用具有良好吸附能力的羟基铝柱撑膨润土作载体,通过FeSO4与NaBH4反应制得羟基铝柱撑膨润土负载的纳米铁(nanoscale zero-valent iron supported on Al-pillared bentonite,NZVI/Al-PILC).用X射线衍射(X-ray diffraction,XRD)(、Brunauer...用具有良好吸附能力的羟基铝柱撑膨润土作载体,通过FeSO4与NaBH4反应制得羟基铝柱撑膨润土负载的纳米铁(nanoscale zero-valent iron supported on Al-pillared bentonite,NZVI/Al-PILC).用X射线衍射(X-ray diffraction,XRD)(、Brunauer-Emmett-Teller,BET)法对NZVI/Al-PILC进行了结构表征.以Cr(Ⅵ)为目标污染物,考察了NZVI/Al-PILC与Cr(Ⅵ)反应过程中,介质pH、不同起始浓度的Cr(Ⅵ)对其去除率的影响,并与相同铁含量的纳米铁(nanoscale zero-valent iron,NZVI)进行了比较.结果表明,在相同实验条件下,Cr(Ⅵ)与NZVI/Al-PILC反应120 min后去除率接近100%,不仅高于相同铁含量NZVI对Cr(Ⅵ)去除率(63.0%),而且也明显优于相同铁含量的NZVI和相同含土量的羟基铝柱撑膨润土对Cr(Ⅵ)去除率的加和(75.4%).展开更多
The catalysis of manganese（Ⅱ） （Mn^2＋） on chromium（Ⅵ） （Cr^6＋） reduction by citrate was studied through batch experiments with the concentration of citrate greatly in excess of Cr^6＋ at 25 ℃ and in pH rang...The catalysis of manganese（Ⅱ） （Mn^2＋） on chromium（Ⅵ） （Cr^6＋） reduction by citrate was studied through batch experiments with the concentration of citrate greatly in excess of Cr^6＋ at 25 ℃ and in pH ranges of 4.0 go 5.0. Results showed that at pH 4.5 within 22 h direct reduction of Cr^6＋ by citrate was not observed, bug for the same time when Mn^2＋ （50 to 200 μmol L^-1） was added, nearly all Cr^6＋ was reduced, with the higher initial Mn^2＋ concentration having faster Cr^6＋ reduction. In the initial stage of the reaction, the Cr^6＋ reduction could be described with a pseudo-first-order kinetics equation. In the lager stage of the reaction, plots of lnc（Cr^6＋） versus t, where c（Cr^6＋） is the Cr^6＋ concentration in the reaction and t is the reaction time, deviated from the initial linear trend. The deviations suggested that the pseudo-first-order kinetics did not apply go the whole experimental period and that some reaction intermediates could have greatly accelerated Cr^6＋ reduction by citrate. The catalysis of the intermediates increased with the reaction time and gradually reached stability. Then, the plot of lnc（Cr^6＋） versus t in the presence of Mn^2＋ was linear again, with the rate constant increasing by 102 times compared with the absence of Mn^2＋. Complexation between Mn^2＋ and citrate was likely a prerequisite for the catalysis of Mn^2＋ on the reaction. Additional experiments showed that introducing eghylenediaminegegraacegic acid （EDTA） into the reaction system strongly suppressed the catalysis of Mn^2＋.展开更多
To develop highly effective adsorbents for chromium removal,a nitrogen-doped biomass-derived carbon(NHPC)was synthesized via direct carbonation of loofah sponge followed by alkali activation and doping modification.NH...To develop highly effective adsorbents for chromium removal,a nitrogen-doped biomass-derived carbon(NHPC)was synthesized via direct carbonation of loofah sponge followed by alkali activation and doping modification.NHPC possessed a hierarchical micro-/mesoporous lamellar structure with nitrogen-containing functional groups(1.33 at%),specific surface area(1792.47 m2/g),and pore volume(1.18 cm^(3)/g).NHPC exhibited a higher Cr(Ⅵ)adsorption affinity than the HPC(without nitrogen doping)or the pristine loofah sponge carbon(LSC)did.The influence of process parameters,including pH,dosage,time,temperature,and Cr(Ⅵ)concentration,on Cr(Ⅵ)adsorption by NHPC were evaluated.The Cr(Ⅵ)adsorption kinetics matched with the pseudo-second-order model(R^(2)≥0.9983).The Cr(Ⅵ)adsorption isotherm was fitted with the Langmuir isotherm model,which indicated the maximum Cr(Ⅵ)adsorption capacities:227.27,238.10,and 285.71 mg/g at 298K,308K,and 318K,respectively.The model analysis also indicated that adsorption of Cr(Ⅵ)on NHPC was a spontaneous,endothermal,and entropy-increasing process.The Cr(Ⅵ)adsorption process potentially involved mixed reductive and adsorbed mechanism.Furthermore,computational chemistry calculations revealed that the adsorption energy between NHPC and Cr(VI)(-0.84 eV)was lower than that of HPC(-0.51 eV),suggesting that nitrogen doping could greatly enhance the interaction between NHPC and Cr(VI).展开更多
Graphene oxide(GO),a new and promising material,has been widely used as a co-catalyst in photocatalytic reactions;however,its capacity as a sole photocatalyst has rarely been investigated.In this study,ultraviolet(UV)...Graphene oxide(GO),a new and promising material,has been widely used as a co-catalyst in photocatalytic reactions;however,its capacity as a sole photocatalyst has rarely been investigated.In this study,ultraviolet(UV) light irradiation was used as a modification method to obtain reduced GO(rGO) samples.The samples were used as photocatalysts to examine their visible light photocatalytic activity toward hexavalent chromium(Cr(Ⅵ)) removal.Atomic force microscopy(AFM),X-ray diffraction(XRD),UV-vis spectrophotometry,Raman spectroscopy,X-ray photoelectron spectroscopy(XPS),and electron spin resonance(ESR) spectroscopy were applied to interpret the surface and structure changes with UV irradiation.The oxygen-containing functional groups(OFGs) on the GO surface were reduced to defective carbons andπ-conjugated C=C(sp^(2) domains) under UV light;this led to a decrease in the interlayer distance between GO sheets,GO fragmentation,and increased disorder on the GO surface.The restoration of sp^(2) domains led to a narrower band gap of GO,which favored the rGO excitation by visible light to generate electron-hole pairs.The rGO pre-irradiated with UV for 1 h(rGO-1),possessing the highest defect density and electron generation efficiency,exhibited the best Cr(Ⅵ) reduction efficiency,which was about three times that of the GO sample;moreover,it outperformed most of the reported GO-based nanomaterials.In addition,low pH and the addition of citric acid as a hole scavenger could further improve the photocatalytic activity.This study proves that GO or rGO can be used as a sole photocatalyst under visible light to remove environmental pollutants such as heavy-metal ions,and it paves the way for the development of this kind of material and its UV-irradiation modification for further applications.展开更多
Based on the principle of bacterial leaching and bacterial metallurgy,a novel technology for the detoxification of chromium-containing slag by Achromobacter sp.CH-1 and chromium recovery was proposed.Strain CH-1 cell ...Based on the principle of bacterial leaching and bacterial metallurgy,a novel technology for the detoxification of chromium-containing slag by Achromobacter sp.CH-1 and chromium recovery was proposed.Strain CH-1 cell morphology before and after Cr(Ⅵ) reduction was observed with a scanning electron microscope(SEM),and the reduction product is found to adhere to terminals of CH-1 cells.Energy-dispersive X-ray(EDX) and electron paramagnetic resonance(EPR) analyses reveal that the main component of the reduction product is Cr(Ⅲ).Furthermore,small and large-scale demonstration projects reveal that Achromobacter sp.can be used to detoxify chromium-containing slag and to selectively recover chromium by using this novel technique.Chromium recovery rate increases with decreasing particle sizes of chromium-containing slag and slagheap height.Chromium recovery rates in 10 t/batch and 20 t/batch of on-site demonstration projects for chromium-containing slag detoxification are more than 90%.展开更多
基金Project supported by the National Natural Science Foundation of China (No. 40671089).
文摘The catalysis of manganese（Ⅱ） （Mn^2＋） on chromium（Ⅵ） （Cr^6＋） reduction by citrate was studied through batch experiments with the concentration of citrate greatly in excess of Cr^6＋ at 25 ℃ and in pH ranges of 4.0 go 5.0. Results showed that at pH 4.5 within 22 h direct reduction of Cr^6＋ by citrate was not observed, bug for the same time when Mn^2＋ （50 to 200 μmol L^-1） was added, nearly all Cr^6＋ was reduced, with the higher initial Mn^2＋ concentration having faster Cr^6＋ reduction. In the initial stage of the reaction, the Cr^6＋ reduction could be described with a pseudo-first-order kinetics equation. In the lager stage of the reaction, plots of lnc（Cr^6＋） versus t, where c（Cr^6＋） is the Cr^6＋ concentration in the reaction and t is the reaction time, deviated from the initial linear trend. The deviations suggested that the pseudo-first-order kinetics did not apply go the whole experimental period and that some reaction intermediates could have greatly accelerated Cr^6＋ reduction by citrate. The catalysis of the intermediates increased with the reaction time and gradually reached stability. Then, the plot of lnc（Cr^6＋） versus t in the presence of Mn^2＋ was linear again, with the rate constant increasing by 102 times compared with the absence of Mn^2＋. Complexation between Mn^2＋ and citrate was likely a prerequisite for the catalysis of Mn^2＋ on the reaction. Additional experiments showed that introducing eghylenediaminegegraacegic acid （EDTA） into the reaction system strongly suppressed the catalysis of Mn^2＋.
基金funded by the National Natural Science Foundation of China(Grant No.41872169)the Project of Education Department of Henan Province(No.21A610002)the Innovation and entrepreneurship training plan for college students of Henan Province in 2020(No.S202011517004)。
文摘To develop highly effective adsorbents for chromium removal,a nitrogen-doped biomass-derived carbon(NHPC)was synthesized via direct carbonation of loofah sponge followed by alkali activation and doping modification.NHPC possessed a hierarchical micro-/mesoporous lamellar structure with nitrogen-containing functional groups(1.33 at%),specific surface area(1792.47 m2/g),and pore volume(1.18 cm^(3)/g).NHPC exhibited a higher Cr(Ⅵ)adsorption affinity than the HPC(without nitrogen doping)or the pristine loofah sponge carbon(LSC)did.The influence of process parameters,including pH,dosage,time,temperature,and Cr(Ⅵ)concentration,on Cr(Ⅵ)adsorption by NHPC were evaluated.The Cr(Ⅵ)adsorption kinetics matched with the pseudo-second-order model(R^(2)≥0.9983).The Cr(Ⅵ)adsorption isotherm was fitted with the Langmuir isotherm model,which indicated the maximum Cr(Ⅵ)adsorption capacities:227.27,238.10,and 285.71 mg/g at 298K,308K,and 318K,respectively.The model analysis also indicated that adsorption of Cr(Ⅵ)on NHPC was a spontaneous,endothermal,and entropy-increasing process.The Cr(Ⅵ)adsorption process potentially involved mixed reductive and adsorbed mechanism.Furthermore,computational chemistry calculations revealed that the adsorption energy between NHPC and Cr(VI)(-0.84 eV)was lower than that of HPC(-0.51 eV),suggesting that nitrogen doping could greatly enhance the interaction between NHPC and Cr(VI).
基金financial support provided by National Natural Science Foundation of China (Nos.21876003 and41961134034)the Second Tibetan Plateau Scientific Expedition and Research (No.2019QZKK0607)the 111 Project Urban Air Pollution and Health Effects (B20009)。
文摘Graphene oxide(GO),a new and promising material,has been widely used as a co-catalyst in photocatalytic reactions;however,its capacity as a sole photocatalyst has rarely been investigated.In this study,ultraviolet(UV) light irradiation was used as a modification method to obtain reduced GO(rGO) samples.The samples were used as photocatalysts to examine their visible light photocatalytic activity toward hexavalent chromium(Cr(Ⅵ)) removal.Atomic force microscopy(AFM),X-ray diffraction(XRD),UV-vis spectrophotometry,Raman spectroscopy,X-ray photoelectron spectroscopy(XPS),and electron spin resonance(ESR) spectroscopy were applied to interpret the surface and structure changes with UV irradiation.The oxygen-containing functional groups(OFGs) on the GO surface were reduced to defective carbons andπ-conjugated C=C(sp^(2) domains) under UV light;this led to a decrease in the interlayer distance between GO sheets,GO fragmentation,and increased disorder on the GO surface.The restoration of sp^(2) domains led to a narrower band gap of GO,which favored the rGO excitation by visible light to generate electron-hole pairs.The rGO pre-irradiated with UV for 1 h(rGO-1),possessing the highest defect density and electron generation efficiency,exhibited the best Cr(Ⅵ) reduction efficiency,which was about three times that of the GO sample;moreover,it outperformed most of the reported GO-based nanomaterials.In addition,low pH and the addition of citric acid as a hole scavenger could further improve the photocatalytic activity.This study proves that GO or rGO can be used as a sole photocatalyst under visible light to remove environmental pollutants such as heavy-metal ions,and it paves the way for the development of this kind of material and its UV-irradiation modification for further applications.
文摘Based on the principle of bacterial leaching and bacterial metallurgy,a novel technology for the detoxification of chromium-containing slag by Achromobacter sp.CH-1 and chromium recovery was proposed.Strain CH-1 cell morphology before and after Cr(Ⅵ) reduction was observed with a scanning electron microscope(SEM),and the reduction product is found to adhere to terminals of CH-1 cells.Energy-dispersive X-ray(EDX) and electron paramagnetic resonance(EPR) analyses reveal that the main component of the reduction product is Cr(Ⅲ).Furthermore,small and large-scale demonstration projects reveal that Achromobacter sp.can be used to detoxify chromium-containing slag and to selectively recover chromium by using this novel technique.Chromium recovery rate increases with decreasing particle sizes of chromium-containing slag and slagheap height.Chromium recovery rates in 10 t/batch and 20 t/batch of on-site demonstration projects for chromium-containing slag detoxification are more than 90%.
