CALCIUM LIGNOSULFONATE

CAS Number:    8061-52-7

Synonyms:
Lignosulfonic acid, calcium salt; CALCIUM LIGNOSULFONATE; 8061-52-7; Caswell No. 146; Lignin calcium sulfonate; UNII-6HPP8U6S23; UNII-33T2H9O73P; EPA Pesticide Chemical Code 115101; Calcium Lignin Sulfonate; Lime fractionated, spent pulping liquor, precipitate; Calcium 3-(2-hydroxy-3-methoxyphenyl)-2-[2-methoxy-4-(3-sulfonato propyl)phenoxy]-1-propanesulfonate; CALCİUM LİGNOSULFONATE; CALCIUM LIGNOSULPHONATE; CALCİUM LİGNOSULPHONATE; calcium linin sulfonate; lignin calcium sulfonate; lignosulfonic acid calcium salt; lignosulfonic acid, calcium salt; lime fractionated spent pulping liquor precipitate; lime fractionated, spent pulping liquor, precipitate; CALCIUM LIGNO SULFONATE; CALCIUM LIGNOSULFONAT; kalsiyum lignosülfonat; kalsiyum lignosülfonate; kalsiyum ligno sülfonat; LIGNOSULFONATE DE CALCIUM; lignosulfonate de  Calcium
 

CALCIUM LIGNOSULFONATE 

Calcium lignosulfonate (40-65) is an amorphous light-yellow-brown powder obtained from the sulfite
pulping of softwood. The organic framework of the additive is a sulfonated random polymer of three aromatic
alcohols: coniferyl alcohol, p-coumaryl alcohol, and sinapyl alcohol, of which coniferyl alcohol is the
principle unit. The commercial product has a weight-average molecular weight range of 40,000 to 65,000 and
the name of the additive is intended to reflect this range and to distinguish it from other calcium
lignosulfonates in the market place. The intended use of calcium lignosulfonate (40-65) is as a carrier
(encapsulating agent) for fat-soluble vitamins, carotenoids, and other functional ingredients in, e.g., fruitbased beverages,vitamin drinks, dairy products, and hard candies. Preparations of such substances will
contain calcium lignosulfonate (40-65) at ratios of active principle to lignosulfonate between 1:5 to 1:200.
Stability studies of the additive 1) stored in polyethylene containers (36 months) and in aluminium-foil bags
(24 months); 2) as a component of a formulation of the additive with ß-carotene (48 weeks); and 3) in a ßcarotene-containing product form in a non-pasteurised, non-carbonated soft drink (3 months) all support the
intended uses.

DESCRIPTION Light yellow-brown to brown powder
FUNCTIONAL USES Carrier
CHARACTERISTICS
IDENTIFICATION
Solubility (Vol. 4) Soluble in water. Practically insoluble in organic solvents.
IR spectrum (Vol. 4) The infrared absorption spectrum of a potassium bromide pellet of
dried sample exhibits characteristic absorptions at 1210-1220 cm-1,
1037 cm-1, and 655 cm-1.

UV spectrum (Vol. 4) A 0.05% sample solution is diluted 1:10 and adjusted to a pH of 2.0-
2.2 by addition of 3 drops of 5 M hydrochloric acid. This solution
exhibits an absorption maximum at 280 nm. 

2. Introduction
Lignosulfonates are commercially available as sodium and calcium salts and have been used by industry in a
wide variety of applications. The usefulness of commercial lignosulfonate products comes from their
dispersing, binding, complexing, and emulsifying properties. The additive calcium lignosulfonate as
described in the Food Chemicals Codex 
has been used for a number of years in the food industry, serving, for example, as an emulsifier in animal
feed, as raw material in the production of vanillin, and as a boiler water additive. The additive calcium
lignosulfonate (40-65), evaluated by the 69th JECFA, is of higher purity than the calcium lignosulfonate
described in the FCC, with a higher degree of polymerization and a lower content of sugars. The intended use of calcium lignosulfonate (40-65) is as a carrier for fat-soluble vitamins, carotenoids, and other functional
ingredients. Calcium lignosulfonate (40-65) corresponds to the material on which the toxicological studies
have been performed and evaluated by JECFA.
3. Description
Calcium lignosulfonate (40-65) is an amorphous material derived from lignin. It is a light-yellow-brown
powder that is soluble in water, but practically insoluble in organic solvents. The product exhibits a weightaverage molecular weight in the range of 40,000 to 65,000 with greater than 90% ranging from 1,000 to
250,000 .
4. Manufacturing process
Calcium lignosulfonate (40-65) is produced from softwood in the sulfite pulping method for manufacturing
paper. The wood chips are digested with acidic calcium bisulfite solution in large reaction vessels where they
are processed through cooking cycles of 6 - 10 hours. The highest temperature during a cooking cycle is approximately 130°. In this process, bisulfite ions react with the native lignin polymer of the wood to form
sulfonated lignin (i.e., lignosulfonate). This reaction increases the water-solubility of the hydrophobic lignin
polymer. The calcium bisulfite provides the calcium ions that stabilise the anionic sulfonate groups in the
lignosulfonates. After the completion of pulping, water-insoluble cellulose and soluble calcium lignosulfonate are separated by filtration.
The brownish filtrate, containing the lignosulfonates, will also contain residual amounts of sulfite salts and
reducing-sugar monomers formed from wood cellulose during pulping. The pH of the filtrate is adjusted by
addition of concentrated sulfuric acid. The water and sulfite (as sulfur dioxide) content are reduced by
subsequent evaporation.
After the first evaporation step, the filtrate may be diluted with water before it is subjected to further
purification by ultrafiltration at moderately elevated temperatures. Ultrafiltration is a liquid/liquid separation
method whereby the filtrate is separated by molecular size through a semi-permeable membrane. The
ultrafiltration step separates the high-molecular weight lignosulfonate fraction from depolymerisation
products, such as low-molecular weight lignosulfonates, and reducing-sugar monomers. According to the
sponsor, the use of other than softwood as a source material would not yield a product with the desireable
high-molecular weight distribution.
The purified calcium lignosulfonate (40-65) from ultrafiltration may be pH-adjusted by addition of dilute
sulfuric acid. This solution is then evaporated at a temperature of 95-105° to a dry-matter content that is
appropriate for spray-drying. The final product is spray-dried to a moisture content in accordance with the
specification for Loss on drying and filled into containers suitable for holding food. 
 Reactions and fate in foods
As there is no analytical method available that permits the quantification of calcium lignosulfonate (40-65) at
the low levels that are expected to be present in food resulting from its use with nutrient and food-colour
preparations, no studies are availble on its reaction and fate in food. Data available from studies submitted by
the sponsor on the stability of the additive itself and from the stability of the additive in carotenoid
preparations provide information that allows extrapolation to the possible reactions and fate in food.
7.1 Stability of calcium lignosulfonate (40-65)
The sponsor provided stability data (pH of a 10% solution, molecular weight, % reducing sugars) for one lot
of powdered calcium lignosulfonate (40-65) stored for 36 months in polyethylene containers and for one lot
stored in closed aluminium-foil bags for 24 months. See Appendix 1, below. The results show that the
powdered product was stable over the time of the tests. Weight-average molecular weight showed a variation
of ± 6 %, within the expected variation of the method of analysis, and reducing sugar levels remained stable
and were within the limit given in the specifications (<5.0 %).
7.2 Stability of calcium lignosulfonate (40-65) in carotenoid preparations
The sponsor tested three batches of a calcium lignosulfonate (40-65)-containing formulation with ß-carotene
and a blank formulation, all prepared from a single lot of the additive, for stability over 48 weeks. Powdered
samples were stored in closed aluminium-foil bags under normal (25°/60% relative humidity) and accelerated
(40°/75% relative humidity) conditions. The formulations and blank also contained corn oil, corn starch, and
glucose syrup. The content of calcium lignosulfonate (40-65) was determined by nitrosating the phenolic
groups of the polymeric fraction of the additive and spectrophotometrically observing the absorbance at 440
nm of the nitrosated products; ß-carotene was determined by HPLC. See Appendix 2, below. Stability was
satisfactory for the length of the tests.
7.3 Stability of calcium lignosulfonate (40-65) in beverages
The sponsor also tested a ß-carotene/calcium lignosulfonate (40-65)-containing product form for stability in a
non-pasteurised, non-carbonated soft drink. The calcium lignosulfonate (40-65)-based product form showed
good physical stability over 3 months and performed equally to that of a product form based on fish gelatin.
7.4 Possible effects on nutrition
The sponsor has noted that calcium lignosulfonate (40-65) is water-soluble and concluded that no interaction
with fat-soluble compounds in the diet is expected, especially because levels of the additive in foods as
consumed are low. The sponsor also provided a report on intake of the additive. A conservative estimate from
its use as a carrier for carotenoids indicates that consumption is unlikely to exceed about 100 mg/day (above
the 90th percentile). The report also states that the intakes resulting from vitamin E use in multi-vitamin
products could result in lignosulfonate intakes up to 300 mg/day. Adding vitamins A, D and K at highest
supplement levels would result in a maximum total intake of lignosulfonate of less than 400 mg/day, when
the proportion of vitamin preparations ingested in powdered form is taken into account.
The sponsor also speculates that, as a non-digestible dietary fiber, calcium lignosulfonate (40-65), when
consumed at high levels, might produce the same side effects (e.g., laxation) as other dietary fibers, such as
lignin, that are consumed at much higher levels in normal human diets. It appears, however, that the intended
applications of calcium lignosulfonate (40-65) will not likely result in a significant contribution to the overall intake of non-digestible dietary fiber.

Lignosulfonates

Lignosulfonates, or sulfonated lignin are water-soluble anionic polyelectrolyte polymers: they are byproducts from the production of wood pulp using sulfite pulping.[1]

Most delignification in sulfite pulping involves acidic cleavage of ether bonds, which connect many of the constituents of lignin.[2] The electrophilic carbocations produced during ether cleavage react with bisulfite ions (HSO3−) to give sulfonates.

R-O-R' + H+ → R+ + R'OH
R+ + HSO3− → R-SO3H
The primary site for ether cleavage is the α-carbon (carbon atom attached to the aromatic ring) of the propyl (linear three carbon) side chain. The following structures do not specify the structure since lignin and its derivatives are complex mixtures: the purpose is to give a general idea of the structure of lignosulfonates. The groups R1 and R2 can be a wide variety of groups found in the structure of lignin. Sulfonation occurs on the side chains, not on the aromatic ring like in p-toluenesulfonic acid.
Lignosulfonate have very broad ranges of molecular mass (they are very polydisperse). A range of from 1000–140,000 da has been reported for softwood lignosulfonates with lower values reported for hardwoods.[1]

Preparation
Lignosulfonates are recovered from the spent pulping liquids (red or brown liquor) from sulfite pulping. Ultrafiltration can also be used to separate lignosulfonates from the spent pulping liquid.[1] A list of CAS numbers for the various metal salts of lignosulfonate is available.[3]

Uses
Lignosulfonates have a wide variety of applications.

The single largest use for lignosulfonates is as plasticizers in making concrete,[1] where they allow concrete to be made with less water (giving stronger concrete) while maintaining the ability of the concrete to flow. Lignosulfonates are also used during the production of cement, where they act as grinding aids in the cement mill and as a rawmix slurry deflocculant (that reduces the viscosity of the slurry).

Lignosulfonates are also used for the production of plasterboard to reduce the amount of water required to make the stucco flow and form the layer between two sheets of paper. The reduction in water content allows lower kiln temperatures to dry the plasterboard, saving energy.

The ability of lignosulfonates to reduce the viscosity of mineral slurries is used to advantage in oil drilling mud, where it replaced tannic acids from quebracho (a tropical tree).

Lignosulfonates are used to disperse pesticides, dyes, carbon black, and other insoluble solids and liquids into water. They are used in tanning leather. They are also used to suppress dust on unpaved roads.

Oxidation of lignosulfonates from softwood trees produced vanillin (artificial vanilla flavor).

Dimethyl sulfide and dimethyl sulfoxide (an important organic solvent) are produced from lignosulfonates. The first step involves heating lignosulfonates with sulfides or elemental sulfur to produce dimethyl sulfide. The methyl groups come from methyl ethers present in the lignin. Oxidation of dimethyl sulfide with nitrogen dioxide produces dimethyl sulfoxide (DMSO). [1]

Also one of the very wide uses of lignosulfonates is deflocculation of clays used in drilling fluids in the oil and gas industry. Furthermore, Lignosulphates are being researched for use in Enhanced oil recovery (EOR) due to their ability to reduce IFT in foams, allowing for improved sweep efficiency, and hence increased recovery factor.

Aqueous Lignosulfonate solutions are also widely used as a non-toxic dust suppression agent for unpaved road surfaces, where it is popularly, if erroneously, called "tree sap". Roads treated with lignosulfonates can be distinguished from those treated with calcium chloride by color: lignosulfonates give the road surface a dark grey color, while calcium chloride lend the road surface a distinctive tan or brown color. As lignosulfonates do not rely on water to provide their binding properties, they tend to be more useful in arid locations.

They also form a constituent of the paste used to coat the lead-antimony-calcium or lead-antimony-selenium grids in a Lead-acid battery.

Besides their use as dispersants lignosulfonates are also good binders. They are used as binders in well-paper, particle boards, linoleum flooring, coal briquettes, and roads.

The anti-oxidant effect of lignosulfonates is utilized in feeds, ensilage and flame retardants.

The UV absorbance of lignosulfonates is utilized in sun screens and bio-pesticides.

Molecular Weight of calcium
lignosulfonate:    528.6 g/mol    Computed by PubChem 2.1 (PubChem release 2019.06.18)
Hydrogen Bond Donor Count of calcium
lignosulfonate:        1    Computed by Cactvs 3.4.6.11 (PubChem release 2019.06.18)
Hydrogen Bond Acceptor Count of calcium
lignosulfonate:        10    Computed by Cactvs 3.4.6.11 (PubChem release 2019.06.18)
Rotatable Bond Count of calcium
lignosulfonate:        10    Computed by Cactvs 3.4.6.11 (PubChem release 2019.06.18)
Exact Mass of calcium
lignosulfonate:        528.04368 g/mol    Computed by PubChem 2.1 (PubChem release 2019.06.18)
Monoisotopic Mass of calcium
lignosulfonate:        528.04368 g/mol    Computed by PubChem 2.1 (PubChem release 2019.06.18)
Topological Polar Surface Area     of calcium
lignosulfonate:    179 Ų    Computed by Cactvs 3.4.6.11 (PubChem release 2019.06.18)
Heavy Atom Count     of calcium
lignosulfonate:    33    Computed by PubChem
Formal Charge of calcium
lignosulfonate:        0    Computed by PubChem
Complexity of calcium
lignosulfonate:        732    Computed by Cactvs 3.4.6.11 (PubChem release 2019.06.18)
Isotope Atom Count of calcium
lignosulfonate:        0    Computed by PubChem
Defined Atom Stereocenter Count of calcium
lignosulfonate:        0    Computed by PubChem
Undefined Atom Stereocenter Count of calcium
lignosulfonate:        1    Computed by PubChem
Defined Bond Stereocenter Count of calcium
lignosulfonate:        0    Computed by PubChem
Undefined Bond Stereocenter Count of calcium
lignosulfonate:        0    Computed by PubChem
Covalently-Bonded Unit Count of calcium
lignosulfonate:        2    Computed by PubChem
Compound Is Canonicalized of calcium
lignosulfonate:        Yes