, clays, silts, and metal oxides. Its ultra-long polymer chains span across solution boundaries to latch onto multiple colloidal particles simultaneously. This overcomes inter-particle electrostatic repulsion to construct dense, heavy, fast-settling flocs, reducing suspended solids (SS) and turbidity by over 90% across diverse industrial and environmental systems.
Key Properties of Anionic Polyacrylamide (APAM)
Molar Mass: Variable; depends on molecular weight and degree of polymerization
Appearance: White to off-white granular powder or solid
Odor: Odorless
Density: Typically ~1.0–1.3 g/cm³, depending on grade and physical form
Boiling Point: Not applicable; decomposes before boiling
Melting Point: Decomposes upon heating; no defined melting point
Solubility: Soluble or dispersible in water; insoluble in most organic solvents
pH: Typically neutral to slightly alkaline in aqueous solution, depending on grade and concentration
Ionic Character: Anionic, with negatively charged functional groups along the polymer chain
Molecular Weight: Typically high to very high, depending on the specific grade
Charge Density: Variable; determined by the degree of anionic modification
Water Absorption: High water-binding capacity
Stability: Generally stable under recommended storage conditions; performance may be affected by extreme pH, high temperatures, and strong oxidizing agents
Working Mechanisms and Behavior
The multi-industry versatility of APAM relies on core physicochemical mechanisms:
Adsorption Bridging & Rapid Sedimentation: Long polymer chains adsorb onto particle surfaces via hydrogen bonding and electrostatic attraction. By bridging multiple fine particles into massive flocs, APAM exponentially speeds up settling rates in clarifiers, thickeners, and tailings ponds.
Shear-Thinning & Drag Reduction: In high-velocity pipe flows or hydraulic fracturing operations, APAM aligns along flow streamlines to suppress turbulent eddies, acting as a highly efficient friction reducer.
Steric Dispersion & Stabilization: At tailored lower molecular weights or specific charge levels, APAM forms protective hydration shells around pigment, resin, or pesticide particles, preventing agglomeration and maintaining long-term suspension stability.
Soil Moisture Retention: Upon hydration, APAM expands into a stable hydrogel network within soil matrices, binding fine earth particles together to prevent erosion while holding plant-available water.
Key Advantages of Anionic Polyacrylamide (APAM)
Exceptional Cost-Efficiency: Highly active at extremely low dosages, significantly lowering chemical consumption while maximizing throughput.
Superior Dewatering Efficiency: Reduces sludge moisture content by 20% to 40% in centrifuges, belt filter presses, and screw presses, drastically cutting cake volume and disposal costs.
Replaces Inorganic Salts: Reduces or completely eliminates the need for traditional alum or iron salts, minimizing corrosive sludge formation and system wear.
Enhanced Water Recycling: Facilitates rapid solid-liquid separation to produce crystal-clear supernatant water, enabling closed-loop recycling and environmental compliance.
Industrial Applications
Water and Wastewater Treatment
APAM is a core clarifying and dewatering agent across municipal and industrial water treatment networks:
Municipal Sewage & Stormwater: Accelerates primary/secondary sedimentation and excess sludge dewatering, reducing suspended solids to below 10 mg/L.
Industrial Effluents: Purifies complex wastewater from chemical manufacturing, steel & metallurgy, electroplating, pharmaceuticals, tanneries, and power generation.
Textile, Printing & Dyeing: Effectively removes residual dyes, organic auxiliaries, and suspended matter, lowering wastewater color intensity and Chemical Oxygen Demand (COD).
Potable Water Treatment: Coagulates fine clays, organic matter, and heavy metal complexes from natural surface water to ensure safe drinking water output.
Mining, Mineral Processing and Coal Washing
Tailings Dewatering: Accelerates the aggregation and settling of fine mineral solids in gold, copper, iron ore, titanium, and aluminum processing tailings.
Coal Slurry Clarification: Clarifies wash water rapidly during coal washing, increasing flotation clean coal recovery rates by 8% to 12%.
Sand & Aggregate Washing: Eliminates fine silt turbidity (reducing NTU levels from 2000 to under 50) and recovers lost sand fines.
Oil & Gas Sector
Enhanced Oil Recovery (EOR): Ultra-high molecular weight APAM increases the viscosity of injected sweep water, recovering an additional 100 to 150 tons of crude oil per ton of polymer injected.
Drilling Fluids: Functions as a shale inhibitor and mud thickener, preventing borehole collapse, controlling fluid loss, and carrying drill cuttings.
Frac Drag Reducer & Water Plugging: Reduces friction losses in hydraulic fracturing fluids and selectively seals off high-permeability water channels in mature reservoirs.
Paper and Pulp Industry
Retention & Drainage Aid: Retains fine fibers, fillers, and functional additives on the paper machine wire, improving sheet strength, smoothness, and printability.
White Water Recovery: Boosts fiber collection efficiency by 15% to 20%, ensuring cleaner recirculating water and reduced fiber loss across writing, packaging, and tissue paper lines.
Agriculture, Soil Treatment and Dust Control
Erosion Control: Applied to agricultural land and construction sites to bind topsoil, prevent wind/water erosion, and reduce sediment runoff into waterways.
Dust Suppression & Moisture Retention: Enhances soil water infiltration in arid zones, stabilizes foundation pits, and suppresses airborne dust on unpaved roads.
Specialized Process Industries
Textiles & Sizing: Acts as a warp sizing agent, dyeing auxiliary, and finishing aid to improve color penetration and fabric uniformness.
Food, Beverage & Sugar Refining: Serves as a clarifying agent for sugar juice, aids in starch and distillers' grain recovery, and thickens dairy waste streams.
Cosmetics & Personal Care: Functions as a stabilizing thickener in creams, lotions, gels, shampoos, and conditioners.
Construction & Building Materials: Improves the workability, cohesiveness, and strength of concrete, mortar, and ceramic/cement slurry wastewater.
Anionic Polyacrylamide (APAM) stands as a vital polymer technology for modern industrial efficiency, resource recovery, and environmental protection. By combining customizable molecular weight options with high anionic charge density and broad pH adaptability, APAM delivers unmatched performance in flocculation, water clarification, sludge dewatering, and oil displacement. Whether optimizing mineral extraction, reducing soil erosion, or enabling closed-loop industrial water reuse, APAM remains an indispensable driving force for sustainable global industry.
