Intensification of a new electrocoagulation system characterized by minimum energy consumption and maximum removal efficiency of heavy metals from simulated wastewater

•A new system for removal of heavy metals by electrocoagulation.•Faster removal of Cu rather than Ni under the same condition.•Low energy consumption and short electrolysis time were investigated.•The relationship between the rate constant (kapp) and electrical energy per order (EEO) was proposed.•Faster removal due to the generation of strong oxidant. In the present study, a new simple self-gas stirred batch electrocoagulation reactor was designed. The new cell consisted of a cylindrical Al sheet anode and a cylindrical Al screen cathode placed at a small distance from the anode. The H2 evolving screen cathode improves the mixing conditions in the cell via turblence promotion and solution recycling which improves the economic efficiency of the electrochemical cell. This favourable hydrodynamic conditions improved considerably the % removal of Ni2+ and Cu2+ ions from a synthetic wastewater. The removal efficiency and apparent removal rate constant (kapp) of Cu2+ were higher than those of Ni2+ as a result of the additional cathodic deposition mechanism. Energy consumption ranged from 4.43–75.71 kW.h/kg depending on the operating conditions. The optimal operational conditions,were current density (c.d) of 1.72 mAcm−2, initial metal concentration (Co) of 100 mg.L−1, NaCl concentration (CN) of 1 g.L−1 and pH (5.5 for Cu and 4 for Ni) at 40 min. of electrolysis. The % removal efficiency ranged from 34.56–100% depending on the operating conditions. This study revealed that the new self stirred cell has the potential to be used for the removal of heavy metal from contaminated water.