This study is to prepare chitosan beads modified with sodium dodecyl sulfate (SDS) to effectively remove Cr(III) from an aqueous solution. The characterizations of SDS-chitosan by scanning electron microscopy-energy d...This study is to prepare chitosan beads modified with sodium dodecyl sulfate (SDS) to effectively remove Cr(III) from an aqueous solution. The characterizations of SDS-chitosan by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), Fourier transform-infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) proved the successful synthesis of the adsorbent. The adsorption of Cr(III) on the SDS material was investigated by varying experimental conditions such as pH, contact time and adsorbent dosage. The maximum adsorption capacity of SDS-chitosan for Cr(III) was estimated to be 3.42 mg?g<sup>-1</sup>. The results of adsorption kinetics and isothermal models show that the adsorption process conforms to the pseudo-second-order and Langmuir isotherm models, indicating that the adsorption is single-layer chemical adsorption. Thermodynamic analyses indicate that the adsorption of Cr(III) is an endothermic reaction. These results show that the new adsorbent has obvious application prospect to eliminate Cr(III).展开更多
In this study, the removal of Cr(VI) from aqueous solution by modified zeolite with 3-aminopropyltriethoxysilane was investigated. The effect of various parameters such as pH, contact time, temperature, initial concen...In this study, the removal of Cr(VI) from aqueous solution by modified zeolite with 3-aminopropyltriethoxysilane was investigated. The effect of various parameters such as pH, contact time, temperature, initial concentration of Cr(VI) ion, common cations, and anions on the adsorption of Cr(VI) was studied. The modified zeolite was characterized by following instrumental analysis of XRD, SEM/EDS, BET, and FT-IR. Based on calculated thermodynamic parameters values (Δ<i>G</i><sup>0</sup> < 0, Δ<i>H</i><sup>0</sup> > 0, and Δ<i>S</i><sup>0</sup> > 0) and kinetic properties of the adsorption of Cr(VI) by modified zeolite, it was concluded that the rate-limiting step of the process is a second-order chemical reaction. The results of the adsorption isotherm study confirmed that the adsorption follows the Langmuir isotherm model. The maximum adsorption capacity was 13.5 mg/g.展开更多
Adsorption experiment from aqueous solutions containing known amount of Cr （chromium） using chitosan was explored to evaluate the efficiency of chitosan as sorbent for Cr. Some variable parameters such as pH, reacti...Adsorption experiment from aqueous solutions containing known amount of Cr （chromium） using chitosan was explored to evaluate the efficiency of chitosan as sorbent for Cr. Some variable parameters such as pH, reaction time and chitosan dosage were optimized. Under the optimum experiment condition, the effect of common ions on the adsorption of Cr （i.e., Na^＋, K^＋, Mg^2＋, Ca^2＋ for Cr（Ⅲ）, and Cl^-, NO3^-, SO4^2- for Cr（Ⅵ）） was also investigated. Furthermore, the sorption mechanism of Cr by chitosan was investigated by applying Langmuir and Freundlich isotherm equations to the data obtained. In addition, to confirm the characteristics of the chitosan, the surface morphology of the biomass was determined by SEM （scanning electron microscope） and specific surface area analyzer （N2-BET （Brunaeur, Emmet and Teller））. Consequently, the following matters have been mainly clarified： （1） chitosan can be an efficient sorbent for Cr （both Cr（Ⅲ） and Cr（Ⅵ））; （2） the effect of common ions on the adsorption ofCr （Cr（Ⅲ） and Cr（Ⅵ）） was not significant under this experimental conditions; （3） adsorption isotherms using the chitosan can be generally described by Langmuir isotherm more satisfactorily for Cr. The adsorption may have occurred mainly by monolayer reaction; （4） the rates of adsorption were found to conform to pseudo-second order kinetics.展开更多
This study investigated the adsorption ability of ZCHC （zeolite/chitosan hybrid composite） as adsorbent for chromium （Cr（Ⅵ））, ZCHC was prepared with sol-gel method by mixing zeolite and chitosan. Adsorption exp...This study investigated the adsorption ability of ZCHC （zeolite/chitosan hybrid composite） as adsorbent for chromium （Cr（Ⅵ））, ZCHC was prepared with sol-gel method by mixing zeolite and chitosan. Adsorption experiment from aqueous solutions containing known amount of Cr（Ⅵ） using zeolite, chitosan and ZCHC was explored to evaluate the efficiency of ZCHC as adsorbent for Cr in a batch system. The amount of Cr（Ⅵ） adsorbed at different pH values, initial concentrations, adsorbent dosages, and contact times were determined by ICP-AES （inductively coupled plasma-atomic emission spectrometry） in order to determine the optimum conditions for Cr（Ⅵ） adsorption. Furthermore, the adsorption mechanism of Cr（Ⅵ） by zeolite, chitosan and ZCHC was investigated by applying Langmuir and Freundlich isotherm equations to the data obtained. In addition, the rates of adsorption were found to conform to pseudo-second order kinetics.展开更多
Mongolian sheep wool was modified by maleic anhydride at different temperatures to obtain new adsorbent for the removal of Cr(III). Adsorption of Cr(III) from aqueous solution onto the modified wool was investigated i...Mongolian sheep wool was modified by maleic anhydride at different temperatures to obtain new adsorbent for the removal of Cr(III). Adsorption of Cr(III) from aqueous solution onto the modified wool was investigated in batch system. In this work, the effect of various parameters such as pH, contact time, temperature and initial concentration on the adsorption capacity was determined by ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometry). Modified wool was characterized by SEM (scanning electron microscopy) and FT-IR (Fourier transform infrared spectrometer). The thermodynamic and kinetic studies were carried out and the results confirmed that the adsorption process was spontaneous in nature, thermodynamically favourable and endothermic. Kinetically, the adsorption process obeys the pseudo-second order model. The modified wool can be an effective adsorbent for the removal of Cr(III) from aqueous solution.展开更多
Adsorption experiment from aqueous solutions containing known amount of chromium （Cr） using hybrid membrane of chitosan and silicon dioxide was explored to evaluate the efficiency of the membrane as sorbent for Cr...Adsorption experiment from aqueous solutions containing known amount of chromium （Cr） using hybrid membrane of chitosan and silicon dioxide was explored to evaluate the efficiency of the membrane as sorbent for Cr（VI）. Some variable parameters such as pH, contact time and the dosage of the membrane were optimized. Adsorption isotherms of Cr（VI） onto the hybrid membrane were measured with varying initial concentrations under optimized condition. Furthermore, the sorption mechanism of Cr by the membrane was investigated by applying Langmuir and Freundlich isotherm equations to the data obtained. The surface morphology of the membrane was determined by SEM （scanning electron microscope） for material characterization. The concentrations of Cr in solution are determined by ICP-MS （inductively coupled plasma mass spectrometry）. Hybrid membrane of chitosan and silicon dioxide can be an efficient sorbent for Cr（VI）.展开更多
The concentration and chemical speciation of heavy metals including REEs （rare earth elements）, Th （thorium） and U （uranium） in domestic sludge and electroplating sludge were investigated, and those of the domes...The concentration and chemical speciation of heavy metals including REEs （rare earth elements）, Th （thorium） and U （uranium） in domestic sludge and electroplating sludge were investigated, and those of the domestic sludge were compared with those of natural soil. Removal of heavy metals in electroplating sludge was studied with bio-surfactants （saponin and sophorolipid） by batch and column experiments. The results suggested that heavy metals have greater concentrations and exist as more relatively unstable fraction in sludge than those in Natural soil. Nonionic saponin is more efficient than sophorolipid for the removal of heavy metals from the electroplating sludge, and mainly reacts with carbonate state （i.e., F3） and Fe-Mn oxide state （i.e., F5） fractions. The recovery efficiency of heavy metals in leachates from the electroplate sludge was attained 88%-97%. Saponin can be reused and be a promising and cost-effective material for the removal of heavy metals in sludge.展开更多
In this paper,the adsorbent for the removal of hexavalent Cr(Chromium)from aqueous solutions has been prepared by modifying chitosan composite with EP(Epichlorohydrin)or GA(Glutaraldehyde).The modified cross-linked ch...In this paper,the adsorbent for the removal of hexavalent Cr(Chromium)from aqueous solutions has been prepared by modifying chitosan composite with EP(Epichlorohydrin)or GA(Glutaraldehyde).The modified cross-linked chitosan was characterized by SEM(Scanning Electron Microscopy)and FT-IR(Fourier Transform Infrared Spectroscopy).Batch adsorption experiments were carried out to evaluate the adsorption of Cr(VI)by the cross-linked chitosan under different conditions.Furthermore,the sorption mechanism of Cr(VI)by the cross-linked chitosan was investigated by applying Langmuir and Freundlich isotherm equations to the data obtained.The concentration of Cr in solution was determined by ICP-MS(Inductively Coupled Plasma Mass Spectrometry).The cross-linked chitosan can be an efficient sorbent for Cr(VI).展开更多
The silicon organic polymer containing PSOT-3 （dioxothiocarbamide groups） has been synthesized and characterized, and the adsorption of Au（III） on PSOT-3 was investigated. The results showed that PSOT-3 had good a...The silicon organic polymer containing PSOT-3 （dioxothiocarbamide groups） has been synthesized and characterized, and the adsorption of Au（III） on PSOT-3 was investigated. The results showed that PSOT-3 had good adsorption capacity for Au（III）, and the adsorption of Au（III） was found to be the most effective in 0.1-0.3 mol/dm^3 hydrochloric acid solution. The adsorption is physical and the process is endothermic, and Freundlich isotherm fits the data better than the Langmuir isotherm. The adsorption can be generally described by electrostatic interaction （Coulomb＇s force） between the adsorbent and the adsorbate. The high adsorption capacity of this sorbent has significant potential for gold recovery from aqueous solutions.展开更多
The hydrotalcite-like compound [Zn2AI（OH）6]NO3-mH20 （shorted as ZnAI-NO3） was intercalated with the chelating agent EDTA （ethylene diamine tetraacetic acid） by anion exchange to uptake cadmium ion from aqueous s...The hydrotalcite-like compound [Zn2AI（OH）6]NO3-mH20 （shorted as ZnAI-NO3） was intercalated with the chelating agent EDTA （ethylene diamine tetraacetic acid） by anion exchange to uptake cadmium ion from aqueous solutions. The materials synthesized in this work were characterized by chemical analysis, FT-IR （fourier transform infrared spectroscopy）, XRD （X-ray powder diffraction） to confirm their properties. In order to investigate the optimum conditions for Cd（II） adsorption, the amount of Cd（ll） adsorbed by Zn-AI LDHs intercalated with EDTA （ZnAI-EDTA） under different conditions （i.e., adsorbent dosage, temperature and contact time） were determined by ICP-AES （inductively coupled plasma-atomic emission spectrometry）. Adsorption isotherms of Cd（II） onto ZnA1-EDTA were measured at varying initial Cd concentrations （0.05 mg/L to 1 mg/L） under optimized conditions. The data were applied to Langmuir and Freundlich isotherms model, and well fitted by the Freundlich isotherms model. The pseudo-second-order kinetic model was more adequate to describe the kinetic in this case.展开更多
In order to investigate the isotopic and chemical characteristics of lagoon waters in Niigata Prefecture in recent years, oxygen and hydrogen stable isotope ratios （i.e., 8180 and 6D）, the concentrations of DOC （di...In order to investigate the isotopic and chemical characteristics of lagoon waters in Niigata Prefecture in recent years, oxygen and hydrogen stable isotope ratios （i.e., 8180 and 6D）, the concentrations of DOC （dissolved organic carbon）, DO （dissolved oxygen） and pH, etc. in water samples of Sakata and Toyanogata were measured. Samples were generally taken monthly at the fixed sampling points from these lagoons. Consequently, the following matters have been mainly clarified： （1） ~D value of water samples in Sakata was generally larger than that in Toyanogata similarly to the case of ~180, though remarkable large difference among samples was not found; （2） the pH value of lagoon water samples is almost 6.5-8.5 （which is generally larger than that of river water）, and pH at the spot of SI （downstream point of Lower Lagoon （Shitakata）） is remarkably high （9.0-9.5）; （3） Lagoon water has the chemical characteristics contrasting to groundwater with a focus on river water from the viewpoint of pH （acidity or alkalinity） and DO. These matters can be closely related to the biological activity such as photosynthesis due to aquatic plant and phytoplankton and the activity of Crustacea plankton etc. in lagoon.展开更多
Time-course of oxygen stable isotopic ratios （i.e., δ^18O） as well as seasonal variation of δ^18O has been examined to investigate the characteristics, sources and the passing route of precipitations in Niigata Pr...Time-course of oxygen stable isotopic ratios （i.e., δ^18O） as well as seasonal variation of δ^18O has been examined to investigate the characteristics, sources and the passing route of precipitations in Niigata Prefecture. The precipitation samples have been mainly collected with a filtrating bulk sampler at the rooftop of Niigata University. Furthermore, backward trajectories analyses have been also conducted for these samples taken sequentially for a short period. Consequently, the following features have been mainly clarified for the precipitations in Niigata Prefecture： （1） the δ^18O values varied between -14.57%o and -3.86%0 in the precipitations of Niigata University; （2） as for the comparison among sampling points, the mean value of δ^18O at seaside spots （i.e., Niigata City： -6.93%0） is larger than that of inland spots （Sanjyo City： -8.68%0）; （3） δ^18O value was generally small in the rainy or typhoon season, and relatively large in summer; （4） decreasing δ^18O content with time is a predominant feature of sequentially sampled rainfalls as predicted by Rayleigh models of atmospheric vapor condensation.展开更多
The hydrotalcite-like compound [Zn2Al·（OH）6] NO3·nH2O and [Mg2Al·（OH）6] NO3·nH2O （shorted as ZnA1-NO3 and MgAl-NO3） was intercalated with the chelating agent EDTA （Ethylenediaminetetraacetic...The hydrotalcite-like compound [Zn2Al·（OH）6] NO3·nH2O and [Mg2Al·（OH）6] NO3·nH2O （shorted as ZnA1-NO3 and MgAl-NO3） was intercalated with the chelating agent EDTA （Ethylenediaminetetraacetic Acid） and EDDS （N, N＇-1, 2-Ethanediylbis-1-Aspartic Acid） by anion exchange. The materials synthesized in this work were characterized by chemical analysis, FT-IR （Fourier Transform Infrared Spectroscopy）, SEM （Scanning Electron Microscopy） and XRD （Powder X-ray Diffraction） to confirm their properties. In order to discuss the adsorption capacity of LDHs （Layered Double Hydroxides）, the adsorption experiment was investigated under the optimum condition （10 mg, 25℃ and 100 μg·L-1）. The amount of metallic ions adsorbed by LDHs intercalated with EDTA and precursor LDHs were determined by ICP-AES （Inductively Coupled Plasma-Atomic Emission Spectrometry） and AAS （Atomic Absorption Spectrometry）. The intercalation of EDTA leads to improve the adsorption capacity of LDHs. LDHs intercalated with chelating agents have generally high affinity for removing metallic ions, and they can be efficient adsorbents for metallic ions.展开更多
The adsorption capacity of activated carbon modified with KMnO4 （potassium permanganate） for Cr（VI） from aqueous solution was investigated. The modified activated carbon was characterized by SEM （scanning electro...The adsorption capacity of activated carbon modified with KMnO4 （potassium permanganate） for Cr（VI） from aqueous solution was investigated. The modified activated carbon was characterized by SEM （scanning electron microscopy）, FT-IR （Fourier transform infrared spectrometer）, and N2 adsorption/desorption tests. Adsorption of Cr（VI） from aqueous solution onto the activated carbon was investigated in a batch system. In the present study, the effect of various parameters such as pH, contact time and initial concentration on the adsorption capacity were determined by ICP-AES （inductively coupled plasma atomic emission spectrometry）. The Cr（VI） adsorption on the activated carbon conforms to the Langmuir and Freundlich isothermal adsorption equation. The rates of adsorption were found to conform to pseudo-second order kinetic. The modified activated carbon can be an effective adsorbent for Cr（VI） from the aqueous solution.展开更多
Adsorption of chromium （Cr） from aqueous solution onto Yukitsubaki carbon has been investigated in a batch system. The effect of pH, contact time and carbon dosage on the adsorption of Cr by Yukitsubaki carbon have ...Adsorption of chromium （Cr） from aqueous solution onto Yukitsubaki carbon has been investigated in a batch system. The effect of pH, contact time and carbon dosage on the adsorption of Cr by Yukitsubaki carbon have been evaluated with ICP-AES （inductively coupled plasma atomic emission spectrometer） in order to obtain the optimum conditions for the Cr adsorption process. Adsorption isotherms of Cr onto the carbon were measured at varying initial concentrations under optimized condition. The surface properties of the carbon were characterized using N2-BET, SEM （scanning electron microscope） and FT-IR （Fourier transform infrared spectroscopy）. Consequently, the following matters have been mainly clarified. （1） Yukitsubaki carbon can be an efficient sorbent for Cr, particularly for cation species Cr（III）; （2） The effect of common ions on the adsorption of Cr was not significant, although the adsorption of Cr（VI） was inhibited under high concentrations of common ions; （3） Adsorption isotherms using the Yukitsubaki carbon can be generally described by Langmuir isotherm more satisfactorily for Cr. The adsorption may have occurred mainly by monolayer reaction; （4） The rates of adsorption were found to conform to pseudo-second order kinetics.展开更多
文摘This study is to prepare chitosan beads modified with sodium dodecyl sulfate (SDS) to effectively remove Cr(III) from an aqueous solution. The characterizations of SDS-chitosan by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), Fourier transform-infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) proved the successful synthesis of the adsorbent. The adsorption of Cr(III) on the SDS material was investigated by varying experimental conditions such as pH, contact time and adsorbent dosage. The maximum adsorption capacity of SDS-chitosan for Cr(III) was estimated to be 3.42 mg?g<sup>-1</sup>. The results of adsorption kinetics and isothermal models show that the adsorption process conforms to the pseudo-second-order and Langmuir isotherm models, indicating that the adsorption is single-layer chemical adsorption. Thermodynamic analyses indicate that the adsorption of Cr(III) is an endothermic reaction. These results show that the new adsorbent has obvious application prospect to eliminate Cr(III).
文摘In this study, the removal of Cr(VI) from aqueous solution by modified zeolite with 3-aminopropyltriethoxysilane was investigated. The effect of various parameters such as pH, contact time, temperature, initial concentration of Cr(VI) ion, common cations, and anions on the adsorption of Cr(VI) was studied. The modified zeolite was characterized by following instrumental analysis of XRD, SEM/EDS, BET, and FT-IR. Based on calculated thermodynamic parameters values (Δ<i>G</i><sup>0</sup> < 0, Δ<i>H</i><sup>0</sup> > 0, and Δ<i>S</i><sup>0</sup> > 0) and kinetic properties of the adsorption of Cr(VI) by modified zeolite, it was concluded that the rate-limiting step of the process is a second-order chemical reaction. The results of the adsorption isotherm study confirmed that the adsorption follows the Langmuir isotherm model. The maximum adsorption capacity was 13.5 mg/g.
文摘Adsorption experiment from aqueous solutions containing known amount of Cr （chromium） using chitosan was explored to evaluate the efficiency of chitosan as sorbent for Cr. Some variable parameters such as pH, reaction time and chitosan dosage were optimized. Under the optimum experiment condition, the effect of common ions on the adsorption of Cr （i.e., Na^＋, K^＋, Mg^2＋, Ca^2＋ for Cr（Ⅲ）, and Cl^-, NO3^-, SO4^2- for Cr（Ⅵ）） was also investigated. Furthermore, the sorption mechanism of Cr by chitosan was investigated by applying Langmuir and Freundlich isotherm equations to the data obtained. In addition, to confirm the characteristics of the chitosan, the surface morphology of the biomass was determined by SEM （scanning electron microscope） and specific surface area analyzer （N2-BET （Brunaeur, Emmet and Teller））. Consequently, the following matters have been mainly clarified： （1） chitosan can be an efficient sorbent for Cr （both Cr（Ⅲ） and Cr（Ⅵ））; （2） the effect of common ions on the adsorption ofCr （Cr（Ⅲ） and Cr（Ⅵ）） was not significant under this experimental conditions; （3） adsorption isotherms using the chitosan can be generally described by Langmuir isotherm more satisfactorily for Cr. The adsorption may have occurred mainly by monolayer reaction; （4） the rates of adsorption were found to conform to pseudo-second order kinetics.
文摘This study investigated the adsorption ability of ZCHC （zeolite/chitosan hybrid composite） as adsorbent for chromium （Cr（Ⅵ））, ZCHC was prepared with sol-gel method by mixing zeolite and chitosan. Adsorption experiment from aqueous solutions containing known amount of Cr（Ⅵ） using zeolite, chitosan and ZCHC was explored to evaluate the efficiency of ZCHC as adsorbent for Cr in a batch system. The amount of Cr（Ⅵ） adsorbed at different pH values, initial concentrations, adsorbent dosages, and contact times were determined by ICP-AES （inductively coupled plasma-atomic emission spectrometry） in order to determine the optimum conditions for Cr（Ⅵ） adsorption. Furthermore, the adsorption mechanism of Cr（Ⅵ） by zeolite, chitosan and ZCHC was investigated by applying Langmuir and Freundlich isotherm equations to the data obtained. In addition, the rates of adsorption were found to conform to pseudo-second order kinetics.
文摘Mongolian sheep wool was modified by maleic anhydride at different temperatures to obtain new adsorbent for the removal of Cr(III). Adsorption of Cr(III) from aqueous solution onto the modified wool was investigated in batch system. In this work, the effect of various parameters such as pH, contact time, temperature and initial concentration on the adsorption capacity was determined by ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometry). Modified wool was characterized by SEM (scanning electron microscopy) and FT-IR (Fourier transform infrared spectrometer). The thermodynamic and kinetic studies were carried out and the results confirmed that the adsorption process was spontaneous in nature, thermodynamically favourable and endothermic. Kinetically, the adsorption process obeys the pseudo-second order model. The modified wool can be an effective adsorbent for the removal of Cr(III) from aqueous solution.
文摘Adsorption experiment from aqueous solutions containing known amount of chromium （Cr） using hybrid membrane of chitosan and silicon dioxide was explored to evaluate the efficiency of the membrane as sorbent for Cr（VI）. Some variable parameters such as pH, contact time and the dosage of the membrane were optimized. Adsorption isotherms of Cr（VI） onto the hybrid membrane were measured with varying initial concentrations under optimized condition. Furthermore, the sorption mechanism of Cr by the membrane was investigated by applying Langmuir and Freundlich isotherm equations to the data obtained. The surface morphology of the membrane was determined by SEM （scanning electron microscope） for material characterization. The concentrations of Cr in solution are determined by ICP-MS （inductively coupled plasma mass spectrometry）. Hybrid membrane of chitosan and silicon dioxide can be an efficient sorbent for Cr（VI）.
文摘The concentration and chemical speciation of heavy metals including REEs （rare earth elements）, Th （thorium） and U （uranium） in domestic sludge and electroplating sludge were investigated, and those of the domestic sludge were compared with those of natural soil. Removal of heavy metals in electroplating sludge was studied with bio-surfactants （saponin and sophorolipid） by batch and column experiments. The results suggested that heavy metals have greater concentrations and exist as more relatively unstable fraction in sludge than those in Natural soil. Nonionic saponin is more efficient than sophorolipid for the removal of heavy metals from the electroplating sludge, and mainly reacts with carbonate state （i.e., F3） and Fe-Mn oxide state （i.e., F5） fractions. The recovery efficiency of heavy metals in leachates from the electroplate sludge was attained 88%-97%. Saponin can be reused and be a promising and cost-effective material for the removal of heavy metals in sludge.
文摘In this paper,the adsorbent for the removal of hexavalent Cr(Chromium)from aqueous solutions has been prepared by modifying chitosan composite with EP(Epichlorohydrin)or GA(Glutaraldehyde).The modified cross-linked chitosan was characterized by SEM(Scanning Electron Microscopy)and FT-IR(Fourier Transform Infrared Spectroscopy).Batch adsorption experiments were carried out to evaluate the adsorption of Cr(VI)by the cross-linked chitosan under different conditions.Furthermore,the sorption mechanism of Cr(VI)by the cross-linked chitosan was investigated by applying Langmuir and Freundlich isotherm equations to the data obtained.The concentration of Cr in solution was determined by ICP-MS(Inductively Coupled Plasma Mass Spectrometry).The cross-linked chitosan can be an efficient sorbent for Cr(VI).
文摘The silicon organic polymer containing PSOT-3 （dioxothiocarbamide groups） has been synthesized and characterized, and the adsorption of Au（III） on PSOT-3 was investigated. The results showed that PSOT-3 had good adsorption capacity for Au（III）, and the adsorption of Au（III） was found to be the most effective in 0.1-0.3 mol/dm^3 hydrochloric acid solution. The adsorption is physical and the process is endothermic, and Freundlich isotherm fits the data better than the Langmuir isotherm. The adsorption can be generally described by electrostatic interaction （Coulomb＇s force） between the adsorbent and the adsorbate. The high adsorption capacity of this sorbent has significant potential for gold recovery from aqueous solutions.
文摘The hydrotalcite-like compound [Zn2AI（OH）6]NO3-mH20 （shorted as ZnAI-NO3） was intercalated with the chelating agent EDTA （ethylene diamine tetraacetic acid） by anion exchange to uptake cadmium ion from aqueous solutions. The materials synthesized in this work were characterized by chemical analysis, FT-IR （fourier transform infrared spectroscopy）, XRD （X-ray powder diffraction） to confirm their properties. In order to investigate the optimum conditions for Cd（II） adsorption, the amount of Cd（ll） adsorbed by Zn-AI LDHs intercalated with EDTA （ZnAI-EDTA） under different conditions （i.e., adsorbent dosage, temperature and contact time） were determined by ICP-AES （inductively coupled plasma-atomic emission spectrometry）. Adsorption isotherms of Cd（II） onto ZnA1-EDTA were measured at varying initial Cd concentrations （0.05 mg/L to 1 mg/L） under optimized conditions. The data were applied to Langmuir and Freundlich isotherms model, and well fitted by the Freundlich isotherms model. The pseudo-second-order kinetic model was more adequate to describe the kinetic in this case.
文摘In order to investigate the isotopic and chemical characteristics of lagoon waters in Niigata Prefecture in recent years, oxygen and hydrogen stable isotope ratios （i.e., 8180 and 6D）, the concentrations of DOC （dissolved organic carbon）, DO （dissolved oxygen） and pH, etc. in water samples of Sakata and Toyanogata were measured. Samples were generally taken monthly at the fixed sampling points from these lagoons. Consequently, the following matters have been mainly clarified： （1） ~D value of water samples in Sakata was generally larger than that in Toyanogata similarly to the case of ~180, though remarkable large difference among samples was not found; （2） the pH value of lagoon water samples is almost 6.5-8.5 （which is generally larger than that of river water）, and pH at the spot of SI （downstream point of Lower Lagoon （Shitakata）） is remarkably high （9.0-9.5）; （3） Lagoon water has the chemical characteristics contrasting to groundwater with a focus on river water from the viewpoint of pH （acidity or alkalinity） and DO. These matters can be closely related to the biological activity such as photosynthesis due to aquatic plant and phytoplankton and the activity of Crustacea plankton etc. in lagoon.
文摘Time-course of oxygen stable isotopic ratios （i.e., δ^18O） as well as seasonal variation of δ^18O has been examined to investigate the characteristics, sources and the passing route of precipitations in Niigata Prefecture. The precipitation samples have been mainly collected with a filtrating bulk sampler at the rooftop of Niigata University. Furthermore, backward trajectories analyses have been also conducted for these samples taken sequentially for a short period. Consequently, the following features have been mainly clarified for the precipitations in Niigata Prefecture： （1） the δ^18O values varied between -14.57%o and -3.86%0 in the precipitations of Niigata University; （2） as for the comparison among sampling points, the mean value of δ^18O at seaside spots （i.e., Niigata City： -6.93%0） is larger than that of inland spots （Sanjyo City： -8.68%0）; （3） δ^18O value was generally small in the rainy or typhoon season, and relatively large in summer; （4） decreasing δ^18O content with time is a predominant feature of sequentially sampled rainfalls as predicted by Rayleigh models of atmospheric vapor condensation.
文摘The hydrotalcite-like compound [Zn2Al·（OH）6] NO3·nH2O and [Mg2Al·（OH）6] NO3·nH2O （shorted as ZnA1-NO3 and MgAl-NO3） was intercalated with the chelating agent EDTA （Ethylenediaminetetraacetic Acid） and EDDS （N, N＇-1, 2-Ethanediylbis-1-Aspartic Acid） by anion exchange. The materials synthesized in this work were characterized by chemical analysis, FT-IR （Fourier Transform Infrared Spectroscopy）, SEM （Scanning Electron Microscopy） and XRD （Powder X-ray Diffraction） to confirm their properties. In order to discuss the adsorption capacity of LDHs （Layered Double Hydroxides）, the adsorption experiment was investigated under the optimum condition （10 mg, 25℃ and 100 μg·L-1）. The amount of metallic ions adsorbed by LDHs intercalated with EDTA and precursor LDHs were determined by ICP-AES （Inductively Coupled Plasma-Atomic Emission Spectrometry） and AAS （Atomic Absorption Spectrometry）. The intercalation of EDTA leads to improve the adsorption capacity of LDHs. LDHs intercalated with chelating agents have generally high affinity for removing metallic ions, and they can be efficient adsorbents for metallic ions.
文摘The adsorption capacity of activated carbon modified with KMnO4 （potassium permanganate） for Cr（VI） from aqueous solution was investigated. The modified activated carbon was characterized by SEM （scanning electron microscopy）, FT-IR （Fourier transform infrared spectrometer）, and N2 adsorption/desorption tests. Adsorption of Cr（VI） from aqueous solution onto the activated carbon was investigated in a batch system. In the present study, the effect of various parameters such as pH, contact time and initial concentration on the adsorption capacity were determined by ICP-AES （inductively coupled plasma atomic emission spectrometry）. The Cr（VI） adsorption on the activated carbon conforms to the Langmuir and Freundlich isothermal adsorption equation. The rates of adsorption were found to conform to pseudo-second order kinetic. The modified activated carbon can be an effective adsorbent for Cr（VI） from the aqueous solution.
文摘Adsorption of chromium （Cr） from aqueous solution onto Yukitsubaki carbon has been investigated in a batch system. The effect of pH, contact time and carbon dosage on the adsorption of Cr by Yukitsubaki carbon have been evaluated with ICP-AES （inductively coupled plasma atomic emission spectrometer） in order to obtain the optimum conditions for the Cr adsorption process. Adsorption isotherms of Cr onto the carbon were measured at varying initial concentrations under optimized condition. The surface properties of the carbon were characterized using N2-BET, SEM （scanning electron microscope） and FT-IR （Fourier transform infrared spectroscopy）. Consequently, the following matters have been mainly clarified. （1） Yukitsubaki carbon can be an efficient sorbent for Cr, particularly for cation species Cr（III）; （2） The effect of common ions on the adsorption of Cr was not significant, although the adsorption of Cr（VI） was inhibited under high concentrations of common ions; （3） Adsorption isotherms using the Yukitsubaki carbon can be generally described by Langmuir isotherm more satisfactorily for Cr. The adsorption may have occurred mainly by monolayer reaction; （4） The rates of adsorption were found to conform to pseudo-second order kinetics.
