Photoreduction of Ni2+ under solar and artificial reactors on the hetero-junction (CuFe2O4/ZnO): Comparison between experimental and theoretical results

The photocatalytic Ni2+ reduction on the hetero-junction CuFe2O4/ZnO (1/1) in both plug flow reactor (PFR) and continuous flow stirred tank reactor (CFSTR), is optimized with respect to Ni2+ initial concentration (Co= 30 ppm), pH similar to 7 and liquid flow (100 mL min(-1)). The spinel CuFe2O4 and the wurtzite ZnO were prepared by nitrate route and characterized photoelectrochemically. The photoelectrochemical characterization predicts the injection of electrons from the spinel CuFe2O4 to the wurtzite ZnO which are subsequently transferred to adsorbed Ni2+ ions. To obtain high efficiencies, the optimal operating conditions for the kinetics of the reduction of the Ni2+ are determined and compared to the theoretical model. Under sunlight, the Ni2+ reduction is improved up to 96% because of the additional UV photons which activate ZnO. The Ni2+ reduction follows a pseudo-first order kinetic with a rate constant of 1.63 x 10(-2) min(-1) according to Langmuir-Hinshelwood. The photoactivity is slightly lowered; under artificial illumination for an optimum concentration of 30 ppm. The comparison with the theoretical model gave a reduction of 99% for a Ni2+ concentration of 30 ppm.

Automated summary

This study optimized the photocalytic reduction of Ni2+ on the hetero-junction CuFe2O4/ZnO. Under sunlight, the reduction rate of Ni2+ reached 96% and followed pseudo-first order kinetic. The results were validated by comparing with a theoretical model.