Publication
Graphitic carbon nitride, g-C3N4, have been receiving intense attention the last decades due to its unique physicochemical properties, and even more importantly, due to the visible light driven photoreactivity. Hence, the design and synthesis of novel photocatalysts based on g-C3N4 is a prosperous approach towards water and wastewater treatment, especially against pollutants of organic nature. Among the various water treatment techniques, electrocoagulation (EC) has the advantages of economical and operational benefits, while photocatalytic approaches, and particularly the solar light driven ones, are assumed as the future towards sustainable design of modern industrialization. Herein, we present a process intensification aspect for environmental remediation applications by coupling EC and photocatalysis processes for the removal of the azo dye carmoisine. The iron-iron electrodes showed a superior removal efficiency of 37% compared to aluminum-aluminum electrodes (23%) for a initial high dye concentration. Regarding the photocatalytic degradation of carmoisine, g-C3N4 doped with 2% Ag showed a higher dye removal efficiency (31%) related to 5% Ag doping (21%). Two quadratic models for dye removal were developed by carrying the experiments according to full factorial design and Box-Behnken design (BBD) for EC and photocatalysis processes, respectively. The models revealed that the electrical potential in EC and irradiation time in photocatalysis are the main variables which affect the process efficiency. The highest dye removal efficiency of 77% in EC was achieved when pH, electric potential, and time were set to 5, 15 V, and 60 min, respectively. Moreover, the optimal conditions for a 90% photocatalytic dye removal was 7.96, 0.59 g/L, 119.8 min, and 62.5 mg/L for pH, Ag(2%)/g-C3N4 dose, solar irradiation time, and initial carmoisine concentration, respectively. The removal efficiency did not change after 3 cycles indicating a physicochemical stability of the photocatalyst. The experimental data were well described well by first and pseudo-first order of kinetic models. Coupling EC and solar-driven photocatalysis showed to be a promising efficient dye removal approach, bearing in mind the need for economic and environmental-friendly method for environmental remediation applications. (C) 2021 Elsevier B.V. All rights reserved.