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A new chelating polymer has been developed wherein Amberlite XAD-4 has been functionalized by coupling it with diethylmalonate after acetylation. The resulting resin has been characterized by IR spectral and microanalysis studies and has been used for preconcentrative separation of thorium(IV) in the presence of alkali, alkaline earth, transition elements and lanthanides. Various physico-chemical parameters influencing the sorption of thorium(IV) onto the polymeric matrix was investigated and optimized by both batch and column methods. Quantitative extraction of thorium(IV) was obtained in the pH range 6.0–8.0. The sorption capacity of the malonic acid functionalized resin is 19.28 mg per g of polymer with an enrichment factor of 500. Moreover, the system showed faster exchange kinetics for extraction of thorium(IV) thus resulting in quantitative enrichment at flow rates as high as 16.0 cm3/min using 0.2 g of resin packed column (7 mm dia). Five replicate determinations of 10 μg of thorium(IV) present in 2.5 dm3of sample solution gave a mean absorbance of 0.160 with a relative standard deviation of 2.54%. The detection limit corresponding to 3 times the standard deviation of the blank was found to be 0.2 μg dm3. The developed procedure has been successfully utilized for the estimation of thorium(IV) content of pure rare earth chloride solution collected from Indian Rare Earths Limited, Alwaye, India.

Cellulose has been functionalized by coupling with 5-chloro-quinoline-8-ol in the presence of alkali. The resulting polymer material has been characterized by IR spectra and has been used for preconcentrating thorium prior to its determination by spectrophotometry. The optimum pH value for quantitative extraction is 5.0–7.0 and can be eluted with 5cm3of 1mol dm-3of HCl. The retention capacity of the quinoline-8-ol modified cellulose is 20.0mg g-1. The effect of various cations, anions and neutral electrolytes on the preconcentration of thorium in conjunction with the determination procedure has been studied and we have found that none of interferents including uranium (up to 10 fold amounts) interfere. The enrichment factor for preconcentration of thorium was found to be 200. Ten replicate determinations of 10μg of thorium (IV) present in 1dm3of sample gave a mean absorbance of 0.084 with a relative standard deviation 1.52. The detection limit (corresponding to three times the standard deviation of the blank) was found to be 2μg dm-3. The thorium content of mixed rare earth chloride solution obtained from Indian Rare Earths Limited (IRE), India was estimated by using quinoline-8-ol immobilized cellulose for preconcentration and subsequent determination by spectrophotometry.

The preparation of solid reagent 1-(2-pyridylazo)-2-naphthol functionalized benzophenone/naphthalene for preconcentration/separation of uranium (VI) is described. These reagents enriches uranium(VI) quantitatively from dilute aqueous solutions in the pH range 10.5-11.0. The solid mixture consisting of the enriched metal ion along with solid phase extractant were dissolved in 2ml of acetone and uranium(VI) content was established spectrophotometrically by using Arsenazo III procedure. Calibration graphs were rectilinear over the uranium(VI) concentration in the range 0.002-0.1μg cm-3. Five replicate determinations of 40μg of uranium present in 1dm3of sample solution gave a mean absorbance of 0.185 with a relative standard deviation of 1.4. The detection limit (corresponding to 3 times the standard deviation of the blank) and the enrichment factor were found to be 2μg dm-3and 500 respectively. Further the possible separation of uranium(VI) from several bivalent, trivalent and tetravalent elements was also established. In addition to validating the developed method by successfully analysing marine sediment reference material (MESS-3), uranium content was established in soil, river and marine sediment samples by the developed method and compared with standard inductively coupled plasma mass spectrometry (ICP-MS) values.

Solid phase extraction (SPE) has emerged as a powerful tool for separation/enrichment of inorganics, organics and biomolecules. The basic principle of SPE is the transfer of analytes from aqueous phase to the active sites of adjacent solid phase. The solid phase materials were prepared by sorption/chemical immobilization/coprecipitation of various chelating reagents or sorption of metal‐chelating agents onto solid supports such as activated carbon, naphthalene, silica and silica gel, glassbeads, cellulose, polyurethane foam and polymer supports. This review highlights the salient features of SPE preconcentrative separation procedures developed so far for inorganics wherein naphthols are used as chelating reagents and evaluates them critically.

Amberlite XAD-4 has been functionalized by coupling it with 5-aminoquinoline-8-ol after acetylation. The resulting resin has been characterized by elemental analysis and IR spectra and has been used for preconcentrating uranyl ions prior to its determination by spectrophotometry. The optimum pH value for quantitative sorption is 4–6, and desorption can be achieved by using 5 mL of 1 mol L–1HCl. The sorption capacity of the resin is 11.5 mmol g–1. The effect of various cations and anions on the preconcentration of uranium in conjunction with the determination procedure has been studied and we have found that none of the ions interfere except thorium. The enrichment factor for preconcentration of uranium was found to be 200. Ten replicate determinations of 40 µg of uranium present in 1 L of sample gave a mean absorbance of 0.185 with a relative standard deviation of 2.64%. The detection limit corresponding to three times the standard deviation of the bank was found to be 2 µg L–1. The validation of the developed preconcentration procedure was carried out by successfully analyzing standard marine sediment reference material. The uranyl content of sediment and soils is estimated by spectrophotometry after its preconcentration with the above chelating resin.

The effect of solvent on the absorption and fluorescence spectra of two liquidcrystalline molecules LC1 and LC2 were studied. These data were used to evaluatethe values of the change in the dipole moment between the ground and excitedstate and the first-order hyperpolarizability “β” in each solvent. The values of βgives an indication of how these liquid crystalline samples can find applicationsas nonlinear materials. The β values are in the range 1–1.9 × 1029esu for LC1and LC2. The values of β indicate that these compounds can be used as goodnonlinear materials. Here solvatochromism has been used as an effective tool toestimate the hyperpolarizability in solution.

The role of electronic polarizabilities in dealing with the phenomenon of molecular adsorption and catalysis by zeolites has been discussed in this work. Making use of the principles of periodic minimal surfaces of crystalline materials and rules of atomic connectivities of zeolite structures, an expression has been derived to evaluate heats of adsorption of hydrocarbons interacting with the surfaces of zeolites that reads HM·· f, where Mis the average polarizability of hydrocarbons, and fare the constants, and the average curvature of the zeolite surface. After determining the polarizabilities of hydrocarbons by a quantum mechanical method and establishing the magnitudes of the curvatures of surfaces of zeolites by differential geometrical approach, the formalism has been applied to evaluate heats of adsorption of C1−C8hydrocarbons on the typical surfaces of MOR, FAU, ZSM-5, and silcalite zeolites. The agreement between theoretical and experimental values of heats of adsorptions of paraffins, naphthenes, olefins, and aromatics has been found to be very good and compares fairly well with those obtained from experimental methods as well as derived by other theoretical methods. The applicability of the data so generated has been demonstrated in estimating the driving force of cracking (activation energy, E) following the Evans−Polyani procedure in the case of n-paraffins interacting with ZSM-5 surface. The data so generated has been used to explain negative activation energy for cracking observed for n-hexadecane and higher alkanes (C16effect).

ZSM-5 was prepared without the aid of an organic template. Effect of synthesis parameters on its catalytic activity in aromatisation ofn-heptane are discussed. Addition of seed material increased the crystallinity of the ZSM-5 phase. The catalytic activity was comparable with a sample prepared using an organic template. Formation of higher amount of C9– aromatics was observed over the non-templated zeolite.

Copper chloride on alumina catalyst used for oxychlorination of ethylene represents a typical system where copper is in a dynamic equilibrium between Cu+and Cu++oxidation states. Surface studies on redox, structural and compositional properties have been undertaken to monitor the changes that occur on the catalyst during use and pinpoint causes for its deactivation. For this, a fresh and a spent catalyst were been chosen for characterization. A core consisting of copper in Cu+state and present as CuAlO2is formed at the centre of the catalyst sphere. Formation of such a nonreversible phase under reaction conditions upsets the redox equilibrium. XPS also shows the absence of potassium in the core and its precipitation as a new phase on use, probably KCl, formed by the decomposition of active component KCuCl3. These factors facilitate deactivation.

Abstract: The electrochemical phase formation (ECPF) of mercury in the underpotential (UPD) region was studied using cyclic voltammetry on a glassy carbon substrate. The UPD peak, conspicous by its absence on the fresh glassy carbon electrode in the first cycle, is formed in the second and subsequent cycles reaching a full monolayer coverage over a few cycles. The characterization of the monolayer peak by the theoretical models suggested for linear sweep conditions showed that the UPD of mercury follows progressive nucleation-growth kinetics. The nucleation parameter and nucleation-growth rate constant were calculated.

Precipitation from a homogeneous solution of aluminium nitrate by neutralisation using urea in presence of succinic acid leads to the formation of a well-defined alumina precursor, basic aluminium succinate, which on calcination yields microspheroidal γ-alumina with excellent free-flowing characteristics.

We have observed a large nonresonant third-order nonlinear susceptibility, X(3) (-?; ?, 0, 0) in the isotropic phase of a nematic liquid crystal 4'-n-hexyl-4-cyanobiphenyl (K18). The highest value of X(3) obtained at 632.8 nm is 1.16274×10-18 m2V-2 corresponding to a temperature 29.3°C. The observed second-order pretransitional temperature T* from our measurements is 1.2°C below the first-order nematic to isotropic transition temperature. The dependence of the Kerr constant on (T-T*)-1 is found to be in good agreement with the predictions of the Landau-de Gennes model.

Effect of sintering on physico-chemical and catalytic properties of Mo, Co-Mo, Ni-Mosupported on ?-Al2O3 is reported. Such effects on hydrodesulfurization (HDS), hydrogenation (HYD) and hydrodeoxygenation (HDO) are investigated as a function of sintering temperature. The results indicated that HDS and HYD have different optimum calcination temperatures and these functionalities originate from different sites. The results are discussed in the light of molybdenum sulfide dispersion, promotional effects and phase transformations of active component, promoters and support.

The electrochemical phase formation (ECPF) of mercury in the underpotential (UPD) region was studied using cyclic voltammetry on a glassy carbon substrate. The UPD peak, conspicous by its absence on the fresh glassy carbon electrode in the first cycle, is formed in the second and subsequent cycles reaching a full monolayer coverage over a few cycles. The characterization of the monolayer peak by the theoretical models suggested for linear sweep conditions showed that the UPD of mercury follows progressive nucleation-growth kinetics. The nucleation parameter and nucleation-growth rate constant were calculated.

This paper describes a third-order derivative Spectrophotometric procedure for the determination of traces of phosphate, based on the formation of a ternary ion-association complex by reaction of phosphate with rhodamine 6G in the presence of molybdate. The pink complex is readily formed in 0.08–0.16M H2SO4 medium and remained stable for 2 h. The influence of various instrumental parameters and reaction conditions for maximum colour development are discussed. The few interfering ions can be masked by the addition of appropriate reagents. The procedure is simple, rapid and reliable and allows the determination of 1.5 µg l-1 of phosphate. The relative standard deviation for the determination of 0.08 mg l-1 of phosphate was 1.1%. The method is applicable to the determination of phosphate in river water, sea water, drinking water, milk powder and standard reference materials.

A method is described for the determination of molybdenum based on reaction with potassium thiocyanate and Rhodamine 6G in 0.55–0.8 mol dm−3hydrochloric acid medium. The method is sensitive (ε=2.63×105l mol−1cm−1) and obeys Beer’s law over the range 0.04–0.24 ppm of molybdenum. Selectivity can be considerably improved by collecting molybdenum on iron (III) hydroxide. In conjunction with the collection procedure, the method is useful to determine as low as 5 ppb of molybdenum present in 100 cm3of aqueous samples.

Vanadium(IV) is determined by reaction with 3,5-dinitrosalicylic acid and rhodamine B in weakly acidic medium. The flotation of the ternary ion-association complex is carried out with cyclohexane followed by dissolution in acetone for subsequent spectrophotometric determination. The molar absorptivity is 5.91×105 l mole-1 cm-1 at 555 nm. Beer's law is obeyed in the range 0.05–1.5 µg vanadium(IV) in 25 ml. The method is selective for vanadium(IV) in the presence of sodium fluoride and has been applied to standard reference materials.

A new method for the direct conversion of carboxylic acids into aldehydes using (chlorosulfinyloxy)N,N-dimethylmethaniminium chloride and lithium triethylhydroborate (super-hydride) was established which provides a convenient way for the chemoselective reduction of carboxylic acids even with such functional groups as halide, ester, nitrile, olefin and ketone.