Enhanced removal of Sb(V) by iron‐spent bleaching earth carbon binary micro‐electrolysis system: performance and mechanism

Abstract

AbstractBACKGROUNDIn this work, the construction of a zero‐valent iron‐loaded spent bleaching earth carbon binary micro‐electrolysis system (Fe0/SBE@C) was first developed for antimony(V) (Sb(V)) removal in water.RESULTSFe0/SBE@C at 4:1 Fe‐to‐SBE@C mass ratio can obtain satisfactory Sb(V) removal and less Fe dissolution under acid (pH 3) and neutral (pH 7) conditions. Sb(V) removal by Fe0/SBE@C accorded with a second‐order kinetic model. Activation energy of Fe0/SBE@C reaction for Sb(V) removal was 27.61 kJ mol−1. Optimal reaction conditions forecasted by the response surface method (RSM) was a dosage of 0.19 g L−1, a temperature of 45 °C and initial pH of 4.0, contributing to Sb(V) removal of 98.2%. Clearly, SO42− and Cl− (as electrolytes) had no obvious effect on Sb(V) removal; CO32−, PO43− and SiO32− showed obvious inhibition, likely due to iron passivation (pH > 10.5) and formation of precipitation (e.g., FeCO3, Fe(OH)2 and Fe2(SiO3)3); N2 atmosphere was more conducive to Sb(V) removal.CONCLUSIONSb(III) concentration in the solution was almost zero without adjusting the initial pH. It was deduced that Sb(V) removal in Fe0/SBE@C micro‐electrolysis system was probably the combined result of adsorption, coagulation and electrochemical reduction. © 2023 Society of Chemical Industry (SCI).