NOPR Collection:

Effect of sample containers on the EDXRF determination of uranium in aqueous solutions

2016-07-20T06:06:20Z

Title: Effect of sample containers on the EDXRF determination of uranium in aqueous solutions Authors: Natarajan, V; Hon, N S; Bhide, M K; Godbole, S V Abstract: The utility of plastic/glass containers in place of regular sample cups made of high density polyethylene for the EDXRF determination of uranium has been examined. A series of uranium solution standards have been prepared and calibrated using different containers. For U solution in plastic cups with thin mylar film base, linearity between U L X-ray intensity and its concentration is observed upto U 20 mg/mL; for higher concentrations, non-linear trend is observed, indicating matrix absorption effects. For U solution in plastic vials, similar behaviour is observed, with reduced matrix absorption. In the case of U solutions in sealed plastic vials, the reduction in the intensities of U X-rays of standard solutions is about 30-70% of those for U in unsealed vials. In the case of glass vials, the intensity of U X-ray peak decreases drastically as compared to that for U in plastic cups with thin mylar film base. The present study suggest the utility of sealed plastic vials for the fast preliminary determination of uranium in low active process / laboratory waste solutions with a precision of about 5-15%. Page(s): 82-84

Spectrophotometric determination of chromium by using sulphanilic acid and N, N-dimethylaniline

2016-07-20T06:05:17Z

Title: Spectrophotometric determination of chromium by using sulphanilic acid and N, N-dimethylaniline Authors: Chandrashekhara, K G; Gopalakrishna, Bhat N; Nagaraj, P Abstract: A sensitive and selective spectrophotometric method for the determination of trace amounts of chromium(VI) directly and chromium(III) after oxidation to chromium(VI) with bromine water has been developed. Chromium(VI) oxidises hydoxylamine using acetate buffer of pH 4 to nitrite, which then diazotises sulphanilic acid to form diazonium salt. These diazonium salts are then coupled with N, N-dimethylaniline in alkaline medium resulting azo dye methyl orange, which induces orange colour in acidic medium shows an absorption maximum at 507 nm. The method is free from the interferences of several metal ions and obeys Beer’s law in the range of 0.1 to 1.8 µg/mL in acidic medium. Molar absorptivity and Sandell’s sensitivity of the system with sulphanilic acid diazoniumchloride and N,N-dimethylaniline couple(methyl orange) in acidic medium are found to be 1.74 × 10⁴Lmol^-1 cm^-1and 3.84 × 10^-3µg/cm² respectively.The optimum reaction condition evaluation and interference of other ions on the determination have been described. The method is useful for the analysis of chromium in soil and pharmaceutical samples. Page(s): 78-81

Sonochemical degradation of p-chlorophenol assisted by H₂O₂and Ag-TiO₂ / TiO₂ catalyst

2016-07-20T06:04:08Z

Title: Sonochemical degradation of p-chlorophenol assisted by H₂O₂and Ag-TiO₂ / TiO₂ catalyst Authors: Nandwani, Shilpa K; Mungray, A K; Chakraborty, Mausumi Abstract: The degradation of p-chlorophenol in aqueous solution by low frequency ultrasound (30 kHz) has been studied. The degradation of p-chlorophenol in US/H₂O₂, US/ Ag- TiO₂ US/TiO₂, US/TiO₂/H₂O₂ and US/ Ag-TiO₂/H₂O₂ systems is also compared. The maximum removal of p-chlorophenol i.e 75% is observed in US/ Ag-TiO₂/H₂O₂ system where as 37% removal is observed in US/TiO₂/H₂O₂ system. Further the effect of initial substrate concentration, pH and temperature on the initial rate of degradation of the model pollutant have also been investigated. Studies reveal that the initial rate of degradation increases with increase in initial substrate concentration whereas the initial rate of degradation decreases with an increase in pH and reaction temperature. Page(s): 73-77

Synthesis of expandable graphite and its effect on flame retardancy properties of polyethylene

2016-07-20T06:02:43Z

Title: Synthesis of expandable graphite and its effect on flame retardancy properties of polyethylene Authors: Pang, Xiuyan; Zhai, Zhixiao; Duan, Mingwei; Tian, Yu Abstract: The graphite intercalating reaction with KMnO₄ as oxidant, H₂SO₄ as intercalating reagent and sodium tetraborate (Na₂B₄O₇·10H₂O) as assistant intercalating reagent has been carried out to prepare a combined intumescent flame retardant consisting of expandable graphite and borate. The method of preparing combined expandable graphite (EG) with a high dilatability and feasible initial expansion temperature is confirmed as following: mass ratio of C:KMnO₄:H₂SO₄(98%): Na₂B₄O₇·10H₂O is controlled as 1.0:0.4:5.5:0.6. H₂SO₄is diluted to 80 wt% before intercalation reaction, and the reaction last 40 min at 40°C. Initial expansion temperature and expansion volume of the EG are 155°C, 515 mL/g, respectively; and its flame retardancy for linear low density polyethylene is also investigated. Addition of 30 wt% EG to the polymer can make the limiting oxygen index increase from 17.1 to 28.4%. The flame retardancy can be improved by addition of ammonium polyphosphate APP, and the limiting oxygen index of 70 LLDPE/10APP/20EG reaches 30.5%. X-ray powder diffraction analysis, thermal gravimetric and Fourier transform infrared analysis have been used to illuminate the retardancy mechanism. The intercalating borate can make EG show higher dilatability and flame retardancy. Page(s): 67-72

NOPR Collection:

Effect of sample containers on the EDXRF determination of uranium in aqueous solutions

Spectrophotometric determination of chromium by using sulphanilic acid and N, N-dimethylaniline

Sonochemical degradation of p-chlorophenol assisted by H2O2 and Ag-TiO2 / TiO2 catalyst

Synthesis of expandable graphite and its effect on flame retardancy properties of polyethylene

Sonochemical degradation of p-chlorophenol assisted by H₂O₂and Ag-TiO₂ / TiO₂ catalyst