Research Of Preparation Amphoteric Lignin Flocculant From Refined Cotton Wastewater

The black liquor of refined cotton is a kind of high COD, high pH value, high chromaand very viscous refractory wastewater, whose lignin percent is very high. If the mainconstituents of lignin in black liquor can be effectively handled and direct emissions, it will bea big impact to the environment, so refined cotton is of great significance to the utilization oflignin in black liquor.This paper take the refined cotton black liquor as the research object, use the acidchromatography extraction of lignin in black liquor, and determine the acid out black liquorlignin in the optimum reaction conditions for pH=3.0, temperature of60℃, water bath timeto20min; using benzene and ethanol mixed solvent purificate the lignin,the ligninpurification rate of79.87%are obtained.Taking Na₂SO₃as sulfonating agent, to sulfonate lignin modification, and discusse theoptimum condition of lignin sulfonation modification is pH=10.5, Na₂SO₃and lignin massratio is3:4, the reaction under90℃for5h. Contrast sodium lignin sulfonate product andhomemade sodium lignosulphonate infrared spectrum indicated that the sodiumlignosulphonate with sulfonic group also has the basic structure of the lignin, and graftingreaction has been added the sulfonic group into the sulfonated lignin, and the reaction hasachieved good results.Thesis with the sodium lignosulphonate and finally between lignin flocculant ofquaternary ammonium salt monomer synthesis, determine the best conditions for preparationof quaternary ammonium salt monomer molar ratio of epichlorohydrin and trimethylaminesolution1:0.7, stir in salt bath-5℃, and react1hour.Flocculant optimum synthesis conditionsfor constant temperature in80℃water bath, to the lignin sulfonic acid sodium salt to add2mol/l NaOH as activator, activation1.0min, reaction2hours.Its flocculation performance andpolyacrylamide has carried on the comparison and analysis. Homemade flocculant usingoptimal conditions were determined as follows: adding the quantity of200ml/L, the reaction temperature of30℃, reaction time is40min, the COD removal rate was32.10%, the chromaremoval rate was75.00%, and polyacrylamide optimum using condition is: the additiveamount of600mL/L, the reaction temperature of30℃, reaction time is40min, the CODremoval rate was40.80%, the chroma removal rate was50.00%. the self-made decolorizingeffect is better than that of polyacrylamide flocculants, but the removal rate of COD is betterthan polyacrylamide.In this paper, according to the characteristics of the wastewater of refined cotton, usingthe basic principle of grafted polymer composite flocculant, systematically carried on therefined cotton waste water comprehensive utilization of experimental research, providereference to solve the problem of refined cotton industrial pollution governance, at the sametime, it provides a basis for the comprehensive utilization of lignin parameters.