Naif A. Darwish

Effects of pH and Inorganic Salts on the Adsorption of Phenol from Aqueous Systems on Activated Decolorizing Charcoal

Abstract An experimental investigation of the effects of pH and three inorganic salts (KCl, KI, and NaCl) on the adsorption isotherms of phenol (from a dilute aqueous solution) on activated charcoal was conducted. Each salt was studied at three different concentrations, i.e., 0.1, 0.001, and 0.005 M. The effect of pH (in the pH range 3 to 11) in the presence of KI, KCl, and NaCl was also investigated. The concentration of phenol in the aqueous systems studied ranged from 10 to 200 ppm. The temperature effect was also studied, and the resulting experimental equilibrium isotherms at 30, 40, and 55°C are well represented by Freundlich, Langmuir, and Redlich—Paterson isotherms. The relevant parameters for these isotherms are presented.

Adsorption of phenol from aqueous systems onto spent oil shale

Abstract To evaluate its ability to remove phenol from aqueous solution, Jordanian “spent” oil shale, an abundant natural resource, has been used in an experimental adsorption study. Equilibrium of the system has been determined at three temperatures: 30, 40, and 55C. The resulting experimental equilibrium isotherms are well represented by Frendlich, Langmuir, and Redlich-Peterson isotherms. The relevant parameters for these isotherms, as regressed from the experimental equilibrium data, are presented. Effects of solution pH (in the range of 3–11), in addition to effects of three inorganic salts (KI, KCl, and NaCl, each at 0.1, 0.01, and 0.005 M), on the equilibrium isotherms have been experimentally investigated. The effects of pH in the presence of KI and NaCl were also investigated for a possible interaction between salts and solution pH. The initial concentration of phenol in the aqueous system studied ranges from 10 to 200 ppm. Experimental results show that while an acidic solution has no effect on ...

Effects of temperature and inorganic salts on the adsorption of phenol from multicomponent systems onto a decolorizing carbon

Abstract Experimental investigation of the effect of temperature and two inorganic salts (KCl and NaCl) on the adsorption of phenol from dilute (10–200 mg/dm3) multicomponent systems onto activated carbon was studied. Focusing on the adsorption of phenol, all combinations of phenol with two other aromatic organic components, (1,4-dihydroxybenzene and 4-amino, 1-naphthalene sulfonic acid-sodium salt) in aqueous solutions were considered. Equilibrium isotherms at three different temperatures (30, 40, and 55°C) were generated. The adsorption of phenol from binary and ternary as well as from single aqueous systems increases with decreasing temperature, as expected of physical adsorption. Effects of KCl and NaCl salts at a concentration of 0.05 M at 30°C were also investigated. The adsorption of phenol from bisolute and trisolute systems slightly decreases by adding either of the salts.

Vapor-liquid equilibrium measurements and data analysis of tert-butanolisobutanol and tert-butanolwater binaries at 94.9 kPa

Abstract Isobaric vapor-liquid equilibrium (VLE) data were measured for the systems tert-butanol-isobutanol and tert-butanolue5f8water at 94.9 kPa using a modified Malanowski equilibrium still. While the experimental data of the former binary showed a slight deviation from ideality, the latter binary showed a significant deviation. The experimental data of this work, in addition to two isobaric VLE data sets from the literature, have been analyzed using Wilson, NRTL, UNIQUAC, ASOG, and the modified UNIFAC models. Optimum interaction parameters, together with their correlation coefficients, for the first three models were generated using the maximum likelihood principles. As to the group contribution models (ASOG and UNIFAC), interaction parameters from the literature were utilized in the data analysis. A comparable correlation of the experimental data was obtained for the first three models; the maximum values of Root-Mean-Square-Deviation (RMSD) of bubble point temperatures and vapor mole fractions were 0.24 K and 0.044, respectively (using NRTL). ASOG and the modified UNIFAC gave similar predictions; the maximum RMSD of bubble point temperatures was found to be 0.7 K whereas that of vapor mole fractions was 0.022.

Isobaric vapor-liquid equilibria of chloroform + ethanol and chloroform + ethanol + calcium chloride at 94.0 kPa

Abstract Vapor-liquid equilibrium data of chloroform + ethanol and chloroform + ethanol + CaCl 2 (at saturation) were measured at a pressure of 94.0 kPa, using a modified Malanowski equilibrium still. The salt investigated in this work, i.e. CaCl 2 , exhibits a slight salting-out effect on chloroform. The experimental results of the salt-free binary were compared with those predicted by ASOG, original UNIFAC, and modified UNIFAC models which predicted the bubble-point temperatures with a root-mean-square-deviation (RMSD) of: 0.40, 0.55, and 1.48 K, respectively. RMSD values of the vapor-phase composition given by these models were: 0.020, 0.019 and 0.039 mole fraction, respectively. On the other hand, the experimental data of the salt-containing system were compared with those predicted by Wilson-Tan and NRTL-Tan models for the effect of the electrolyte on the phase behavior of the system under study which has an azeotrope around x 1 = 0.93. Both models showed similar capability in predicting the bubble-point temperatures and vapor-phase compositions: temperatures were predicted by both models with an RMSD of about 0.4 K whereas the RMSD values of the vapor-phase mole fractions, predicted by these models, were 0.026 and 0.022, respectively.

A comparison between four cubic equations of state in predicting the inversion curve and spinodal curve loci of methane

Four equations of state, the Redlich-Kwong (RK), Peng-Robinson (PR) modified by Melhem et al., Trebble-Bishnoi (TB), and Jan-Tsai, were compared in predicting the inversion and spinodal curve loci of methane. The inversion locus of methane was also generated from a PVT framework based on the experimental data of gaseous methane. This enables us to judge the accuracy of the results obtained from the different equations of state. The calculated inversion curves were also compared to that fitted by the Gunn-Chueh-Prausnitz correlation. Results predicted by the PR equation modified by Melhem et al. showed good agreement with the experimental behavior up to a reduced pressure of 10. The RK equation shows a clear underestimate of the high pressures (above a reduced pressure of 9.5). The TB equation shows a comparable behavior to that of RK but with better predictions in high-pressure regions. The TB equation shows a good performance up to a reduced temperature of 2.3 after which it shows a deviation from the experimental data. The Jan-Tsai equation was found to be the poorest among the four equations considered in this work.

Isobaric vapor-liquid equilibria of the system ethyl acetaten-butanol at 70.5 and 94.0 kPa

Abstract Isobaric vapor-liquid equilibrium (VLE) data of ethyl acetate n- butanol were measured at 70.5 and 94.0 kPa using a modified Othmer equilibrium still. The experimental VLE data of this work, which show a positive deviation from ideal solution behavior, were analyzed using the following four group-contribution methods: the ASOG, UNIFAC, modified UNIFAC and UNIQUAC models. For the first three models, interaction parameters from the literature were utilized in the data analysis, whereas in the case of the UNIQUAC model, the optimum interaction binary parameters were obtained by regressing the experimental data using maximum likelihood principles. ASOG predicted the experimental data with the highest deviation in terms of RMSD (root-mean-square deviation) in temperature and vapor-phase mole fraction (1.12 K and 0.042 mole fraction). The modified UNIFAC correlated the experimental data with a maximum RMSD of 0.38 K and 0.015 mole fraction versus an RMSD of 0.92 K and 0.019 mole fraction given by the original UNIFAC. The best correlation was given by the UNIQUAC model (0.11 K and 0.004 mole fraction) which is expected because of the direct regression of the experimental VLE data. Activity coefficients at infinite dilution were calculated from the experimental data and compared with the prediction of the ASOG, UNIFAC, and modified UNIFAC models. The best agreement with experimental limiting activity coefficients was obtained from the modified UNIFAC model (with an absolute average deviation of 11.5%).

Quaternary adsorption equilibria from aqueous systems onto decolourizing activated carbon

Abstract An experimental study has been conducted to obtain the adsorption isotherms of four typical pollutants from quaternary aqueous systems onto decolourizing activated carbon. The four materials investigated are: Phenol, 1,4-dihydroxybenzene, 4-amino-l-naphthalene sulfonic acid-sodium salt and Benzoic acid. The study has concentrated on the dilute region of concentrations which range from 10 to 165 ppm (mg/L) at an operating temperature of 30 °C. The quaternary adsorption equilibria have been modeled using the extended Langmuir predictive model and the ideal adsorbed solution (IAS) theory. In employing these models for the prediction of multicomponent adsorption equilibria, the single-solute isotherms are needed. These isotherms have been fitted to Langmuir, Freundlich, and Dubinin models and the resulting model parameters, which are needed for the prediction of multicomponent adsorption equilibria, are reported. Predictions obtained from the extended Langmuir predictive model and the ideal adsorbed solution (IAS) model are in agreement, however, they deviate to an appreciable extent from experimental observations.

Isobaric vapor-liquid equilibria of the system toluene + n-butanol at 94.0, 70.5, and 56.4 kPa

Abstract Isobaric vapor-liquid equilibrium (VLE) data were measured for the binary toluene + n -butanol system at 94.0, 70.5, and 56.4 kPa using a modified Malanowski equilibrium still. The experimental VLE data showed significant positive deviation from ideality. Upon reducing the pressure from 94.0 to 56.4 kPa, the azeotrope had shifted from an azeotropic mole fraction (of toluene) of 0.67 to 0.82. The thermodynamic consistency of the VLE data was verified by correlating the excess Gibbs energy with composition using the UNIQUAC model. The experimental data of this work, in addition to some literature VLE data for the same binary system, have been analyzed using three activity coefficient models; UNIQUAC, ASOG, and UNIFAC.

Adsorption of p-Dihydroxybenzene from Single, Binary and Ternary Aqueous Systems onto Activated Charcoal

The adsorption of para-dihydroxybenzene (p-DHB) from aqueous multi-component systems onto activated charcoal was investigated. The study involved the adsorption of p-DHB from systems containing all combinations of p-DHB, phenol and 4-amino-1-naphthalene sulphonic acid sodium salt (ANSA) in aqueous solutions. Equilibrium isotherms were generated at three temperature values (30°C, 40°C and 55°C). As expected for exothermic physical adsorption, the adsorption of p-DHB from the single-component system and from the binary system containing ANSA decreased with increasing temperature. However, the adsorption of p-DHB from the binary system containing phenol increased with temperature. The effect of KCl and NaCl (at a concentration of 0.05 M) at 30°C was also investigated. The adsorption of p-DHB varied from one system to another. Both salts reduced the adsorption of p-DHB from the single and binary systems. The reduction in adsorption capacity (relative to the adsorption capacity in a salt-free system) attained only ca. 35% in the case of single-solute adsorption and ca. 20% and 33% from the binary systems containing p-DHB and phenol or ANSA, respectively. In contrast, the presence of KCl or NaCl had no appreciable effect on the adsorption of p-DHB from the ternary system.