The influence of interlayer anions such as NO3-, 5042- and Cl- on Mg-AI hydrotalcites for Cr（Vl） removal from aqueous solution was studied. The structure of the prepared LDHs was characterized by XRD, SEM, FTIR, TGA...The influence of interlayer anions such as NO3-, 5042- and Cl- on Mg-AI hydrotalcites for Cr（Vl） removal from aqueous solution was studied. The structure of the prepared LDHs was characterized by XRD, SEM, FTIR, TGA, BET surface area and pHzpc. The sorbent ability and sorption mechanisms were also investigated. The LDHs exhibit high removal for Cr（VI）, and the sorbed amount depends on the nature of interlayer anion, which decreased in the following order： NO3- 〉 Cl 〉 SO42-, Nitrate-containing LDH reached a Cr（VI） sorption equilibrium within only 30 min. The effects of operating conditions, including initial concentration, solution pH, agitation time and sorbent amount have been studied in batch mode. The optimum conditions were observed at an initial concen- tration of 100 mg. L- 1, pH = 6, agitation time of 60 min and a sorbent dose of 2 g.L- 1. The equilibrium data were fitted to the Langmuir, Freundlich and Dubinin-Radushkevich isotherm models. The Langmuir model was found to sufficiently describe the sorption process, offering a maximum sorption capacity of 71.91 mg-g 1. The sorp- tion kinetic follows pseudo-second-order reaction with high accuracy. Thermodynamic parameters suggested that the sorption process is spontaneous and endothermic in nature.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
Litbium intercalated bilayer graphene has been investigated using first-principles density functional theory calculations. Re- sults show that there exist AB and AA stacking sequences for bilayer graphene in which the...Litbium intercalated bilayer graphene has been investigated using first-principles density functional theory calculations. Re- sults show that there exist AB and AA stacking sequences for bilayer graphene in which the latter is more favorable for the Li storage and the former will evolve into the latter with the intercalation of Li ions. The relationship between the interlayer dis- tance of two graphene sheets and the intercalated capacity of Li ions is discussed, It is found that structural defect is identified to store Li ions more favorably than pristine bilayer graphene and an isolated C atom vacancy in bilayer graphene can capture three Li ions between two graphene sheets.展开更多
基金financially supported by both the department of Process Engineering and Chemistry of USTHB(Algiers)
文摘The influence of interlayer anions such as NO3-, 5042- and Cl- on Mg-AI hydrotalcites for Cr（Vl） removal from aqueous solution was studied. The structure of the prepared LDHs was characterized by XRD, SEM, FTIR, TGA, BET surface area and pHzpc. The sorbent ability and sorption mechanisms were also investigated. The LDHs exhibit high removal for Cr（VI）, and the sorbed amount depends on the nature of interlayer anion, which decreased in the following order： NO3- 〉 Cl 〉 SO42-, Nitrate-containing LDH reached a Cr（VI） sorption equilibrium within only 30 min. The effects of operating conditions, including initial concentration, solution pH, agitation time and sorbent amount have been studied in batch mode. The optimum conditions were observed at an initial concen- tration of 100 mg. L- 1, pH = 6, agitation time of 60 min and a sorbent dose of 2 g.L- 1. The equilibrium data were fitted to the Langmuir, Freundlich and Dubinin-Radushkevich isotherm models. The Langmuir model was found to sufficiently describe the sorption process, offering a maximum sorption capacity of 71.91 mg-g 1. The sorp- tion kinetic follows pseudo-second-order reaction with high accuracy. Thermodynamic parameters suggested that the sorption process is spontaneous and endothermic in nature.
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.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50802089 and 51072183)the Scientific Research Foundation for the Returned Overseas Chinese Scholars, Ministry of Education of China (Grant No. [2008] 890)the Natural Science Foundation of Zhejiang Province (Grant No. Y4090280)
文摘Litbium intercalated bilayer graphene has been investigated using first-principles density functional theory calculations. Re- sults show that there exist AB and AA stacking sequences for bilayer graphene in which the latter is more favorable for the Li storage and the former will evolve into the latter with the intercalation of Li ions. The relationship between the interlayer dis- tance of two graphene sheets and the intercalated capacity of Li ions is discussed, It is found that structural defect is identified to store Li ions more favorably than pristine bilayer graphene and an isolated C atom vacancy in bilayer graphene can capture three Li ions between two graphene sheets.
