Lignosulfonate Production

Further refinement of the spent sulfite liqueurs is possible and common. Typically, the pH must be increased to reduce corrosion rates on process equipment and ease the handling. Fermentation of hexoses into bioethanol or pentoses into yeast is feasible. Alternatively, they can be converted to acids in different chemical processes. Ligno-sulfonates have a broad molecular weight distribution, but with the use of ultrafiltration lignosulfonates with narrower molecular weight distributions may be produced. 

The lignosulfonate counterion is determined by the bisulfite salt used together with sulfurous acid during pulping of the wood chips. It is possible via different ion-exchange processes to change the counterion. 

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Lignins are most usually employed as various types of sodium lig-nosulfonate and are products of sulfite pulping. (Kraft lignins from the Kraft pulping process are also available.) They are used as dispersants, binders, sequestrants, and emulsifiers. Sodium lignosulfonate product variables include color, MW, and the degree of carboxylation and sulfonation on the lignin backbone. 

Lignosite Lignosulfonate products are derived from the lignin in softwood trees by the calcium bisulfite pulping process at GeorgiarPacific s mill in Bellingham, Washington. 

Applications. Experience. Ultrafiltration of SSL. This processing has been going on on a regular commercial basis since 1974 for manufacture of lignosulfonate products with a lignosulfonate content in the 90%+ range O). Not only the lignosulfonate content of the product is of importance, often also the molecular... 

Through reaction with sulfide or elemental sulfur at 215°C, lignosulfonates can also be used in the commercial production of dimethyl sulfide and methyl mercaptan (77). Dimethyl sulfide produced in the reaction is further oxidized to dimethyl sulfoxide (DMSO), a useful industrial solvent (see Sulfoxides). 

Dispersants (qv) have been added to the pulper to maintain stickies in a colloidal state. The small particle size reduces the problems stickies cause on the paper machine and in paper products. Among the chemicals that have been used are fatty alcohol ethoxylates, alkylphenol ethoxylates, lignosulfonates, and naphthalene sulfonates (18). 

Maracel XE is a general-purpose BW lignosulfonate that imparts a darker color to the finished product than, say, the Marasperse products (which are often used in CW formulations). 

Surface-active compounds, especially the anionic surfactants, are derived from fossil raw materials as well as from recent raw materials. The portion of the biomass on the production of anionic surfactants is about 75% if the soap, the quantitatively most important anionic surfactant, is included. Considering only the synthetic surfactants, the syndets, the portion of fossil raw materials in the production of these surfactants, is about 75%. Without the lignosulfonates (and the petroleum sulfonates) this portion is about 90%. Due to strong efforts... 

The use of the lignin fraction is much more cumbersome currently the best-known chemical of a real commercial importance is vanillin, which is obtained by oxidation of the black liquor. Another example is a product called spray-dried lignosulfonate (as sodium salt) obtained from the older, acidic sulfite pulping process. It is sold as a commercial product primarily as a concrete additive for enhanced strength. Since the cement industry is one of the big contributors of carbon dioxide emissions (due to the production of calcium oxide from calcium carbonate), the use of this renewable, wood-derived product not only is fossil-carbon neutral in itself but also reduces carbon dioxide emission due to the diminished need for cement in large infrastructures made of concrete. 

Iron and chromic salts from lignosulfonate are also a source for metal ions [1000]. Lignosulfonates are waste products from the paper industry. 

Howard A process for separating lignosulfonates from sulfite liquor from papermaking. The lignosulfonates are precipitated as their calcium salts. The product is used in the manufacture of vanillin. 

The production of vanillin for flavoring pxurposes still provides a major useful outlet for softwood lignins, but the lignosulfonates from a few mills suffice to saturate the market, even though the yield of vanillin is low. 

Some lignosulfonic acids are used as a tanning auxiliary. The tanning effect is due to the sulfonic acid groups and not to the phenolic hydroxyls in the product there is only about one free phenol group in every third Cg unit in hgnin and many of these may be sterically inaccessible. Leather tanned with lignosulfonates is therefore not water-proof. 

It is now 20 years and 13 years since the first and second editions respectively of Chemical Admixtures for Concrete were published. A first glance at the international admixture business could lead to the impression that not a lot had changed in 20 years certainly not enough to justify the complete revision of the second edition of the book. While it is true that products based on lignosulfonates, sodium glucoheptonate and com symp are still provided to the market in thousands of tonnes every year, there have been several significant changes ... 

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