Lignin is one of the versatile chemicals , nature has ever produced. These biomaterials areabundantly available in plant biomass and can be utilized as such or as derivatives for variousapplications. It can be utilized as dispersants for a variety of iorganic materials ,e.g., clay,cement, calcium carbonate, and titanium dioxide, asphalt emulsifiers and emulsion stabilizers,base for industrial detergents(washing powders and liquid soaps),drilling mud thinner,surfactants, coagulants and flocculants(for sewage and waste water treatment), retention aids, fireretarding agents( chlorobrominated lignin),drug formulation, catalyst substrate, carriers foradhesives, insecticides and herbicides, as plastics,binders and adhesives such as lignin reinforcedpolymers, and graft polymers including polyurethanes, polyesters, polyamines and epoxies, andrubber additives. The main lignin polymers are lignin sulphonates which are used inemulsification, defloccuation, chelation, adsorption and adhesion. The most importantapplications are for oil well drilling muds, cement and concrete additives, protein precipitants,sequestering agents, dispersants for a variety of products such as refractories, tiles, absorbants,cosmetics, crayons, medicines, paint, paper coatings, tooth powder and dyes, ore floatation, andelectrolytic refining,tanning agents , ion-exchange resins etc. Other uses of lignosulphonates arelime plastering medium, storage battery plates-as expander and component of separator., limeplaster-use of less water with improved settling properties, crystal growth inhibitor, Ingot moldwash, and many more. Lignin- polyisocyanate/polyurethane foam,lignin-urea/phenolformaldehyde, thermosetting resins, lignin-starch, lignin-geletin,glues with polyvinyl alcohol/acetate, are some of the notable examples as biodegradable polymers and composites. Some lowmolecular weight compounds like vanillin, dimethyl sulphonates, dimethyl sulphoxide, furfural,methyl mercaptan, phenolics can also be obtained from lignin.The main source of lignin and its derivatives in pulp and paper industry is black liquor or sodaliquor and sulphite waste liquor though lignin can also be obtained from liquor obtained fromsteam explosion, hydrothermolysis and pure organosolv process.Presently Indian pulp and paper industry is passing through a crisis from various anglesincluding scarcity of raw materials and has been rated as highly capital , energy and pollutionintensive. Majority of mills using non-forest-based raw materials and agricultural residues( ricestraw, bagasse, wheat straw etc.) discharge these valuable chemicals to waste on one hand andpolluting the environment to a large extent on the other. These chemicals are also nonbiodegradable.According to rough estimate for every ton of bleached pulp produced, about 0.5ton of lignin is either wasted to sewer or used as a low value fuel. Though some Indianindustries of the later category have attempted to design recovery plant or bio-methanationprocess or to recover lignin based chemicals, it is not very wide spread practice. The process oflignin isolation and separation though known from many years, has not been practiced inindustrial scale. The major problems lie in the process of isolation of lignin or its substitutes
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