Preparation and performance of a novel starch-based inorganic/organic composite coagulant for textile wastewater treatment

Inorganic/organic composite coagulants have received wide attention in recent years due to their outstanding properties in wastewater treatment. However, non-biodegradable synthetic polymers are largely applied as the organic components of these composites, leading to negative environmental impacts. To acquire efficient composite coagulant with less environmental risks, a novel inorganic/natural polymer composite PAFC-Starch-g-p(AM-DMDAAC) (polyaluminum ferric chloride-starch graft copolymer with acrylamide and dimethyl diallyl ammonium chloride) was prepared, and applied for textile wastewater treatment. The results showed that PAFC-Starch-g-p(AM-DMDAAC) exhibited higher and more stable dye removal efficiencies than other prepared composite coagulants. For synthetic textile wastewater treatment, PAFC-Starch-g-p(AM-DMDAAC) could reduce the chemical dosage by more than 50% compared with conventional coagulation-flocculation process. The effects of wastewater pH, conductivity and temperature on the coagulation performance were studied. High-temperature accelerated storage test proved that PAFC-Starch-g-p(AM-DMDAAC) had a strong storage stability. PAFC-Starch-g-p(AM-DMDAAC) is an eco-friendly composite coagulant with excellent performances and broad utilization range, showing promising application prospects.