No abstract

Copper (Cu), chromium (Cr), and nickel (Ni) removal from metal plating wastewater by electrocoagulation and chemical coagulation was investigated. Chemical coagulation was performed using either aluminum sulfate or ferric chloride, whereas electrocoagulation was done in an electrolytic cell using aluminum or iron electrodes. By chemical coagulation, Cu-, Cr-, and Ni-removal of 99.9 % was achieved with aluminum sulfate and ferric chloride dosages of 500, 1000, and 2000 mg L -1 , respectively. Removal of metals by electrocoagulation was affected by the electrode material, wastewater pH, current density, number of electrodes, and electrocoagulation time. Electrocoagulation with iron electrodes at a current density of 10 mA cm -2 , electrocoagulation time of 20 min, and pH 3.0 resulted in 99.9 % Cu-, 99.9 % Cr-, and 98 % Ni-removal.

In this study, the performance of electrocoagulation process in the treatment of metal plating wastewater was investigated using different combinations of aluminum (Al) and iron (Fe) electrodes. The effect of applied current, metal concentration, and treatment time on the metal removal efficiency was investigated. The results show that electrocoagulation can effectively reduce metal ions to a very low level. The Fe‐Fe and Fe‐Al electrode combinations were more effective for the removal of Cu, Cr, and Ni from metal plating wastewater. Almost 100% removal of Cu, Cr, and Ni was achieved with initial Cu concentration of 335 mg/L, Cr concentration of 193 mg/L, Ni concentration of 526 mg/L after 60 min of electrocoagulation at current of 2.0 A with Fe‐Al electrode combination. © 2011 American Institute of Chemical Engineers Environ Prog, 2011.

A B S T R A C TThe adsorptive properties of natural sepiolite in the removal of copper (Cu 2+ ) from aqueous solution were investigated. The results show that the amount of adsorption of copper ion increases with initial copper concentration, contact time, and solution pH. The pseudo-firstorder, pseudo-second-order, and Elovich models were used to describe the kinetic data and the rate constants were evaluated. The adsorption of the copper onto natural sepiolite at different operating conditions followed the pseudo-second-order model. The equilibrium data were analyzed using the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich (D-R) isotherm models. The equilibrium adsorption results are fitted better with Langmuir isotherm compared to the other models. The Langmuir monolayer adsorption capacity of sepiolite was estimated as 9.64 mg/g at pH 6.0 and temperature of 20˚C. An increase in temperature was found to induce a positive effect on the sorption process. Sorption of Cu 2+ onto sepiolite was spontaneous and endothermic. The values of the enthalpy (ΔH) and entropy of activation (ΔS) were 14.892 kJ/mol and 96.342 J/mol K, respectively, at pH 5.0.