RSM based optimization for sustainable removal of Cr(VI) and Pb(II) from tannery effluent using rotating disk mesh electrode by electrocoagulation

The tanning process involves the usage of various toxic chemicals, disrupting concentrations in the ecosystem. The aim of this research was to develop an efficient electrode design and utilize it as an anode for treating chromium (Cr) and lead (Pb) present in tannery effluent through the electrocoagulation process in a sustainable manner and utilize the resulting sludge for pigment application. Performance of electrodes was analyzed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The electrode's surface morphology and chemical composition were analyzed using SEM and EDX techniques, respectively. The SEM analysis revealed that the newly developed rotating disk mesh electrode (RDME) exhibited minimal scaling of contaminant and oxide layer of metal formation on its surface and better removal performance of chromium and lead from tannery effluent. EDX shows the evidence of elements attached due to passivation and the metal oxide layer in effluent. Furthermore, the process parameters optimized were current density, pH, RPM, and treatment time using the Box-Behnkin Design method with Design Expert 13.6 software. At optimized conditions with a current density of 19.26 mA/cm 2 , pH of 7, RPM of 160, and treatment time of 90 minutes, the rotating disk mesh electrode demonstrated impressive Cr and Pb removal efficiencies of 90% and 94% respectively. Moreover, the energy consumption for treatment of Cr and Pb were 31.75 kWh/m 3 for the rotating disk mesh electrode (RDME). It showed great potential of the rotating disk mesh electrode design as the optimal choice for commercial-scale application, offering efficient removal and less energy consuming process for the removal of Cr and Pb from tannery effluent through the electrocoagulation process. • Two electrode designs were compared with the rotating disk mesh electrode. • Design Expert 13.0 was used for optimization of operating variables current density, Treatment time. pH and RPM. • The optimized conditions obtained were current density 19.26 mA/cm 2 , RPM 160, treatment time is 90 min and pH 7. • Rotating disk mesh electrode design was proved to be more efficient for removal of Cr and Pb than conventional designs.