Antimony removal from textile wastewater by combining PFS&PAC coagulation: Enhanced Sb(V) removal with presence of dispersive dye

Abstract

Abstract Antimony (Sb) is a typical contaminant in textile wastewater due to its extensive use in fabric production. Although Fe coagulant showed good performance towards Sb in simulated condition, co-existing components including dye, coexisting ion, and humic acid (HA) in actual textile wastewater would hinder its application. This study proposed a combining PFS&PAC coagulation to remove ppb-level Sb(V) from both simulated and actual textile matrix with presence of typical dispersive dye. By optimizing the operating parameters, maximum Sb(V) removal efficiency of 95.0% was observed with coexistence of 100 mg L−1 dispersive black UD at pH 3, with dosage of 200 mg L−1 PFS and 100 mg L−1 PAC. The response surface methodology indicated that nitrate and chloride had negligible effect on the Sb(V) removal capacity, while HA and phosphate inhibited Sb(V) removal. When compared with single PFS, combining PFS&PAC coagulant would also largely reduce the turbidity caused by dispersive black UD in both simulated (from 450 to 22 NTU) and actual textile wastewater (from 116 to 42 NTU). The mechanistic study suggested that Sb(V) can be bounded with O atom, which belong to hydrolysis product of PFS. Newly produced flocs derived from combining PFS&PAC coagulation can adsorb 63% Sb(V) in 30 min, which was 2.3 folds than that of PFS only. The PAC addition may retard transformation from amorphous ferrihydrite to crystalline iron oxide, thus providing more active adsorption sites for Sb(V) removal with presence of competing dispersive dye.