58 research outputs found
Prediction of Ionic Cr (VI) Extraction Efficiency in Flat Sheet Supported Liquid Membrane Using Artificial Neural Networks (ANNs)
No full textArtificial neural networks (ANNs) are computer techniques that attempt to simulate the functionality and decision-making processes of the human brain. In the past few decades, artificial neural networks (ANNs) have been extensively used in a wide range of engineering applications. There are only a few applications in liquid membrane process. The objective of this research was to develop artificial neural networks (ANNs) model to estimate Cr (VI) extraction efficiency in feed phase. Data set (413 experiment records) were obtained from a laboratory scale experimental study. Various combinations of experimental data, namely % (w/w) extractant Alamine 336 concentration in membrane phase, stirring speed in feed and stripping phase, flat sheet support type, stripping phase NaOH concentration, feed phase pH, diluents type, % (w/w) diluents concentration, polymer support type, extractant type, and time are used as inputs into the ANN so as to evaluate the degree of effect of each of these variables on Cr (VI) extraction efficiency in feed phase. The results of the ANN model is compared with multiple linear regression model (MLR). Mean square error (MSE), average absolute relative error (AARE) and coefficient of determination (R(2)) statistics are used as comparison criteria for the evaluation of the model performances. Based on the comparisons, it was found that the ANN model could be employed successfully in estimating the Cr (VI) extraction efficiency
Overlapping Large Polaron Conductivity Mechanism and Dielectric Properties of Al0.2Cd0.8Fe2O4 Ferrite Nanocomposite
No full textIn this work, the conduction and dielectric properties of Al0.2Cd0.8Fe2O4 ferrite nanoparticle, which was synthesized by a co-precipitation method, were investigated. Experimental data were taken from 20 Hz to 10 MHz and from 293 to 613 K. AC conductivity of the sample was analyzed within the framework of the overlapping large polaron tunneling (OLPT) mechanism. DC conductivity behavior fits the classical Arrhenius-type conductivity in the examined temperature range. Electrical properties of the material sample have been studied using an impedance spectroscopy technique. The effect of frequency and temperature on dielectric constant (epsilon (')), dielectric loss (tan oee integral), and impedance (Z' and Z'') has been discussed in terms of hopping of charge carriers between Fe2+ and Fe3+ ions. According to results, a relaxation process fits the Cole-Cole model
A comprehensive study for selective removal of Cr(VI) by asymmetric imidazolium bromide salts as environmentally-friendly extractant
No full text.The study was to determine selective removal and recovery of Cr(VI) from acidic media by solvent extraction (SX) using asymmetric imidazolium-based room temperature imidazolium bromide salts (ARTILs) as the extractants. The relevant parameters on the extraction and the stripping of Cr(VI) were investigated to identify optimum conditions. The optimum conditions were determined as equilibration time 5 minutes, acid concentration and type 0.5 mol/L H2SO4, stirring speed 1200 rpm, extractant concentration and type 0.5 mol/L ARTIL5, phase ratio 2.0 and stripping reagent type, and concentration 2.0 mol/L NH3. In optimum conditions, decyl substituted ARTIL was best in extraction process about 99.7% of extraction rate, whereas moderately hydrophobic pentyl substituted ARTIL was best in stripping process about 70.0% of stripping rate. Also, the optimized process was found as so selective toward Cr(VI) in the presence of the other metal ions with an environmental-friendly liquid–liquid–based SX method
Separation of Co(II) from Zinc Plant Acidic Thiocyanate Leach Solutions Containing Co(II) and Ni(II) by Solvent Extraction Using Trioctylamine in Toluene
No full textIn this study, a zinc plant purification cake (CINKUR Co. Turkey) was leached with sulphuric acid and an acidic leach solution containing Zn(II), Fe(II), Pb(II), Al(III), Cu(II), Co(II) and Ni(II) ions was obtained. After purification, ammonium thiocyanate and water were added to the remaining leach solution containing Co(II) and Ni(II) ions to adjust the chemical media and ion concentration. The acidic thiocyanate leach solutions were used in solvent extraction experiments. The various parameters were studied to determine the extraction and striping behaviour of Co(II). These parameters were diluent type, feed solution pH, extractant concentration, mixing speed, phase ratio, stripping solution type and concentration and etc. Under optimum extraction conditions, the maximum extraction efficiency (99.9 %) was achieved when using 5.0 %(v/v) TOA in toluene within 5 min. The extracted Co(II) was stripped effectively from the organic phase using 5.0 M NH3 solution
An assessment of alkyl chain length effect of symmetric midazolium salts as a carrier for selective separation of Cr(VI)
No full textSelective solvent extraction (SSX) of Cr(VI) and recovery was evaluated by using a homologous series of symmetric imidazolium bromide salts (SIMs) having various alkyl chain length. Therefore, propyl, pentyl, hexyl, octyl, and decyl substituted SIMs were used as an ion carrier. The executive parameters affecting both extraction and stripping conditions were investigated for optimization. Finally, a direct correlation was observed a between increasing alkyl chain length and selective Cr(VI) extraction from acidic solutions containing Cr(VI), Fe(III), Co(II), Cd(II), Ni(II). This relationship was reversed in the stripping conditions. Optimal extraction and stripping were obtained for SIM5 and SIM2 as 97.49% and 70.00%, respectively
The Organizational Citizenship Behaviour of Academic Staff in North Cyprus
No full textAbstractDue to its contribution to the effective functioning of organizations the topic of Organizational Citizenship Behaviour (OCB) has gained much attention over the past years and has been studied in a diversity of settings. The purpose of this study was to examine OCB in the higher education sector. More specifically, the study investigated the degree of OCB that exists amongst the academic staff at a private university in North Cyprus. The study instrument utilized was the “Organizational Citizenship Behaviour Scale” developed by Podsakoff et al. (1990) which is the most widely used OCB study instrument in the literature. The 24 item scale measures the five subscales/dimensions of OCB, namely altruism, conscientiousness, sportsmanship, courtesy, and civic virtue. The average of all 24 items calculates overall OCB. The study results indicate that OCB does exist amongst the academic staff at the Faculty of Economics and Administrative Sciences; however the results are only partial in that the study is still ongoing. The complete study results will enable the researcher to conclude whether academic staff from different faculties indicates different levels of OCB
Selective and Synergistic Extraction of Nickel from Simulated Cr-Ni Electroplating Bath Solutions using LIX 63 and D2EHPA as Carriers
No full textThe main goal of the present study is to explain synergistic extraction of nickel from simulated Cr-Ni electroplating bath solutions (SEBS) using 5,8-diethyl-7-hydroxydodecane-6-one oxime (LIX 63) and di-(2-ethylhexyl) phosphoric acid (D2EHPA) as extractants by emulsion liquid membrane (ELM) technique. The importance of membrane composition and aqueous phase properties on nickel extraction percentage has been highlighted for the selective extraction of nickel. Some important parameters like acid concentration, stripping solution type and concentration, mixing speed, extractant concentrations, phase ratio, and surfactant concentration was studied to improve the extraction and stripping efficiencies. Higher than > 99% of nickel was recovered at optimum conditions within 6 min. The higher separation factors (beta(Ni/Cr)) were obtained as 580. As a result, the nickel extraction kinetic with D2EHPA has been defined as faster than LIX63. So, the kinetic transport of nickel mainly depends on LIX63 than D2EHPA. According to these results, D2EHPA behaves as a synergistic extractant in the present extraction mechanism
Extraction of Ni(II) from spent Cr-Ni electroplating bath solutions using LIX 63 and 2BDA as carriers by emulsion liquid membrane technique
No full textIn the present study, the synergistic extraction of Ni(II) from spent Cr-Ni electroplating bath solutions (SEBS) was determined using 5,8-diethyl-7-hydroxydodecan-6-one oxime(LIX 63) and 2-bromodecanoic acid(2BDA) by emulsion liquid membranes(ELM)s. The effect of membrane and aqueous phase properties on Ni(II) transport was experimentally investigated. Ni(II) extraction was obtained to be higher than 98.5% in the optimum conditions within 6 min. The higher separation factor (beta Ni/Cr) was obtained as 677. In addition, Ni(II) extraction kinetics depends on LIX63 because the extraction kinetics of LIX63 is slower than 2BDA. Therefore, we have determined that 2BDA acts as a synergist in present extraction system. (C) 2014 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved
Synergistic and selective extraction of Cd2+ from acidic solution containing Cd2+, Co2+, Ni2+ by triisooctylamine (TIOA) and tributyl phosphate (TBP)
No full textSelective and synergistic extraction of cadmium from acidic iodine solutions containing Cd2+, Co2+ and Ni(2+)using solvent extraction (SX) technique is presented in this study. The study has highlighted the importance of main and synergistic extractants composition. The mixtures have evident synergistic effects on Cd2+ with a synergistic enhancement factor of 2.22. The various experimental parameters were studied to determine the optimum extraction and stripping conditions of Cd2+. Under optimum conditions, the maximum extraction efficiency (99.7%) was achieved when using 1.5% (v/v) TIOA and 0.5% (v/v) TOP in dichloromethane within 5 min. Extracted Cd2+ was stripped effectively from the organic phase using 2.0 mol/L NaOH solution. (c) 2012 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved
Determination by ICP/MS of trace metal content in ten edible wild mushrooms from Turkey
No full textThe determination of nineteen trace metal levels (Li, Be, Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Cd, Sn, Sb, Te, Hg and Pb) was performed for ten naturally growing edible mushroom species in three different provinces of Turkey. The possibility of using the mushrooms as a bio-indicator of environmental pollution was investigated. Trace metal contents were determined by inductively coupled plasma mass spectrometry (ICP-MS), after wet digestion procedure. The highest amounts of Li, Al, V, Fe and Se were found in C. cornucopioides (0.41, 285.92, 0.595, 300.87 and 0.780 µg g–1, respectively), the highest amounts of Co, Ni, Cu, Sb and Hg were found in H. lacunosa (1.736, 1.687, 13.22, 0.452 and 0.402 µg g–1, respectively), the highest amounts of Cr and Zn were found in S. squamosus (0.700 and 29.16 µg g–1, respectively), the highest amounts of Te and Pb were found in T. anatolicum (0.007 and 1.102 µg g–1, respectively), the highest amounts of Be were found in M. costata (0.018 µg g–1), and the highest levels of Mn were found in R. roseolus (8.49 µg g–1). The Pb, Cd, Cr, As, Ni, Sn and Hg contents determined in the edible mushrooms which we analysed were lower than the observed values in literature. Also, available data indicate that the mushroom collection area was not polluted by toxic heavy metals. These data are important in the fields of toxicology, food chemistry and environmental protection. © 2015, Scibulcom Ltd. All rights reserved
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