Preparation and application of a new cationic starch ether – Starch–methylene dimethylamine hydrochloride

A new cationic starch ether – starch–methylene dimethylamine hydrochloride (SMMAHC) was synthesized by the reaction of corn starch with cationic reagent hydroxymethyl dimethylamine hydrochloride (HMMAHC) using dry process according to Mannich reaction. Reaction parameters (temperature, time, molar ratio of HMMAHC to anhydrous glucose unit (AGU) of starch, and content of HMMAHC) and their effects on the degree of substitution (DS) and reaction efficiency (RE) had been investigated. Under the optimal reaction conditions, SMMAHC with high DS of 0.79% and RE of 96.3% was obtained. The structures of SMMAHC were characterized by 13C-NMR and DEPT-135 spectroscopy. SMMAHC was used as flocculant to treat dyestuff (reactive brilliant red KE-3B) wastewater. The effects of DS and pH on the flocculation were studied and the dyestuff flocculation value reached a maximum of 209 mg/g.