Magnetic multi-wall carbon nanotubes were prepared with wet chemical treatments and characterized by a transmission electron microscope （TEM） and X-ray diffraction （XRD）. They were used as adsorbents for the remov...Magnetic multi-wall carbon nanotubes were prepared with wet chemical treatments and characterized by a transmission electron microscope （TEM） and X-ray diffraction （XRD）. They were used as adsorbents for the removal of Cr（VI） in aqueous solutions. The effects of adsorbent dosage, the concentration of Cr（VI） in aqueous solution, temperature, and pH value on the removal efficiency were studied. Results showed that the adsorption capacity of the magnetic multi-wall carbon nanotubes increased with the initial Cr（VI） concentration, but decreased with the increase of adsorbent dosage. The adsorption amount increased with contact time. The adsorption kinetics were best represented by the pseudo second-order kinetic model, and the adsorption isotherms indicated that the Langmuir model better reflected the adsorption process. The ob- tained calculation results for the Gibbs free energy revealed that the adsorption was a spontaneous and endothermic process. The enthalpy deviation was 3.835 kJ.mol 1. The magnetic multi-wall carbon nanotubes showed significant potential for application in adsorption of heavy metal ions.展开更多
Rice husk-based activated carbon was prepared with the help of zinc chloride using microwave and electrical dual-mode heating.The pore characteristics and chemical properties of rice husk-based activated carbon(RH-AC)...Rice husk-based activated carbon was prepared with the help of zinc chloride using microwave and electrical dual-mode heating.The pore characteristics and chemical properties of rice husk-based activated carbon(RH-AC)were characterized by BET,XRD,Raman spectra,FTIR and pHIEP(pH of isoelectric point).The specific surface area of RH-AC is 1719.32 m^(2)/g with a total pore volume of 1.05 cm^(3)/g.The performance of RH-AC for removing Cr(VI)from aqueous solution was examined considering the variation of the contact time(0-120 min),pH value(2.0-9.0),adsorbent dose(0.5-3.0 g/L),initial concentration(28-145 mg/L)and solvent temperature(15-45℃).The ideal pH for Cr(VI)removal is between 2.0 and 3.0 with the equilibrium time of 90 min,achieving the maximum adsorption capacity of 56.82 mg/g with the pH of 3.0.Comparable study on the established kinetic models and isotherms to simulate the removal of Cr(VI)by RH-AC was carried out to sort out the inherent mechanism of the absorption.Reasonable agreements could be obtained by the pseudo-second-order kinetic model and Langmuir,Freundlich and Tempkin isothermal models.Results from Body model simulation suggest that external mass transfer was the essential cause for rate-controlling in the adsorption process of Cr(VI).展开更多
As a strong reducing radical,carbon dioxide anion radical(CO·-2)can be generated by initiating sulfate radical(SO·-4)in the presence of tonnate anions(FA)for Cr(Ⅵ)reduction.Moreover,activated carbon(AC)-cat...As a strong reducing radical,carbon dioxide anion radical(CO·-2)can be generated by initiating sulfate radical(SO·-4)in the presence of tonnate anions(FA)for Cr(Ⅵ)reduction.Moreover,activated carbon(AC)-catalyzed persultate(PS)oxidation is an economically justifiable,enⅥronmentally friendly,and easy-to-scalemethod to produce SO·-4 The complete removal of Cr(Ⅵ)was achieved within 280 min for an initial Cr(Ⅵ)concentration of 50 mg/L under the optional condition of c(AC)=1 g/L,[PS]0=1O mmol/L,[FA]0=10 mmol/L,T=30℃,and unadjusted pH.When the molar ratio of FA to PS was greater than or equal to 1,the system maintained a strong reduction state.The mechanism investigation confirmed that FA was converted to carboxyl anion radical(CO2·-2)as the predominant radical tor Cr(Ⅵ)reduction.This novel system may offer a potential plattbnn teclmology tor Cr(Ⅵ)wastewater treatment.展开更多
基金supported by the Research Grant of the Phytochemistry Key Laboratory of Shaanxi Province(Grant No.13JS005)the Project of Baoji University of Arts and Sciences(Grant No.YK1417)the Project of Baoji Sciences and Technology Bureau(Grant No.2013R7-5)
文摘Magnetic multi-wall carbon nanotubes were prepared with wet chemical treatments and characterized by a transmission electron microscope （TEM） and X-ray diffraction （XRD）. They were used as adsorbents for the removal of Cr（VI） in aqueous solutions. The effects of adsorbent dosage, the concentration of Cr（VI） in aqueous solution, temperature, and pH value on the removal efficiency were studied. Results showed that the adsorption capacity of the magnetic multi-wall carbon nanotubes increased with the initial Cr（VI） concentration, but decreased with the increase of adsorbent dosage. The adsorption amount increased with contact time. The adsorption kinetics were best represented by the pseudo second-order kinetic model, and the adsorption isotherms indicated that the Langmuir model better reflected the adsorption process. The ob- tained calculation results for the Gibbs free energy revealed that the adsorption was a spontaneous and endothermic process. The enthalpy deviation was 3.835 kJ.mol 1. The magnetic multi-wall carbon nanotubes showed significant potential for application in adsorption of heavy metal ions.
基金the National Key R&D Program of China(Grant No.2019YFC1906805).
文摘Rice husk-based activated carbon was prepared with the help of zinc chloride using microwave and electrical dual-mode heating.The pore characteristics and chemical properties of rice husk-based activated carbon(RH-AC)were characterized by BET,XRD,Raman spectra,FTIR and pHIEP(pH of isoelectric point).The specific surface area of RH-AC is 1719.32 m^(2)/g with a total pore volume of 1.05 cm^(3)/g.The performance of RH-AC for removing Cr(VI)from aqueous solution was examined considering the variation of the contact time(0-120 min),pH value(2.0-9.0),adsorbent dose(0.5-3.0 g/L),initial concentration(28-145 mg/L)and solvent temperature(15-45℃).The ideal pH for Cr(VI)removal is between 2.0 and 3.0 with the equilibrium time of 90 min,achieving the maximum adsorption capacity of 56.82 mg/g with the pH of 3.0.Comparable study on the established kinetic models and isotherms to simulate the removal of Cr(VI)by RH-AC was carried out to sort out the inherent mechanism of the absorption.Reasonable agreements could be obtained by the pseudo-second-order kinetic model and Langmuir,Freundlich and Tempkin isothermal models.Results from Body model simulation suggest that external mass transfer was the essential cause for rate-controlling in the adsorption process of Cr(VI).
基金Supported by the National Nature Science Foundation of China(No.41302184)the Project of the Research on Water Environmental Protection Strategy and Management Policy in Beijing-Tianjin-Hebei Region,China(No.2018ZX07111001)+2 种基金the Scientific Frontier and Interdisciplinary Research Project of Jilin Universitythe Outstanding Youth Cultivation Plan of Jilin University,the Fund of the Key Laboratory of Groundwater Resources and Environmental of Ministry of Education(Jilin University) Chinathe Project of the National and Local Joint Engineering Laboratory for Petrochemical Contaminated Site Control and Remediation Teclmology of China.
文摘As a strong reducing radical,carbon dioxide anion radical(CO·-2)can be generated by initiating sulfate radical(SO·-4)in the presence of tonnate anions(FA)for Cr(Ⅵ)reduction.Moreover,activated carbon(AC)-catalyzed persultate(PS)oxidation is an economically justifiable,enⅥronmentally friendly,and easy-to-scalemethod to produce SO·-4 The complete removal of Cr(Ⅵ)was achieved within 280 min for an initial Cr(Ⅵ)concentration of 50 mg/L under the optional condition of c(AC)=1 g/L,[PS]0=1O mmol/L,[FA]0=10 mmol/L,T=30℃,and unadjusted pH.When the molar ratio of FA to PS was greater than or equal to 1,the system maintained a strong reduction state.The mechanism investigation confirmed that FA was converted to carboxyl anion radical(CO2·-2)as the predominant radical tor Cr(Ⅵ)reduction.This novel system may offer a potential plattbnn teclmology tor Cr(Ⅵ)wastewater treatment.
