The adsorption behavior of naphthalene using clay and sandy soil as adsorbents is examined under ambient conditions. The adsorption equilibrium of naphthalene on clay and sandy soil was evaluated by the Langmuir, Freu...The adsorption behavior of naphthalene using clay and sandy soil as adsorbents is examined under ambient conditions. The adsorption equilibrium of naphthalene on clay and sandy soil was evaluated by the Langmuir, Freundlich and Tempkin isotherms. The results showed that the equilibrium data for naphthalene fitted the Freundlich model best within the concentration range studied for both clay and sandy soil. Experimental results showed that the time taken to attain adsorption equilibrium for naphthalene was 26 hrs and 20 hrs for clay and sandy soil, respectively. Among the tested kinetic models in this study, the pseudo-second order successfully predicted the adsorption process.展开更多
The sorption behaviour of benzene, toluene, ethyl benzene, xylene and naphthalene using clay and sand sediments under ambient conditions is examined in this study. Experimental results showed that, the time taken to a...The sorption behaviour of benzene, toluene, ethyl benzene, xylene and naphthalene using clay and sand sediments under ambient conditions is examined in this study. Experimental results showed that, the time taken to attain adsorption equilibrium for naphthalene, and BTEX were 28, 30, 30, 32, 28 hrs and 20, 22, 22, 24, 22 hrs while the desorption equilibrium time were 10, 13, 12, 15, 12 hrs and 9, 9, 9, 11, 10 hrs in clay and sand respectively. All of the naphthalene, and BTEX were adsorbed at the different equilibrium times, using clay while the amount of naphthalene and BTEX adsorbed by sand, at different equilibrium times were 117, 121, 127, 123 and 134 mg. Following the results of the adsorption/desorption experiments, quantitative measurements showed that sand exhibited higher affinity for the solute as retained more chemicals (as high as between 58% - 66%) within it pores while nearly all the chemicals adsorbed by the clay were released at the attainment of equilibrium. The implication of this is that occlusion within the sand particles may likely be the resultant effect of continued sand-chemicals contact. The amount of contaminant solute adsorbed and desorbed affirmed that clay has a better capacity to retain naphthalene and BTEX than sand and this may not be unrelated to its large surface area, high porosity and higher hydraulic conductivity for the solutes arising from its good binding sites (small pore sizes) that tend to hold the adsorbates to its particles.展开更多
The adsorption potential of clay and sandy soil to remove benzene from liquid-phase system was examined. A series of batch adsorption tests were carried out for various concentrations of benzene (50 - 250 mg/l) in tig...The adsorption potential of clay and sandy soil to remove benzene from liquid-phase system was examined. A series of batch adsorption tests were carried out for various concentrations of benzene (50 - 250 mg/l) in tightly corked 1000 ml flasks for clay and sandy soil, respectively. Equilibrium and kinetics data were obtained from the batch experiments. Adsorption increased with increasing initial benzene concentration. The equilibrium data obtained from the adsorption of benzene were well fitted to the Freundlich isotherm model. The adsorption kinetics process showed that the kinetic model of pseudo second-order was the best fit to the experimental data. The results showed that clay and sandy soil had good potential for the removal of aromatic hydrocarbon, benzene from aqueous solution.展开更多
This paper examined the influence of acid, base and salt modifications of clay on its rates of naphthalene adsorption. The modifiers used include hydrochloric acid (HCl), citric acid, sodium hydroxide (NaOH), ammonium...This paper examined the influence of acid, base and salt modifications of clay on its rates of naphthalene adsorption. The modifiers used include hydrochloric acid (HCl), citric acid, sodium hydroxide (NaOH), ammonium hydroxide (NH4OH), sodium chloride (NaCl) and zinc chloride (ZnCl2). The results obtained showed that equilibrium adsorption of naphthalene from the bulk solution was attained at a faster rate using modified clay when compared with the unmodified clay. HCl-modified clay had the highest rate of adsorption with a surface area and porosity of 49.05 mm2 and 53.4%. This was closely followed by NaOH-modified clay while down the order was the ZnCl2-modified clay which had the least rate of adsorption with a surface area of 44.3 mm2 and porosity of 43.4%. The implication of the retention time obtained from the equilibrium study is significant as it provides the bench mark for interplay between sorption and degradation for transport and transformation of contaminant solutes within the soil matrix.展开更多
文摘The adsorption behavior of naphthalene using clay and sandy soil as adsorbents is examined under ambient conditions. The adsorption equilibrium of naphthalene on clay and sandy soil was evaluated by the Langmuir, Freundlich and Tempkin isotherms. The results showed that the equilibrium data for naphthalene fitted the Freundlich model best within the concentration range studied for both clay and sandy soil. Experimental results showed that the time taken to attain adsorption equilibrium for naphthalene was 26 hrs and 20 hrs for clay and sandy soil, respectively. Among the tested kinetic models in this study, the pseudo-second order successfully predicted the adsorption process.
文摘The sorption behaviour of benzene, toluene, ethyl benzene, xylene and naphthalene using clay and sand sediments under ambient conditions is examined in this study. Experimental results showed that, the time taken to attain adsorption equilibrium for naphthalene, and BTEX were 28, 30, 30, 32, 28 hrs and 20, 22, 22, 24, 22 hrs while the desorption equilibrium time were 10, 13, 12, 15, 12 hrs and 9, 9, 9, 11, 10 hrs in clay and sand respectively. All of the naphthalene, and BTEX were adsorbed at the different equilibrium times, using clay while the amount of naphthalene and BTEX adsorbed by sand, at different equilibrium times were 117, 121, 127, 123 and 134 mg. Following the results of the adsorption/desorption experiments, quantitative measurements showed that sand exhibited higher affinity for the solute as retained more chemicals (as high as between 58% - 66%) within it pores while nearly all the chemicals adsorbed by the clay were released at the attainment of equilibrium. The implication of this is that occlusion within the sand particles may likely be the resultant effect of continued sand-chemicals contact. The amount of contaminant solute adsorbed and desorbed affirmed that clay has a better capacity to retain naphthalene and BTEX than sand and this may not be unrelated to its large surface area, high porosity and higher hydraulic conductivity for the solutes arising from its good binding sites (small pore sizes) that tend to hold the adsorbates to its particles.
文摘The adsorption potential of clay and sandy soil to remove benzene from liquid-phase system was examined. A series of batch adsorption tests were carried out for various concentrations of benzene (50 - 250 mg/l) in tightly corked 1000 ml flasks for clay and sandy soil, respectively. Equilibrium and kinetics data were obtained from the batch experiments. Adsorption increased with increasing initial benzene concentration. The equilibrium data obtained from the adsorption of benzene were well fitted to the Freundlich isotherm model. The adsorption kinetics process showed that the kinetic model of pseudo second-order was the best fit to the experimental data. The results showed that clay and sandy soil had good potential for the removal of aromatic hydrocarbon, benzene from aqueous solution.
文摘This paper examined the influence of acid, base and salt modifications of clay on its rates of naphthalene adsorption. The modifiers used include hydrochloric acid (HCl), citric acid, sodium hydroxide (NaOH), ammonium hydroxide (NH4OH), sodium chloride (NaCl) and zinc chloride (ZnCl2). The results obtained showed that equilibrium adsorption of naphthalene from the bulk solution was attained at a faster rate using modified clay when compared with the unmodified clay. HCl-modified clay had the highest rate of adsorption with a surface area and porosity of 49.05 mm2 and 53.4%. This was closely followed by NaOH-modified clay while down the order was the ZnCl2-modified clay which had the least rate of adsorption with a surface area of 44.3 mm2 and porosity of 43.4%. The implication of the retention time obtained from the equilibrium study is significant as it provides the bench mark for interplay between sorption and degradation for transport and transformation of contaminant solutes within the soil matrix.
