The synthesis of oxygen vacancies(OVs)-modified TiO_(2)under mild conditions is attractive.In this work,OVs were easily introduced in TiO_(2)lattice during the hydrothermal doping process of trivalent iron ions.Theore...The synthesis of oxygen vacancies(OVs)-modified TiO_(2)under mild conditions is attractive.In this work,OVs were easily introduced in TiO_(2)lattice during the hydrothermal doping process of trivalent iron ions.Theoretical calculations based on a novel charge-compensation structure model were employed with experimental methods to reveal the intrinsic photocatalytic mechanism of Fe-doped TiO_(2)(Fe-TiO_(2)).The OVs formation energy in Fe-TiO_(2)(1.12 eV)was only 23.6%of that in TiO_(2)(4.74 eV),explaining why Fe^(3+)doping could introduce OVs in the TiO_(2)lattice.The calculation results also indicated that impurity states introduced by Fe^(3+)and OVs enhanced the light absorption activity of TiO_(2).Additionally,charge carrier transport was investigated through the carrier lifetime and relative mass.The carrier lifetime of Fe-TiO_(2)(4.00,4.10,and 3.34 ns for 1at%,2at%,and 3at%doping contents,respectively)was longer than that of undoped TiO_(2)(3.22 ns),indicating that Fe^(3+) and OVs could promote charge carrier separation,which can be attributed to the larger relative effective mass of electrons and holes.Herein,Fe-TiO_(2)has higher photocatalytic indoor NO removal activity compared with other photocatalysts because it has strong light absorption activity and high carrier separation efficiency.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
The industrial silica fume pretreated by nitric acid at 80 °C was re-used in this work. Then, the obtained silica nanoparticles were surface functionalized by silane coupling agents, such as(3-Mercaptopropyl) tri...The industrial silica fume pretreated by nitric acid at 80 °C was re-used in this work. Then, the obtained silica nanoparticles were surface functionalized by silane coupling agents, such as(3-Mercaptopropyl) triethoxysilane(MPTES) and(3-Amincpropyl) trithoxysilane(APTES). Some further modifications were studied by chloroaceetyl choride and 1,8-Diaminoaphalene for amino modified silica. The surface functionalized silica nanoparticles were characterized by Fourier transform infrared(FI-IR) and X-ray photoelectron spectroscopy(XPS). The prepared adsorbent of surface functionalized silica nanoparticles with differential function groups were investigated in the selective adsorption about Pb2+, Cu2+, Hg2+, Cd2+ and Zn2+ions in aqueous solutions. The results show that the(3-Mercaptopropyl) triethoxysilane functionalized silica nanoparticles(SiO2-MPTES) play an important role in the selective adsorption of Cu2+ and Hg2+, the(3-Amincpropyl) trithoxysilane(APTES) functionalized silica nanoparticles(SiO2-APTES) exhibited maximum removal efficiency towards Pb2+ and Hg2+, the 1,8-Diaminoaphalene functionalized silica nanoparticles was excellent for removal of Hg2+ at room temperature, respectively.展开更多
Between the two major arsenic-containing salts in natural water, arsenite(As(Ⅲ)) is far more harmful to human and the environment than arsenate(As(V)) due to its high toxicity and transportability. Therefore, preoxid...Between the two major arsenic-containing salts in natural water, arsenite(As(Ⅲ)) is far more harmful to human and the environment than arsenate(As(V)) due to its high toxicity and transportability. Therefore, preoxidation of As(Ⅲ) to As(V) is considered to be an effective means to reduce the toxicity of arsenic and to promote the removal efficiency of arsenic. Due to their high catalytic activity and arsenic affinity, iron-based functional materials can quickly oxidize As(Ⅲ) to As(V) in heterogeneous Fenton-like systems, and then remove As(V) from water through adsorption and surface coprecipitation. In this review, the effects of different iron-based functional materials such as zero-valent iron and iron(hydroxy) oxides on arsenic removal are compared, and the catalytic oxidation mechanism of As(Ⅲ) in heterogeneous Fenton process is further clarified. Finally, the main challenges and opportunities faced by iron-based As(Ⅲ) oxidation functional materials are prospected.展开更多
Filtration efficiency of Ni(II) from aqueous solution using pristine and modified MWCNTs filters was investigated as a function of Ni(II) ion concentration, p H, and filter mass. MWCNTs were synthesized by CVD method ...Filtration efficiency of Ni(II) from aqueous solution using pristine and modified MWCNTs filters was investigated as a function of Ni(II) ion concentration, p H, and filter mass. MWCNTs were synthesized by CVD method and modified using two complementary treatments, purification(using a mixture of hydrochloric acid and hydrogen peroxide) and functionalization(using nitric acid). The effect and mechanism of each treatment on the structural integrity of pristine MWCNTs has been studied. Morphology of the pristine and modified filters was investigated by Raman Spectrometry(RS), Scanning Electron Microscopy(SEM), Energy Dispersive X-ray Spectroscopy(EDS),Fourier Transform Infrared(FTIR) spectrometry and Thermogravimetric analysis. It was found from Raman spectra that the ratio of the intensity of D-band to that of G-band decreased by purification process, and increased by functionalization process. The adsorption mechanism of Ni(II) onto the surface functional groups of modified MWCNTs was confirmed by FTIR spectrum. The filtration results showed that the removal efficiency of Ni(II) is strongly dependent on pH and could reach 85% at pH = 8. Also, modified MWCNT filters can be reused through many cycles of regeneration with high performance. Functionalized MWCNTs filters may be a promising adsorbent candidate for heavy metal removal from wastewater.展开更多
An innovative approach to H2 S capture has been developed using several metal-based ionic liquids([Bmim]Cl·CuCl_2, [Bmim]Cl·FeCl_3, [Bmim]Cl·ZnCl_2, [Bmim]Br·CuCl_2, and [Bmim]Br·FeCl_3) immob...An innovative approach to H2 S capture has been developed using several metal-based ionic liquids([Bmim]Cl·CuCl_2, [Bmim]Cl·FeCl_3, [Bmim]Cl·ZnCl_2, [Bmim]Br·CuCl_2, and [Bmim]Br·FeCl_3) immobilized on the sol-gel derived silica, which is superior to purely viscous ionic liquid with a crucial limit of high temperature, low mass transfer rate,and mass loss. The adsorbents were characterized by the Fourier transform infrared spectrometer, transmission electron microscope, N_2 adsorption/desorption, X-ray photoelectron spectroscopy, and thermal analysis techniques. The effects of the metal and halogen in IL, the loading amount of IL, and the adsorption temperature were studied by dynamic adsorption experiments at a gas flow rate of 100 mL/min. The H2 S adsorption results have showed that the optimal adsorbent and adsorption temperature are 5% [Bmim]Cl·CuCl_2/silica gel and 20—50 ℃, respectively. H_2 S can be captured and oxidized to elemental sulfur, and [Bmim]Cl·CuCl_2/silica gel can be readily regenerated by air. The excellent efficiency of H2 S removal may be attributed to the formation of nano-scaled and high-concentration [Bmim]Cl·CuCl_2 confined in silica gel, indicating that the immobilization of [Bmim]Cl·CuCl_2 on the sol-gel derived silica can be used for H2 S removal promisingly.展开更多
Affinity membranes are fabricated for boric acid removal by the surface functionalization of microporous polypropylene membrane(MPPM)with lactose-based polyols.The affinity is based on specific complexation between bo...Affinity membranes are fabricated for boric acid removal by the surface functionalization of microporous polypropylene membrane(MPPM)with lactose-based polyols.The affinity is based on specific complexation between boric acid and saccharide polyols.A photoinduced grafting-chemical reaction sequence was used to prepare these affinity membranes.Poly(2-aminoethyl methacrylate hydrochloride)[poly(AEMA)]was grafted on the surfaces of MPPM by UV-induced graft polymerization.Grafting in the membrane pores was visualized by dying the cross-section of poly(AEMA)-grafted MPPM with fluorescein disodium and imaging with confocal laser scanning microscopy.It is concluded that lactose ligands can be covalently immobilized on the external surface and in the pores by the subsequent coupling of poly(AEMA)with lactobionic acid(LA).Physical and chemical properties of the affinity membranes were characterized by field emission scanning electron microscopy and Fourier Transform Infrared/Attenuated Total Refraction spectroscopy(FT-IR/ATR).3-Aminophenyl boric acid(3-APBA)was removed from aqueous solution by a single piece of lactose-functionalized MPPM in a dynamic filtration system.The results show that the 3-APBA removal reaches an optimal efficiency(39.5%)under the alkaline condition(pH9.1),which can be improved by increasing the immobilization density of LA.Regeneration of these affinity membranes can be easily realized through acid-base washing because the complexation of boric acid and saccharide polyol is reversible.展开更多
A method was proposed for removing zirconium （Zr） from hydrous titanium dioxide （HTD） by the NaF solution. The effects of main parameters, i.e. pH values, NaF dosage, temperature and retention time, on the removal...A method was proposed for removing zirconium （Zr） from hydrous titanium dioxide （HTD） by the NaF solution. The effects of main parameters, i.e. pH values, NaF dosage, temperature and retention time, on the removal of zirconium were stud- ied. The optimal conditions were found as the following： pH value, 〈5.5; molar ratio of NaF to TiQ, 0.6; retention time, 80 min and temperature, 80℃. The removal rate of Zr under the optimized conditions was above 87.7%. The adsorption energy of the preferential absorption of hydrofluoric acid for Zr（OH）2SOt（OH2） on the （001） crystal surface of HTD was determined by theo- retical calculation. The possible mechanism of the removal process was also discussed.展开更多
The working mechanism of MFC used for simultaneous nitrogen removal and electricity generation was studied.The results show that the electrode biofilms and suspension had different modes of electron transfer.The micro...The working mechanism of MFC used for simultaneous nitrogen removal and electricity generation was studied.The results show that the electrode biofilms and suspension had different modes of electron transfer.The microorganisms growing on the electrodes and bioflocs could transfer electrons by direct contact and intermediaries respectively.The electrode biofilms and bioflocs were dominant in different functional spaces,and played a synergistic role in the process of contaminant removal,but showed a certain competitive relationship in the process of electricity generation.This study can provide a theoretical basis for the development of a new low-consumption wastewater treatment technology and promote technological innovation in wastewater treatment.展开更多
In this paper, the inference for the Burr-X model under progressively first-failure censoring scheme is discussed. Based on this new censoring were the number of units removed at each failure time has a discrete binom...In this paper, the inference for the Burr-X model under progressively first-failure censoring scheme is discussed. Based on this new censoring were the number of units removed at each failure time has a discrete binomial distribution. The maximum likelihood, Bootstrap and Bayes estimates for the Burr-X distribution are obtained. The Bayes estimators are obtained using both the symmetric and asymmetric loss functions. Approximate confidence interval and highest posterior density interval (HPDI) are discussed. A numerical example is provided to illustrate the proposed estimation methods developed here. The maximum likelihood and the different Bayes estimates are compared via a Monte Carlo simulation study.展开更多
基金supported by the BJAST High-level Innovation Team Program (No.BGS202001)the Beijing Postdoctoral Research Foundation (No.2022-ZZ-046)+3 种基金the National Natural and Science Foundation of China (No.51972026)the Japan Society for the Promotion of Science (JSPS)Grant-in-Aid for the Scientific Research (KAKENHI,Nos.16H06439 and 20H00297)the Dynamic Alliance for Open Innovations Bridging Human,Environment and Materials,the Cooperative Research Program of“Network Joint Research Center for Materials and Devices.”the scholarship granted to a visiting Ph.D.student of the Inter-University Exchange Project by the China Scholarship Council (CSC,No.201906460113)。
文摘The synthesis of oxygen vacancies(OVs)-modified TiO_(2)under mild conditions is attractive.In this work,OVs were easily introduced in TiO_(2)lattice during the hydrothermal doping process of trivalent iron ions.Theoretical calculations based on a novel charge-compensation structure model were employed with experimental methods to reveal the intrinsic photocatalytic mechanism of Fe-doped TiO_(2)(Fe-TiO_(2)).The OVs formation energy in Fe-TiO_(2)(1.12 eV)was only 23.6%of that in TiO_(2)(4.74 eV),explaining why Fe^(3+)doping could introduce OVs in the TiO_(2)lattice.The calculation results also indicated that impurity states introduced by Fe^(3+)and OVs enhanced the light absorption activity of TiO_(2).Additionally,charge carrier transport was investigated through the carrier lifetime and relative mass.The carrier lifetime of Fe-TiO_(2)(4.00,4.10,and 3.34 ns for 1at%,2at%,and 3at%doping contents,respectively)was longer than that of undoped TiO_(2)(3.22 ns),indicating that Fe^(3+) and OVs could promote charge carrier separation,which can be attributed to the larger relative effective mass of electrons and holes.Herein,Fe-TiO_(2)has higher photocatalytic indoor NO removal activity compared with other photocatalysts because it has strong light absorption activity and high carrier separation efficiency.
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.
基金Project(2012CB722803)supported by the Key Project of National Basic Research and Development Program of ChinaProject(U1202271)supported by the National Natural Science Foundation of ChinaProject(IRT1250)supported by the Program for Innovative Research Team in University of Ministry of Education of China
文摘The industrial silica fume pretreated by nitric acid at 80 °C was re-used in this work. Then, the obtained silica nanoparticles were surface functionalized by silane coupling agents, such as(3-Mercaptopropyl) triethoxysilane(MPTES) and(3-Amincpropyl) trithoxysilane(APTES). Some further modifications were studied by chloroaceetyl choride and 1,8-Diaminoaphalene for amino modified silica. The surface functionalized silica nanoparticles were characterized by Fourier transform infrared(FI-IR) and X-ray photoelectron spectroscopy(XPS). The prepared adsorbent of surface functionalized silica nanoparticles with differential function groups were investigated in the selective adsorption about Pb2+, Cu2+, Hg2+, Cd2+ and Zn2+ions in aqueous solutions. The results show that the(3-Mercaptopropyl) triethoxysilane functionalized silica nanoparticles(SiO2-MPTES) play an important role in the selective adsorption of Cu2+ and Hg2+, the(3-Amincpropyl) trithoxysilane(APTES) functionalized silica nanoparticles(SiO2-APTES) exhibited maximum removal efficiency towards Pb2+ and Hg2+, the 1,8-Diaminoaphalene functionalized silica nanoparticles was excellent for removal of Hg2+ at room temperature, respectively.
基金financially supported by the National Science Fund for Excellent Young Scholars of China (No. 52022111)the Distinguished Young Scholars of China (No. 51825403)the National Natural Science Foundation of China (Nos. 51634010, 51974379)。
文摘Between the two major arsenic-containing salts in natural water, arsenite(As(Ⅲ)) is far more harmful to human and the environment than arsenate(As(V)) due to its high toxicity and transportability. Therefore, preoxidation of As(Ⅲ) to As(V) is considered to be an effective means to reduce the toxicity of arsenic and to promote the removal efficiency of arsenic. Due to their high catalytic activity and arsenic affinity, iron-based functional materials can quickly oxidize As(Ⅲ) to As(V) in heterogeneous Fenton-like systems, and then remove As(V) from water through adsorption and surface coprecipitation. In this review, the effects of different iron-based functional materials such as zero-valent iron and iron(hydroxy) oxides on arsenic removal are compared, and the catalytic oxidation mechanism of As(Ⅲ) in heterogeneous Fenton process is further clarified. Finally, the main challenges and opportunities faced by iron-based As(Ⅲ) oxidation functional materials are prospected.
基金Supported by the Program of MSU Development and Russian Foundation for Basic Research(RFBR)(No.14-02-01230a and No.14-02-31147 mol_a)
文摘Filtration efficiency of Ni(II) from aqueous solution using pristine and modified MWCNTs filters was investigated as a function of Ni(II) ion concentration, p H, and filter mass. MWCNTs were synthesized by CVD method and modified using two complementary treatments, purification(using a mixture of hydrochloric acid and hydrogen peroxide) and functionalization(using nitric acid). The effect and mechanism of each treatment on the structural integrity of pristine MWCNTs has been studied. Morphology of the pristine and modified filters was investigated by Raman Spectrometry(RS), Scanning Electron Microscopy(SEM), Energy Dispersive X-ray Spectroscopy(EDS),Fourier Transform Infrared(FTIR) spectrometry and Thermogravimetric analysis. It was found from Raman spectra that the ratio of the intensity of D-band to that of G-band decreased by purification process, and increased by functionalization process. The adsorption mechanism of Ni(II) onto the surface functional groups of modified MWCNTs was confirmed by FTIR spectrum. The filtration results showed that the removal efficiency of Ni(II) is strongly dependent on pH and could reach 85% at pH = 8. Also, modified MWCNT filters can be reused through many cycles of regeneration with high performance. Functionalized MWCNTs filters may be a promising adsorbent candidate for heavy metal removal from wastewater.
基金financially supported by the Research and Development Program of the Ministry of Science and Technology of China (Grant No. 2014BAC28B01)the Jiangsu Key Laboratory of Anaerobic Biotechnology (Jiangnan University) Supported Research Project (No. JKLAB201703)
文摘An innovative approach to H2 S capture has been developed using several metal-based ionic liquids([Bmim]Cl·CuCl_2, [Bmim]Cl·FeCl_3, [Bmim]Cl·ZnCl_2, [Bmim]Br·CuCl_2, and [Bmim]Br·FeCl_3) immobilized on the sol-gel derived silica, which is superior to purely viscous ionic liquid with a crucial limit of high temperature, low mass transfer rate,and mass loss. The adsorbents were characterized by the Fourier transform infrared spectrometer, transmission electron microscope, N_2 adsorption/desorption, X-ray photoelectron spectroscopy, and thermal analysis techniques. The effects of the metal and halogen in IL, the loading amount of IL, and the adsorption temperature were studied by dynamic adsorption experiments at a gas flow rate of 100 mL/min. The H2 S adsorption results have showed that the optimal adsorbent and adsorption temperature are 5% [Bmim]Cl·CuCl_2/silica gel and 20—50 ℃, respectively. H_2 S can be captured and oxidized to elemental sulfur, and [Bmim]Cl·CuCl_2/silica gel can be readily regenerated by air. The excellent efficiency of H2 S removal may be attributed to the formation of nano-scaled and high-concentration [Bmim]Cl·CuCl_2 confined in silica gel, indicating that the immobilization of [Bmim]Cl·CuCl_2 on the sol-gel derived silica can be used for H2 S removal promisingly.
基金Supported by the National Natural Science Foundation of China(50933006)the National Basic Research Program of China(2009CB623401)
文摘Affinity membranes are fabricated for boric acid removal by the surface functionalization of microporous polypropylene membrane(MPPM)with lactose-based polyols.The affinity is based on specific complexation between boric acid and saccharide polyols.A photoinduced grafting-chemical reaction sequence was used to prepare these affinity membranes.Poly(2-aminoethyl methacrylate hydrochloride)[poly(AEMA)]was grafted on the surfaces of MPPM by UV-induced graft polymerization.Grafting in the membrane pores was visualized by dying the cross-section of poly(AEMA)-grafted MPPM with fluorescein disodium and imaging with confocal laser scanning microscopy.It is concluded that lactose ligands can be covalently immobilized on the external surface and in the pores by the subsequent coupling of poly(AEMA)with lactobionic acid(LA).Physical and chemical properties of the affinity membranes were characterized by field emission scanning electron microscopy and Fourier Transform Infrared/Attenuated Total Refraction spectroscopy(FT-IR/ATR).3-Aminophenyl boric acid(3-APBA)was removed from aqueous solution by a single piece of lactose-functionalized MPPM in a dynamic filtration system.The results show that the 3-APBA removal reaches an optimal efficiency(39.5%)under the alkaline condition(pH9.1),which can be improved by increasing the immobilization density of LA.Regeneration of these affinity membranes can be easily realized through acid-base washing because the complexation of boric acid and saccharide polyol is reversible.
基金supports by the Major Program of the National Natural Science Foundation of China (No. 51090380)the National Science Foundation for Distinguished Young Scholars of China (No. 51125018)the National Natural Science Foundation of China (Nos. 51004091, 21006115,51104139)
文摘A method was proposed for removing zirconium （Zr） from hydrous titanium dioxide （HTD） by the NaF solution. The effects of main parameters, i.e. pH values, NaF dosage, temperature and retention time, on the removal of zirconium were stud- ied. The optimal conditions were found as the following： pH value, 〈5.5; molar ratio of NaF to TiQ, 0.6; retention time, 80 min and temperature, 80℃. The removal rate of Zr under the optimized conditions was above 87.7%. The adsorption energy of the preferential absorption of hydrofluoric acid for Zr（OH）2SOt（OH2） on the （001） crystal surface of HTD was determined by theo- retical calculation. The possible mechanism of the removal process was also discussed.
基金Supported by Natural Science Foundation of Shandong Province,China(ZR2019QEE039)Natural Science Foundation of Zhejiang Province,China(LY18E080007)National Natural Science Foundation of China(51808494)
文摘The working mechanism of MFC used for simultaneous nitrogen removal and electricity generation was studied.The results show that the electrode biofilms and suspension had different modes of electron transfer.The microorganisms growing on the electrodes and bioflocs could transfer electrons by direct contact and intermediaries respectively.The electrode biofilms and bioflocs were dominant in different functional spaces,and played a synergistic role in the process of contaminant removal,but showed a certain competitive relationship in the process of electricity generation.This study can provide a theoretical basis for the development of a new low-consumption wastewater treatment technology and promote technological innovation in wastewater treatment.
文摘In this paper, the inference for the Burr-X model under progressively first-failure censoring scheme is discussed. Based on this new censoring were the number of units removed at each failure time has a discrete binomial distribution. The maximum likelihood, Bootstrap and Bayes estimates for the Burr-X distribution are obtained. The Bayes estimators are obtained using both the symmetric and asymmetric loss functions. Approximate confidence interval and highest posterior density interval (HPDI) are discussed. A numerical example is provided to illustrate the proposed estimation methods developed here. The maximum likelihood and the different Bayes estimates are compared via a Monte Carlo simulation study.
