Copper electrode for the removal of chromium from dyestuff industries effluent by electrocoagulation: kinetic study and operating cost

Abstract

Copper electrode was introduced for the removal of chromium from dyestuff industries effluent (DIE) by electrocoagulation (EC). The initial concentration of chromium was 82.7 mg/L in the DIE. In the present study, EC method was used to investigate the effect of process variables such as pH, current density, supporting electrolyte (NaCl) concentration, chromium concentration, and electrode distance for the removal of chromium from DIE. The copper electrode showed removal efficiency 99.70% at a current density (CD) = 68.87 A/m², pH = 5.83, chromium concentration (C_c) = 82.7 mg/L, electrode distance (ED) = 0.7 cm, and time of EC = 50 minutes. Experimental results indicated that the removal of chromium follows the first order reaction during kinetic analysis in CD range from 13.77 to 68.87 A/m². The rate constant (k) enhanced from 0.0286 to 0.114 min⁻¹. The analysis of sludge was carried out using FESEM-EDX, which confirmed the presence of chromium, copper hydroxide, and other elements in sludge. The present work confirms that EC is an efficient process for chromium removal from DIE with a calculated operating cost of 0.277 US$/m³ and energy consumption of 3.32 kWh/m³.

Graphical Abstract

Keywords:

• Electrocoagulation (EC)
• dyestuff industries effluent (DIE)
• copper electrodes
• chromium removal
• kinetics