Taguchi’s optimization of process parameters for effective degradation of Rhodamine B and energy harvesting through photocatalytic fuel cell with dual photoelectrodes

Abstract

Rapid industrialization and urbanization are polluting water supplies due to release of untreated wastewater in water bodies. Rhodamine B (RhB) is one of the commonly found pollutants in wastewater. In this study, dual-photoelectrode Photocatalytic Fuel Cell (PFC) prepared from ZnO/TiO₂ photoanode and Cu₂O/CuO photocathode is used with Taguchi’s standard L16 Orthogonal Array to optimise RhB degradation and electricity generation. X-ray diffraction, field emission-scanning electron microscopes, energy dispersive X-ray and ultraviolet–visible diffuse reflectance spectroscopy are used for characterization of photoelectrodes. Analysis of mean revealed the maximum RhB removal of 91.77% and power density of 297.81 µA cm⁻² at pH 8, 44 W light-intensity, two number of TiO₂ layers, 550 °C calcination temperature and 300 min irradiation-time. While analysis of variation determined the percentage contribution of each process parameter in descending order for RhB degradation as pH > irradiation time > calcination temperature > number of TiO₂ layers on photoanode > light intensity. Kinetics study indicated that RhB degradation followed pseudo-first order model (kinetic constant = 0.0085 min⁻¹) at optimum conditions. While short-circuit current density (J_sc), open-circuit voltage (V_oc) and maximum power (P_max) were 283.64 µA cm⁻², 945.63 mV and 297.81 µW cm⁻², respectively. Stability analysis revealed excellent stability of photoelectrodes for RhB degradation by 4th cycle, confirming reusability of photoelectrodes in PFC.