Novel anode made of iron scrap for a reduced-cost electrocoagulator

•A novel anode was a PVC tube packed with machine shop turnings.•Apparent density of the packed-bed was 493 kg/m3.•Reactive Blue 21 in the phthalocyanine class was used as the model compound.•Optimal current and the electrocoagulation time was 0.9 A and 10 min.•Energy was 0.39–0.50 kWhe/m3 for the color and COD removals of 98% and 93%.

This paper deals with the development of a reduced-cost electrode as a substitute for a plate or tubular electrode. A polyvinyl chloride (PVC) tube with an internal diameter of 28 mm was packed with machine shop turnings. The packed bed had an apparent density of 493 kg/m3. The PVC tube had distributed 5 mm-holes on its surface to allow the transport of metal ions from the electrode to the bulk solution. Various electrical current and electrocoagulation times were investigated for achieving high color and Chemical Oxygen Demand (COD) removals. The required electrical current and electrocoagulation time for achieving a maximum color removal of 98% and a maximum COD removal of 93% were found to be 0.9 A and 10 min. The performances of the packed-bed anode electrocoagulator were compared with those of a conventional tubular iron anode electrocoagulator. It was found that the removal efficiencies of the packed-bed anode were higher than those of the tubular anode for the first 8 min. The higher removal performances of the packed-bed anode may be due to its higher surface area for the distribution of the electroactive species. However, at the optimal electrocoagulation time of 10 min, the energy consumption for the packed-bed anode (0.50 kWh/m3) was higher than that of the tubular anode (0.38 kWh/m3). The higher electrical energy consumption of the packed-bed electroagulator was expected to be due to the increased resistance associated with increased concentration overpotential (volt) for this anode.

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