Water pollution from wastewater containing heavy metals, such as lead (Pb), cadmium (Cd), and nickel (Ni), is a serious environmental concern because these contaminants are toxic, non-biodegradable, and capable of accumulating in the food chain. Electrocoagulation is a promising treatment method that uses the electrochemical dissolution of electrodes to generate coagulants in situ. Current density is a critical operating parameter because it influences coagulant generation, gas-bubble formation, and contaminant removal efficiency. This study investigated the effect of current density on the removal efficiencies of Pb, Cd, and Ni from synthetic wastewater using aluminium electrodes in a batch reactor. Current densities of 13, 26, and 40 mA/cm² were tested at an initial pH of 9 and a treatment time of 60 minutes. The initial concentration of each metal was 20 mg/L. The results demonstrated that current density significantly affected heavy-metal removal. Among the tested conditions, 13 mA/cm² provided the best performance, achieving an average removal efficiency above 97%. Under single-metal conditions, the removal efficiencies of Pb, Cd, and Ni were 93.20%, 99.85%, and 99.39%, respectively. Under simultaneous-metal conditions, the corresponding efficiencies were 94.71%, 99.65%, and 98.81%. These findings confirm the effectiveness of aluminium-electrode electrocoagulation for treating heavy-metal-contaminated wastewater.
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