NISCAIR Online Periodicals Repository Collection: IJCT Vol.12(4) [July 2005]

Inhibition of corrosion of mild steel in hydrochloric acid by N-cyclohexyl-N'- phenyl thiourea

Title: Inhibition of corrosion of mild steel in hydrochloric acid by N-cyclohexyl-N'- phenyl thiourea

Authors: Shetty, S Divakara; Shetty, Prakash; Nayak, H V Sudhaker

Abstract: The inhibition of corrosion of mild steel in 0.01-0.1 N HCl solutions by N-cyclohexyl-N'-phenyl thiourea (CPTU) has been studied using potentiodynamic polarization technique. Results obtained reveal that CPTU performs excellently as anodic inhibitor for mild steel in HCl solution. The inhibitor functions through adsorption following Temkins’ adsorption isotherm. The influence of parameters like temperature, hydrochloric acid concentration and inhibitor concentration on the corrosion of mild steel has also been studied.

Page(s): 462-465

Micellar–enhanced ultrafiltration of chromate [Cr(VI)] ion from aqueous streams by using cationic surfactant

Title: Micellar–enhanced ultrafiltration of chromate [Cr(VI)] ion from aqueous streams by using cationic surfactant

Authors: Kamble, S B; Marathe, K V

Abstract: Hexavalent chromium [Cr(VI)] in industrial effluent is one of the most serious environmental problems in India and also in other countries. Micellar-Enhanced Ultrafiltration (MEUF) of the chromate anions from aqueous solutions has been studied at room temperature (28±2°C) using cationic surfactants, cetyltrimethylammonium bromide (CTAB) and cetylpyridinium chloride (CPC), micelles of which adsorb the chromate ions by electrostatic interactions. The solution is processed by ultrafiltration, using a membrane with a pore size small enough to block the passage of the micelles and the adsorbed ions. The process is highly efficient in removing the chromate ions. In the absence of other electrolytes, chromate ion rejection up to 99% was observed at optimal conditions of pH, pressure, temperature, feed chromate and surfactant concentrations. The presence of added NaCl reduces the chromate rejection, but it was still considerable (up to 82%), even in the presence of 100 mM NaCl. The rejection rate of chromate was found to be highly dependent on the pH of the feed solution. The solute rejection is also affected by anion charge density, and interaction of fixed membrane charge sites with ionic solutes.

Page(s): 393-400

Pinacol-Pinacolone rearrangement over solids supported metal ion catalysts

Title: Pinacol-Pinacolone rearrangement over solids supported metal ion catalysts

Authors: Shamshuddin, S Z Mohamed; Kuriakose, George; Nagaraju, N

Abstract: Catalytic activity of hydrated Al₂O₃, SiO₂, ZrO₂,AlPO₄, zeolite-HY and Fe(III) ions supported on these solids has been evaluated in pinacol-pinacolone rearrangement (2,3-dimethyl-2,3-butanediol to 3,3-dimethyl-2-butanone). The effect of method of preparation of catalysts on their catalytic activity has been evaluated. Studies on catalytic activity have been performed in vapour phase at different reaction temperatures. Pinacolone and 2,3-dimethyl-1,3-butadiene were formed as the major products. The percentage conversion of pinacol and the selectivity of the products have been found to be influenced by the reaction temperature, the nature of the support, the metal ion present on the support and the method of preparation of supported catalysts. Al₂O₃ and AlPO₄ containing 5% Fe ions on their surface are found to convert pinacol to pinacolone to an extent of 88% with a selectivity of 83% for ketone at 200 °C with 10 mL/h flow rate of the reactant. A comparative study of the catalytic activity of the materials containing 5% Fe ions on Al₂O₃ and those containing same percentage of Ni or Co ions in the chosen reaction at 200 °C, revealed a good correlation between the redox potential of the metal ions and their selective catalytic activity in the formation of pinacolone.

Page(s): 447-454

Removal and recovery of lead from aqueous solution using supported liquid membrane

Title: Removal and recovery of lead from aqueous solution using supported liquid membrane

Authors: Anupama, R; Palanivelu, K

Abstract: A laboratory study was conducted to remove and recover lead from aqueous solution using supported liquid membrane (SLM) process. Preliminary solvent extraction studies, on lead revealed the iodo system with tributyl phosphate (TBP) as liquid membrane and sodium hydroxide as strippant to be an efficient one. Using synthetic lead(II) solution, the process parameters like feed side pH, strippant concentration, KI concentration and stirring speed were optimized. The initial lead concentration of 25 mg/L gave satisfactory result with complete removal and recovery in 4 h of operation with a permeability coefficient of 1.146 × 10^-5 m/s.

Page(s): 436-440