Examine of the Most Influential Variables in the Process of Removing Copper from Simulated Wastewater by Using an Electrocoagulation Reactor

Abstract

There are many variables described as affected factors on electrocoagulation reaction EC, so this study includes investigation impact of eight variables on the EC process; contact time, current density, the voltage supplied, stirring rate, initial copper concentration, solution pH, reaction temperature, and type of anode were chosen as controlled variables on EC reaction, while copper removal efficiency used as a process response. The feed is simulated wastewater prepared by adding copper nitrate as a copper ions source. The most influential variables on copper removal during EC reaction were identified by two levels according to Plackett-Burman design PBD. Results show that the initial copper concentration, solution pH, reaction temperature, and contact time are the most significant variables on EC reaction, on the other hand, the predicted results show that maximum removal efficiency (97%) will be obtained at optimum operation conditions; contact time (40 minutes), current density (3 A/cm2), voltage supply (10 volts), initial copper concentration (400 ppm), reaction temperature (70°C) with no stirring rate and using Fe as an anode. The EC reaction kinetics and thermodynamics parameters were estimated; the reaction obeys second order with reaction rate constants are  (k) are 0.6572, 0.6829 and 0.8308 [(mol/L) sec-1]-1  at 50, 60, and 70 °C respectively, apparent activation energy value is 10.719 kJ/mol obtained for the process by the Arrhenius equation. A negative entropy change ΔS (-0.218 kJ/mol K) with the positive enthalpy change ΔH and Gibbs free energy ΔG values were obtained EC reaction.