This work investigated the removal, kinetics and thermodynamics of iron(II) ions (Fe(II)) by adsorption in static and dynamic conditions in aqueous media on activated carbons (AC-i30min, AC-i1h, and AC-i24h), prepared...This work investigated the removal, kinetics and thermodynamics of iron(II) ions (Fe(II)) by adsorption in static and dynamic conditions in aqueous media on activated carbons (AC-i30min, AC-i1h, and AC-i24h), prepared from palm nut shells collected in the city of Franceville to Gabon, using potassium hydroxide (KOH) as the activating agent. Results on the elimination of Fe(II) in static and dynamic adsorption on prepared activated carbons (ACs) showed that the AC-i24h adsorbent has the best Fe(II) adsorption capacities at saturation (Qsat). The Qsat obtained on AC-i24h in static and dynamic conditions (17.87 and 10.38 mg/g, respectively) were higher than those of AC-i30min (13.89 and 5.54 mg/g respectively) and AC-i1h (14.92 and 8.64 mg/g respectively). Moreover, the static adsorption was more effective in the removal of Fe(II) ions in aqueous media in our experimental conditions. The percentage removal (%E) of Fe(II) obtained on prepared activated carbons in static conditions was better than those obtained in dynamic conditions, especially on AC-i24h, where the %E was 89.27% in static and 61.56% in dynamic. In kinetics, results showed that the pseudo-second-order kinetic model best described the adsorption mechanisms of Fe(II) on prepared activated carbons in static adsorption, with mainly of chemisorption on the solid surfaces. However, in dynamic conditions, the pseudo-first-order kinetic model was more suitable. In addition to the weak interactions between Fe(II) and the activated carbon surfaces, strong interactions (chemisorption) were also observed. Also, thermodynamic data obtained on AC-i24h in static adsorption indicated that the adsorption of Fe(II) was spontaneous and increased with temperature (ΔG˚ H˚ = 503.54 KJ/mol).展开更多
Degradation of nitrobenzene(NB)via Fenton-like reaction is considered as an efficient approach for contaminated groundwater remediation.However,the poor stability of H2O2limits the application of traditional Fenton re...Degradation of nitrobenzene(NB)via Fenton-like reaction is considered as an efficient approach for contaminated groundwater remediation.However,the poor stability of H2O2limits the application of traditional Fenton reactions in soil and groundwater due to the transportation risks of H_(2)O_(2).In this study,we synthesized a controlled release nano calcium peroxide(n CP)by coating it with polydopamine(PDA)as a solid H2O2to construct a Fe(Ⅱ)/PDA@n CP Fenton-like system for contaminants degradation.The phenolquinone transformations of catechol groups on the PDA surface facilitated the Fe(Ⅱ)/Fe(Ⅲ)cycle,resulting in enhanced generation of hydroxyl radicals(HO·)and effective long-term degradation of NB.Moreover,the PDA shell modulated the n CP decomposition rate and inhibited sharp p H fluctuations,and the NB removal efficiency was achieved up to 96.8%at p H ranging from 3.0 to 9.0.This study demonstrated the promising application potential of PDA@n CP as a solid-controlled release H2O2source in Fenton-like system for groundwater contamination remediation.展开更多
The novel Fe-N co-doped ordered mesoporous carbon with high catalytic activity in m-cresol removal was prepared by urea-assisted impregnation and simple pyrolysis method.During the preparation of the Fe-NC catalyst,th...The novel Fe-N co-doped ordered mesoporous carbon with high catalytic activity in m-cresol removal was prepared by urea-assisted impregnation and simple pyrolysis method.During the preparation of the Fe-NC catalyst,the complexation of N elements in urea could anchor Fe,and the formation of C3N4during urea pyrolysis could also prevent migration and aggregation of Fe species,which jointly improve the dispersion and stability of Fe.The FeN4sites and highly dispersed Fe nanoparticles synergistically trigger the dual-site peroxymonosulfate (PMS) activation for highly efficient m-cresol degradation,while the ordered mesoporous structure of the catalyst could improve the mass transfer rate of the catalytic process,which together promote catalytic degradation of m-cresol by PMS activation.Reactive oxygen species (ROS) analytic experiments demonstrate that the system degrades m-cresol by free radical pathway mainly based on SO_(4)^(-)·and·OH,and partially based on·OH as the active components,and a possible PMS activation mechanism by 5Fe-50 for m-cresol degradation was proposed.This study can provide theoretical guidance for the preparation of efficient and stable catalysts for the degradation of organic pollutants by activated PMS.展开更多
Fast Fe(III)/Fe(II)circulation in heterogeneous peroxymonosulfate(PMS)activation remains as a bottleneck issue that restricts the development of PMS based advanced oxidation processes.Herein,we proposed a facile ammon...Fast Fe(III)/Fe(II)circulation in heterogeneous peroxymonosulfate(PMS)activation remains as a bottleneck issue that restricts the development of PMS based advanced oxidation processes.Herein,we proposed a facile ammonia reduction strategy and synthesized a novel FeVO3-x catalysts to activate PMS for the degradation of a typical pharmaceutical,carbamazepine(CBZ).Rapid CBZ removal could be achieved within 10 min,which outperforms most of the other iron or vanadium-based catalysts.Electron paramagnetic resonance analysis and chemical probe experiments revealed SO_(4)^(·-),·OH,O_(2)^(·-)and high valent iron(Fe(IV))were all generated in this system,but SO4·-and Fe(IV)primarily contributed to the degradation of CBZ.Besides,X-ray photoelectron spectroscopy and X-ray adsorption spectroscopy indicated that both the generated low-valent V provides and oxygen vacancy acted as superior electron donors and accelerated internal electron transfer via the unsaturated V-O-Fe bond.Finally,the proposed system also exhibited satisfactory performance in practical applications.This work provides a promising platform in heterogeneous PMS activation.展开更多
Thermodynamics of the precipitation from Li-Fe（II）-P-H2O system at 298 K was investigated.The results demonstrate that LiFePO4 can be formed at room temperature under pH value of 0-11.3,and the impurities Li3PO4 and...Thermodynamics of the precipitation from Li-Fe（II）-P-H2O system at 298 K was investigated.The results demonstrate that LiFePO4 can be formed at room temperature under pH value of 0-11.3,and the impurities Li3PO4 and Fe（OH）2 will be yielded at pH value above 11.3 and 12.9,respectively.The optimum pH value for LiFePO4 precipitation is 8-10.5.Considering the low rate of phase transformation kinetics,metastable Li-Fe（II）-P-H2O system was also studied.The results indicate that equimolar ratio of co-precipitation precursor Fe3（PO4）2.8H2O and Li3PO4 cannot be obtained at the initial molar ratio 1：1：1 and 1：1：3 of Li：Fe：P.In contrast,equimolar ratio of the co-precipitation precursor can be yielded by adjusting the pH value to 7-9.2,matching the molar ratio 3：1：1 of Li：Fe：P,meaning that Li＋-excess is one of the essential conditions for LiFePO4 preparation by co-precipitation method.展开更多
文摘This work investigated the removal, kinetics and thermodynamics of iron(II) ions (Fe(II)) by adsorption in static and dynamic conditions in aqueous media on activated carbons (AC-i30min, AC-i1h, and AC-i24h), prepared from palm nut shells collected in the city of Franceville to Gabon, using potassium hydroxide (KOH) as the activating agent. Results on the elimination of Fe(II) in static and dynamic adsorption on prepared activated carbons (ACs) showed that the AC-i24h adsorbent has the best Fe(II) adsorption capacities at saturation (Qsat). The Qsat obtained on AC-i24h in static and dynamic conditions (17.87 and 10.38 mg/g, respectively) were higher than those of AC-i30min (13.89 and 5.54 mg/g respectively) and AC-i1h (14.92 and 8.64 mg/g respectively). Moreover, the static adsorption was more effective in the removal of Fe(II) ions in aqueous media in our experimental conditions. The percentage removal (%E) of Fe(II) obtained on prepared activated carbons in static conditions was better than those obtained in dynamic conditions, especially on AC-i24h, where the %E was 89.27% in static and 61.56% in dynamic. In kinetics, results showed that the pseudo-second-order kinetic model best described the adsorption mechanisms of Fe(II) on prepared activated carbons in static adsorption, with mainly of chemisorption on the solid surfaces. However, in dynamic conditions, the pseudo-first-order kinetic model was more suitable. In addition to the weak interactions between Fe(II) and the activated carbon surfaces, strong interactions (chemisorption) were also observed. Also, thermodynamic data obtained on AC-i24h in static adsorption indicated that the adsorption of Fe(II) was spontaneous and increased with temperature (ΔG˚ H˚ = 503.54 KJ/mol).
基金supported by the National Natural Science Foundation of China(Nos.42077185,U22A20591)the Sichuan Science and Technology Program for Distinguished Young Scholars(Nos.2022JDJQ0010,2022ZYD0040)+1 种基金the National Key Research and Development Program of China(No.2020YFC1808300)the Research Fund of State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(No.SKLGP2020Z002)。
文摘Degradation of nitrobenzene(NB)via Fenton-like reaction is considered as an efficient approach for contaminated groundwater remediation.However,the poor stability of H2O2limits the application of traditional Fenton reactions in soil and groundwater due to the transportation risks of H_(2)O_(2).In this study,we synthesized a controlled release nano calcium peroxide(n CP)by coating it with polydopamine(PDA)as a solid H2O2to construct a Fe(Ⅱ)/PDA@n CP Fenton-like system for contaminants degradation.The phenolquinone transformations of catechol groups on the PDA surface facilitated the Fe(Ⅱ)/Fe(Ⅲ)cycle,resulting in enhanced generation of hydroxyl radicals(HO·)and effective long-term degradation of NB.Moreover,the PDA shell modulated the n CP decomposition rate and inhibited sharp p H fluctuations,and the NB removal efficiency was achieved up to 96.8%at p H ranging from 3.0 to 9.0.This study demonstrated the promising application potential of PDA@n CP as a solid-controlled release H2O2source in Fenton-like system for groundwater contamination remediation.
基金gratefully acknowledge the financial support of the National Natural Science Foundation of China(22108145 and 21978143)the Shandong Province Natural Science Foundation(ZR2020QB189)+1 种基金State Key Laboratory of Heavy Oil Processing(SKLHOP202203008)the Talent Foundation funded by Province and Ministry Co-construction Collaborative Innovation Center of Eco-chemical Engineering(STHGYX2201).
文摘The novel Fe-N co-doped ordered mesoporous carbon with high catalytic activity in m-cresol removal was prepared by urea-assisted impregnation and simple pyrolysis method.During the preparation of the Fe-NC catalyst,the complexation of N elements in urea could anchor Fe,and the formation of C3N4during urea pyrolysis could also prevent migration and aggregation of Fe species,which jointly improve the dispersion and stability of Fe.The FeN4sites and highly dispersed Fe nanoparticles synergistically trigger the dual-site peroxymonosulfate (PMS) activation for highly efficient m-cresol degradation,while the ordered mesoporous structure of the catalyst could improve the mass transfer rate of the catalytic process,which together promote catalytic degradation of m-cresol by PMS activation.Reactive oxygen species (ROS) analytic experiments demonstrate that the system degrades m-cresol by free radical pathway mainly based on SO_(4)^(-)·and·OH,and partially based on·OH as the active components,and a possible PMS activation mechanism by 5Fe-50 for m-cresol degradation was proposed.This study can provide theoretical guidance for the preparation of efficient and stable catalysts for the degradation of organic pollutants by activated PMS.
基金the Shanghai Tongji Gao Tingyao Environmental Science&Technology Development Foundation.Additionally,the authors acknowledge the staff at beamline 1WB at the Beijing Synchronic Radiation Facility(BSRF)for their assistance during the XAS measurements.And the authors would like to acknowledge the financial support from National Natural Science Foundation of China(Nos.52070133,2022NSFSC0972)Sichuan Science and Technology Program:Key Research and Development Program(Nos.2019YFG0314,2017SZ0180 and 2019YFG0324).
文摘Fast Fe(III)/Fe(II)circulation in heterogeneous peroxymonosulfate(PMS)activation remains as a bottleneck issue that restricts the development of PMS based advanced oxidation processes.Herein,we proposed a facile ammonia reduction strategy and synthesized a novel FeVO3-x catalysts to activate PMS for the degradation of a typical pharmaceutical,carbamazepine(CBZ).Rapid CBZ removal could be achieved within 10 min,which outperforms most of the other iron or vanadium-based catalysts.Electron paramagnetic resonance analysis and chemical probe experiments revealed SO_(4)^(·-),·OH,O_(2)^(·-)and high valent iron(Fe(IV))were all generated in this system,but SO4·-and Fe(IV)primarily contributed to the degradation of CBZ.Besides,X-ray photoelectron spectroscopy and X-ray adsorption spectroscopy indicated that both the generated low-valent V provides and oxygen vacancy acted as superior electron donors and accelerated internal electron transfer via the unsaturated V-O-Fe bond.Finally,the proposed system also exhibited satisfactory performance in practical applications.This work provides a promising platform in heterogeneous PMS activation.
基金Project (2007CB613603) supported by the National Basic Research Program of China
文摘Thermodynamics of the precipitation from Li-Fe（II）-P-H2O system at 298 K was investigated.The results demonstrate that LiFePO4 can be formed at room temperature under pH value of 0-11.3,and the impurities Li3PO4 and Fe（OH）2 will be yielded at pH value above 11.3 and 12.9,respectively.The optimum pH value for LiFePO4 precipitation is 8-10.5.Considering the low rate of phase transformation kinetics,metastable Li-Fe（II）-P-H2O system was also studied.The results indicate that equimolar ratio of co-precipitation precursor Fe3（PO4）2.8H2O and Li3PO4 cannot be obtained at the initial molar ratio 1：1：1 and 1：1：3 of Li：Fe：P.In contrast,equimolar ratio of the co-precipitation precursor can be yielded by adjusting the pH value to 7-9.2,matching the molar ratio 3：1：1 of Li：Fe：P,meaning that Li＋-excess is one of the essential conditions for LiFePO4 preparation by co-precipitation method.
