The feasibility of employing nanofiltration for the removal of chromium（VI） from wastewater was investigated. Poly （m-phenylene isophthalamide） （PMIA） was used to fabricate asymmetric nanofiltration membrane thr...The feasibility of employing nanofiltration for the removal of chromium（VI） from wastewater was investigated. Poly （m-phenylene isophthalamide） （PMIA） was used to fabricate asymmetric nanofiltration membrane through the phase-inversion technique. Scanning electron microscopy （SEM） and atomic force microscopy （AFM） were used to characterize the obtained membrane, and the both confirmed a much smoother surface which could reduce membrane fouling. The PMIA membrane showed different rejections to electrolytes in a sequence of Na2SO4 〉 MgSO4 〉 NaC1 〉 MgC12, which was similar to the sequence of the negatively charged nanofiltration membranes. Separation experiments on chromium（VI） solution were conducted at various operating conditions, such as feed concentration, applied pressure and pH. It is concluded that chromium（VI） could be effectively removed from chromiumcontaining wastewater by the PMIA nanofiltration membranes while maintaining their pollution resistance under alkaline condition.展开更多
The activated carbon with high surface area was prepared by KOH activation.It was further modified by H2SO4 and HNO3 to introduce more surface functional groups.The pore structure of the activated carbons before and a...The activated carbon with high surface area was prepared by KOH activation.It was further modified by H2SO4 and HNO3 to introduce more surface functional groups.The pore structure of the activated carbons before and after modification was analyzed based on the nitrogen adsorption isotherms.The morphology of those activated carbons was characterized using scanning electronic microscopy （SEM）.The surface functional groups were determined by Fourier transform infrared spectroscopy （FTIR）.The quantity of those groups was measured by the Boehm titration method.Cr（VI） removal by the activated carbons from aqueous solution was investigated at different pH values.The results show that compared with H2SO4,HNO3 destructs the original pore of the activated carbon more seriously and induces more acidic surface functional groups on the activated carbon.The pH value of the solution plays a key role in the Cr（VI） removal.The ability of reducing Cr（VI） to Cr（III） by the activated carbons is relative to the acidic surface functional groups.At higher pH values,the Cr（VI） removal ratio is improved by increasing the acidic surface functional groups of the activated carbons.At lower pH values,however,the acidic surface functional groups almost have no effect on the Cr（VI） removal by the activated carbon from aqueous solution.展开更多
基金supported by the High Technology Research and Development Program (863) of China(No. 2007AA06Z339)the National Key Technologies R&D Program of China (No. 2006BAD01B02-02,2006BAJ08B00)
文摘The feasibility of employing nanofiltration for the removal of chromium（VI） from wastewater was investigated. Poly （m-phenylene isophthalamide） （PMIA） was used to fabricate asymmetric nanofiltration membrane through the phase-inversion technique. Scanning electron microscopy （SEM） and atomic force microscopy （AFM） were used to characterize the obtained membrane, and the both confirmed a much smoother surface which could reduce membrane fouling. The PMIA membrane showed different rejections to electrolytes in a sequence of Na2SO4 〉 MgSO4 〉 NaC1 〉 MgC12, which was similar to the sequence of the negatively charged nanofiltration membranes. Separation experiments on chromium（VI） solution were conducted at various operating conditions, such as feed concentration, applied pressure and pH. It is concluded that chromium（VI） could be effectively removed from chromiumcontaining wastewater by the PMIA nanofiltration membranes while maintaining their pollution resistance under alkaline condition.
文摘The activated carbon with high surface area was prepared by KOH activation.It was further modified by H2SO4 and HNO3 to introduce more surface functional groups.The pore structure of the activated carbons before and after modification was analyzed based on the nitrogen adsorption isotherms.The morphology of those activated carbons was characterized using scanning electronic microscopy （SEM）.The surface functional groups were determined by Fourier transform infrared spectroscopy （FTIR）.The quantity of those groups was measured by the Boehm titration method.Cr（VI） removal by the activated carbons from aqueous solution was investigated at different pH values.The results show that compared with H2SO4,HNO3 destructs the original pore of the activated carbon more seriously and induces more acidic surface functional groups on the activated carbon.The pH value of the solution plays a key role in the Cr（VI） removal.The ability of reducing Cr（VI） to Cr（III） by the activated carbons is relative to the acidic surface functional groups.At higher pH values,the Cr（VI） removal ratio is improved by increasing the acidic surface functional groups of the activated carbons.At lower pH values,however,the acidic surface functional groups almost have no effect on the Cr（VI） removal by the activated carbon from aqueous solution.
