Comparative study of humic acids flocculation with chitosan hydrochloride and chitosan glutamate

Flocculation of dissolved humic acids (HA) and their complexes with metal ions and organic pollutants is a crucial step in drinking water preparation due to significant undesirable effects of humic compounds on water quality. Constant demand for cheap, effective and environmentally friendly flocculants brings about the interest to natural cationic polymers which can be used to neutralize negative charge of humic colloids through polyelectrolyte complexes (PEC) formation. In this work, the interaction of HA with two types of soluble chitosan salts (hydrochloride and glutamate) at different pH and polymer ratios was studied with a focus on electrical charge of PEC formed and effectiveness of color removal in the flocculation process. For both chitosan forms flocculation window was found at pH close to the PEC isoelectric point (pI) in a wide concentration range; however, lower flocculant dose was required when chitosan glutamate was used.