Preparation,Characterization and Evaluation of Anionic Starch Derivatives as Flocculants and for Metal Removal

Anionic starch derivatives bearing carboxyl groups were prepared by reacting maize starch and hydrolyzed maize starch with a previously synthesized citric acid adduct (2‐hydroxy‐3‐chloropropylcitric acid) using the dry process. Different factors affecting the preparation, i.e. catalyst concentration, citric acid adduct concentration, duration and temperature have been studied. The modified starch was characterized by IR spectroscopy, X‐ray diffraction analysis and scanning electronic microscopy. The anionic starch derivatives were evaluated as flocculants. Different factors affecting the flocculation efficiency of the prepared flocculants were studied. These factors include effect of dose, acid content, pH of the flocculation medium and molar mass. The anionic starch samples were chelated with different metal cations such as Cu²⁺, Co²⁺, Mg²⁺, and Hg²⁺, in the form of acetates, chlorides and sulfates.