Luciano Marder

Removal of cadmium and cyanide from aqueous solutions through electrodialysis

The discharge of galvanic industry wastewaters containing heavy metals and cyanide is one of the largest sources of water pollution. The use of the electrodialysis technique for the treatment of a synthetic wastewater containing approximately 0.0089 mol L-1 cadmium and 0.081 mol L-1 cyanide was studied using a five-compartment electrodialysis cell. The results demonstrate that the removal of cadmium and cyanide depends on the applied current density and it is limited by the precipitation of cadmium on the cation-exchange membrane in the diluate central cell compartment.

Analysis of different current density conditions in the electrodialysis of zinc electroplating process solution

ABSTRACT The use of currents below and above the limiting one for the treatment by electrodialysis of a solution prepared as a surrogate of a rinse water of the acid zinc electroplating processes was studied. The ionic transport behavior was evaluated by chronopotentiometry. The limiting current values were obtained through current–voltage curves. The trials performed with different current densities showed that the electrodialysis removed at least 98% of the contaminants without insoluble species precipitation on membrane surfaces. The water reuse is possible after electrodialysis treatment with current densities above the limiting one and considering a demineralization rate of 60%.

Effect of operational parameters and Pd/In catalyst in the reduction of nitrate using copper electrode

ABSTRACT Water with high concentration of nitrate may cause damage to health and to the environment. This study investigated how concentration, current density, flow, pH, the use of Pd/In catalyst and operating mode (constant current density and constant cell potential) have an influence in the electrochemical reduction of nitrate and in the formation of gaseous compounds using copper electrode. Experiments were performed in two-compartment electrolytic cells separated by a cationic membrane with nitrate model solutions prepared as a surrogate of concentrated brines from membrane desalination plants. The results show that the electroreduction process has potential for reduction of nitrate and that it is influenced by the operational conditions. The best conditions found for the treatment – with satisfactory reduction of nitrate, formation of gaseous compounds and reproducibility – were at nitrate concentrations of 600 and 1000u2005mgu2005L−1, current density of 1.1u2005mAu2005cm−2 and without pH control, since in these conditions the production of gaseous compounds is higher than the production of nitrite. When Pd/In catalyst was used, the nitrate reduction was 50% after 6u2005h of experiment and the predominant product were gaseous compounds. When compared to the experiment without the catalyst, the arrangement with Pd/In was the most efficient one.