Separation of oil-water emulsions by a novel packed bed electrocoagulation (EC) process using anode from recycled aluminum beverage cans

Abstract

Electrocoagulation (EC) is an emerging technology for the elimination of oil and COD content from oily wastewaters. However, higher operating costs and electrode passivation are pressing challenges for its wide speared application. To overcome this setback, the present work has attempted to develop a new and inexpensive electrode using recycled aluminum (Al) beverage cans for the treatment of oily wastewater by electrocoagulation (EC) technology. It could be an alternative to conventional plate or tube electrodes in the EC process, it is the first contribution into the literature. In current work, recycled Al beverage cans filled with steel wool was used as anode, and commercial stainless-steel mesh (304) with cylindrical shape was used as cathode. The main EC performance measure was COD removal efficiency, impacts of significant process parameters in the EC process (such as operating voltage, electrocoagulation time, stirring rate, and NaCl concentration) on the effectiveness of EC process were investigated by using response surface methodology (RSM) based Box-Behnken Design (BBD) model. The RSM analysis results demonstrated that the highest COD removal rate of 93.53% was achieved under optimal conditions of operating voltage (15 V), electrocoagulation time (10 min), stirring rate (250 rpm), and NaCl concentration (1 g/L). In addition, energy consumption analysis was performed, an electrical energy efficiency of 0.160 kWh/kg COD was achieved. Afterward, ATR-FTIR spectroscopy, scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), and XRD analysis were performed under optimal conditions to characterize anode, and generated sludge during the EC process. Collectively, the findings in this study paves the way toward the development of sustainable EC technology for separation of emulsified oil-water mixtures, which gives the importance of the circular economy and sustainable management of industrial wastewaters.