NOPR Collection:

Extraction spectrophotometric determination of micro amounts of palladium(II) in catalysts

Mon, 01 Aug 2005 00:00:00 GMT

Title: Extraction spectrophotometric determination of micro amounts of palladium(II) in catalysts Authors: Gaikwad, S H; Lokhande, T N; Anuse, M A Abstract: A new reagent, 4-(2ʹ-furalideneimino)-3-methyl-5-mercapto- 1,2,4-triazole, has been synthesized and used as a chromogenic reagent for palladium(II). Palladium(II) has been extracted as a yellow complex (λ_max 410 nm) from an aqueous solution at pH 5.4 with FIMMT in n-butanol. The molar extinction coefficient and Sandell's sensitivity are 1.4 ×10³ L mol^-1 cm^-1 and 0.073μg cm^-2, respectively. The effects of pH, reagent concentration, solvent, shaking time and stability of the complex have been studied. The complex system confirms to Beer's law over the range 5-50 ppm of palladium(II) with optimum range 17-50 ppm of the metal as evaluated from Ringbom's plot. The tolerance limit for many metal ions has been determined. The method has been applied successfully for the determination of palladium(II) in synthetic mixtures corresponding to alloys and palladium(II) in various hydrogenation catalysts. Page(s): 1625-1630

Determination of mercury in geological samples by cold vapour atomic absorption spectrometric technique

Mon, 01 Aug 2005 00:00:00 GMT

Title: Determination of mercury in geological samples by cold vapour atomic absorption spectrometric technique Authors: Mathur, Ramavati; Balaram, V; Babu, S Suresh Abstract: A method for determination of total mercury in geological samples using acid digestion and subsequent measurement by cold vapour atomic absorption spectrometric technique is described. Sample digestion has been carried out using a combination of hydrochloric and nitric acids followed by reduction of mercury (II) in the extract of its elemental form by stannous chloride. The absorption signal at 253.7 nm has been monitored with a mercury analyzer. The method is simple, cost effective and gives reliable results as indicated by the data obtained on a few international geochemical reference samples, analyzed in this study. Precision of the measurements is within 5% RSD for closed vessel digestion. The detection limit of mercury is found to be 5 ng when 1 ml of 1% sample solution is ulilized. Comparison of data obtained for the same set of standards using both open vessel and closed Savillex pressure decomposition vessel digestions demonstrates enhanced extraction in several cases while using closed vessel digestion. Results indicate that the method can be applied for determination of low levels of mercury in a variety of geological samples for exploration studies. Page(s): 1619-1624

Biosorption of europium radionuclide by calcium alginate beads

Mon, 01 Aug 2005 00:00:00 GMT

Title: Biosorption of europium radionuclide by calcium alginate beads Authors: Nayak, Dalia Abstract: Studies on adsorption behaviour of ¹⁵²Eu have been carried out with calcium alginate beads. High removal is achieved in a wide pH range 2-8. Nearly 98% europium removal has been attained at pH 3. Recovery or europium radionuclide has also been achieved using HCl. It has been observed that 1 M HCl could remove 95% of adsorbed ¹⁵²Eu . Page(s): 1615-1618

Electrochemical studies on polystyrene based membrane of zirconium(IV) antimonoarsenate

Mon, 01 Aug 2005 00:00:00 GMT

Title: Electrochemical studies on polystyrene based membrane of zirconium(IV) antimonoarsenate Authors: Mittal, Susheel K; Sharma, Harish Kumar Abstract: Electrochemical studies have been carried out on heterogeneous ion-exchange membranes of zirconium(IV) antimonoarsenate using polystyrene as a binder. Electrical characteristics like transport number, permselectivity and fixed charge density of the exchanger membrane and halide salts of some alkali and alkaline earth metals as electrolytes have been determined. The membrane potential data conforms to the Kobatake theoretical treatment of irreversible processes. The effect of electrolyte concentration on transport numbers and permselectivity has also been studied. Results indicate that the membrane is permselective for counterions and possesses weak electrical character. Page(s): 1610-1614