Novel adsorbent, Fe(Ⅲ)-loaded ligand exchange cotton cellulose adsorbent [Fe(Ⅲ) LECCA], was used to in vestigate the adsorption performances and mechanism of fluoride removal from aqueous solutions. The adsorben...Novel adsorbent, Fe(Ⅲ)-loaded ligand exchange cotton cellulose adsorbent [Fe(Ⅲ) LECCA], was used to in vestigate the adsorption performances and mechanism of fluoride removal from aqueous solutions. The adsorbent was found to adsorb fluoride rapidly and effectively. The fluoride removal was influenced by pH. Adsorption mode followed first-order reaction at different temperature, theapparent adsorption activated energy Ea was 6.37 kJ·mol^-1, and adsorption enthalpy △H was 5.35 kJ·mol^-1. The adsorption enfluoride on adsorbent was 3.2 mmol·g^-1 (dry weight). The maximal integer coordination ratio of fluoride with Fe(Ⅲ) LECCA was 3:1. The ligand exchange mechanism of adsorption was elucidated through chemical methods and IR spectral analysis.展开更多
Humic acid(HA)was carbonized at 300,400 and 500℃ and then functionalized with 1 wt%–12 wt%Fe(Ⅲ)respectively[CHA300/400/500-Fe(Ⅲ)].Adsorption of such Fe(III)-functionalized carbonized HA as adsorbents to aqueous te...Humic acid(HA)was carbonized at 300,400 and 500℃ and then functionalized with 1 wt%–12 wt%Fe(Ⅲ)respectively[CHA300/400/500-Fe(Ⅲ)].Adsorption of such Fe(III)-functionalized carbonized HA as adsorbents to aqueous tetracycline(TC:25 mg·L^-1)was studied.The adsorption equilibrium time for CHA400-Fe(Ⅲ)to TC was 6 h faster and the adsorption removal efficiency(Re)was two times higher than that of HA/CHA.The adsorption Reof CHA400-Fe(Ⅲ)loaded 10%iron[CHA400-(10%)Fe(Ⅲ)]to TC could reach 99.8%at 8 h and still kept80.6%after 8 cycles.The adsorption kinetics were well fitted to the pseudo-second-order equation and the adsorption isotherms could be well delineated via Langmuir equations(R^2N 0.99),indicating that the homogeneous chemical adsorption of TC occurred on the adsorbents.The main adsorption mechanisms of TC were complexation Fe(III)and hydrophobic distribution.Electropositive and electronegative repulsion between TC and CHA400-(10%)Fe(Ⅲ)at lowly p H(2)and highly p H(8–10)respectively,leaded to the relatively low adsorption capacity and more notable influence of ion concentration.When the p H was between 4 and 8,TC mainly existed in neutral molecules(TCH2),so the influence of ion concentration was not obvious.The dynamic adsorption results showed that the CHA400-(10%)Fe(Ⅲ)could continuously treat about 2.4 L TC(27 mg·L^-1)wastewater with the effluent concentration as low as 0.068 mg·L^-1.Our study suggested a broad application prospect of a new,effective,lowcost and environment-friendly adsorbent CHA400-(10%)Fe(Ⅲ)for treatment of low-concentration TC polluted wastewater.展开更多
The effect of FeCl_3 coagulation-filtration on the removal of trace Mo(Ⅵ) from water is investigated in the p H range of 4. 00 to 9. 00 and the effects of sulfate,silicate,phosphate and humic acid( HA) on the process...The effect of FeCl_3 coagulation-filtration on the removal of trace Mo(Ⅵ) from water is investigated in the p H range of 4. 00 to 9. 00 and the effects of sulfate,silicate,phosphate and humic acid( HA) on the process were determined. Overall,the removal of Mo(Ⅵ) is determined by two factors: the content of Fe intercepted from water( Intercepted Fe) and the affinity between Mo(Ⅵ)( or co-existing background constituents) and adsorption sites. At low p H,where the agglomeration of the iron flocs is limited,the former factor is dominant,so the methods that can promote the agglomeration of the iron flocs,such as increasing the p H,adding co-existing constituents( sulfate,phosphate or HA),can increase the removal of Mo(Ⅵ). While at high p H,the second factor dominated. Increasing the p H weakens the affinity between Mo(Ⅵ) and the iron flocs,and co-existing background constituents( sulfate,phosphate,silicate or HA) compete with Mo(Ⅵ) for adsorption sites,both effects result in a decrease in Mo(Ⅵ) removal. The Mo(Ⅵ) removal efficiency of FeCl_3 in natural water decreases as the p H increases from 4. 00 to 9. 00,and it is better to operate the coagulation process at p H 5.00 in the practical water treatment engineering.展开更多
A mesh-type structured anodic alumina supported Cu/Ni bi-functional catalyst was developed for steam reforming of dimethyl ether (SRD). It was found that the Cu/Ni/γ-Al2O3/Al catalyst had remarkable catalytic activit...A mesh-type structured anodic alumina supported Cu/Ni bi-functional catalyst was developed for steam reforming of dimethyl ether (SRD). It was found that the Cu/Ni/γ-Al2O3/Al catalyst had remarkable catalytic activity and stability, but a high CO selectivity. Therefore, a multi-functional catalyst was proposed by metals (Fe, Zn, or La) addition to inhibit CO formation during the SRD process. The results show that promoter Fe can improve the Cu dispersion and decrease the reduction temperature of catalyst, and CO selectivity was minimized from 27% to around 3%. However, the addition of Zn and La only can decrease the CO selectivity to 12%. Furthermore, there was an excellent synergetic effect between Cu/Ni/γ-Al2O3 and Fe over the Cu/Ni/Fe/γ-Al2O3/Al catalyst by evaluating catalytic performance of catalysts with different packing structures. And the synergetic mechanism of the active components (γ-Al2O3, Cu or Cu2O, and Fe3O4) for SRD and CO in suit removal was proposed. Finally, a 400-h durability test was carried out and the results show that the Cu/Ni/Fe/γ-Al2O3/Al catalyst had an excellent stability with a 100% DME conversion and low CO selectivity.展开更多
The products of monoammonium phosphate containing Cr^3+resulted in disqualification,and further posed a serious threat to ecological environment and human beings.Herein,the porous adsorbent of fluor(calcium silicate)c...The products of monoammonium phosphate containing Cr^3+resulted in disqualification,and further posed a serious threat to ecological environment and human beings.Herein,the porous adsorbent of fluor(calcium silicate)composites(FCSc)was prepared by hydrothermal method using diatomaceous earth,hydrated lime and additive(NaF)as raw materials,which was characterized and used for the removal of Cr^3+from monoammonium phosphate solutions.The effects of different parameters,such as solution pH,initial Cr^3+concentration,temperature and contact time on the adsorption of Cr^3+onto FCSc were investigated in details.The results indicated that the adsorption process was in agreement with the pseudo-second-order kinetic model and Freundlich isotherm.The spontaneous and endothermic nature of the adsorption process was obtained by analyzing various thermodynamic parameters(△G0,△H0,and△S0).In addition,computational monte carlo simulations between Cr3+ions and FCSc were conducted to elucidate the adsorption mechanism.Such kind of porous adsorbent provided a potential application in the removal of impurities from monoammonium phosphate industry.展开更多
Sugarcane pulp residue (SPR), a waste from sugar-refinery, which possesses a large surface area, can be used for removing chromium (Cr(Ⅲ) and Cr(Ⅵ)) from wastewater. In this work, the kinetics, isotherms of Cr(Ⅲ) a...Sugarcane pulp residue (SPR), a waste from sugar-refinery, which possesses a large surface area, can be used for removing chromium (Cr(Ⅲ) and Cr(Ⅵ)) from wastewater. In this work, the kinetics, isotherms of Cr(Ⅲ) and Cr(Ⅵ) adsorption and their removal by SPR were investigated. The results show that the removal percentages of Cr(Ⅵ) and Cr(Ⅲ) increase with increasing SPR dosage and temperature and decrease with increasing SPR particle size and the initial concentration of chromium ions. However, the influence of pH value on the Cr( Ⅵ) removal differs from that of the Cr( Ⅲ) removal. The Cr(Ⅵ) removal percentage decreases with increasing pH values, while the Cr(Ⅲ) removal percentage increases with increasing pH value. The adsorption kinetics of Cr(Ⅵ) and Cr(Ⅲ) well fits with pseudo-second-order model. Langmuir adsorption isotherm can well describe the adsorption phenomena of chromium ions with the maximum adsorption capacity of 0.567 mg/g for Cr( Ⅵ) and 3.446 mg/g for Cr( Ⅲ) . Moreover, SPR reveals higher adsorption capacity for Cr(Ⅲ) than that for Cr(Ⅵ), which implies that SPR has more potential application for Cr(III)-containing wastewater treatment than that for Cr(Ⅵ)-containing wastewater treatment.展开更多
The use of hybrid advanced oxidation processes(AOPs) for the removal of pollutants from industrial effluents has been extensively studied in recent literature. The aim of this study is to compare the performance of th...The use of hybrid advanced oxidation processes(AOPs) for the removal of pollutants from industrial effluents has been extensively studied in recent literature. The aim of this study is to compare the performance of the photo,Fenton, photo-Fenton and ozone–photo–Fenton processes in terms of color removal and chemical oxygen demand(COD) removal of distillery industrial effluent together with the associated electrical energy per order. It was observed from the experimental results that the O_3/UV/Fe^(2 +)/H_2O_2 process yielded a 100% color and95.50% COD removals with electrical energy per order of 0.015 k W·h·m^(-3) compared to all other combinations of the AOPs. The effects of various operating parameters such as H_2O_2 and Fe^(2+) concentration, effluent pH, COD concentration and UV power on the removal of color, COD and electrical energy per order for the ozone–photo–Fenton process was critically studied and reported. The color and COD removals were analyzed using a UV/Vis spectrometer and closed reflux method.展开更多
Hydrous magnesium oxide coated fly ash(MFA) has environmental remediation potential by providing a substrate for the adsorption of aqueous Cr(Ⅲ). Aqueous Cr(Ⅲ) adsorption onto MFA was examined as a function of MFA d...Hydrous magnesium oxide coated fly ash(MFA) has environmental remediation potential by providing a substrate for the adsorption of aqueous Cr(Ⅲ). Aqueous Cr(Ⅲ) adsorption onto MFA was examined as a function of MFA dosage, p H and initial Cr(Ⅲ) concentration with the Box–Behnken approach used for experimental design and optimization using response surface methodology(RSM). p H and dosage(dosage and concentration) have significant interactive effects on Cr(Ⅲ) adsorption efficiency. Analysis of variance shows that the response surface quadratic model is highly significant and can effectively predict the experimental outcomes. Cr(Ⅲ) removal efficiency of 98% was obtained using optimized conditions of MFA dosage, p H and initial Cr(Ⅲ) concentration of 1.57 g·L^(-1), 4.11 and 126 mg·L^(-1), respectively. Cr(Ⅲ) adsorption onto MFA is mainly attributed to the interaction between Cr(Ⅲ) and the functional group \\OH of the hydrous magnesium oxide, in all probability caused by chemisorptions. The results of this study can conduce to reveal the interactions between Cr(Ⅲ) pollutant and MFA characteristics, posing important implications for the cost-effective alternative adsorption technology in the treatment of heavy metal containing wastewater.展开更多
文摘Novel adsorbent, Fe(Ⅲ)-loaded ligand exchange cotton cellulose adsorbent [Fe(Ⅲ) LECCA], was used to in vestigate the adsorption performances and mechanism of fluoride removal from aqueous solutions. The adsorbent was found to adsorb fluoride rapidly and effectively. The fluoride removal was influenced by pH. Adsorption mode followed first-order reaction at different temperature, theapparent adsorption activated energy Ea was 6.37 kJ·mol^-1, and adsorption enthalpy △H was 5.35 kJ·mol^-1. The adsorption enfluoride on adsorbent was 3.2 mmol·g^-1 (dry weight). The maximal integer coordination ratio of fluoride with Fe(Ⅲ) LECCA was 3:1. The ligand exchange mechanism of adsorption was elucidated through chemical methods and IR spectral analysis.
基金financially supported by the National Natural Science Foundation of China(No.51641209)。
文摘Humic acid(HA)was carbonized at 300,400 and 500℃ and then functionalized with 1 wt%–12 wt%Fe(Ⅲ)respectively[CHA300/400/500-Fe(Ⅲ)].Adsorption of such Fe(III)-functionalized carbonized HA as adsorbents to aqueous tetracycline(TC:25 mg·L^-1)was studied.The adsorption equilibrium time for CHA400-Fe(Ⅲ)to TC was 6 h faster and the adsorption removal efficiency(Re)was two times higher than that of HA/CHA.The adsorption Reof CHA400-Fe(Ⅲ)loaded 10%iron[CHA400-(10%)Fe(Ⅲ)]to TC could reach 99.8%at 8 h and still kept80.6%after 8 cycles.The adsorption kinetics were well fitted to the pseudo-second-order equation and the adsorption isotherms could be well delineated via Langmuir equations(R^2N 0.99),indicating that the homogeneous chemical adsorption of TC occurred on the adsorbents.The main adsorption mechanisms of TC were complexation Fe(III)and hydrophobic distribution.Electropositive and electronegative repulsion between TC and CHA400-(10%)Fe(Ⅲ)at lowly p H(2)and highly p H(8–10)respectively,leaded to the relatively low adsorption capacity and more notable influence of ion concentration.When the p H was between 4 and 8,TC mainly existed in neutral molecules(TCH2),so the influence of ion concentration was not obvious.The dynamic adsorption results showed that the CHA400-(10%)Fe(Ⅲ)could continuously treat about 2.4 L TC(27 mg·L^-1)wastewater with the effluent concentration as low as 0.068 mg·L^-1.Our study suggested a broad application prospect of a new,effective,lowcost and environment-friendly adsorbent CHA400-(10%)Fe(Ⅲ)for treatment of low-concentration TC polluted wastewater.
基金Sponsored by the State Key Laboratory of Urban Water Resource and Environment(Grant No.HIT,2013TS04)the National Science&Technology Pillar Program,China(Grant No.2012BAC05B02)
文摘The effect of FeCl_3 coagulation-filtration on the removal of trace Mo(Ⅵ) from water is investigated in the p H range of 4. 00 to 9. 00 and the effects of sulfate,silicate,phosphate and humic acid( HA) on the process were determined. Overall,the removal of Mo(Ⅵ) is determined by two factors: the content of Fe intercepted from water( Intercepted Fe) and the affinity between Mo(Ⅵ)( or co-existing background constituents) and adsorption sites. At low p H,where the agglomeration of the iron flocs is limited,the former factor is dominant,so the methods that can promote the agglomeration of the iron flocs,such as increasing the p H,adding co-existing constituents( sulfate,phosphate or HA),can increase the removal of Mo(Ⅵ). While at high p H,the second factor dominated. Increasing the p H weakens the affinity between Mo(Ⅵ) and the iron flocs,and co-existing background constituents( sulfate,phosphate,silicate or HA) compete with Mo(Ⅵ) for adsorption sites,both effects result in a decrease in Mo(Ⅵ) removal. The Mo(Ⅵ) removal efficiency of FeCl_3 in natural water decreases as the p H increases from 4. 00 to 9. 00,and it is better to operate the coagulation process at p H 5.00 in the practical water treatment engineering.
文摘A mesh-type structured anodic alumina supported Cu/Ni bi-functional catalyst was developed for steam reforming of dimethyl ether (SRD). It was found that the Cu/Ni/γ-Al2O3/Al catalyst had remarkable catalytic activity and stability, but a high CO selectivity. Therefore, a multi-functional catalyst was proposed by metals (Fe, Zn, or La) addition to inhibit CO formation during the SRD process. The results show that promoter Fe can improve the Cu dispersion and decrease the reduction temperature of catalyst, and CO selectivity was minimized from 27% to around 3%. However, the addition of Zn and La only can decrease the CO selectivity to 12%. Furthermore, there was an excellent synergetic effect between Cu/Ni/γ-Al2O3 and Fe over the Cu/Ni/Fe/γ-Al2O3/Al catalyst by evaluating catalytic performance of catalysts with different packing structures. And the synergetic mechanism of the active components (γ-Al2O3, Cu or Cu2O, and Fe3O4) for SRD and CO in suit removal was proposed. Finally, a 400-h durability test was carried out and the results show that the Cu/Ni/Fe/γ-Al2O3/Al catalyst had an excellent stability with a 100% DME conversion and low CO selectivity.
基金the National Natural Science Foundation of China(U1633203)the Major Project of the Civil Aviation Administration of China(J2020-108)。
文摘The products of monoammonium phosphate containing Cr^3+resulted in disqualification,and further posed a serious threat to ecological environment and human beings.Herein,the porous adsorbent of fluor(calcium silicate)composites(FCSc)was prepared by hydrothermal method using diatomaceous earth,hydrated lime and additive(NaF)as raw materials,which was characterized and used for the removal of Cr^3+from monoammonium phosphate solutions.The effects of different parameters,such as solution pH,initial Cr^3+concentration,temperature and contact time on the adsorption of Cr^3+onto FCSc were investigated in details.The results indicated that the adsorption process was in agreement with the pseudo-second-order kinetic model and Freundlich isotherm.The spontaneous and endothermic nature of the adsorption process was obtained by analyzing various thermodynamic parameters(△G0,△H0,and△S0).In addition,computational monte carlo simulations between Cr3+ions and FCSc were conducted to elucidate the adsorption mechanism.Such kind of porous adsorbent provided a potential application in the removal of impurities from monoammonium phosphate industry.
基金Projects(2006AA06Z374, 2007AA021304) supported by the National High-Tech Research and Development Program of ChinaProject(2008SK2007) supported by the Key Program of Science and Technology of Hunan Province, China
文摘Sugarcane pulp residue (SPR), a waste from sugar-refinery, which possesses a large surface area, can be used for removing chromium (Cr(Ⅲ) and Cr(Ⅵ)) from wastewater. In this work, the kinetics, isotherms of Cr(Ⅲ) and Cr(Ⅵ) adsorption and their removal by SPR were investigated. The results show that the removal percentages of Cr(Ⅵ) and Cr(Ⅲ) increase with increasing SPR dosage and temperature and decrease with increasing SPR particle size and the initial concentration of chromium ions. However, the influence of pH value on the Cr( Ⅵ) removal differs from that of the Cr( Ⅲ) removal. The Cr(Ⅵ) removal percentage decreases with increasing pH values, while the Cr(Ⅲ) removal percentage increases with increasing pH value. The adsorption kinetics of Cr(Ⅵ) and Cr(Ⅲ) well fits with pseudo-second-order model. Langmuir adsorption isotherm can well describe the adsorption phenomena of chromium ions with the maximum adsorption capacity of 0.567 mg/g for Cr( Ⅵ) and 3.446 mg/g for Cr( Ⅲ) . Moreover, SPR reveals higher adsorption capacity for Cr(Ⅲ) than that for Cr(Ⅵ), which implies that SPR has more potential application for Cr(III)-containing wastewater treatment than that for Cr(Ⅵ)-containing wastewater treatment.
基金Supported by the University of Malaya High Impact Research Grant(HIR-MOHED000037-16001)from the Ministry of Higher Education Malaysia
文摘The use of hybrid advanced oxidation processes(AOPs) for the removal of pollutants from industrial effluents has been extensively studied in recent literature. The aim of this study is to compare the performance of the photo,Fenton, photo-Fenton and ozone–photo–Fenton processes in terms of color removal and chemical oxygen demand(COD) removal of distillery industrial effluent together with the associated electrical energy per order. It was observed from the experimental results that the O_3/UV/Fe^(2 +)/H_2O_2 process yielded a 100% color and95.50% COD removals with electrical energy per order of 0.015 k W·h·m^(-3) compared to all other combinations of the AOPs. The effects of various operating parameters such as H_2O_2 and Fe^(2+) concentration, effluent pH, COD concentration and UV power on the removal of color, COD and electrical energy per order for the ozone–photo–Fenton process was critically studied and reported. The color and COD removals were analyzed using a UV/Vis spectrometer and closed reflux method.
基金Supported by the State Key Development Program for Basic Research of China(2014CB460601)the International S&T Cooperation Program of China(2014DFE70070)
文摘Hydrous magnesium oxide coated fly ash(MFA) has environmental remediation potential by providing a substrate for the adsorption of aqueous Cr(Ⅲ). Aqueous Cr(Ⅲ) adsorption onto MFA was examined as a function of MFA dosage, p H and initial Cr(Ⅲ) concentration with the Box–Behnken approach used for experimental design and optimization using response surface methodology(RSM). p H and dosage(dosage and concentration) have significant interactive effects on Cr(Ⅲ) adsorption efficiency. Analysis of variance shows that the response surface quadratic model is highly significant and can effectively predict the experimental outcomes. Cr(Ⅲ) removal efficiency of 98% was obtained using optimized conditions of MFA dosage, p H and initial Cr(Ⅲ) concentration of 1.57 g·L^(-1), 4.11 and 126 mg·L^(-1), respectively. Cr(Ⅲ) adsorption onto MFA is mainly attributed to the interaction between Cr(Ⅲ) and the functional group \\OH of the hydrous magnesium oxide, in all probability caused by chemisorptions. The results of this study can conduce to reveal the interactions between Cr(Ⅲ) pollutant and MFA characteristics, posing important implications for the cost-effective alternative adsorption technology in the treatment of heavy metal containing wastewater.