http://nopr.niscair.res.in/handle/123456789/55 Fri, 30 Jun 2017 09:36:26 GMT 2017-06-30T09:36:26Z http://nopr.niscair.res.in/handle/123456789/41864 Title: Response surface methodology for optimization of phenol adsorption by activated carbon: Isotherm and kinetics study Authors: Tabassi, Dorra; Harbi, Soumaya; Louati, Islem; Hamrouni, Bechir Abstract: The effect of four different parameters such as <i>p</i>H, initial phenol concentration, adsorbent dose and temperature on the adsorptive removal of phenol from aqueous solution over commercial granular activated carbon (GAC) has been studied. Two-level full factorial design (FFD) combined with response surface methodology (RSM) have applied to find the best operating conditions. The optimum <i>p</i>H, initial phenol concentration, adsorbent dose and temperature have been found by applying desirability function (DF) to be 6, 1000 mg/L, 3 g and 28.75°C. The granular activated carbon has been characterized using different physicochemical methods. The experimental data best fits in Freundlich isotherm Equation and the removal follow pseudo-first-order kinetics. Thermodynamic parameter reveals that the removal process is feasible, exothermic and spontaneous in nature. The adsorbent is regenerated with 0.1 M NaOH solution for further reuse. Page(s): 239-255 Mon, 01 May 2017 00:00:00 GMT http://nopr.niscair.res.in/handle/123456789/41864 2017-05-01T00:00:00Z http://nopr.niscair.res.in/handle/123456789/41863 Title: Experimental, surface characterization and computational evaluation of the acid corrosion inhibition of mild steel by methoxycarbonylmethyltriphenylphosphonium bromide (MCMTPPB) Authors: Goyal, Madhusudan; Yadav, Ompal; Kumar, Raman; Sharma, Raj Kishore; Singh, Gurmeet Abstract: The inhibition performance of the methoxycarbonylmethyltriphenylphosphonium bromide (MCMTPPB) on mild steel (MS) corrosion in 0.5 M H₂SO₄ has been evaluated using galvanostatic polarization (GP), potentiostatic polarization (PP), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and atomic force microscopy (AFM) techniques and complemented with the computational quantum calculations. GP study illustrates that the inhibition efficiency (%<i>IE</i>) increase with an increase in inhibitor concentration from 82.7% for 10^-5 M to achieve 99.8% for 10^-2M. Polarization tafel curves clearly signify that MCMTPPB operates as a mixed type inhibitor. PP graph indicates that passivation was observed only for a lower concentration of MCMTPPB. Impedance results show that the double layer capacitance (<i>C_dl</i>) decrease and charge-transfer resistance (<i>R_ct</i>) increase with increase in the inhibitor concentration and hence increasing inhibition efficiency. Temperature influences the corrosion rate; inhibition efficiency and surface coverage decrease with increase in the temperature (298 K to 328 K). Surface characterization SEM with EDAX provide strong facts for the existence of inhibitor sheet over the MS surface. AFM studies are in good agreement with the results obtained by other techniques. Quantum chemical (QC) parameters obtained using AM1 Semi-empirical methods are found to be in good agreement with the experimentally measured inhibition efficiencies. Page(s): 256-268 Mon, 01 May 2017 00:00:00 GMT http://nopr.niscair.res.in/handle/123456789/41863 2017-05-01T00:00:00Z http://nopr.niscair.res.in/handle/123456789/41862 Title: Extractive removal of Cr(VI) from aqueous acidic media by aliquat 336/xylene system: Optimization and modelling of equilibrium Authors: Senol, Aynur Abstract: The extractive removal of Cr (VI) from aqueous sulfate and nitrate solutions by Aliquat 336/xylene system has been studied at 298.2 K and 101.3 kPa. The extraction efficiency of Cr (VI) by Aliquat 336 follow the order H₂SO₄ > HNO₃. The carrier yields a maximum Cr (VI) removal efficiency fixed at the concentration ratio (Aliquat 336/Cr (VI) ≤ 0.5) for 0.1 mol/dm³ aqueous acidity. Separation profile of Cr (VI) is dependent equally strongly on the types and concentrations of the carrier, acid and the transferred Cr (VI) species. Distribution data have been subjected to formulation of an optimization structure for an effective Cr (VI) separation based on a derivative variation method. The method calls for the use the first order derivatives of the optimized quantity. 0.2 mol/dm³ Aliquat 336 concentration is optimal for achieving 99 and 80% Cr (VI) removal from aqueous sulfate and nitrate media, respectively. Re-extraction results indicate that Cr (VI) is stripped successfully from the organic phase by NaOH, NaCl and Na₂SO₄ solutions, yielding 88, 54.5 and 13.8% stripping degrees, respectively. Modelling efforts based on the LSER (linear solvation energy relation) and mass-action law principles have shown considerable success. The LSER-based solvation model using nine physical descriptors of components yielded a mean error of 10% and satisfies established limiting behaviour of the physical event. Page(s): 269-283 Mon, 01 May 2017 00:00:00 GMT http://nopr.niscair.res.in/handle/123456789/41862 2017-05-01T00:00:00Z http://nopr.niscair.res.in/handle/123456789/41861 Title: Nano Fe(OH)₃/zeolite as a novel, green and recyclable adsorbent for efficient removal of toxic phosphate from water Authors: Mikhak, Azadeh; Kassaee, Mohammad Zaman; Sohrabi, Akbar; Feizian, Mohammad Abstract: Magnetic Fe(OH)₃ is dispersed and stabilized over zeolite, giving rise to nano Fe(OH)₃/zeolite, which is used as an efficient, recyclable absorbent for phosphate removal from water. Phosphate removal is insensitive to the ionic concentration, yet is directly proportional with the concentration of the adsorbent, and is inversely proportional with the initial phosphate concentration and <i>p</i>H. The coexisting nitrate and bicarbonate anions have no significant influence on phosphate adsorption, while the presence of citrate or silicate decreases such adsorption. In contrast, the presence of acetate increases the phosphate removal. Kinetic data are well fitted in the pseudo-second-order model. High phosphate uptake capability and good reusability make Fe(OH)₃/Zeolite a potentially attractive adsorbent for the removal of toxic phosphate from water. Evidently this type of work is a step forward for large scale elimination of undesired contaminants from water which may benefit the world community. Page(s): 284-293 Mon, 01 May 2017 00:00:00 GMT http://nopr.niscair.res.in/handle/123456789/41861 2017-05-01T00:00:00Z