High concentrations of copper ions(Cu(Ⅱ)) in water will pose health risks to humans and the ecological environment. Therefore, this study aims to utilize ultrasonic-cured modified municipal solid waste incineration(M...High concentrations of copper ions(Cu(Ⅱ)) in water will pose health risks to humans and the ecological environment. Therefore, this study aims to utilize ultrasonic-cured modified municipal solid waste incineration(MSWI) fly ash for Cu(Ⅱ) adsorption to achieve the purpose of “treating waste by waste.” The effects of p H, adsorption time, initial concentration, and temperature on the modified MSWI fly ash’s adsorption efficiency were systematically studied in this article. The adsorption performance of the modified MSWI fly ash can be enhanced by the ultrasonic modification. At pH = 2, 3 and 4, the adsorption capacity of the modified MSWI fly ash for Cu(Ⅱ) increased by 2.7, 1.9 and 1.2 times, respectively. Furthermore, it was suggested that the adsorption process of the modified MSWI fly ash can be better simulated by the pseudo-second-order kinetic model, with a maximum adsorption capacity calculated by the Langmuir model of 24.196 mg.g-1. Additionally, the adsorption process is spontaneous,endothermic, and chemisorption-dominated from the thermodynamic studies(ΔH and ΔS > 0, ΔG < 0).Finally, the enhanced adsorption performance of the modified MSWI fly ash for Cu(Ⅱ) may be attributed to electrostatic interaction and chelation effects.展开更多
Adsorptive removal of heavy metal ions from wastewater is very important,and the key is the development of efficient sorbents.In this work,oxygenated alkynyl carbon materials(OACMs)were synthesized via mechanochemical...Adsorptive removal of heavy metal ions from wastewater is very important,and the key is the development of efficient sorbents.In this work,oxygenated alkynyl carbon materials(OACMs)were synthesized via mechanochemical reaction of CaC_(2) and a carbonate(CaCO_(3),Na2CO_(3),or NaHCO_(3))at ambient temperature.The resultant OACMs are micro mesoporous carbon nanomaterials with high specific area(>648 m2 g^(-1)),highly crosslinked texture,and rich alkynyl and oxygenated groups.The OACMs exhibit excellent Hg(Ⅱ)adsorption due to the soft acid-soft base interaction between alkynyl and Hg(Ⅱ),and OACM-3 derived from CaC_(2) and NaHCO_(3) has the saturated Hg(Ⅱ)adsorbance of 483.9 mg g^(-1)along with good selectivity and recyclability.The adsorption is mainly chemisorption following the Langmuir mode.OACM-3 also shows high adsorbance for other heavy metal ions,e.g.256.6 mg g^(-1)for Pb(II),232.4 mg g^(-1)for Zn(II),and 198.7 mg g^(-1)for Cu(II).This work expands the mechnochemical reaction of CaC_(2)with carbonates and possibly other oxyanionic salts,provides a new synthesis approach for functional alkynyl carbon materials with excellent adsorption performance for heavy metal ions,as well as a feasible approach for CO2 resource utilization.展开更多
[Objective] The aim of the study was to make research on adsorption of Chinese walnut（Juglans mandshurica Maxim.） Shell（CWS） to Hg（Ⅱ） in water.[Method] Shells of Juglans mandshurica Maxim were used as biosorpti...[Objective] The aim of the study was to make research on adsorption of Chinese walnut（Juglans mandshurica Maxim.） Shell（CWS） to Hg（Ⅱ） in water.[Method] Shells of Juglans mandshurica Maxim were used as biosorption to remove Hg（Ⅱ） in water solution to explore the influence to adsorption of Hg（Ⅱ） under different conditions,like pH solution,adsorption time,and Hg（Ⅱ）.[Result] The experimental results show that when absorptivity of Hg（Ⅱ） by CWS reached the highest,pH ranged within 5.0-6.0.The adsorptivity decreased as initial Hg（Ⅱ） concentrations increased.Fourier Transform Infrared Spectroscopy（FTIR） spectrum revealed some chemical groups of CWS may affect the adsorption of Hg（Ⅱ）,such as hydroxyl groups,methyl groups,aromatic methoxyl groups,unconjugated carbonyl,and typical aromatic ring,etc.Adsorption equation can be concluded considering the biosorption process relationship with Langmuir and Frendrich isotherm.[Conclusion] The study found that CW could be employed as a promising biosorption to remove Hg（Ⅱ） from aqueous environments.展开更多
A novel adsorbent(MTZ-MOFs)was synthesized by a one-step reaction of zinc nitrate hexahydrate and 1-(2-dimethylaminoethyl)-1H-5-mercaptotetrazole to remove mercury from waste water.The results showed that MTZ-MOFs had...A novel adsorbent(MTZ-MOFs)was synthesized by a one-step reaction of zinc nitrate hexahydrate and 1-(2-dimethylaminoethyl)-1H-5-mercaptotetrazole to remove mercury from waste water.The results showed that MTZ-MOFs had excellent selectivity and repeatability for Hg(Ⅱ),the optimum pH was 3.0,the maximum adsorption capacity was 872.8 mg/g,and the process was a spontaneous exothermic reaction.The adsorption behavior was chemisorption,which conformed to the pseudo-second-order kinetic and Freundlich isothermal model.Moreover,the adsorption mechanism showed that the adsorption process mainly depended on ion exchange and chelation,and the synergistic action of S and N atoms played a key role.So,MTZ-MOFs were an efficient adsorbent for mercury ion removal.展开更多
Mercury(Hg)ions can lead to a serious impact on the environment;therefore,it was necessary to find an effective method for absorbing these toxic Hg ions.Here,the adsorbent(Zn-AHMT)was synthesized from zinc nitrate and...Mercury(Hg)ions can lead to a serious impact on the environment;therefore,it was necessary to find an effective method for absorbing these toxic Hg ions.Here,the adsorbent(Zn-AHMT)was synthesized from zinc nitrate and 4-amino 3-hydrazine-5 mercapto-1,2,4-triazole(AHMT)by one-step method and,characterized the microstruc-ture and absorption performance by fourier transform infrared spectroscopy(FTIR),field emission scanning electron microscopy(FESEM),X-ray diffraction(XRD),Brunauer-Emmett Teller(BET),Thermal Gravimetric Analyzer(TGA)and X-ray photoelectron spectroscopy(XPS).Through a plethora of measurements,we found that the maximum adsorption capacity was 802.8 mg/g when the optimal pH of Zn-AHMT was 3.0.The isothermal and kinetic experiments confirm that the reaction process of Zn-AHMT was chemisorption,while the adsorption process conforms to the Hill model and pseudo second order kinetic model.Thermodynamic experiments showed that the adsorption process was spontaneous and exothermic.Selective experiments were performed in the simulated wastewater containing Mn,Mg,Cr,Al,Co,Ni,Hg ions.Our results showed that the Zn-AHMT has a stronger affinity for Hg ions.The removal rate of Zn-AHMT remained above 98%,indicating that the Zn-AHMT had a good stability validated by three adsorption-desorption repeatable tests.According to the XPS results,the adsorption reaction of Zn-AHMT was mainly attributed to the chelation and ion exchange.This was further explained by both density functional theory(DFT)calculation and frontier molecular orbital theory.We therefore propose the adsorption mechanism of Zn-AHMT.The adsorption reaction facilitates via the synergistic action of S and N atoms.Moreover,the bonding between the adsorbent and the N atom has been proved to be more stable.Our study demonstrated that Zn-AHMT had a promising application prospect in mercury removal.展开更多
Amino-functionalized magnetic nanoparticle （NH2-MNP） were prepared by a sol-gel approach. The adsorption behavior of Cu（II） ions on NH2-MNP was discussed systematically by batch experiments. The effects of initial...Amino-functionalized magnetic nanoparticle （NH2-MNP） were prepared by a sol-gel approach. The adsorption behavior of Cu（II） ions on NH2-MNP was discussed systematically by batch experiments. The effects of initial Cu（II） ions concentration, time, pH and temperature were investigated. In kinetic studies, the pseudo-second-order model was successfully employed, and the pseudo-first-order model substantiated that Cu（II） adsorption on NH2-MNP was a diffusion-based process. Langmuir model and Dubinin-Radushkevich model （R2〉0.99） were more corresponded with the adsorption isotherm data of Cu（II） ions than Freundlich model. The adsorption capacity was increased with the increment of temperature and pH. NH2-MNP remains excellent Cu（II） recoveries after reusing five adsorption and desorption cycles, making NH2-MNP a promising candidate for repetitively removing heavy metal ions from environmental water samples. According to the results obtained from adsorption activation energy and thermodynamic studies, it can be inferred that the main adsorption mechanism between absorbent and Cu（II） ions is ion exchange-surface complexation.展开更多
The adsorption and desorption of Cu（Ⅱ） and Pb（Ⅱ） on upland red soil,and paddy soils which were originated from the upland soil and cultivated for 8,15,35 and 85 years,were investigated using the batch method.The...The adsorption and desorption of Cu（Ⅱ） and Pb（Ⅱ） on upland red soil,and paddy soils which were originated from the upland soil and cultivated for 8,15,35 and 85 years,were investigated using the batch method.The study showed that the organic matter content and cation exchange capacity （CEC） of the soils are important factors controlling the adsorption and desorption of Cu（Ⅱ） and Pb（Ⅱ）.The 15-Year paddy soil had the highest adsorption capacity for Pb（Ⅱ）,followed by the 35-Year paddy soil.Both the 35-Year paddy soil and 15-Year paddy soil adsorbed more Cu（Ⅱ） than the upland soil and other paddy soils.The 15-Year paddy soils exhibited the highest desorption percentage for both Cu（Ⅱ） and Pb（Ⅱ）.These results are consistent with the trend for the CEC of the soils tested.The high soil CEC contributes not only to the adsorption of Cu（Ⅱ） and Pb（Ⅱ） but also to the electrostatic adsorption of the two heavy metals by the soils.Lower desorption percentages for Cu（Ⅱ） （36.7% to 42.2%） and Pb（Ⅱ） （50.4% to 57.9%） were observed for the 85-Year paddy soil.The highest content of organic matter in the soil was responsible for the low desorption percentages for the two metals because the formation of the complexes between the organic matter and the metals could increase the stability of the heavy metals in the soils.展开更多
Surface ion-imprinted in combination with sol-gel process was applied to synthesis a new Pb（Ⅱ）-imprinted polymer for selective separation and enrichment of trace Pb（Ⅱ） from aqueous solution. The prepared materia...Surface ion-imprinted in combination with sol-gel process was applied to synthesis a new Pb（Ⅱ）-imprinted polymer for selective separation and enrichment of trace Pb（Ⅱ） from aqueous solution. The prepared material was characterized by using the infrared spectra, X-ray diffractometer, and scanning electron microscopy. The batch experiments were conducted to study the optimal adsorption condition of adsorption trace Pb（Ⅱ） from aqueous solutions on Pb（Ⅱ）-imprinted polymer. The equilibrium was achieved in approximately 4,0 h, and the experimental kinetic data were fitted the pseudo second-order model better. The maximum adsorption capacity was 22.7 mg/g, and the Langmuir equation fitted the adsorption isotherm data. The results of selectivity experiment showed that selectively adsorbed rate of Pb（Ⅱ） on Pb（Ⅱ）-imprinted polymer was higher than all other studied ions. Desorption conditions of the adsorbed Pb（Ⅱ） from the Pb（Ⅱ）-imprinted polymer were also studied in batch experiments. The prepared Pb（Ⅱ）-imprinted polymer was shown to be promising for the separation and enrichment of trace Pb（Ⅱ） from water samples. The adsorption and desorption mechanisms were proposed.展开更多
The adsorption of Cu（Ⅱ） from aqueous solution onto humic acid （HA） which was isolated from cattle manure （CHA）, peat （PHA）, and leaf litter （LHA） as a function of contact time, pH, ion strength, and initial...The adsorption of Cu（Ⅱ） from aqueous solution onto humic acid （HA） which was isolated from cattle manure （CHA）, peat （PHA）, and leaf litter （LHA） as a function of contact time, pH, ion strength, and initial concentration was studied using the batch method. X-ray absorption spectroscopy （XAS） was used to examine the coordination environment of the Cu（ll） adsorbed by HA at a molecular level. Moreover, the chemical compositions of the isolated HA were characterized by elemental analysis and solid-state 13C nuclear magnetic resonance spectroscopy （NMR）. The kinetic data showed that the adsorption equilibrium can be achieved within 8 h. The adsorption kinetics followed the pseudo-second-order equation. The adsorption isotherms could be well fitted by the Langmuir model, and the maximum adsorption capacities of Cu（ll） on CHA, PHA, and LHA were 229.4,210.4, and 197.7 mg g-1, respectively. The adsorption of Cu（Ⅱ） on HA increased with the increase in pH from 2 to 7, and maintained a high level at pH〉7. The adsorption of Cu（Ⅱ） was also strongly influenced by the low ionic strength of 0.01 to 0.2 mol L-1 NaNO3, but was weakly influenced by high ionic strength of 0.4 to 1 mol L-1 NaNO3. The Cu（Ⅱ） adsorption on HA may be mainly attributed to ion exchange and surface complexation. XAS results revealed that the binding site and oxidation state of Cu adsorbed on HA surface did not change at the initial Cu（Ⅱ） concentrations of 15 to 40 mg L 1. For all the Cu（Ⅱ） adsorption samples, each Cu atom was surrounded by 40/N atoms at a bond distance of 1.95 A in the first coordination shell. The presence of the higher Cu coordination shells proved that Cu（Ⅱ） was adsorbed via an inner-sphere covalent bond onto the HA surface. Among the three HA samples, the adsorption capacity and affinity of CHA for Cu（Ⅱ） was the greatest, followed by that of PHA and LHA. All the three HA samples exhibited similar types of elemental and functional groups, but different contents of elemental and functional groups. CHA contained larger proportions of methoxyl C, phenolic C and carbonyl C, and smaller proportions of alkyl C and carbohydrate C than PHA and LHA. The structural differences of the three HA samples are responsible for their distinct adsorption capacity and affinity toward Cu（Ⅱ）. These results are important to achieve better understanding of the behavior of Cu（Ⅱ） in soil and water bodies in the presence of organic materials.展开更多
Adsorption/desorption in a new Zn（Ⅱ）-TiO2 adsorption system was investigated at different particle concentrations （Cp）. TEM, SEM and XRD analyses revealed that the TiO2 particles were an aggregation of nano-sized...Adsorption/desorption in a new Zn（Ⅱ）-TiO2 adsorption system was investigated at different particle concentrations （Cp）. TEM, SEM and XRD analyses revealed that the TiO2 particles were an aggregation of nano-sized （approximately 10 nm） pure anatase-type TiO2. Adsorption experiments were carried out with particle concentrations of 100, 400 and 1000 mg/L, and their adsorption isotherms were found to decline successively, showing an obvious Cp effect. Desorption experiments indicated that adsorption in this system was irreversible, and the irreversibility increased with increasing Cp. These phenomena could be explained by the MEA （metastable equilibrium adsorption） theory and the Cp effect could be modeled well with an MEA-Freundlich-type Cp effect isotherm equation. This study may heln understand environmental behavior of contaminants on ultrafine natural particles.展开更多
Zeolites Y,A and mordenite(ZY,ZA and ZM)were obtained from diatomite in a template-free system,and the products were modified by thiourea(TU).Characterization studies results indicated that the TU molecules were loade...Zeolites Y,A and mordenite(ZY,ZA and ZM)were obtained from diatomite in a template-free system,and the products were modified by thiourea(TU).Characterization studies results indicated that the TU molecules were loaded onto the exterior surfaces of the synthetic zeolites as well as the channels.Elemental analysis and energy-dispersive X-ray spectrometer proved that the TU molecules loaded on to ZA were more than ZY and ZM.Removal of Cd(Ⅱ)was investigated,and itwas found that themodified zeolites have higher removal capacity,modified ZA is especially noticeable.In the adsorption experiments,the effects of various parameters such as sorbent content,contact time,concentration of cadmium solution,pH,selectivity and regeneration were discussed.At the best removal efficiency by modified zeolites,the maximum adsorption capacity is 94.3 mg·g^−1,103.2 mg·g^−1 and 89.7 mg·g^−1 at 25℃,respectively.The sorbents show good efficiency for the removal of Cd(Ⅱ)in the presence of different multivalent cations and have good regeneration effect.For the modified samples,removal experiments take place via ion exchange and complexation processes.展开更多
基金supported by the key program of the National Natural Science Foundation of China(52236008).
文摘High concentrations of copper ions(Cu(Ⅱ)) in water will pose health risks to humans and the ecological environment. Therefore, this study aims to utilize ultrasonic-cured modified municipal solid waste incineration(MSWI) fly ash for Cu(Ⅱ) adsorption to achieve the purpose of “treating waste by waste.” The effects of p H, adsorption time, initial concentration, and temperature on the modified MSWI fly ash’s adsorption efficiency were systematically studied in this article. The adsorption performance of the modified MSWI fly ash can be enhanced by the ultrasonic modification. At pH = 2, 3 and 4, the adsorption capacity of the modified MSWI fly ash for Cu(Ⅱ) increased by 2.7, 1.9 and 1.2 times, respectively. Furthermore, it was suggested that the adsorption process of the modified MSWI fly ash can be better simulated by the pseudo-second-order kinetic model, with a maximum adsorption capacity calculated by the Langmuir model of 24.196 mg.g-1. Additionally, the adsorption process is spontaneous,endothermic, and chemisorption-dominated from the thermodynamic studies(ΔH and ΔS > 0, ΔG < 0).Finally, the enhanced adsorption performance of the modified MSWI fly ash for Cu(Ⅱ) may be attributed to electrostatic interaction and chelation effects.
基金supports from the National Natural Science Foundation of China(No.21776015)the University Scientific Research Project of Anhui Province(No.KJ2018A0065&KJ2020A0245).
文摘Adsorptive removal of heavy metal ions from wastewater is very important,and the key is the development of efficient sorbents.In this work,oxygenated alkynyl carbon materials(OACMs)were synthesized via mechanochemical reaction of CaC_(2) and a carbonate(CaCO_(3),Na2CO_(3),or NaHCO_(3))at ambient temperature.The resultant OACMs are micro mesoporous carbon nanomaterials with high specific area(>648 m2 g^(-1)),highly crosslinked texture,and rich alkynyl and oxygenated groups.The OACMs exhibit excellent Hg(Ⅱ)adsorption due to the soft acid-soft base interaction between alkynyl and Hg(Ⅱ),and OACM-3 derived from CaC_(2) and NaHCO_(3) has the saturated Hg(Ⅱ)adsorbance of 483.9 mg g^(-1)along with good selectivity and recyclability.The adsorption is mainly chemisorption following the Langmuir mode.OACM-3 also shows high adsorbance for other heavy metal ions,e.g.256.6 mg g^(-1)for Pb(II),232.4 mg g^(-1)for Zn(II),and 198.7 mg g^(-1)for Cu(II).This work expands the mechnochemical reaction of CaC_(2)with carbonates and possibly other oxyanionic salts,provides a new synthesis approach for functional alkynyl carbon materials with excellent adsorption performance for heavy metal ions,as well as a feasible approach for CO2 resource utilization.
基金Supported by National Water Major Project of China (2008ZX07211-007)~~
文摘[Objective] The aim of the study was to make research on adsorption of Chinese walnut（Juglans mandshurica Maxim.） Shell（CWS） to Hg（Ⅱ） in water.[Method] Shells of Juglans mandshurica Maxim were used as biosorption to remove Hg（Ⅱ） in water solution to explore the influence to adsorption of Hg（Ⅱ） under different conditions,like pH solution,adsorption time,and Hg（Ⅱ）.[Result] The experimental results show that when absorptivity of Hg（Ⅱ） by CWS reached the highest,pH ranged within 5.0-6.0.The adsorptivity decreased as initial Hg（Ⅱ） concentrations increased.Fourier Transform Infrared Spectroscopy（FTIR） spectrum revealed some chemical groups of CWS may affect the adsorption of Hg（Ⅱ）,such as hydroxyl groups,methyl groups,aromatic methoxyl groups,unconjugated carbonyl,and typical aromatic ring,etc.Adsorption equation can be concluded considering the biosorption process relationship with Langmuir and Frendrich isotherm.[Conclusion] The study found that CW could be employed as a promising biosorption to remove Hg（Ⅱ） from aqueous environments.
基金supported by the Hubei Provincial Department of Education Science and Technology Research Program Young Talent Project,China (No. Q20201102)the National Natural Science Foundation of China (Nos. 51864042, 51804220)
文摘A novel adsorbent(MTZ-MOFs)was synthesized by a one-step reaction of zinc nitrate hexahydrate and 1-(2-dimethylaminoethyl)-1H-5-mercaptotetrazole to remove mercury from waste water.The results showed that MTZ-MOFs had excellent selectivity and repeatability for Hg(Ⅱ),the optimum pH was 3.0,the maximum adsorption capacity was 872.8 mg/g,and the process was a spontaneous exothermic reaction.The adsorption behavior was chemisorption,which conformed to the pseudo-second-order kinetic and Freundlich isothermal model.Moreover,the adsorption mechanism showed that the adsorption process mainly depended on ion exchange and chelation,and the synergistic action of S and N atoms played a key role.So,MTZ-MOFs were an efficient adsorbent for mercury ion removal.
基金the Hubei Provincial Department of Education Science and Technology Research Program Young Talent Project(Q20201102)the National Natural Science Foundation of China(51864042 and 51804220).
文摘Mercury(Hg)ions can lead to a serious impact on the environment;therefore,it was necessary to find an effective method for absorbing these toxic Hg ions.Here,the adsorbent(Zn-AHMT)was synthesized from zinc nitrate and 4-amino 3-hydrazine-5 mercapto-1,2,4-triazole(AHMT)by one-step method and,characterized the microstruc-ture and absorption performance by fourier transform infrared spectroscopy(FTIR),field emission scanning electron microscopy(FESEM),X-ray diffraction(XRD),Brunauer-Emmett Teller(BET),Thermal Gravimetric Analyzer(TGA)and X-ray photoelectron spectroscopy(XPS).Through a plethora of measurements,we found that the maximum adsorption capacity was 802.8 mg/g when the optimal pH of Zn-AHMT was 3.0.The isothermal and kinetic experiments confirm that the reaction process of Zn-AHMT was chemisorption,while the adsorption process conforms to the Hill model and pseudo second order kinetic model.Thermodynamic experiments showed that the adsorption process was spontaneous and exothermic.Selective experiments were performed in the simulated wastewater containing Mn,Mg,Cr,Al,Co,Ni,Hg ions.Our results showed that the Zn-AHMT has a stronger affinity for Hg ions.The removal rate of Zn-AHMT remained above 98%,indicating that the Zn-AHMT had a good stability validated by three adsorption-desorption repeatable tests.According to the XPS results,the adsorption reaction of Zn-AHMT was mainly attributed to the chelation and ion exchange.This was further explained by both density functional theory(DFT)calculation and frontier molecular orbital theory.We therefore propose the adsorption mechanism of Zn-AHMT.The adsorption reaction facilitates via the synergistic action of S and N atoms.Moreover,the bonding between the adsorbent and the N atom has been proved to be more stable.Our study demonstrated that Zn-AHMT had a promising application prospect in mercury removal.
基金Project(CXZZ11-0812)supported by Graduate Students Innovative Projects of Jiangsu Province,ChinaProject(J20122288)supported by Guizhou Provincial Natural Science Foundation of China+1 种基金Project(Y4110235)supported by Zhejiang Provincial Natural Science Foundation of ChinaProject(JKY2011008)supported by Fundamental Research Funds for the Central Universities,China
文摘Amino-functionalized magnetic nanoparticle （NH2-MNP） were prepared by a sol-gel approach. The adsorption behavior of Cu（II） ions on NH2-MNP was discussed systematically by batch experiments. The effects of initial Cu（II） ions concentration, time, pH and temperature were investigated. In kinetic studies, the pseudo-second-order model was successfully employed, and the pseudo-first-order model substantiated that Cu（II） adsorption on NH2-MNP was a diffusion-based process. Langmuir model and Dubinin-Radushkevich model （R2〉0.99） were more corresponded with the adsorption isotherm data of Cu（II） ions than Freundlich model. The adsorption capacity was increased with the increment of temperature and pH. NH2-MNP remains excellent Cu（II） recoveries after reusing five adsorption and desorption cycles, making NH2-MNP a promising candidate for repetitively removing heavy metal ions from environmental water samples. According to the results obtained from adsorption activation energy and thermodynamic studies, it can be inferred that the main adsorption mechanism between absorbent and Cu（II） ions is ion exchange-surface complexation.
基金supported by the Knowledge Innovation Program Foundation of the Chinese Academy of Sciences(No. KZCX2-YW-Q10-3,ISSASIP0713)
文摘The adsorption and desorption of Cu（Ⅱ） and Pb（Ⅱ） on upland red soil,and paddy soils which were originated from the upland soil and cultivated for 8,15,35 and 85 years,were investigated using the batch method.The study showed that the organic matter content and cation exchange capacity （CEC） of the soils are important factors controlling the adsorption and desorption of Cu（Ⅱ） and Pb（Ⅱ）.The 15-Year paddy soil had the highest adsorption capacity for Pb（Ⅱ）,followed by the 35-Year paddy soil.Both the 35-Year paddy soil and 15-Year paddy soil adsorbed more Cu（Ⅱ） than the upland soil and other paddy soils.The 15-Year paddy soils exhibited the highest desorption percentage for both Cu（Ⅱ） and Pb（Ⅱ）.These results are consistent with the trend for the CEC of the soils tested.The high soil CEC contributes not only to the adsorption of Cu（Ⅱ） and Pb（Ⅱ） but also to the electrostatic adsorption of the two heavy metals by the soils.Lower desorption percentages for Cu（Ⅱ） （36.7% to 42.2%） and Pb（Ⅱ） （50.4% to 57.9%） were observed for the 85-Year paddy soil.The highest content of organic matter in the soil was responsible for the low desorption percentages for the two metals because the formation of the complexes between the organic matter and the metals could increase the stability of the heavy metals in the soils.
基金supported by the National Natural Science Foundation of China (No. 20877036)
文摘Surface ion-imprinted in combination with sol-gel process was applied to synthesis a new Pb（Ⅱ）-imprinted polymer for selective separation and enrichment of trace Pb（Ⅱ） from aqueous solution. The prepared material was characterized by using the infrared spectra, X-ray diffractometer, and scanning electron microscopy. The batch experiments were conducted to study the optimal adsorption condition of adsorption trace Pb（Ⅱ） from aqueous solutions on Pb（Ⅱ）-imprinted polymer. The equilibrium was achieved in approximately 4,0 h, and the experimental kinetic data were fitted the pseudo second-order model better. The maximum adsorption capacity was 22.7 mg/g, and the Langmuir equation fitted the adsorption isotherm data. The results of selectivity experiment showed that selectively adsorbed rate of Pb（Ⅱ） on Pb（Ⅱ）-imprinted polymer was higher than all other studied ions. Desorption conditions of the adsorbed Pb（Ⅱ） from the Pb（Ⅱ）-imprinted polymer were also studied in batch experiments. The prepared Pb（Ⅱ）-imprinted polymer was shown to be promising for the separation and enrichment of trace Pb（Ⅱ） from water samples. The adsorption and desorption mechanisms were proposed.
基金supported by the Key Technologies R&D Program of China (2013BAD07B02 and 2013BAC09B01)the Special Fund for Agro-Scientific Research in the Public Interest of China (201103003)+1 种基金the Postdoctoral Project of Jilin Province, China (01912)the Doctoral Initiative Foundation of Jilin Agricultural University, China (201216)
文摘The adsorption of Cu（Ⅱ） from aqueous solution onto humic acid （HA） which was isolated from cattle manure （CHA）, peat （PHA）, and leaf litter （LHA） as a function of contact time, pH, ion strength, and initial concentration was studied using the batch method. X-ray absorption spectroscopy （XAS） was used to examine the coordination environment of the Cu（ll） adsorbed by HA at a molecular level. Moreover, the chemical compositions of the isolated HA were characterized by elemental analysis and solid-state 13C nuclear magnetic resonance spectroscopy （NMR）. The kinetic data showed that the adsorption equilibrium can be achieved within 8 h. The adsorption kinetics followed the pseudo-second-order equation. The adsorption isotherms could be well fitted by the Langmuir model, and the maximum adsorption capacities of Cu（ll） on CHA, PHA, and LHA were 229.4,210.4, and 197.7 mg g-1, respectively. The adsorption of Cu（Ⅱ） on HA increased with the increase in pH from 2 to 7, and maintained a high level at pH〉7. The adsorption of Cu（Ⅱ） was also strongly influenced by the low ionic strength of 0.01 to 0.2 mol L-1 NaNO3, but was weakly influenced by high ionic strength of 0.4 to 1 mol L-1 NaNO3. The Cu（Ⅱ） adsorption on HA may be mainly attributed to ion exchange and surface complexation. XAS results revealed that the binding site and oxidation state of Cu adsorbed on HA surface did not change at the initial Cu（Ⅱ） concentrations of 15 to 40 mg L 1. For all the Cu（Ⅱ） adsorption samples, each Cu atom was surrounded by 40/N atoms at a bond distance of 1.95 A in the first coordination shell. The presence of the higher Cu coordination shells proved that Cu（Ⅱ） was adsorbed via an inner-sphere covalent bond onto the HA surface. Among the three HA samples, the adsorption capacity and affinity of CHA for Cu（Ⅱ） was the greatest, followed by that of PHA and LHA. All the three HA samples exhibited similar types of elemental and functional groups, but different contents of elemental and functional groups. CHA contained larger proportions of methoxyl C, phenolic C and carbonyl C, and smaller proportions of alkyl C and carbohydrate C than PHA and LHA. The structural differences of the three HA samples are responsible for their distinct adsorption capacity and affinity toward Cu（Ⅱ）. These results are important to achieve better understanding of the behavior of Cu（Ⅱ） in soil and water bodies in the presence of organic materials.
基金Project supported by the National Natural Science Foundation of China(No.20537020)the "Hundred Talent Scientist Program" of the Chinese Academy of Sciences.
文摘Adsorption/desorption in a new Zn（Ⅱ）-TiO2 adsorption system was investigated at different particle concentrations （Cp）. TEM, SEM and XRD analyses revealed that the TiO2 particles were an aggregation of nano-sized （approximately 10 nm） pure anatase-type TiO2. Adsorption experiments were carried out with particle concentrations of 100, 400 and 1000 mg/L, and their adsorption isotherms were found to decline successively, showing an obvious Cp effect. Desorption experiments indicated that adsorption in this system was irreversible, and the irreversibility increased with increasing Cp. These phenomena could be explained by the MEA （metastable equilibrium adsorption） theory and the Cp effect could be modeled well with an MEA-Freundlich-type Cp effect isotherm equation. This study may heln understand environmental behavior of contaminants on ultrafine natural particles.
文摘Zeolites Y,A and mordenite(ZY,ZA and ZM)were obtained from diatomite in a template-free system,and the products were modified by thiourea(TU).Characterization studies results indicated that the TU molecules were loaded onto the exterior surfaces of the synthetic zeolites as well as the channels.Elemental analysis and energy-dispersive X-ray spectrometer proved that the TU molecules loaded on to ZA were more than ZY and ZM.Removal of Cd(Ⅱ)was investigated,and itwas found that themodified zeolites have higher removal capacity,modified ZA is especially noticeable.In the adsorption experiments,the effects of various parameters such as sorbent content,contact time,concentration of cadmium solution,pH,selectivity and regeneration were discussed.At the best removal efficiency by modified zeolites,the maximum adsorption capacity is 94.3 mg·g^−1,103.2 mg·g^−1 and 89.7 mg·g^−1 at 25℃,respectively.The sorbents show good efficiency for the removal of Cd(Ⅱ)in the presence of different multivalent cations and have good regeneration effect.For the modified samples,removal experiments take place via ion exchange and complexation processes.
