Enhancing floc size and strength with a hybrid polymer of zinc oxide, acrylamide, and tannin in textile wastewater

Abstract

This study involved synthesising new hybrid polymers called ZOPAT, made up of zinc oxide, acrylamide, and tannin, using a blended technique. The effectiveness of ZOPAT in treating textile wastewater was then tested by measuring floc growth rate, flocculation index, strength factor, and recovery factor under optimised conditions. The study also identified the zeta potential, morphology, elemental composition, and functional groups of the polymers. Response surface methodology determines the optimal pH and ZOPAT dose, resulting in 93% colour, 80% chemical oxygen demand (COD), 100% turbidity, and suspended solids (SS) removal at pH 9.22 and 737 mg/L ZOPAT. The study found that ZOPAT was more effective than commercial Polyaluminium chloride in reducing colour and COD, producing larger and stronger flocs, and requiring a shorter coagulation time of 17.5 min. ZOPAT was also easy to homogenise and operate due to its one-unit dosing system. The study attributes the success of ZOPAT to the presence of Zn, N, and K, which create electrostatic attraction with opposite charged particles, and the formation of dye–particle–dye with amide, hydroxyl, and carboxyl groups in ZOPAT, which remove colour, turbidity, COD, and SS. Overall, the study concludes that ZOPAT has significant potential for textile wastewater treatment. HIGHLIGHTS Introducing ZOPAT: a hybrid coagulant inducing charge neutralisation and sweep coagulation for efficient dye particle destabilisation.; 100% turbidity and SS reduction, 80% COD reduction, and 93% colour reduction.; ZOPAT generates larger flocs for faster settling and lower SVI.; It exhibits high recovery factor, ensuring improved floc regrowth post-breakage.; Na, Si, and S in treated sludge link to toxic dye effluents.;

Keywords

• cod reduction
• colour removal
• floc growth rate
• hybrid polymers
• textile wastewater treatment