S. Vasudevan

Adsorption of herbicide 2-(2,4-dichlorophenoxy)propanoic acid by electrochemically generated aluminum hydroxides: an alternative to chemical dosing

This research article presents an in situ electrosynthesis of aluminum hydroxides by anodic dissolution of sacrificial aluminum anode and their application towards the adsorption of herbicide 2-(2,4-dichlorophenoxy)propanoic acid (2,4-DP) from aqueous solution. Different sacrificial anode material like iron, magnesium, zinc and aluminum are tested and stainless steel is used as the cathode. The optimization of different experimental parameters like current density, pH, temperature and inter-electrode distance on the adsorption of 2,4-DP was carried out. The results showed that the maximum removal efficiency of 93.0% was achieved with aluminum as sacrificial anode at a current density of 0.10 A dm−2 and pH of 7.0. The adsorption of 2,4-DP preferably followed the Langmuir adsorption isotherm. The adsorption kinetic studies showed that the adsorption of 2,4-DP was best described using the second-order kinetic model. Thermodynamic parameters indicates that the adsorption of 2,4-DP on aluminum hydroxides was feasible, spontaneous and endothermic.

Eco-friendly and facilely prepared silica modified amorphous titania (TiO2–SiO2) electrocatalyst for the O2 and H2 evolution reactions

An eco-friendly silica modified amorphous titania (TiO2–SiO2) electrocatalyst is prepared. This silica modified amorphous titania (TiO2–SiO2) composite material is prepared by facile spurting of silica (obtained from a sustainable resource) over a titanium plate and identified as an active electrocatalyst for O2 and H2 evolution by water oxidation. The prepared composite shows a maximum current density of 12 mA cm−2 at 2 V (versus RHE) in 1 M KOH electrolyte. This is because the semiconductor heterostructure of the structurally and chemically dissimilar amorphous TiO2–SiO2 composite introduces new collective electronic states with improved electrical conductivity, with a decrease in the work function. The catalytic activity is found to be stable in continuous operation for about 10 h. The physicochemical characterization of the electrocatalyst was carried out using scanning electron microscopy, energy dispersive X-rays, X-ray diffraction, X-ray photoelectron spectra, and electron paramagnetic resonance and the work function was examined by a Scanning Kelvin Probe. Because of the simple, cheap, and scalable preparation procedure, the electrocatalyst is highly promising for practical low cost and high technology applications. Interestingly, the system is active in the oxygen and hydrogen evolution reactions, leading to a promising bifunctional electrocatalyst.

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.