Adsorption by solid amine adsorbent is a promising technology for decarbonization of flue gas.However,adsorption properties of many solid amine adsorbents need to be enhanced,and it is necessary to further study the C...Adsorption by solid amine adsorbent is a promising technology for decarbonization of flue gas.However,adsorption properties of many solid amine adsorbents need to be enhanced,and it is necessary to further study the CO_(2)adsorption mechanism.A novel CO_(2)adsorbent with high capacity was obtained by grafting 3-aminopropyltriethoxysilane(APTES)on a micro-mesoporous composite molecular sieve ZSM-5/MCM-48 as the support,and then impregnated with tetraethylenepentamine(TEPA)or polyethyleneimine(PEI).The maximum adsorption capacity of APTES-ZSM-5/MCM-48-TEPA-60(A-ZM-T60),loaded with 60%(in mass)TEPA,for CO_(2)reaches 5.82 mmol·g^(-1) at 60℃in 15%(in volume)CO_(2).Carbamate,alkyl ammonium carbamate and carbonate are generated during the chemical adsorption,which is dominant for CO_(2)adsorption because of the reaction between CO_(2)and amino groups on the adsorbent,simultaneously accompanied by weak physical adsorption.All above data confirm that these composites display an outstanding adsorption performance with a bright future for CO_(2)capture from flue gas after desulfurization.展开更多
Hydroxyapatite nanoparticles(HAP NPs)were synthesized by a one‐step hydrothermal method.The surface of HAP NPs was grafted-SH and-COOH chelating groups via in situ surface‐modification with iminodiacetic acid(IDA)an...Hydroxyapatite nanoparticles(HAP NPs)were synthesized by a one‐step hydrothermal method.The surface of HAP NPs was grafted-SH and-COOH chelating groups via in situ surface‐modification with iminodiacetic acid(IDA)and 3‐mercaptopropyl trimethoxysilane(MPS)to afford dual surface‐capped nano‐amendment HAPIDA/MPS.The structure of HAP‐IDA/MPS was characterized,and its adsorption performance for Hg^(2+),Cu^(2+),Zn^(2+),Ni^(2+),Co^(2+),and Cd^(2+)was evaluated.The total adsorption capacity of 0.10 g HAP‐IDA/MPS nano‐amendment for Hg^(2+),Cu^(2+),Zn^(2+),Ni^(2+),Co^(2+),and Cd^(2+)with an initial mass concentration of 20 mg·L^(-1) reached 13.7 mg·g^(-1),about 4.3 times as much as that of HAP.Notably,HAP‐IDA/MPS nano‐amendment displayed the highest immobilization rate for Hg^(2+),possibly because of its chemical reaction with-SH to form sulfide,possessing the lowest solubility product constant among a variety of metal sulfides.展开更多
Adsorption as an effective technique for the remediation of wastewater has been widely used in industrial wastewater treatment due to the advantage of cost-effectiveness,availability of the adsorbent and ease of opera...Adsorption as an effective technique for the remediation of wastewater has been widely used in industrial wastewater treatment due to the advantage of cost-effectiveness,availability of the adsorbent and ease of operation.However,the low adsorption capacity of the reported adsorbents is still a challenge for wastewater treatment with highefficiency.Here,we developed a super adsorbent(SUA-1),which was a kind of porous carbon nanofibers derived from a composite of PAN-based electrospinning and ZIF-8(PAN/ZIF-8)via simple heat treatment process.The asprepared SUA showed an ultra-high adsorption capacity for adsorbing methyl blue(MB)at nearly three times its own weight,as high as 2998.18 mg/g.A series tests demonstrated that the pore-making effect of ZIF-8 during heat treatment process endowed high BET surface area and generated ZnO components as chemical adsorption center.Under the synergistic effect of bonding and non-bonding forces including ionic bond,electrostatic interaction,andπ-πinteraction,the adsorption capacity has been greatly improved.In view of promising efficiency,this work provides guidance and insights for the preparation of highly efficient adsorbents based on electrospinning derived porous carbon nanofibers.展开更多
Since the discovery of carbon dots(CDs)in 2004,the unique photoluminescence phenomenon of CDs has attracted widespread attention.However,the molecular weight of CDs has not been adequately quantified at present,due to...Since the discovery of carbon dots(CDs)in 2004,the unique photoluminescence phenomenon of CDs has attracted widespread attention.However,the molecular weight of CDs has not been adequately quantified at present,due to CDs are atomically imprecise and their molecular weight distribution is broad.In this paper,a series of Pluronic-modified CDs were prepared and the structure of the CDs was briefly analyzed.Subsequently,a molecular weight measurement method based on colligative properties was developed,and the correction coefficient in the algorithm was briefly analyzed.The calculated molecular weight was applied to the determination of surface adsorption capacity.This work provided a method for averaging the molecular weight of atomically imprecise particulate materials,which is expected to provide new opportunities in related fields.展开更多
With the growing awareness of environmental protection and the increasing demand for rare earth elements(REEs),it has become necessary to efficiently remove and recover REEs from mine wastewater.In this study,jarosite...With the growing awareness of environmental protection and the increasing demand for rare earth elements(REEs),it has become necessary to efficiently remove and recover REEs from mine wastewater.In this study,jarosite(Jar)and schwertmannite(Sch)were biosynthesized using Acidithiobacillus ferrooxidans for the adsorption of REEs.Additionally,the adsorption capacities of Jar and Sch for La^(3+),Ce^(3+),Pr^(3+),Nd^(3+),Sm^(3+),Gd^(3+),Dy^(3+),and Y^(3+)in mine wastewater were improved by mechanical activation.XRD,FTIR,BET,and SEM-EDS analyses revealed that mechanical activation did not alter the phase of the material,but increased the amount of surface-OH and SO42−groups,as well as the specific surface area.This significantly enhanced the adsorption performance of Jar and Sch for REEs.The optimum adsorption time and pH were determined through batch adsorption experiments.Besides,the adsorption kinetics were studied and found to align well with the pseudo-second-order model.Furthermore,the thermodynamic parameters(ΔG^(Θ),ΔH^(Θ)andΔS^(Θ))and adsorption isotherms were analyzed.The results indicated that mechanically activated schwertmannite(M-Sch)exhibited superior adsorption performance for REEs compared to mechanically activated jarosite(M-Jar).Moreover,M-Sch was reusable and exhibited high adsorption efficiency of REEs in actual mine wastewater,exceeding 92%.展开更多
Understanding the adsorption behavior of heavy metals and metalloids on clay minerals is essential for remediating heavy metal-contaminated soils.The adsorption of heavy metals and metalloids on illite(001)and sodium ...Understanding the adsorption behavior of heavy metals and metalloids on clay minerals is essential for remediating heavy metal-contaminated soils.The adsorption of heavy metals and metalloids on illite(001)and sodium montmorillonite(Na-MMT)(001)surfaces was investigated using first-principles calculations in this study,especially As atom and H_(3)AsO_(3) molecule.The adsorption energies of the As atom were−1.94 eV on the illite(001)and−0.56 eV on the Na-MMT(001),whereas,the adsorption energies of the H_(3)AsO_(3) molecule were−1.40 eV on illite(001)and−1.01 eV on Na-MMT(001).The above results indicate that the adsorption was more energetically favorable on illite(001).Additionally,compared to Na-MMT(001),there were more significant interactions between the atoms/molecules on the illite(001).After As atom and H_(3)AsO_(3) molecule adsorption,the electrons were transferred from mineral surface atoms to the adsorbates on both illite(001)and Na-MMT(001)surfaces.Moreover,the adsorption of As atom on illite(001)and Na-MMT(001)surfaces were more energy favorable compared to Hg,Cd,and Cr atoms.Overall,this work provides new insights into the adsorption behavior of As atoms and As molecules on illite and Na-MMT.The results indicate that illite rich soils are more prone to contamination by arsenic compared to soils primarily composed of Na-MMT minerals.展开更多
In this study,Schwertmannite,Akaganéite and ammoniojarosite were biosynthesized by different bacteria and characterized.The results showed that bacteria are critical in mediating the mineral formation process:the...In this study,Schwertmannite,Akaganéite and ammoniojarosite were biosynthesized by different bacteria and characterized.The results showed that bacteria are critical in mediating the mineral formation process:the morphology,crystallinity,grain size and specific surface area of each mineral varied upon different bacteria and culturing conditions.In addition,the formed minerals’elemental composition and group disparity lead to different morphology,crystallinity and subsequent adsorption performance.In particular,adsorption difference existed in iron minerals biosynthesized by different bacteria.The maximal adsorption capacities of Akaganéite,Schwertmannite and ammoniojarosite were 26.6 mg/g,17.5 mg/g and 3.90 mg/g respectively.Cr(VI)adsorption on iron-minerals involves hydrogen bonding,electrostatic interaction,and ligand exchange.The adsorption only occurred on the surface of ammoniojarosite,while for Akaganéite and Schwertmannite,the tunnel structure greatly facilitated the adsorption process and improved adsorption capacity.Thus,the molecular structure is the primary determining factor for adsorption performance.Collectively,the results can provide useful information in selecting suitable bacteria for synthesizing heavy-metal scavenging minerals according to different environmental conditions.展开更多
Traditional selection of combustion catalysis is time-consuming and labor-intensive.Theoretical calculation is expected to resolve this problem.The adsorption energy of HMX and O atoms on 13 metal oxides was calculate...Traditional selection of combustion catalysis is time-consuming and labor-intensive.Theoretical calculation is expected to resolve this problem.The adsorption energy of HMX and O atoms on 13 metal oxides was calculated using DMol3,since HMX and O are key substances in decomposition process.And the relationship between the adsorption energy of HMX,O on metal oxides(TiO_(2),Al_(2)O_(3),PbO,CuO,Fe_(2)O_(3),Co_(3)O_(4),Bi_(2)O_(3),NiO)and experimental T30 values(time required for the decomposition depth of HMX to reach 30%)was depicted as volcano plot.Thus,the T30 values of other metal oxides was predicted based on their adsorption energy on volcano plot and validated by previous experimental data.Further,the adsorption energy of HMX on ZrO_(2)and MnO_(2)was predicted based on the linear relationship between surface energy and adsorption energy,and T30 values were estimated based on volcano plot.The apparent activation energy data of HMX/MgO,HMX/SnO_(2),HMX/ZrO_(2),and HMX/MnO_(2)obtained from DSC experiments are basically consistent with our predicted T30 values,indicating that it is feasible to predict the catalytic activity based on the adsorption calculation,and it is expected that these simple structural properties can predict adsorption energy to reduce the large quantities of computation and experiment cost.展开更多
Platinum(Pt)-based noble metal catalysts(PGMs)are the most widely used commercial catalysts,but they have the problems of high cost,low reserves,and susceptibility to small-molecule toxicity.Transition metal oxides(TM...Platinum(Pt)-based noble metal catalysts(PGMs)are the most widely used commercial catalysts,but they have the problems of high cost,low reserves,and susceptibility to small-molecule toxicity.Transition metal oxides(TMOs)are regarded as potential substitutes for PGMs because of their stability in oxidizing environments and excellent catalytic performance.In this study,comprehensive investigation into the influence of elastic strains on the adsorption energies of carbon(C),hydrogen(H)and oxygen(O)on TMOs was conducted.Based on density functional theory(DFT)calculations,these effects in both tetragonal structures(PtO_(2),PdO_(2))and hexagonal structures(ZnO,CdO),along with their respective transition metals were systematically explored.It was identified that the optimal adsorption sites on metal oxides pinpointed the top of oxygen or the top of metal atom,while face-centered cubic(FCC)and hexagonal close-packed(HCP)holes were preferred for the transition metals.Furthermore,under the influence of elastic strains,the results demonstrated significant disparities in the adsorption energies of H and O between oxides and transition metals.Despite these differences,the effect of elastic strains on the adsorption energies of C,H and O on TMOs mirrored those on transition metals:adsorption energies increased under compressive strains,indicating weaker adsorption,and decreased under tension strains,indicating stronger adsorption.This behavior was rationalized based on the d-band model for adsorption atop a metallic atom or the p-band model for adsorption atop an oxygen atom.Consequently,elastic strains present a promising avenue for tailoring the catalytic properties of TMOs.展开更多
The interest in curtailing environmental pollution issues through physical separation processes has inspired an extensive search for novel nanoporous materials with exceptional adsorption capabilities.Covalent triazin...The interest in curtailing environmental pollution issues through physical separation processes has inspired an extensive search for novel nanoporous materials with exceptional adsorption capabilities.Covalent triazine frameworks(CTFs),emerged as a class of crystalline covalent organic frameworks(COFs),have been widely examined for various separation applications,owing to their large porosity,high stability,and rich nitrogen(N)doping.The development of CTFs for efficient adsorption of mercury(Ⅱ)(Hg^(2+))is of great importance for the field,whereas it is rarely attempted,on account of limited synthetic strategies and unknown structural-property relations of conventional CTFs derived from ionothermal approaches.Herein,we report rational synthesis of a crystalline CTF with methylthio pendant arms for efficient removal of Hg^(2+)with an exceptional capacity of 751 mg·g^(-1),ranking at the top among previously-reported adsorbents.This work may open up new possibility in the synthesis of COFs for various separations.展开更多
The potential of di-(m-Formylphenol)-1,2-cyclohexandiimine as an environmentally friendly corrosion inhibitor for steel was investigated in 1 mol/L HCl using potentiodynamic polarization, electrochemical impedance spe...The potential of di-(m-Formylphenol)-1,2-cyclohexandiimine as an environmentally friendly corrosion inhibitor for steel was investigated in 1 mol/L HCl using potentiodynamic polarization, electrochemical impedance spectroscopy and chronoamperometry measurements. All electrochemical measurements suggest that this compound is an excellent corrosion inhibitor for mild steel and the inhibition efficiency increases with the increase in inhibitor concentration. The effect of temperature on the corrosion behavior of mild steel with the addition of the Schiff base was studied in the temperature range from 25 °C to 65 °C. It is found that the adsorption of this inhibitor follows the Langmuir adsorption isotherms. The value of activation energy and the thermodynamic parameters such as ΔHads, ΔSads, Kads and ΔGads were calculated by the corrosion currents at different temperatures using the adsorption isotherm. The morphology of mild steel surface in the absence and presence of inhibitor was examined by scanning electron microscopy(SEM) images.展开更多
A novel microwave digestion and alkali fusion assisted hydrothermal method was proposed to synthesize zeolite from coal fly ash and the zeolite product was studied for removal of Cd(II)from aqueous solution through ba...A novel microwave digestion and alkali fusion assisted hydrothermal method was proposed to synthesize zeolite from coal fly ash and the zeolite product was studied for removal of Cd(II)from aqueous solution through batch experiments.The adsorbent was characterized by X-ray diffraction,scanning electron microscopy,Fourier transform infrared spectroscopy,surface area analyzer and zeta potential measurement.The results show that the synthetic zeolite was identified as faujasite.The optimum conditions for removal of Cd(II)are found to be:adsorbent dose of0.5g/L,pH6,contact time of90min and initial concentration of20mg/L,the removal rate of Cd(II)is98.55%.The experimental kinetic data agree well with the pseudo second-order equation;the Langmuir isotherm model is found to be more suitable to explicate the experimental equilibrium isotherm results than Freundlich,Dubinin-Radushkevich and Temkin models,and the maximum adsorption capacity of Cd(II)is found to be86.96mg/g.The thermodynamic parameters such asΔGΘ,ΔHΘandΔSΘwere evaluated and the results show that the adsorption of Cd(II)onto the as-synthesized zeolite is spontaneous,endothermic and feasible under studied conditions.展开更多
Chitosan-coated fly ash(CWF)was prepared by the acid leaching-coating method.Chitosan and fly ash were crosslinked in the solution of acetic acid and sulfuric acid.The microstructure of CWF was conducted by scanning e...Chitosan-coated fly ash(CWF)was prepared by the acid leaching-coating method.Chitosan and fly ash were crosslinked in the solution of acetic acid and sulfuric acid.The microstructure of CWF was conducted by scanning electron microscope(SEM)and X-ray diffraction(XRD).The removal of Cr(VI)from water by CWF was studied by adsorption experiments.The composite prepared by the experiment developed a pore structure and a crystal structure similar to SiO_(2) and chitosan chain-like coating was formed on the surface of fly ash.The new modified material has larger surface roughness,specific surface area and more adsorption channels.The Cr(VI)was enriched in modified materials by electrostatic adsorption between CrO_(4)^(2−)、CrO_(7)^(2−)and-NH_(3)^(+) group and surface acid functional groups.The movement of Cr(VI)in solution is a diffusion process from the main body of the liquid phase to the surface of the liquid film.展开更多
Two reagents including salicylhydroxamic acid(SHA) and tributyl phosphate(TBP) were tested as collectors either separately or together for electro-flotation of fine cassiterite(<10 μm).Subsequently,the flotation m...Two reagents including salicylhydroxamic acid(SHA) and tributyl phosphate(TBP) were tested as collectors either separately or together for electro-flotation of fine cassiterite(<10 μm).Subsequently,the flotation mechanism of the fine cassiterite was investigated by adsorbance determination,electrophoretic mobility measurements and Fourier transform infra-red(FT-IR) spectrum checking.Results of the flotation experiments show that with SHA as a collector,the collecting performance is remarkably impacted by the pulp pH value as the floatability of cassiterite varies sharply when the pH changes,and flotation with SHA gives distinct maximum at about pH 6.5.Additionally,the floatability of cassiterite is determined by using SHA and TBP as collectors.The range of pulp pH for good floatability is broadened in the presence of TBP as auxiliary collector,and the utilization of TBP improves the recovery of cassiterite modestly.Moreover,the optimum pH value for cassiterite flotation is associated with adsorbance.The results of FT-IR spectrum and the electrophoretic mobility measurements indicate that the adsorption interaction between the collectors and the cassiterite is dominantly a kind of chemical bonding in the form of one or two cycle chelate rings due to the coordination of carbonyl group,hydroxamate and P=O group to the metal tin atoms,where the oxygen atoms contained in carbonyl group,hydroxamate and P=O group of the polar groups have the stereo conditions to form five-membered rings.In addition,the adsorption interactions of SHA and TBP on the surfaces of cassiterite are also dominated by means of hydrogen bonds.展开更多
Pb2+ and Cd2+ in leachate were adsorbed on clay-solidified grouting curtain for waste landfills with equilibrium experiment. The cation exchange capacity was determined with ammonium acetate. And the concentration of ...Pb2+ and Cd2+ in leachate were adsorbed on clay-solidified grouting curtain for waste landfills with equilibrium experiment. The cation exchange capacity was determined with ammonium acetate. And the concentration of heavy metal cations in leachate was determined with atomic absorption spectrophotometer. Their equilibrium isotherms were measured, and the experimental isotherm data were analyzed by using Freundlich and Langmuir models. The results show that the adsorption capacities of the heavy metal cations are closely related to the compositions of clay-solidified grouting curtain, and the maximum adsorption appears at the ratio of cement to clay of 2∶4 in the experimental conditions. At their maximum adsorption and pH 5.0, the adsorption capacities of Pb 2+ and Cd 2+ are 16.19mg/g and 1.21mg/g. The competitive adsorption coefficients indicate that the adsorption of clay-solidified grouting curtain for Pb2+ is stronger than that for Cd 2+ . The adsorption process conforms to Freundlich’s model with related coefficient higher than 0.996.展开更多
To investigate the influence of the activated carbon pore structure on the adsorption of volatile organic compounds （VOCs）, three commercial activated carbon samples were chosen. The fixed-bed thermostatic adsorptio...To investigate the influence of the activated carbon pore structure on the adsorption of volatile organic compounds （VOCs）, three commercial activated carbon samples were chosen. The fixed-bed thermostatic adsorption experiments were conducted under certain conditions, where toluene, acetone, and 1, 2-dichloroethane acted as adsorbents. Then, the incidence relation between the experimental results and the activated carbon pore structure was analyzed. After that, the results of the correlation analysis were verified in accordance with fractal theory and adsorption characteristic curve analysis. The results show that the pore diameter gradient is helpful for strengthening the intemal diffusion. Under the same condition, the adsorption of organic gases tends to be selective, and the positions of toluene, acetone and 1, 2-dichloroethane adsorbed on the activated carbon are mainly in the ranges of 1.27-1.49 nm, 0.67-0.84 nm and 1.39-1.75 nm, respectively. The relationship between adsorption capacity and activated carbon pore volume can accurately explain the spreading process of the adsorbents in the activated carbon.展开更多
The adsorption of the bentonite toward Ni(II) from aqueous solution was studied to obtain optimum conditions,equilibrium model,thermodynamic and kinetic parameters.Statistical method was used to evaluate maximum amoun...The adsorption of the bentonite toward Ni(II) from aqueous solution was studied to obtain optimum conditions,equilibrium model,thermodynamic and kinetic parameters.Statistical method was used to evaluate maximum amount of adsorbed Ni(II).In this work,p H of solution during stirring,contact time,initial Ni(II) concentration,particle size of bentonite and amount of bentonite were considered as effective parameters which should be examined.The increase of temperature has negative effect on the Ni(II) adsorption.The equilibrium data were correlated well with Freundlich and Dubinin–Radushkevich isotherm models the correlation coefficients of which are(R^2) 0.994 and 0.971,respectively.This model indicates heterogeneous and chemical absorption or ion exchange process.The values of thermodynamic parameters such as ΔH°,ΔS° and ΔG° of nickel adsorption reveal that it is a spontaneous,exothermic and associative process.The experimental data fit the pseudo-second-order kinetic very well with correlation coefficient(R^2) more than 0.995.展开更多
To improve the understanding of the transport mechanism in shale gas reservoirs and build a theoretical basic for further researches on productivity evaluation and efficient exploitation, various gas transport mechani...To improve the understanding of the transport mechanism in shale gas reservoirs and build a theoretical basic for further researches on productivity evaluation and efficient exploitation, various gas transport mechanisms within a shale gas reservoir exploited by a horizontal well were thoroughly investigated, which took diffusion, adsorption/desorption and Darcy flow into account. The characteristics of diffusion in nano-scale pores in matrix and desorption on the matrix surface were both considered in the improved differential equations for seepage flow. By integrating the Langmuir isotherm desorption items into the new total dimensionless compression coefficient in matrix, the transport function and seepage flow could be formalized, simplified and consistent with the conventional form of diffusion equation. Furthermore, by utilizing the Laplace change and Sethfest inversion changes, the calculated results were obtained and further discussions indicated that transfer mechanisms were influenced by diffusion, adsorption/desorption. The research shows that when the matrix permeability is closed to magnitude of 10^-9D, the matrix flow only occurs near the surfacial matrix; as to the actual production, the central matrix blocks are barely involved in the production; the closer to the surface of matrix, the lower the pressure is and the more obvious the diffusion effect is; the behavior of adsorption/desorption can increase the matrix flow rate significantly and slow down the pressure of horizontal well obviously.展开更多
基金National Natural Science Foundation of China(51966002)Natural Science Foundation of Guangxi Province(2020GXNSFAA159144)。
文摘Adsorption by solid amine adsorbent is a promising technology for decarbonization of flue gas.However,adsorption properties of many solid amine adsorbents need to be enhanced,and it is necessary to further study the CO_(2)adsorption mechanism.A novel CO_(2)adsorbent with high capacity was obtained by grafting 3-aminopropyltriethoxysilane(APTES)on a micro-mesoporous composite molecular sieve ZSM-5/MCM-48 as the support,and then impregnated with tetraethylenepentamine(TEPA)or polyethyleneimine(PEI).The maximum adsorption capacity of APTES-ZSM-5/MCM-48-TEPA-60(A-ZM-T60),loaded with 60%(in mass)TEPA,for CO_(2)reaches 5.82 mmol·g^(-1) at 60℃in 15%(in volume)CO_(2).Carbamate,alkyl ammonium carbamate and carbonate are generated during the chemical adsorption,which is dominant for CO_(2)adsorption because of the reaction between CO_(2)and amino groups on the adsorbent,simultaneously accompanied by weak physical adsorption.All above data confirm that these composites display an outstanding adsorption performance with a bright future for CO_(2)capture from flue gas after desulfurization.
文摘Hydroxyapatite nanoparticles(HAP NPs)were synthesized by a one‐step hydrothermal method.The surface of HAP NPs was grafted-SH and-COOH chelating groups via in situ surface‐modification with iminodiacetic acid(IDA)and 3‐mercaptopropyl trimethoxysilane(MPS)to afford dual surface‐capped nano‐amendment HAPIDA/MPS.The structure of HAP‐IDA/MPS was characterized,and its adsorption performance for Hg^(2+),Cu^(2+),Zn^(2+),Ni^(2+),Co^(2+),and Cd^(2+)was evaluated.The total adsorption capacity of 0.10 g HAP‐IDA/MPS nano‐amendment for Hg^(2+),Cu^(2+),Zn^(2+),Ni^(2+),Co^(2+),and Cd^(2+)with an initial mass concentration of 20 mg·L^(-1) reached 13.7 mg·g^(-1),about 4.3 times as much as that of HAP.Notably,HAP‐IDA/MPS nano‐amendment displayed the highest immobilization rate for Hg^(2+),possibly because of its chemical reaction with-SH to form sulfide,possessing the lowest solubility product constant among a variety of metal sulfides.
基金Natural Science Foundation of China(22134005,22204011)Chongqing Talents Program for Outstanding Scientists(cstc2021ycjh-bgzxm0179)。
文摘Adsorption as an effective technique for the remediation of wastewater has been widely used in industrial wastewater treatment due to the advantage of cost-effectiveness,availability of the adsorbent and ease of operation.However,the low adsorption capacity of the reported adsorbents is still a challenge for wastewater treatment with highefficiency.Here,we developed a super adsorbent(SUA-1),which was a kind of porous carbon nanofibers derived from a composite of PAN-based electrospinning and ZIF-8(PAN/ZIF-8)via simple heat treatment process.The asprepared SUA showed an ultra-high adsorption capacity for adsorbing methyl blue(MB)at nearly three times its own weight,as high as 2998.18 mg/g.A series tests demonstrated that the pore-making effect of ZIF-8 during heat treatment process endowed high BET surface area and generated ZnO components as chemical adsorption center.Under the synergistic effect of bonding and non-bonding forces including ionic bond,electrostatic interaction,andπ-πinteraction,the adsorption capacity has been greatly improved.In view of promising efficiency,this work provides guidance and insights for the preparation of highly efficient adsorbents based on electrospinning derived porous carbon nanofibers.
文摘Since the discovery of carbon dots(CDs)in 2004,the unique photoluminescence phenomenon of CDs has attracted widespread attention.However,the molecular weight of CDs has not been adequately quantified at present,due to CDs are atomically imprecise and their molecular weight distribution is broad.In this paper,a series of Pluronic-modified CDs were prepared and the structure of the CDs was briefly analyzed.Subsequently,a molecular weight measurement method based on colligative properties was developed,and the correction coefficient in the algorithm was briefly analyzed.The calculated molecular weight was applied to the determination of surface adsorption capacity.This work provided a method for averaging the molecular weight of atomically imprecise particulate materials,which is expected to provide new opportunities in related fields.
基金Project(2022YFC2105300) supported by the National Key Research and Development Program of ChinaProject(52274288) supported by the National Natural Science Foundation of China。
文摘With the growing awareness of environmental protection and the increasing demand for rare earth elements(REEs),it has become necessary to efficiently remove and recover REEs from mine wastewater.In this study,jarosite(Jar)and schwertmannite(Sch)were biosynthesized using Acidithiobacillus ferrooxidans for the adsorption of REEs.Additionally,the adsorption capacities of Jar and Sch for La^(3+),Ce^(3+),Pr^(3+),Nd^(3+),Sm^(3+),Gd^(3+),Dy^(3+),and Y^(3+)in mine wastewater were improved by mechanical activation.XRD,FTIR,BET,and SEM-EDS analyses revealed that mechanical activation did not alter the phase of the material,but increased the amount of surface-OH and SO42−groups,as well as the specific surface area.This significantly enhanced the adsorption performance of Jar and Sch for REEs.The optimum adsorption time and pH were determined through batch adsorption experiments.Besides,the adsorption kinetics were studied and found to align well with the pseudo-second-order model.Furthermore,the thermodynamic parameters(ΔG^(Θ),ΔH^(Θ)andΔS^(Θ))and adsorption isotherms were analyzed.The results indicated that mechanically activated schwertmannite(M-Sch)exhibited superior adsorption performance for REEs compared to mechanically activated jarosite(M-Jar).Moreover,M-Sch was reusable and exhibited high adsorption efficiency of REEs in actual mine wastewater,exceeding 92%.
基金Project(22376221)supported by the National Natural Science Foundation of ChinaProject(2024JJ2074)supported by the Natural Science Foundation of Hunan Province,ChinaProject(2023QNRC001)supported by the Young Elite Scientists Sponsorship Program by CAST。
文摘Understanding the adsorption behavior of heavy metals and metalloids on clay minerals is essential for remediating heavy metal-contaminated soils.The adsorption of heavy metals and metalloids on illite(001)and sodium montmorillonite(Na-MMT)(001)surfaces was investigated using first-principles calculations in this study,especially As atom and H_(3)AsO_(3) molecule.The adsorption energies of the As atom were−1.94 eV on the illite(001)and−0.56 eV on the Na-MMT(001),whereas,the adsorption energies of the H_(3)AsO_(3) molecule were−1.40 eV on illite(001)and−1.01 eV on Na-MMT(001).The above results indicate that the adsorption was more energetically favorable on illite(001).Additionally,compared to Na-MMT(001),there were more significant interactions between the atoms/molecules on the illite(001).After As atom and H_(3)AsO_(3) molecule adsorption,the electrons were transferred from mineral surface atoms to the adsorbates on both illite(001)and Na-MMT(001)surfaces.Moreover,the adsorption of As atom on illite(001)and Na-MMT(001)surfaces were more energy favorable compared to Hg,Cd,and Cr atoms.Overall,this work provides new insights into the adsorption behavior of As atoms and As molecules on illite and Na-MMT.The results indicate that illite rich soils are more prone to contamination by arsenic compared to soils primarily composed of Na-MMT minerals.
基金Project(42277256)supported by the National Natural Science Foundation of ChinaProjects(HBKT-2021011,HBKT-2021014)supported by the Hunan Province Environmental Protection Research Program,ChinaProject(CDSKY-2023-05)supported by the Scientific Research of Project Hunan Provincial Urban Geological Survey and Monitoring Institute,China。
文摘In this study,Schwertmannite,Akaganéite and ammoniojarosite were biosynthesized by different bacteria and characterized.The results showed that bacteria are critical in mediating the mineral formation process:the morphology,crystallinity,grain size and specific surface area of each mineral varied upon different bacteria and culturing conditions.In addition,the formed minerals’elemental composition and group disparity lead to different morphology,crystallinity and subsequent adsorption performance.In particular,adsorption difference existed in iron minerals biosynthesized by different bacteria.The maximal adsorption capacities of Akaganéite,Schwertmannite and ammoniojarosite were 26.6 mg/g,17.5 mg/g and 3.90 mg/g respectively.Cr(VI)adsorption on iron-minerals involves hydrogen bonding,electrostatic interaction,and ligand exchange.The adsorption only occurred on the surface of ammoniojarosite,while for Akaganéite and Schwertmannite,the tunnel structure greatly facilitated the adsorption process and improved adsorption capacity.Thus,the molecular structure is the primary determining factor for adsorption performance.Collectively,the results can provide useful information in selecting suitable bacteria for synthesizing heavy-metal scavenging minerals according to different environmental conditions.
基金supported by Key Science and Technology Innovation Team of Shaanxi Province(No.2022TD-33)National Natural Science Foundation of China(Grant Nos.21373161,21504067)。
文摘Traditional selection of combustion catalysis is time-consuming and labor-intensive.Theoretical calculation is expected to resolve this problem.The adsorption energy of HMX and O atoms on 13 metal oxides was calculated using DMol3,since HMX and O are key substances in decomposition process.And the relationship between the adsorption energy of HMX,O on metal oxides(TiO_(2),Al_(2)O_(3),PbO,CuO,Fe_(2)O_(3),Co_(3)O_(4),Bi_(2)O_(3),NiO)and experimental T30 values(time required for the decomposition depth of HMX to reach 30%)was depicted as volcano plot.Thus,the T30 values of other metal oxides was predicted based on their adsorption energy on volcano plot and validated by previous experimental data.Further,the adsorption energy of HMX on ZrO_(2)and MnO_(2)was predicted based on the linear relationship between surface energy and adsorption energy,and T30 values were estimated based on volcano plot.The apparent activation energy data of HMX/MgO,HMX/SnO_(2),HMX/ZrO_(2),and HMX/MnO_(2)obtained from DSC experiments are basically consistent with our predicted T30 values,indicating that it is feasible to predict the catalytic activity based on the adsorption calculation,and it is expected that these simple structural properties can predict adsorption energy to reduce the large quantities of computation and experiment cost.
基金Science and Technology Commission of Shanghai Municipality(21ZR1472900,22ZR1471600)。
文摘Platinum(Pt)-based noble metal catalysts(PGMs)are the most widely used commercial catalysts,but they have the problems of high cost,low reserves,and susceptibility to small-molecule toxicity.Transition metal oxides(TMOs)are regarded as potential substitutes for PGMs because of their stability in oxidizing environments and excellent catalytic performance.In this study,comprehensive investigation into the influence of elastic strains on the adsorption energies of carbon(C),hydrogen(H)and oxygen(O)on TMOs was conducted.Based on density functional theory(DFT)calculations,these effects in both tetragonal structures(PtO_(2),PdO_(2))and hexagonal structures(ZnO,CdO),along with their respective transition metals were systematically explored.It was identified that the optimal adsorption sites on metal oxides pinpointed the top of oxygen or the top of metal atom,while face-centered cubic(FCC)and hexagonal close-packed(HCP)holes were preferred for the transition metals.Furthermore,under the influence of elastic strains,the results demonstrated significant disparities in the adsorption energies of H and O between oxides and transition metals.Despite these differences,the effect of elastic strains on the adsorption energies of C,H and O on TMOs mirrored those on transition metals:adsorption energies increased under compressive strains,indicating weaker adsorption,and decreased under tension strains,indicating stronger adsorption.This behavior was rationalized based on the d-band model for adsorption atop a metallic atom or the p-band model for adsorption atop an oxygen atom.Consequently,elastic strains present a promising avenue for tailoring the catalytic properties of TMOs.
基金The National Natural Science Foundation of China(22078349,22005319,52170109)Self-deployment Program from Lanzhou Institute of Chemical Physics(E30159SQ).
文摘The interest in curtailing environmental pollution issues through physical separation processes has inspired an extensive search for novel nanoporous materials with exceptional adsorption capabilities.Covalent triazine frameworks(CTFs),emerged as a class of crystalline covalent organic frameworks(COFs),have been widely examined for various separation applications,owing to their large porosity,high stability,and rich nitrogen(N)doping.The development of CTFs for efficient adsorption of mercury(Ⅱ)(Hg^(2+))is of great importance for the field,whereas it is rarely attempted,on account of limited synthetic strategies and unknown structural-property relations of conventional CTFs derived from ionothermal approaches.Herein,we report rational synthesis of a crystalline CTF with methylthio pendant arms for efficient removal of Hg^(2+)with an exceptional capacity of 751 mg·g^(-1),ranking at the top among previously-reported adsorbents.This work may open up new possibility in the synthesis of COFs for various separations.
文摘The potential of di-(m-Formylphenol)-1,2-cyclohexandiimine as an environmentally friendly corrosion inhibitor for steel was investigated in 1 mol/L HCl using potentiodynamic polarization, electrochemical impedance spectroscopy and chronoamperometry measurements. All electrochemical measurements suggest that this compound is an excellent corrosion inhibitor for mild steel and the inhibition efficiency increases with the increase in inhibitor concentration. The effect of temperature on the corrosion behavior of mild steel with the addition of the Schiff base was studied in the temperature range from 25 °C to 65 °C. It is found that the adsorption of this inhibitor follows the Langmuir adsorption isotherms. The value of activation energy and the thermodynamic parameters such as ΔHads, ΔSads, Kads and ΔGads were calculated by the corrosion currents at different temperatures using the adsorption isotherm. The morphology of mild steel surface in the absence and presence of inhibitor was examined by scanning electron microscopy(SEM) images.
基金Projects(2013BAC15B01,2013BAB07B03)supported by the National Key Technology Research and Development Program of the Ministry of Science and Technology of ChinaProject(Qian Ke He JZ[2014]2009)supported by the Key Foundation of Science and Technology of Guizhou Province,China
文摘A novel microwave digestion and alkali fusion assisted hydrothermal method was proposed to synthesize zeolite from coal fly ash and the zeolite product was studied for removal of Cd(II)from aqueous solution through batch experiments.The adsorbent was characterized by X-ray diffraction,scanning electron microscopy,Fourier transform infrared spectroscopy,surface area analyzer and zeta potential measurement.The results show that the synthetic zeolite was identified as faujasite.The optimum conditions for removal of Cd(II)are found to be:adsorbent dose of0.5g/L,pH6,contact time of90min and initial concentration of20mg/L,the removal rate of Cd(II)is98.55%.The experimental kinetic data agree well with the pseudo second-order equation;the Langmuir isotherm model is found to be more suitable to explicate the experimental equilibrium isotherm results than Freundlich,Dubinin-Radushkevich and Temkin models,and the maximum adsorption capacity of Cd(II)is found to be86.96mg/g.The thermodynamic parameters such asΔGΘ,ΔHΘandΔSΘwere evaluated and the results show that the adsorption of Cd(II)onto the as-synthesized zeolite is spontaneous,endothermic and feasible under studied conditions.
基金Project(41602310)supported by the National Natural Science Foundation of ChinaProject(2017M611044)supported by the China Postdoctoral Science Foundation。
文摘Chitosan-coated fly ash(CWF)was prepared by the acid leaching-coating method.Chitosan and fly ash were crosslinked in the solution of acetic acid and sulfuric acid.The microstructure of CWF was conducted by scanning electron microscope(SEM)and X-ray diffraction(XRD).The removal of Cr(VI)from water by CWF was studied by adsorption experiments.The composite prepared by the experiment developed a pore structure and a crystal structure similar to SiO_(2) and chitosan chain-like coating was formed on the surface of fly ash.The new modified material has larger surface roughness,specific surface area and more adsorption channels.The Cr(VI)was enriched in modified materials by electrostatic adsorption between CrO_(4)^(2−)、CrO_(7)^(2−)and-NH_(3)^(+) group and surface acid functional groups.The movement of Cr(VI)in solution is a diffusion process from the main body of the liquid phase to the surface of the liquid film.
基金Project(50774094) supported by the National Natural Science Foundation of ChinaProject(2010CB630905) supported by the National Basic Research Program of China
文摘Two reagents including salicylhydroxamic acid(SHA) and tributyl phosphate(TBP) were tested as collectors either separately or together for electro-flotation of fine cassiterite(<10 μm).Subsequently,the flotation mechanism of the fine cassiterite was investigated by adsorbance determination,electrophoretic mobility measurements and Fourier transform infra-red(FT-IR) spectrum checking.Results of the flotation experiments show that with SHA as a collector,the collecting performance is remarkably impacted by the pulp pH value as the floatability of cassiterite varies sharply when the pH changes,and flotation with SHA gives distinct maximum at about pH 6.5.Additionally,the floatability of cassiterite is determined by using SHA and TBP as collectors.The range of pulp pH for good floatability is broadened in the presence of TBP as auxiliary collector,and the utilization of TBP improves the recovery of cassiterite modestly.Moreover,the optimum pH value for cassiterite flotation is associated with adsorbance.The results of FT-IR spectrum and the electrophoretic mobility measurements indicate that the adsorption interaction between the collectors and the cassiterite is dominantly a kind of chemical bonding in the form of one or two cycle chelate rings due to the coordination of carbonyl group,hydroxamate and P=O group to the metal tin atoms,where the oxygen atoms contained in carbonyl group,hydroxamate and P=O group of the polar groups have the stereo conditions to form five-membered rings.In addition,the adsorption interactions of SHA and TBP on the surfaces of cassiterite are also dominated by means of hydrogen bonds.
基金Project (200065) supported by University Key Teacher Foundation of the Ministry of Education of China
文摘Pb2+ and Cd2+ in leachate were adsorbed on clay-solidified grouting curtain for waste landfills with equilibrium experiment. The cation exchange capacity was determined with ammonium acetate. And the concentration of heavy metal cations in leachate was determined with atomic absorption spectrophotometer. Their equilibrium isotherms were measured, and the experimental isotherm data were analyzed by using Freundlich and Langmuir models. The results show that the adsorption capacities of the heavy metal cations are closely related to the compositions of clay-solidified grouting curtain, and the maximum adsorption appears at the ratio of cement to clay of 2∶4 in the experimental conditions. At their maximum adsorption and pH 5.0, the adsorption capacities of Pb 2+ and Cd 2+ are 16.19mg/g and 1.21mg/g. The competitive adsorption coefficients indicate that the adsorption of clay-solidified grouting curtain for Pb2+ is stronger than that for Cd 2+ . The adsorption process conforms to Freundlich’s model with related coefficient higher than 0.996.
基金Projects(20976200)supported by the National Natural Science Foundation of China
文摘To investigate the influence of the activated carbon pore structure on the adsorption of volatile organic compounds （VOCs）, three commercial activated carbon samples were chosen. The fixed-bed thermostatic adsorption experiments were conducted under certain conditions, where toluene, acetone, and 1, 2-dichloroethane acted as adsorbents. Then, the incidence relation between the experimental results and the activated carbon pore structure was analyzed. After that, the results of the correlation analysis were verified in accordance with fractal theory and adsorption characteristic curve analysis. The results show that the pore diameter gradient is helpful for strengthening the intemal diffusion. Under the same condition, the adsorption of organic gases tends to be selective, and the positions of toluene, acetone and 1, 2-dichloroethane adsorbed on the activated carbon are mainly in the ranges of 1.27-1.49 nm, 0.67-0.84 nm and 1.39-1.75 nm, respectively. The relationship between adsorption capacity and activated carbon pore volume can accurately explain the spreading process of the adsorbents in the activated carbon.
文摘The adsorption of the bentonite toward Ni(II) from aqueous solution was studied to obtain optimum conditions,equilibrium model,thermodynamic and kinetic parameters.Statistical method was used to evaluate maximum amount of adsorbed Ni(II).In this work,p H of solution during stirring,contact time,initial Ni(II) concentration,particle size of bentonite and amount of bentonite were considered as effective parameters which should be examined.The increase of temperature has negative effect on the Ni(II) adsorption.The equilibrium data were correlated well with Freundlich and Dubinin–Radushkevich isotherm models the correlation coefficients of which are(R^2) 0.994 and 0.971,respectively.This model indicates heterogeneous and chemical absorption or ion exchange process.The values of thermodynamic parameters such as ΔH°,ΔS° and ΔG° of nickel adsorption reveal that it is a spontaneous,exothermic and associative process.The experimental data fit the pseudo-second-order kinetic very well with correlation coefficient(R^2) more than 0.995.
基金Foundation item： Project（PLN1129）supported by Opening Fund of State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation （Southwest Petroleum University）, China
文摘To improve the understanding of the transport mechanism in shale gas reservoirs and build a theoretical basic for further researches on productivity evaluation and efficient exploitation, various gas transport mechanisms within a shale gas reservoir exploited by a horizontal well were thoroughly investigated, which took diffusion, adsorption/desorption and Darcy flow into account. The characteristics of diffusion in nano-scale pores in matrix and desorption on the matrix surface were both considered in the improved differential equations for seepage flow. By integrating the Langmuir isotherm desorption items into the new total dimensionless compression coefficient in matrix, the transport function and seepage flow could be formalized, simplified and consistent with the conventional form of diffusion equation. Furthermore, by utilizing the Laplace change and Sethfest inversion changes, the calculated results were obtained and further discussions indicated that transfer mechanisms were influenced by diffusion, adsorption/desorption. The research shows that when the matrix permeability is closed to magnitude of 10^-9D, the matrix flow only occurs near the surfacial matrix; as to the actual production, the central matrix blocks are barely involved in the production; the closer to the surface of matrix, the lower the pressure is and the more obvious the diffusion effect is; the behavior of adsorption/desorption can increase the matrix flow rate significantly and slow down the pressure of horizontal well obviously.
