In order to greatly improve adsorption capacity, the diatomite was pillared by polyhydroxyl-aluminum.A series of adsorption tests were conducted to obtain the optimum condition for pillared diatomite synthesis. The sc...In order to greatly improve adsorption capacity, the diatomite was pillared by polyhydroxyl-aluminum.A series of adsorption tests were conducted to obtain the optimum condition for pillared diatomite synthesis. The scanning electron microscopy （SEM）, Fourier transform infrared spectroscopy （FTIR）, surface area and porosity analyzer and micro-electrophoresis were used to determine pore structure and surface property.The pillared diatomite attaining the optimal adsorption densities （qe） of Pb^2＋ and Cd^2＋ was synthesized with the following conditions： Addition of pillaring solution containing Al3＋-oligomers with a concentration range of 0.1-0.2 mol/L to a suspension containing Na＋-diatomite to obtain the required Al/diatomite ratio of 10 mmol/g; synthesis temperature of 80 ℃ for 120 min; aging at a temperature of 105 ℃ for 16 h. The adsorption capacities of Pb^2＋ and Cd^2＋ on pillared diatomite increase by 23.79% and 27.36% compared with natural diatomite, respectively. The surface property of pillared diatomite is more favorable for ion adsorption than natural diatomite. The result suggests that diatomite can be modified by pillaring with polyhydroxyl-aluminum to improve its adsorption properties greatly.展开更多
Pb2+ and Cd2+ in leachate were adsorbed on clay-solidified grouting curtain for waste landfills with equilibrium experiment. The cation exchange capacity was determined with ammonium acetate. And the concentration of ...Pb2+ and Cd2+ in leachate were adsorbed on clay-solidified grouting curtain for waste landfills with equilibrium experiment. The cation exchange capacity was determined with ammonium acetate. And the concentration of heavy metal cations in leachate was determined with atomic absorption spectrophotometer. Their equilibrium isotherms were measured, and the experimental isotherm data were analyzed by using Freundlich and Langmuir models. The results show that the adsorption capacities of the heavy metal cations are closely related to the compositions of clay-solidified grouting curtain, and the maximum adsorption appears at the ratio of cement to clay of 2∶4 in the experimental conditions. At their maximum adsorption and pH 5.0, the adsorption capacities of Pb 2+ and Cd 2+ are 16.19mg/g and 1.21mg/g. The competitive adsorption coefficients indicate that the adsorption of clay-solidified grouting curtain for Pb2+ is stronger than that for Cd 2+ . The adsorption process conforms to Freundlich’s model with related coefficient higher than 0.996.展开更多
The adsorption behavior of Pb2+ and Cd2+ ions on bauxite flotation tailings was investigated to demonstrate the adsorptivity of the bauxite flotation tailings.The adsorption percentage of Pb2+ and Cd2+ ions as a funct...The adsorption behavior of Pb2+ and Cd2+ ions on bauxite flotation tailings was investigated to demonstrate the adsorptivity of the bauxite flotation tailings.The adsorption percentage of Pb2+ and Cd2+ ions as a function of adsorbent dosage,solution pH value and shaking time were determined by batch experiments.The maximum adsorption percentage of 99.93% for Pb2+ ions and 99.75% for Cd2+ ions were obtained by using bauxite flotation tailings as adsorbent.The methods,such as zeta potentials,specific surface area measurements and the analysis of adsorption kinetics,were introduced to analyze the adsorption mechanisms of the Pb2+ ions on bauxite flotation tailings.The isoelectric point of bauxite flotation tailings shifts from 3.6 to 5.6 in the presence of Pb2+ ions.The specific surface area of bauxite flotation tailings changes from 12.57 to 20.63 m2/g after the adsorption of Pb2+ ions.These results indicate that a specific adsorption of the cation species happens on the surface of bauxite flotation tailings.Adsorption data of Pb2+ ions on the surface of bauxite flotation tailings can be well described by Langmuir model,and the pseudo-second-order kinetic model provides the best correlation for the adsorption data of Pb2+ and Cd2+ ions on bauxite flotation tailings.展开更多
A novel chelating resin with sulfonic group was synthesized by chemical modification of D401 resin with sulphonation reaction and characterized by FT-IR spectrometry. The adsorption properties of the novel chelating r...A novel chelating resin with sulfonic group was synthesized by chemical modification of D401 resin with sulphonation reaction and characterized by FT-IR spectrometry. The adsorption properties of the novel chelating resin for Pb2+ were studied by batch adsorption, and the adsorption process was analyzed from thermodynamics and kinetics aspects. The adsorption mechanism of Pb2+ on the modified D401 chelating resin was discussed by FT-IR spectrometry. Experimental results show that in the Pb2+ concentration range of 200-400 mg/L, the adsorption capacities of the modified D401 chelating resin for Pb2+ increase by 77%-129%, and Langmuir isothermal adsorption model is more suitable for the equilibrium adsorption data. Adsorption is an endothermic process that runs spontaneously. Kinetic analysis shows that the adsorption rate is mainly governed by liquid film diffusion. The best pH value under adsorption condition is 4-5. The saturated resin can be regenerated by 3 mol/L nitric acid, and the adsorption capacity remains stable after five consecutive adsorption-desorption cycles. The maximal static saturated adsorption capacity of the resin is 206 mg/g at 333 K in the Pb2+ concentration range of 200-400 mg/L. The modified D401 chelating resin is an efficient adsorbent for the removal of Pb2+ from its single-metal ion solution.展开更多
The adsorption properties of a novel macroporous weak acid resin （D152） for Pb^2＋ were investigated with chemical methods. The optimal adsorption condition of D152 resin for Pb^2＋ is at pH 6.00 in HAc-NaAc medium....The adsorption properties of a novel macroporous weak acid resin （D152） for Pb^2＋ were investigated with chemical methods. The optimal adsorption condition of D152 resin for Pb^2＋ is at pH 6.00 in HAc-NaAc medium. The statically saturated adsorption capacity is 527 mg/g at 298 K. Pb^2＋ adsorbed on D152 resin can be eluted with 0.05 mol/L HCI quantitatively. The adsorption rate constants determined under various temperatures are k288 n=2.22×10-5 s^-1, k298 K=2.51 × 10^-5 s^-1, and k308 K= 2.95 × 10^-5 s^-1, respectively. The apparent activation energy, Ea is 10.5 kJ/mol, and the adsorption parameters of thermodynamics are ΔH^Θ=13.3 kJ/mol, ΔS^Θ=119 J/（mol·K）, and ΔG^Θ298 K =-22.2 kJ/mol, respectively. The adsorption behavior of D152 resin for Pb^2＋ follows Langmuir model.展开更多
基金Project(12JJ8016)supported by the Hunan Provincial Natural Science Foundation of ChinaProject(CX2012B317)supported by Hunan Provincial Innovation Foundation For Postgraduate,ChinaProject(2006180)supported by the Hunan Key Discipline Construction Found of Environmental Science,China
文摘In order to greatly improve adsorption capacity, the diatomite was pillared by polyhydroxyl-aluminum.A series of adsorption tests were conducted to obtain the optimum condition for pillared diatomite synthesis. The scanning electron microscopy （SEM）, Fourier transform infrared spectroscopy （FTIR）, surface area and porosity analyzer and micro-electrophoresis were used to determine pore structure and surface property.The pillared diatomite attaining the optimal adsorption densities （qe） of Pb^2＋ and Cd^2＋ was synthesized with the following conditions： Addition of pillaring solution containing Al3＋-oligomers with a concentration range of 0.1-0.2 mol/L to a suspension containing Na＋-diatomite to obtain the required Al/diatomite ratio of 10 mmol/g; synthesis temperature of 80 ℃ for 120 min; aging at a temperature of 105 ℃ for 16 h. The adsorption capacities of Pb^2＋ and Cd^2＋ on pillared diatomite increase by 23.79% and 27.36% compared with natural diatomite, respectively. The surface property of pillared diatomite is more favorable for ion adsorption than natural diatomite. The result suggests that diatomite can be modified by pillaring with polyhydroxyl-aluminum to improve its adsorption properties greatly.
基金Project (200065) supported by University Key Teacher Foundation of the Ministry of Education of China
文摘Pb2+ and Cd2+ in leachate were adsorbed on clay-solidified grouting curtain for waste landfills with equilibrium experiment. The cation exchange capacity was determined with ammonium acetate. And the concentration of heavy metal cations in leachate was determined with atomic absorption spectrophotometer. Their equilibrium isotherms were measured, and the experimental isotherm data were analyzed by using Freundlich and Langmuir models. The results show that the adsorption capacities of the heavy metal cations are closely related to the compositions of clay-solidified grouting curtain, and the maximum adsorption appears at the ratio of cement to clay of 2∶4 in the experimental conditions. At their maximum adsorption and pH 5.0, the adsorption capacities of Pb 2+ and Cd 2+ are 16.19mg/g and 1.21mg/g. The competitive adsorption coefficients indicate that the adsorption of clay-solidified grouting curtain for Pb2+ is stronger than that for Cd 2+ . The adsorption process conforms to Freundlich’s model with related coefficient higher than 0.996.
基金Project(2005CB623701) supported by the Major State Basic Research Development Program of China
文摘The adsorption behavior of Pb2+ and Cd2+ ions on bauxite flotation tailings was investigated to demonstrate the adsorptivity of the bauxite flotation tailings.The adsorption percentage of Pb2+ and Cd2+ ions as a function of adsorbent dosage,solution pH value and shaking time were determined by batch experiments.The maximum adsorption percentage of 99.93% for Pb2+ ions and 99.75% for Cd2+ ions were obtained by using bauxite flotation tailings as adsorbent.The methods,such as zeta potentials,specific surface area measurements and the analysis of adsorption kinetics,were introduced to analyze the adsorption mechanisms of the Pb2+ ions on bauxite flotation tailings.The isoelectric point of bauxite flotation tailings shifts from 3.6 to 5.6 in the presence of Pb2+ ions.The specific surface area of bauxite flotation tailings changes from 12.57 to 20.63 m2/g after the adsorption of Pb2+ ions.These results indicate that a specific adsorption of the cation species happens on the surface of bauxite flotation tailings.Adsorption data of Pb2+ ions on the surface of bauxite flotation tailings can be well described by Langmuir model,and the pseudo-second-order kinetic model provides the best correlation for the adsorption data of Pb2+ and Cd2+ ions on bauxite flotation tailings.
基金Project(708049) supported by the Important Item Cultivation Foundation of Scientific Innovation Project of Colleges and Universities of China
文摘A novel chelating resin with sulfonic group was synthesized by chemical modification of D401 resin with sulphonation reaction and characterized by FT-IR spectrometry. The adsorption properties of the novel chelating resin for Pb2+ were studied by batch adsorption, and the adsorption process was analyzed from thermodynamics and kinetics aspects. The adsorption mechanism of Pb2+ on the modified D401 chelating resin was discussed by FT-IR spectrometry. Experimental results show that in the Pb2+ concentration range of 200-400 mg/L, the adsorption capacities of the modified D401 chelating resin for Pb2+ increase by 77%-129%, and Langmuir isothermal adsorption model is more suitable for the equilibrium adsorption data. Adsorption is an endothermic process that runs spontaneously. Kinetic analysis shows that the adsorption rate is mainly governed by liquid film diffusion. The best pH value under adsorption condition is 4-5. The saturated resin can be regenerated by 3 mol/L nitric acid, and the adsorption capacity remains stable after five consecutive adsorption-desorption cycles. The maximal static saturated adsorption capacity of the resin is 206 mg/g at 333 K in the Pb2+ concentration range of 200-400 mg/L. The modified D401 chelating resin is an efficient adsorbent for the removal of Pb2+ from its single-metal ion solution.
基金Project(2008F70059) supported by the Scientific and Technological Research Planning of Zhejiang Province, China
文摘The adsorption properties of a novel macroporous weak acid resin （D152） for Pb^2＋ were investigated with chemical methods. The optimal adsorption condition of D152 resin for Pb^2＋ is at pH 6.00 in HAc-NaAc medium. The statically saturated adsorption capacity is 527 mg/g at 298 K. Pb^2＋ adsorbed on D152 resin can be eluted with 0.05 mol/L HCI quantitatively. The adsorption rate constants determined under various temperatures are k288 n=2.22×10-5 s^-1, k298 K=2.51 × 10^-5 s^-1, and k308 K= 2.95 × 10^-5 s^-1, respectively. The apparent activation energy, Ea is 10.5 kJ/mol, and the adsorption parameters of thermodynamics are ΔH^Θ=13.3 kJ/mol, ΔS^Θ=119 J/（mol·K）, and ΔG^Θ298 K =-22.2 kJ/mol, respectively. The adsorption behavior of D152 resin for Pb^2＋ follows Langmuir model.
