Preparation of starch-based cationic flocculants and its study on the removal of textile dyes

Abstract To effectively solve the problem of wastewater pollution. In this paper, a starch (St) based natural polymer cationic flocculant (DMSt-g-DMC) was prepared via a tetherification, esterification and grafting co-polymerization triple modification using corn starch as raw material, 3-chloro-2-hydroxypropyl triethylammonium chloride (CTA), vinyl acetate (VAC) and methylacryloxyethyltrimethyl ammonium chloride (DMC) were used as etherifying agents, esterifying agents and grafting monomers. The results by FT-IR, 13 C NMR and XPS showed that acetyl, quaternary ammonium and DMC grafted chain segments were introduced into the starch macromolecular backbone. XRD, SEM analysis and polarized light observation showed that the structure of DMSt-g-DMC was disrupted water solubility was increased. Zeta potential test showed DMSt-g-DMC has increased positive charge quantity and isoelectric point PI. GPC analysis showed that DMSt-g-DMC maintained a high molecular weight and increased the degree of branching to improve flocculation performance. 94.1% removal of acid light yellow G by DMSt-g-DMC, 83.7% and 97.1% removal by reactive brilliant blue X-BR and direct lake blue 5B, respectively. St-g-DMC had a wide flocculation window from 5 g/L to 12 g/L. It also maintained good flocculation performance over a wide pH range. This is advantageous for treating wastewater with high alkalinity and complex composition.