Enhanced Removal of Sb(V) by Iron-Spent Bleaching Earth Carbon Binary Micro-Electrolysis System: Performance and Mechanism

BACKGROUND: In this work, the construction of a zero-valent iron-loaded spent bleaching earth carbon binary micro-electrolysis system (Fe-0/SBE@C) was first developed for antimony(V) (Sb(V)) removal in water. RESULTS: F(e)0/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 Fe-0/SBE@C accorded with a second-order kinetic model. Activation energy of Fe-0/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 degrees 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 Fe-2(SiO3)(3)); N-2 atmosphere was more conducive to Sb(V) removal. CONCLUSION: Sb(III) concentration in the solution was almost zero without adjusting the initial pH. It was deduced that Sb(V) removal in Fe-0/SBE@C micro-electrolysis system was probably the combined result of adsorption, coagulation and electrochemical reduction. (c) 2023 Society of Chemical Industry (SCI).