Removal of linear alkylbenzene sulfonate by electrocoagulation/flotation using a cylindrical vertical reactor

Abstract

This study proposes a vertical electrocoagulation/flotation reactor model and evaluates its efficiency through hydraulic tests and the removal of linear alkylbenzene sulfonate (LAS), a common wastewater surfactant. Residence time distribution assays and computational fluid dynamics verified the fluid flow pattern. Response surface methodology (RSM) was used to assess the impact of pH, electric current, and sodium chloride concentration on LAS removal. Ecotoxicity tests using Artemia salina detected no toxic byproducts from electrocoagulation/flotation (ECF). Adsorption kinetics and isotherms were used to evaluate the removal behavior of LAS, which showed the highest efficiencies with an electric current of 1.5 A, a pH of 5.73, and a NaCl concentration of 4652.4 mg/L. The electric current and pH were the most influential variables. The ecotoxicity assay indicated no toxic byproduct generation, even at high chloride concentrations, and increased LAS biodegradability posttreatment. Adsorption kinetics followed a pseudo-first-order model at 20 mg/L and a pseudo-second-order model at 240 mg/L. The Freundlich isotherm indicated a high affinity between the LAS and aluminum hydroxide flakes, achieving nearly 90 % removal in 30 min at an energy cost of 5.25 Wh.