Research on the Graft Copolymerization of EH-lignin with acrylamide

Lignin isolated from enzymatic hydrolyzed cornstalks (EH-lignin) is a renewable natural polymer noted for its versatility and applicability in a variety of uses. Graft copolymerization of EH-lignin with acrylamide (AM) and the application of this copolymer as a flocculant in dye wastewater treatment were studied in this article. The influences of some factors on yield of copolymer and the grafting ratio were investigated and the structure of EH-lignin/AM graft copolymer was characterized by FT-IR. According to the yield and the grafting ratio, the optimum conditions for graft copolymerization were as follows: initiator K2S2O8-Na2S2O3 with a quantity 3 wt% of EH-lignin, mass ratio of AM to EH-lignin was 2~3, reaction time 4h and temperature at 50°C. It was found that the absorption capacity of graft copolymer to two azo-dyes was enhanced with the increase of grafting ratio. Furthermore, the residue concentration of EH-lignin/AM graft copolymer remained in the supernatant after flocculation was much lower than that of pure EH-lignin.