NOPR Collection:

Novel electrochemical synthesis of oxadiazoles at graphite electrode

2011-02-16T16:30:41Z

Title: Novel electrochemical synthesis of oxadiazoles at graphite electrode Authors: Shivaraj, Y; Geetha, A; Shashishekar, T R; Sherigara, B S; Kalluraya, B Abstract: Electrochemical methods involve electrons transfer without the use of any oxidizing or reducing reagents and hence result in the formation of useful and/or novel organic compounds under mild conditions. In this paper, we report the preparation of 3-substituted-1,2,3-oxadiazole-5-one derivatives by the electrochemical reduction of 3-arylsydnones on graphite electrode is reported. The –N=N– moiety in these compounds undergo electrochemical reduction. Products of the electrolyzed species are isolated by bulk electrolysis at graphite electrode with a larger surface area. Characterizations of the reduced products are done by spectral and analytical data. Page(s): 76-80

A comparative evaluation for adsorption of dye on Neem bark and Mango bark powder

2011-02-16T16:30:41Z

Title: A comparative evaluation for adsorption of dye on Neem bark and Mango bark powder Authors: Srivastava, Ruchi; Rupainwar, D C Abstract: The use of low cost adsorbent has been investigated as a replacement for the current expensive methods of removing dyes from wastewater. As such, Neem bark and Mango bark generated as a wood waste is collected and converted into a powder form and then used as a low-cost adsorbent for removal of dyes from wastewater. Adsorption studies are carried out at different temperatures, pH, initial dye concentrations and adsorbent doses. The adsorption of malachite green (dye) is found to increase with increase in temperature. The linear form of Langmuir and Freundlich models fitted the adsorption data. The results indicated that Langmuir adsorption isotherm fitted the data better than Freundlich isotherm. Thermodynamic parameters such as the free energies, enthalpy and entropy of adsorption of the dye-Mango bark, Neem bark powder systems are also evaluated. The negative values of free energy indicated the feasibility and spontaneous nature of the process, and the positive heats of enthalpy suggest the endothermic nature of the process. The adsorption of Malachite green follow the second-order kinetics in both the adsorbents. Page(s): 67-75

Comparative study on biosorption of Zn(II), Cu(II) and Cr(VI) from textile dye effluent using activated rice husk and activated coconut fibre

2011-02-15T16:30:41Z

Title: Comparative study on biosorption of Zn(II), Cu(II) and Cr(VI) from textile dye effluent using activated rice husk and activated coconut fibre Authors: Gopalakrishnan, K; Jeyadoss, T Abstract: This paper reports the results of the study on the performance of the low cost adsorbents such as activated rice husk (ARH) and activated coconut fibre (ACF) in removing the heavy metals such as Zn(II), Cu(II) and Cr(VI) from textile dye effluent. Biosorption studies are carried out through various parameters such as adsorbent dosage, pH and contact time. Removal of heavy metal ions from the textile dye effluent increases with increase in adsorbent dosage. In ARH, at 50 g/L the maximum of 62%, 68% and 65% removal of Zn(II), Cu(II) and Cr(VI) are obtained respectively, whereas, in ACF, at 50 g/L the maximum of 64%, 67% and 72% removal of Zn(II), Cu(II) and Cr(VI) are obtained respectively. In the effect of pH, the maximum removal of metal ions occurs at pH 1-3 for both the adsorbents. In contact time, the maximum removal of heavy metal ions is observed at optimum time of 300 min. The maximum removal of heavy metal ions from the textile dye effluent using ARH and ACF is evaluated successfully through the percentage of seed germination of Vigna mungo L with the treated adsorbents. On comparison, ACF is good adsorbent when compared with ARH. Page(s): 61-66

Removal of Eriochrome black-T by adsorption on to eucalyptus bark using green technology

2011-02-16T16:30:40Z

Title: Removal of Eriochrome black-T by adsorption on to eucalyptus bark using green technology Authors: Dave, Pragnesh N; Kaur, Satindar; Khosla, Ekta Abstract: The efficiency of eucalyptus bark as a low cost adsorbent for removing an azo dye from an aqueous solution has been investigated in batch mode. The azo dye, Eriochrome black-T (EBT) is removed by adsorption over field waste eucalyptus bark after minimum chemical treatment. The investigations are carried out to study the effects of pH, adsorbate concentration, adsorbent dosage, contact time and temperature. The thermodynamic parameters were obtained from Langmuir and Freundlich adsorption isotherm models. The kinetic studies showed that the adsorption reaction is of first order. A fixed-bed column has been designed, and necessary parameters have been calculated by applying a mass transfer kinetic approach. Experiments are also performed for the recovery of loaded dye through chemical regeneration of spent columns. Page(s): 53-60