Optimization of electrocoagulation process for the simultaneous removal of mercury, lead, and nickel from contaminated water

The present study provides an optimization of electrocoagulation process for the simultaneous removal of heavy metals such as mercury, lead, and nickel from water. In doing so, the thermodynamic, adsorption isotherm and kinetic studies were also carried out. Magnesium alloy, magnesium, aluminum, and mild steel sheet of size 2 dm(2) were used as anode and galvanized iron as cathode. To optimize the maximum removal efficiency, different parameters like effect of initial concentration, effect of temperature, pH, and effect of current density were studied. Mercury-, lead-, and nickel-adsorbed magnesium hydroxide coagulant was characterized by SEM and EDAX. The results showed that the maximum removal efficiency was achieved for mercury, lead, and nickel with magnesium alloy as anode and galvanized iron as cathode at a current density of 0.15 /dm(2) and pH of 7.0. The adsorption of mercury, lead, and nickel are preferably fitting the Langmuir adsorption isotherm suggests monolayer coverage of adsorbed molecules. The adsorption process follows second-order kinetics. Temperature studies showed that adsorption was endothermic and spontaneous in nature. The magnesium hydroxide generated in the cell removes the heavy metals present in the water and reduces to a permissible level, making it drinkable.