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    Adsorption of levulinic acid from aqueous solution by Amberlite XAD-4
    (Elsevier Science Bv, 2017) Datta, Dipaloy; Uslu, Hasan
    Levulinic acid (LA) from aqueous solutions was removed by using commercial adsorbent Amberlite XAD-4 (XAD-4). The equilibrium and kinetic studies were performed to investigate the effect of adsorbent amount (1 g to 3.5 g at 298 K, 308 K and 318 K), initial acid concentration (2 g.L-1 to 4 g.L-1 at 298 K, 308 K and 318 K), and contact time (t, 10 min to 90 min at 298 K) on the capability of XAD-4. The uptake capability and removal efficiency of XAD-4 for the adsorption of LA was observed to increase by increasing amount of adsorbent. In the equilibrium experiments of LA adsorption, adsorption capacity value was increased to 26.85 mg.g(-1) from 10 mg.g(-1) at 298 K with an increase in the amount of XAD-4. In the kinetic studies, the equilibrium time of 70 min was obtained. Also equilibrium study was performed at three different temperatures, 298, 308 and 318 K. The maximum removal was obtained at 298 K. Thermodynamic model parameters such as Delta G degrees, Delta H degrees and Delta S degrees are estimated at three different LA concentration (2 g.L-1, 3 g.L-1 and 4 g.L-1). Different isotherm and kinetic models were applied to estimate the equilibrium and kinetic parameters. (C) 2017 Elsevier B.V. All rights reserved.
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    Adsorptive Separation of Lead (Pb2+) from Aqueous Solution Using Tri-n-octylamine Supported Montmorillonite
    (Amer Chemical Soc, 2017) Datta, Dipaloy; Uslu, Hasan
    Divalent lead present in the water stream was removed by using adsorption techniques with montmorillonite clay (Mt) modified with tri-n-octylamine (Mt-TOA). Batch adsorption data at equilibrium were determined with different initial Pb2+ ions concentration (8, 10, 12, 14, and 16 mg.L-1) in the aqueous solution at 298 K, and these results were correlated by using three different isotherm models, for instance, the Langmuir, the Freundlich, and the Temkin. The two-parameter Langmuir model was the best fit to the equilibrium data with a coefficient (R-2) greater than 0.99. The maximum capacities for monolayer adsorption of Mt and Mt-TOA were determined to be 3.37 mg.g(-1) and 33.1 mg.g(-1), respectively, as estimated from Langmuir. Also, experimental values were generated to evaluate the influence of adsorbent amount (w, 0.05-0.3 g for Mt, 0.01-0.06 g for Mt-TOA), starting Pb2+ ion concentration (C-0,8 mg.L-1 to 16 mg.L-1), pH (between 1 and 9), and contact period (t, from 10 to 110 min) on the removal effectiveness and adsorption capability of Mt and Mt-TOA adsorbents. In respect to kinetic studies, the removal efficiency of Pb2+ ion reached to a fixed value of 81.42% with Mt (0.1 g) and 80.67% by Mt-TOA (0.01 g) next 100 and 80 min, respectively. Pseudo-first order, pseudo-second order, and intraparticle diffusion models were studied to obtain the kinetic parameters of the adsorption practice. It is observed that the rate of mass transfer of Pb2+ ions was mainly governed by the intraparticle diffusion mechanism.
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    Separation of 2,4,6-trinitrophenol from aqueous solution by liquid-liquid extraction method: Equilibrium, kinetics, thermodynamics and molecular dynamic simulation
    (Elsevier Science Sa, 2016) Uslu, Hasan; Datta, Dipaloy; Santos, Dheiver; Bamufleh, Hisham S.; Bayat, Cuma
    In this paper, the equilibrium and kinetic studies on the extraction of 2,4,6-trinitrophenol (picric acid) (0.021-0.061 kmol m(-3)) using Amberlite LA2, a secondary amine (ALA2: 0.118-0.588 kmol m(-3)) dissolved in a polar active solvent, methyl-iso-butyl ketone (MIBK) are performed. Also, the temperature effect (293.2 +/- 1 K, 303.2 +/- 1 K and 313.2 +/- 1 K) on the extraction mechanism and efficiency is evaluated. Thermodynamic parameters like the change in entropy and enthalpy are determined. From the values of loading ratio (Z < 0.5), it is inferred that the amine molecule form 1:1 complex with the acid molecule in the organic phase. The mass transfer coefficient (k(L), = 3.1 x 10(-5) m s(-1)) of picric acid in MIBK is determined. The Hatta number is calculated, and observed to vary in the range of 0.0032-0.0054, indicating that there is a very slow chemical reaction taking place between the acid and the amine molecule in the bulk of the organic phase. The reaction order is estimated to be 0.9 w.r.t picric acid, and 0.6 w.r.t ALA2 with rate constants of 14.95 x 10(-6) (kmol m(-3))(-0.5) s(-1), and 8.94 x 10(-7) (kmol m(-3))(-0.5) s(-1), for forward and backward reaction, respectively. Kinetic and potential energies of components during reactive extraction have been determined by molecular dynamic modeling. (C) 2016 Elsevier B.V. All rights reserved.
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    Separation of copper ion (Cu2+) from aqueous solution using tri n butyl phosphate and di 2 ethylhexyl phosphoric acid as extractants
    (Elsevier Science Bv, 2018) Ghosh, Amritendu; Datta, Dipaloy; Uslu, Hasan; Bamufleh, Hisham S.; Kumar, Sushil
    In this study, separation of copper ion (Cu2+) from aqueous solution using two phosphorous based extractants (tri n butyl phosphate and di 2 ethylhexyl phosphoric acid) was aimed. The parameters monitored under the equilibrium study were initial copper concentration, extractant concentration, and pH. The copper concentration was taken in the range of 20 to 100 ppm, the extractant composition in the organic phase was varied from 10 to 40 vol% dissolving in toluene as an inactive diluent, and the pH effect was studied in the range of 1 to 11. The distribution coefficients were calculated, and a model equation was developed to estimate model parameters like the number of reacting molecules of the extractant and equilibrium constant using experimental results. In the kinetic study, the initial aqueous phase copper concentration, and the extractant concentration were changed, and initial rates of extraction were found out to develop a kinetic model and their parameters like rate constant and order of reaction. (C) 2018 Elsevier B.V. All rights reserved.
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    Separation of Levulinic Acid Using Polymeric Resin, Amberlite IRA-67
    (Amer Chemical Soc, 2019) Uslu, Hasan; Datta, Dipaloy; Santos, Dheiver; Öztürk, Muhsin
    The adsorptive separation of levulinic acid (LA) from its aqueous solution was studied by using a commercial adsorbent and weakly basic anion exchange resin, Amberlite IRA-67 (IRA-67). The data were generated for equilibrium and kinetic studies, and to analyze the performance of IRA-67 on the removal efficiency. The equilibrium study was performed to see the effect of adsorbent quantity (0.25-1.5 g) and initial LA concentrations (2-4 g.L-1) at three different temperatures (298, 308, and 318 K). To determine the kinetics of adsorption process, concentration profile was achieved up to a time of 90 min at 298 K. It was observed that both the intake capacity (32-64 mg.g(-1)) and removal efficiency (6.75-72.5%) of IRA-67 were increased with an increase in the quantity of adsorbent (0.25-1.5 g) at 298 K. From the kinetics of adsorption, 50 min was considered as an equilibrium time. Different isotherm and kinetic models were used to determine the equilibrium and kinetic parameters of LA adsorption process. From the temperature study (298, 308, and 318 K), the thermodynamic properties were also estimated at three different LA concentrations.
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    Solvent Polarity Effect when Amberlite-LA2 Is Used in the Extraction of Picric Acid
    (Amer Chemical Soc, 2017) Uslu, Hasan; Datta, Dipaloy; Bamufleh, Hisham S.
    The separation and recovery of picric acid (0.061 mol-kg(-1)) from its aqueous solution was studied at a fixed temperature of 298 K. The extraction experiments were performed by using a secondary amine, Amberlite-LA2 (ALA2), dissolved in five different solvents such as dichloromethane (DCM), dodecanol, toluene, benzene, and dodecane. Physical extraction data were also produced by pure solvent alone. The experimental data obtained from the batch studies were analyzed by calculating the distribution coefficient (K-D), extraction efficiency (%E), and loading factor (Z). The highest synergistic effect was achieved with DCM in ALA2 at a concentration of 0.588 mol.kg(-1) as 83.61%. The equilibrium constants for the complex formation between acid and amine (1:1 and 2:1) were calculated for all the solvents applying the mass action law.
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    Zn2+ Ion Adsorption from Aqueous Solution Using Montmorillonite Clay Impregnated with Tri-n-octylamine
    (Amer Chemical Soc, 2017) Uslu, Hasan; Datta, Dipaloy; Bamufleh, Hisham S.
    Montmorillonite (Mt) clay was used to remove zinc (Zn2+) ion from the aqueous solution. This clay material was modified (Mt-TOA) by impregnating trin-octylamine (TOA), a tertiary amine. The experiments on equilibrium and kinetics were done to analyze the effect of adsorbent amount (w, 0.05 to 0.3 g for Mt, 0.01 to 0.06 g for Mt-TOA), initial Zn2+ ion concentration (C-0, 15 mg.L-1 to 35 mg.L-1), pH (1 to 9), and contact time (t, 0 to 100 min) on the efficacy of both adsorbents. With a greater amount of adsorbent, the intake capacity of Mt and Mt-TOA for Zn2+ ion removal was found to lower but there was an increase in the separation efficiency. The optimum amount of Mt and Mt-TOA was found to be 0.1 and 0.01 g, respectively. The pH of the aqueous solution could be maintained at 7 to achieve a better adsorption of Zn2+ ion. In the kinetic experiments, after 90 min, the separation efficiency of Zn2+ ion from aqueous solution reached to a value of 86.68% with Mt (0.1 g) and 84.56% with Mt-TOA (0.01 g). Modeling of the equilibrium and kinetic data were done by using the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich, and by using the pseudo-first-order, pseudo-second-order, and intraparticle diffusion models, respectively, and the best fitted model is presented.