Novel Biodegradable Flocculating Agents Based on Grafted Starch Family for the Industrial Effluent Treatment

Grafting of acrylamide (AM), N,N-dimethylacrylamide (DMA) and a mixture of N,N-dimethylacrylamide and acrylic acid (AA) onto starch family namely Starch (St), amylopectin (AP) and hydroxyethyl starch (HES) were carried out by free radical polymerization technique in water medium. The so prepared graft copolymers were characterized by different characterization techniques. The flocculation characteristics of all the graft copolymers were performed in an industrial textile dye effluent, a paper mill waste water and municipal sewage waste water. Their flocculation performances were also evaluated in 0.25 wt% iron ore slime, 1.0 wt% kaolin clay, 1.0 wt% coal and 1.0 wt% silica suspensions separately. A comparative study was also made among the three graft copolymers in each series (St, AP and HES) in all the suspensions along with the real waste water. The flocculation characteristics of the best performing graft copolymer was also compared with some commercial flocculants like magnafloc 1011, telfloc 2230 and percol 181 in all the synthetic suspensions, industrial effluents and municipal sewage waste water. In coal, iron ore slime and silica suspensions and in municipal sewage waste water polysaccharide-g-PDMA showed best results but in kaolin clay suspension, in paper mill effluent and in textile dye effluent polysaccharide-g-(PDMA-co-AA) showed best performance. Among all the graft copolymers, graft copolymer based on HES showed best flocculation performance when compared to other graft copolymers as well as to some commercially available flocculants.