Preparation and flocculation performance of a cationic starch based flocculant

To increase the specific surface area of corn starch and remove the anion contaminant in water, STP-OGG-DD, which is composed of porous corn starch (Stp), methylpropenoxyethyl trimethyl ammonium chloride (DMC) and dimethyldiallyl ammonium chloride (DMDAAC), was prepared and used for the flocculation of humic acid (HA). In this preparation, ferrous sulfate and hydrogen peroxide act as initiators for free radicals that attract cationic monomers to gather on starch chains. The effects of reaction time, reaction temperature, dosage of cationic monomer, and initiator on the reaction performance were investigated. The results showed that the conversion rate of starch monomer was 97.69 %, the grafting rate was 96.47 %, and the grafting efficiency was 95.85 %. Stp-OG-DD was characterized by scanning electron microscopy, and its structure was characterized by X-ray diffraction and infrared spectroscopy. In the flocculation test. The flocculation effect of 30 mg/L flocculants with different grafting rates on 30 mg/L humic acid was investigated, and the relationship between the two was studied. The results showed that the flocculant with a high starch grafting rate had a better removal effect on humic acid and was positively correlated. Different from the traditional gelatinization method, the enzymatic hydrolysis method is used to pretreat starch, which not only saves energy but also enlarges the specific surface area of molecules. In addition, adding two cationic monomers improved the grafting effect of starch. DMC and DMDAAC could be polymerized alternately onto the starch backbone, providing long molecular chains and abundant positive charge for enzymatic hydrolysis of starch molecular chains. In addition to exploring the grafting of samples under reaction conditions, flocculants prepared under different conditions were used to flocculate 30 mg/L humic acid to further determine the role of grafting rate in the removal effect.