A significant reduction in the cost of the iron electrodes-based electrocoagulation process with higher tetracycline removal performances when addressed by a time-integrated performance index

Abstract

Abstract This work used a time-integrated performance index to address the low cost of the Electrocoagulation process to strengthen its tetracycline removal performance significantly. A reasonable control of the time-depending tetracycline removal efficiency of the electrocoagulation process was searched by choosing a better combination of the electrode material and electrolyte species types for getting a stabilization condition of the total electric voltage. The response surface methodology was included to address, compare and rescue the best results of the time-integrated performance index. The electrolyte type, pH of the aqueous media, electric conductivity, and electric voltage were assessed to better respond to the performance of tetracycline removal. In this regard, an iron-based electrocoagulation reactor was operated over a range of 40 to 67 A m-2 of electric current density supported by 5 to 10 mS cm-1 electric conductivity values. To increase the electrical conductivity, four electrolytes (Cr3+, Zn2+, Ca2+, and K+) were added separately to tetracycline synthetic solutions. The best performance was obtained by Ca2+ electrolytes stabilizing the total electric voltage due to maintaining a constant electric conductivity and pH buffering at the alkaline region. From a Box-Behnken experimental design, a 40 A m-2 electric current density allowed getting the maximal time-integrated performance index value over 30 min time, removing above 97% tetracycline with minimal electric power consumption.