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

Antimony (Sb) is a typical contaminant in textile wastewater due to its extensive use in fabric production. Although Fe coagulant shows good performance towards Sb in simulated condition, co-existing components such as dye, coexisting ion, and humic acid (HA) in actual textile wastewater would hinder its application. This study proposes a combination of poly ferric sulfate and poly aluminum chloride (PFS&PAC) 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% is 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 indicates that nitrate and chloride have negligible effect on the Sb(V) removal capacity, while HA and phosphate inhibit Sb(V) removal. When compared with PFS, combining PFS&PAC coagulation also reduces 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 XPS spectra of flocs suggests that Sb(V) can be bounded with O atom. Aging test suggests the PAC addition retards transformation of flocs from amorphous ferrihydrite to crystalline phases, thus providing more active adsorption sites for Sb(V) removal with presence of competing dispersive dye. Newly produced flocs derived from combining PFS&PAC coagulation can adsorb 63% Sb(V) in 30 min, which is 2.3 folds than that of PFS only.