Hexavalent chromium removal by electrocoagulation using iron scrap electrodes: Optimization and kinetic modeling

Abstract

Electrocoagulation is an advanced process that ensures efficiency in treating effluents containing heavy metals. The cost minimization through the reuse of scrap metal as electrodes gains prominence due to its high efficiency. This study aimed to evaluate and establish an optimized system for Cr(VI) electrocoagulation using scrap iron electrodes. The optimized system was derived through a series of experimental designs such as Plackett–Burman and Central Composite Rotatable Design, considering variables such as pH, Cr(VI) concentration, system temperature, agitation, applied electrical current, and reaction time. The results demonstrated that an efficient and optimized system for Cr(VI) removal through electrocoagulation using scrap iron electrodes, achieved for a 1 L volume, involves the use of: a current of 0.7 A, pH 1.5, 0.75 mg L⁻¹ of NaCl, and a time range of 30–45 min for concentrations ranging from 80 to 150 mg L⁻¹.