NOPR Collection:

Utilization of sodium montmorillonite clay for enhanced electrochemical sensing of amlodipine

2016-05-01T00:00:00Z

Title: Utilization of sodium montmorillonite clay for enhanced electrochemical sensing of amlodipine Authors: Sikkander, A Mohamed; Vedhi, C; Manisankar, P Abstract: Nanosize surface of sodium montmorillonite has been prepared via sonication and deposited on glassy carbon electrodes for use as working electrode in a highly sensitive electrochemical biosensor for the detection of trace amounts of the calcium channel blocking drug, amlodipine. The cyclic voltammetric behaviour of amlodipine is studied in the pH range of 1.0−13.0. In alkali medium (pH 13.0) the sensor shows good response. Cyclic voltammograms show one oxidation peak and one broad reduction peak, which may be due to the oxidation of secondary amino group and reduction of chlorine and nitro groups respectively. Plots of log peak current and potential when correlated with log scan rate, indicate irreversible electron diffusion controlled redox reaction. The optimum conditions have been established by differential pulse stripping voltammetry. The anodic peak current is linear with concentration of the analyte at optimum conditions; the detection limit has been determined to be 0.01 μg/mL. A simple, sensitive and time-saving differential pulse stripping voltammetric procedure has been developed for estimation of amlodipine in its formulations as tablets. Page(s): 571-575

Synthesis of heteroatom-doped ZnO nanoparticles as an efficient visible light photocatalyst and its photoelectrochemical performance

2016-05-01T00:00:00Z

Title: Synthesis of heteroatom-doped ZnO nanoparticles as an efficient visible light photocatalyst and its photoelectrochemical performance Authors: Wu, Wenjie; Zhu, Xiaodan; Yin, Qiaoqiao; Tan, Linxiang; Ke, Xiaoxia; Qiao, Ru Abstract: Heteroatom-doped ZnO nanoparticles (Zn_1-xNi_xO NPs) have been synthesized by a simple solvothermal approach. The photocatalytic activity of the products has been evaluated by a photoassisted degradation of Rhodamine B in aqueous solution under visible light irradiation. All the heteroatom-doped semiconductors exhibit better photocatalytic activities than pure ZnO, with the 1 mol% Ni²⁺-doped ZnO showing the best photocatalytic activity. From the transient photocurrent response and electrochemical impedance spectroscopic experiments it is observed that the photogenerated charges of the Ni-doped ZnO show longer lifetime and higher separation than that of pure ZnO, leading to its superior visible light photoactivity. The active species tests indicate that the hydroxyl radical and active holes were primarily responsible for the enhanced photocatalytic performance of Rhodamine B, and the superoxide radical takes part partially in the oxidation process. A possible photocatalytic mechanism is proposed. Good photostability and reusability of the product show that the studied nanoparticles have potential application in dye wastewater treatment. Page(s): 566-570

Hydrolytic cleavage of paraoxon and parathion by oximate and functionalized oximate ions: A comparative study

2016-05-01T00:00:00Z

Title: Hydrolytic cleavage of paraoxon and parathion by oximate and functionalized oximate ions: A comparative study Authors: Dewangan, Hitesh K; Kandpal, Neha; Nagwanshi, Rekha; Satnami, Manmohan L Abstract: Bimolecular reactions of O,O-diethyl-O-p-nitrophenylphosphate (paraoxon) and O,O-diethyl-O-p-nitrophenyl phosphorothioate (parathion) with oximate (pyridinealdoxime 2-PyOx^- and 4-PyOx^-) and its functionalized oximate, 4-(hydroxyimino)methyl)-1-alkylpyridinium bromide ions (alkyl = C₁₀H₂₁ (4-C₁₀PyOx^-); alkyl = C₁₂H₂₅ (4-C₁₂PyOx^-)) have been investigated in aqueous and cationic micellar media of cetylpyridinium bromide, cetyltrimethyl-ammonium bromide and cetyltetradecyltrimethylammonium bromide at pH 9.5 and 27 ^oC. Under the micellized condition, a 1.2×10³ fold and 9.0×10⁶ fold rate enhancement over the aqueous reaction of paraoxon (k_o = 7.5×10^-8 s^-1) and parathion (k_o = 9.5×10^-11) is observed. Page(s): 560-565

Vapour phase hydrogenation of aqueous levulinic acid to γ-valerolactone over CuZnAlO hydrotalcite

2016-05-01T00:00:00Z

Title: Vapour phase hydrogenation of aqueous levulinic acid to γ-valerolactone over CuZnAlO hydrotalcite Authors: Jaya, V Swarna; Sudhakar, Medak Abstract: Vapour phase hydrogenation of levulinic acid to γ-valerolactone has been accomplished in aqueous phase over copper-zinc-aluminum hydrotalcite, prepared by co-precipitation method using nitrate salts as their precursors. The hydrotalcite system exhibits superior activity in the hydrogenation and cyclization of 10% aqueous solution of levulinic acid with >99% selectivity for γ-valerolactone at 275 ^oC under atmospheric pressure of hydrogen (flow rate of H₂-30 mL/min). Page(s): 554-559