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The removal of Al from the octahedral layer of montmorillonite by organic acid treatment results in increased microporosity generating a material with different surface features from the virgin clay. The micropores thus generated are found to be responsible for ester to ketone transformation. Various parameters of the newly generated pores such as the pore diameter, pore structure, pore volumes and acidity by pyridine-FTIR were evaluated with respect to ester to ketone formation. The best correlation was found between the volume accessibility factors (VAF) and the ketone yield. The VAF reflects the extent of volume space available around the acid site for the reactant to orient in a specific way for the transformation to occur within the pore to form a specific product. This acid site accessibility aspect was further verified by extending to micropores with large VAF generated by treatment with phenoldisulfonic acid (PDSA).

Acetalization of glycerol with aldehydes to form cyclic acetals is an industrially important reaction and is generally carried out using acid catalysts. Base catalysts such as LDH can bring about microwave-assisted acetalization of glycerol and aldehydes to form 5-membered and 6-membered cyclic acetals. Among the different LDHs used, Mg–Al-LDH was found to exhibit maximum conversion of glycerol into 5-membered cyclic acetal. Modification of Mg–Al-LDH involving calcination at 450 °C and subsequent microwave-assisted rehydration showed improved glycerol conversion rate under similar reaction conditions. Rehydration of calcined Mg–Al-LDH by microwave irradiation was found to result in LDH regaining its layered structure with higher basicity possibly exposing more hydroxyl ions responsible for basicity. Multiple use of methanol washed spent catalyst showed good repeatability for conversion up to three cycles which subsequently showed a marginal decrease in the conversion. Further dehydration followed by rehydration of the spent LDH catalyst under microwave irradiation was found to rejuvenate the catalytic activity to its initial level.

AbstractIn the last decade, there have been fundamental changes in the nature, form and variety of peace operations. In fact, the very coining of a new term, ‘Peace Operations’ (PO), as distinct from the earlier ‘Peacekeeping Operations’ (PKOs), illustrates a new degree of diversity and complexity in these operations. India has been, and continues to be, a major player in UN Peacekeeping Operations (UNPKOs). It has participated in 41 of the 59 UN Missions established so far and has contributed more than 70,000 personnel. India has a current deployment of over 4,000 personnel in 8 of the 16 ongoing peacekeeping operations. This is likely to increase substantially in 2005 with the induction of additional Indian troops in the UN missions in Congo and Sudan. The objective of this paper is to delineate the nature of change in modern peacekeeping operations, identify the current trends and look at future issues and challenges, including some inferences and implications for India.

Studies on the sorption of phosphorus, exchangeable aluminum, exchangeable acidity, and surface area on four soils have been made. The sorption of phosphorus at zero time, which was taken as the time just required to mix 2 g of soil sample with 25 ml of potassium dihydrogen phosphate solution, was found to be in good agreement with the true exchangeable aluminum measured by the graphical method of Sivasubramaniam and Talibudeen (1972). The zero-time phosphorus sorption also correlated with the exchangeable acidity but not with the surface area.

The adsorption behaviour of iodine on chemically modified swelling type of clays has been studied. Chemical modification was brought about by interacting the clay with surfactants such as tween-80 and polyethylene glycol. Adsorption of iodine was found to increase by several orders of magnitude on chemical modification which remained constant between pH 1 and 10. The adsorption isotherms were non-linear and fitted the Freundlich equation for swelling clays. Scatchard analysis of the data indicated minimum two types of active sites with the tween-80 modified clay and one type with the polyethylene glycol modified one. The iodine sorbed on the surface was found to get desorbed almost completely on leaching with water. Modification of the clay surface with surfactant thus offers a method of designing a recyclable adsorbent for iodine.