NOPR Collection:

Synthesis and characterization of a Hg(II) selective II-butyl acetate cerium(IV) phosphate as a new intercalated fibrous ion exchanger: Effect of surfactants on the adsorption behaviour

Tue, 01 Aug 2006 00:00:00 GMT

Title: Synthesis and characterization of a Hg(II) selective II-butyl acetate cerium(IV) phosphate as a new intercalated fibrous ion exchanger: Effect of surfactants on the adsorption behaviour Authors: Varshney, K G; Rafiquee, M Z A; Somya, Amita; Drabik, Milan Abstract: n-butyl acetate Ce(IV) phosphate, a new Hg(II) selective, intercalated fibrous ion exchanger, has been synthesized and characterized by its ion exchange properties, thermal stability and adsorption behaviour for metal ions, X-ray, IR, TGA/DTA and SEM studies. Effect of surfactants on the adsorption behaviour of the material has also been studied. The exchanger has been found to be selective for Hg(II), hence, it can be utilized for the separation of this metal ion from other heavy metals from aqueous media. Studies on the effect of surfactants on the adsorption behaviour of this material show that for heavy metals ion, the adsorption increases with the concentration of anionic surfactants up to the CMC value and then decreases. But, for cationic, surfactants, the reverse is true. For non-ionic surfactant, adsorption remains constant up to the CMC value and then increases. For alkaline earths, the exchanger shows the same trend as above for cationic and non-ionic surfactants. However, for anionic surfactants, it is constant throughout the whole concentration range. Page(s): 1856-1860

Solid phase extraction and spectrophotometric determination of platinum(IV) with N-(3,5-dihydroxyphenyl)N'-(4-aminobenzenesulfonate)-thiourea

Tue, 01 Aug 2006 00:00:00 GMT

Title: Solid phase extraction and spectrophotometric determination of platinum(IV) with N-(3,5-dihydroxyphenyl)N'-(4-aminobenzenesulfonate)-thiourea Authors: Li, Zhigang; Li, Xuemei; Zhu, Liya; Hu, Qiufen; Chen, Jing; Yang, Guangyu Abstract: A highly sensitive, selective and rapid method for the determination of platinum(IV) based on its rapid reaction with N-(3,5-dihydroxyphenyl)-Nʹ -(4-aminobenzenesulfonate)-thiourea (DHPABT) and the solid phase extraction of the Pt(IV)-DHPABT complex with a polymer-based C₁₈ cartridge has been developed. In 0.05 - 0.5 mol L^-1 HCl medium, DHPABT reacts with platinum(IV) to form a violet complex of a molar ratio 1:3 (platinum: DHPABT). This complex is enriched by the solid phase extraction with polymer-based C₁₈ cartridge and an enrichment factor of 200 has been obtained. The molar absorptivity of the complex is 1.01 × 10⁵L mol^-1 cm^-1 at 760 nm, and Beer's law is obeyed in the range of 0.01-3.0 μg mL^-1. The relative standard deviation for eleven replicate analysis of 0.01μg mL^-1 solution is 1.86 %. The detection limit reaches 0.02 μg/L in the original samples. This method has been applied to the determination of platinum (IV) in water and soil samples. The relative standard deviation is 3.0- 3.3% and the standard recoveries are in the range 88 -107%. The determined values agree with those obtained by ICP-MS method. Page(s): 1852-1855

Voltammetric response of 2,4-D-molecularly imprinted film modified glassy carbon electrodes

Tue, 01 Aug 2006 00:00:00 GMT

Title: Voltammetric response of 2,4-D-molecularly imprinted film modified glassy carbon electrodes Authors: Wang, Zhihua; Kang, Jingwan; Liu, Xiaoyu; Ma, Yongjun Abstract: A novel voltammetric sensor has been developed by changing medium based on the molecular recognition of the template by imprinted technology. The sensitive layer has been prepared by electropolymerization of ortho-phenylenediamine and resorcinol on glassy carbon electrode in the presence of the template molecule. Cyclic voltammetry and a.c. impedance studies have been carried out to investigate the properties of the polymeric film. After the template extraction from the resultant solution, rebinding of 2,4-D has been done from 0.1 mol/L H₂SO₄ containing the analyte. The amount of bonded 2,4-D has been determined by differential pulse voltammetry. The sensor exhibits good sensitivity and reproducibility for 2,4-D by virtue of the interaction between molecularly imprinted binding sites and template. Page(s): 1848-1851

LSER and LFER in the reaction of benzimidazole with benzyl bromide

Tue, 01 Aug 2006 00:00:00 GMT

Title: LSER and LFER in the reaction of benzimidazole with benzyl bromide Authors: Reddy, S Ranga; Manikyamba, P Abstract: The second order rate constants of the nucleophilic substitution reaction of benzyl bromide with benzimidazole have been obtained conductometrically in 11 different solvents in the temperature range 303-318 K. The rate constants are correlated with the polarisability (P) of the solvent and hydrogen bond acceptor basicity (β) of tile solvent leading to a biparametric equation, log k = -7.86+20.23P + 1.45β (n = 11, R = 0.93, SE =0.08). Substituent effect on rate of the reaction suggests that both electron donating group (p-CH₃) and electron withdrawing groups (p -NO₂, p-Br) enhance the rate of the reaction compared to the unsubstituted compound. The substituted (p -NO₂, p-Br) and the unsubstituted compound form a linear free energy relationship. Page(s): 1844-1847