Rengarajan Balaji

Methanesulphonic acid in electroplating related metal finishing industries

SUMMARY During the past ten years, methanesulphonic acid has largely replaced fluoroboric acid as the electrolyte of choice for the electrodeposition of tin and tin-lead solder on electronic devices. Certain other electrochemical processes involving lead, most notably the electrorefining of lead by the Betts process, are currently carried out in fluorosilicic acid based electrolytes but those based on methanesulphonic acid (MSA) are being actively investigated as environmentally superior alternatives to the currently used systems. Also, a number of commercial strip steel tinplating operations have recently converted to methanesulphonic acid based tin-plating electrolytes. There are also developing markets for methanesulphonic acid in silver, nickel, copper, cadmium and zinc electroplating. This paper reviews the chemical and physical properties of methanesulphonic acid and its current applications in the field of metal finishing and also its superiority over other electrolytes especially with respect to environmental pollution.

Sulfonated Polystyrene-Block-(Ethylene-Ran-Butylene)-Block-Polystyrene (SPSEBS) Membrane for Sea Water Electrolysis to Generate Hydrogen

Sea water oxidation is one of the promising ways to produce hydrogen since it is available in plentiful supply on the earth. However, in sea water electrolysis poisonous chlorine evolution is the most favored reaction over oxygen evolution at the anode. In this work, study has been focused on the development of electrode materials with high selectivity for oxygen evolution reaction over chlorine evolution. We employed perm selective membrane i.e. sulfonated polystyrene-block-(ethylene-ran-butylene)-block-polystyrene (SPSEBS) which electrostaticlly repels the chloride ion (Cl-) to the electrode surface and thereby enhances the oxygen evolution and reduces the chlorine evolution at the anode. The electrochemical behavior of both modified and bare IrO2 electrodes were characterized using polarization studies and the gas evolution efficiencies are calculated based on bulk electrolysis method. The surface morphology of the electrode was analyzed before and after electrolysis using scanning electron microscope (SEM). The results suggest that the nearly 95% oxygen evolution efficiency could be achieved when the surface of IrO2/Ti electrode was modified with perm selective membrane.

Carbon assisted water electrolysis for hydrogen generation

Carbon Assisted Water Electrolysis (CAWE) is an energy efficient process in that H2 can be produced at lower applied voltage (∼1.0 V) compared to nearly 2.0 V needed for ordinary water electrolysis for the same H2 evolution rate. In this process, carbon is oxidized to oxides of carbon at the anode of an electrochemical cell and hydrogen is produced at the cathode. These gases are produced in relatively pure state and would be collected in a separate chamber. In this paper, we present the results of influence of various operating parameters on efficiency of CAWE process. The results showed that H2 can be produced at applied voltages Eo as low as 1.0V (vs. SHE) and its production rate is strongly dependent on the type of the carbon used and its concentration in the electrolyte. It has also been found that the performance of CAWE process is higher in acidic electrolyte than in alkaline electrolyte.