Novel ZnFe2O4/TiO2/flake graphite composite as particle electrodes for efficient photoelectrocatalytic degradation of rhodamine B in water.

A novel ZnFe2O4/TiO2/flake graphite composite material was synthesized and used as particle electrodes in a photoelectrocatalytic (PEC) system to investigate the degradation of rhodamine B as a model dye pollutant in water. Results showed that a PEC process with the new composite evidently led to enhanced degradation of rhodamine B due to a synergistic effect of photocatalysis and electrocatalysis. Operating variables including electrolyte concentration, applied cell voltage, air flow, composite dosage, solution pH, and dye concentration were also found to play important roles in rhodamine B removal. A 99.0% removal efficiency was observed within 30 min of treatment under optimum conditions of 0.01 mol/L Na2SO4, applied cell voltage of 15 V, air flow of 20 mL/min, composite dosage of 10 g/L, solution pH of 2, and rhodamine B concentration of 20 mg/L, with a pseudo-first-order rate constant of 0.278 min-1. These findings could provide new insights into the development of efficient PEC technologies on degradation of residual dyes in water.