Efficient adsorptive removal of Sb(Ⅲ) and Sb(V) from printing and dyeing wastewater by TiCl4

Abstract

Significant amounts of Sb(III) and Sb(V) are present in printing and dyeing wastewater (PDW), which leads to the detrimental effects on the environment if not treated properly. In this paper, the adsorptive removal of Sb(III) and Sb(V) by TiCl4 derived flocs and the oxidation process were investigated. The results showed that TiCl4 conducted superior coagulation performance on Sb(III) removal than Sb(V) in terms of dosage, pH range and immunity to interference. When the dosage was 50 mg/L and the final pH was 5.0, the concentration of Sb(III) and Sb(V) was reduced from 2000 μg/L to 100 μg/L and 180 μg/L, respectively. According to the Langmuir model, The adsorption for Sb(III) (74.27 mg/g) by TiCl4 derived flocs was higher than Sb(V) (68.45 mg/g). The Sb(III) in the solution could partially inhibit the adsorption of Sb(V). It was also observed that the Sb(III) was oxidized to Sb(V), which was owing to the molecular oxygen during the coagulation and the flocs might act as catalyst. The actual printing and dyeing wastewater treatment experiments results showed that pre-reduction of Sb(V) to Sb(Ⅲ) could considerably improve the total Sb removal from 83 % to 98.8 %. The characterization results, such as zeta potential and x-ray photoelectron spectroscopy (XPS), indicated that the Sb(Ⅲ) removal was mainly achieved by chemisorption. The Sb(V) removal was mainly dependent on chemisorption and electrostatic adsorption, while the latter contributed more than former. The results of DFT calculations explained the reason for higher removal efficiencies of Sb(III) than Sb(V) in the TiCl4 coagulation system. This study provides a new idea for the efficient removal of Sb(III) and Sb(V) using TiCl4 in PDW to save the cost in engineering practice.