This study addresses the synthesis of nanoscale zero-valent iron(n ZVI) in the presence of natural bentonite(B-n ZVI) using green tea extract. The natural bentonite and B-n ZVI were then applied for the removal of pho...This study addresses the synthesis of nanoscale zero-valent iron(n ZVI) in the presence of natural bentonite(B-n ZVI) using green tea extract. The natural bentonite and B-n ZVI were then applied for the removal of phosphorus from aqueous solutions at various concentrations, p H levels and contact time. The desorption of phosphorus(P) from adsorbents was done immediately after sorption at the maximum initial concentration using the successive dilution method. The characterization of FTIR, SEM, and XRD indicated that n ZVI was successfully loaded to the surface of natural bentonite. The sorption of phosphorus on B-n ZVI was observed to be p H-dependent, with maximum phosphorus removal occurring at the p H range of 2 to 5. The results demonstrate that the maximum sorption capacities of natural bentonite and B-n ZVI were 4.61 and 27.63 mg·g^(-1), respectively.Langmuir, Freundlich, and Redlich–Peterson models properly described the sorption isotherm data. For either adsorbent, desorption isotherms did not coincide with their corresponding sorption isotherms, suggesting the occurrence of irreversibility and hysteresis. The average percentages of retained phosphorus released from natural bentonite and B-n ZVI were 80% and 9%, respectively. The results indicated that sorption kinetics was best described by the pseudo-second-order model. The present study suggests that B-n ZVI could be used as a suitable adsorbent for the removal of phosphorus from aqueous solutions.展开更多
Diclofenac(DCF)is one of the most frequently detected pharmaceuticals in groundwater,posing a great threat to the environment and human health due to its toxicity.To mitigate the DCF contamination,experiments on DCF d...Diclofenac(DCF)is one of the most frequently detected pharmaceuticals in groundwater,posing a great threat to the environment and human health due to its toxicity.To mitigate the DCF contamination,experiments on DCF degradation by the combined process of zero-valent iron nanoparticles(nZVI)and nano calcium peroxide(nCaO_(2))were performed.A batch experiment was conducted to examine the influence of the adding dosages of both nZVI and nCaO_(2)nanoparticles and pH value on the DCF removal.In the meantime,the continuous-flow experiment was done to explore the sustainability of the DCF degradation by jointly adding nZVI/nCaO_(2)nanoparticles in the reaction system.The results show that the nZVI/nCaO_(2)can effectively remove the DCF in the batch test with only 0.05 g/L nZVI and 0.2 g/L nCaO_(2)added,resulting in a removal rate of greater than 90%in a 2-hour reaction with an initial pH of 5.The degradation rate of DCF was positively correlated with the dosage of nCaO_(2),and negatively correlated with both nZVI dosage and the initial pH value.The order of significance of the three factors is identified as pH value>nZVI dosage>nCaO_(2)dosage.In the continuous-flow reaction system,the DCF removal rates remained above 75%within 150 minutes at the pH of 5,with the applied dosages of 0.5 g/L for nZVI and 1.0 g/L for nCaO_(2).These results provide a theoretical basis for the nZVI/nCaO_(2)application to remove DCF in groundwater.展开更多
Considering the need for efficiently and rapidly treating oily wastewater while preventing secondary pollution,the nanoscale zero-valent iron(nZVI)was supported on biochar prepared by using a spent mushroom substrate(...Considering the need for efficiently and rapidly treating oily wastewater while preventing secondary pollution,the nanoscale zero-valent iron(nZVI)was supported on biochar prepared by using a spent mushroom substrate(SMS),to produce an iron-carbon composite(SMS-nZVI).The ability of the SMS-nZVI to treat wastewater containing high concentration of oil was then comprehensively evaluated.The morphology,structure,and other properties of the composite were characterized by using scanning electron microscopy,transmission electron microscopy,the Brunauer-Emmett-Teller nitrogen sorption analysis,and the Fourier transform infrared spectroscopy.The results show that the biochar prepared by using the SMS can effectively prevent the agglomeration of nZVI and increase the overall specific surface area,thereby enhancing the absorption of petroleum by the composite.Experiments reveal that compared with the SMS and nZVI,the SMS-nZVI composite removes petroleum faster and more efficiently from wastewater.Under optimized conditions involving an nZVI to biochar mass ratio of 1:5 and a pH value of 4,the efficiency for removal of petroleum from wastewater with an initial petroleum concentration of 1000 mg/L could reach 95%within 5 h.Based on a natural aging treatment involving exposure to air for 30 d,the SMS-nZVI composite retained an oil removal rate of higher than 62%,and this result could highlight its stability for practical applications.展开更多
The present research investigated a novel route for the synthesis of nanoparticle zero-valent iron(NZVI)utilizing an aqueous extract of green tea waste as a reductant with ferric chloride.Also,the supported nanopartic...The present research investigated a novel route for the synthesis of nanoparticle zero-valent iron(NZVI)utilizing an aqueous extract of green tea waste as a reductant with ferric chloride.Also,the supported nanoparticle zerovalent iron was synthesized using natural silty clay as a support material(SC-NZVI).The NZVI and SC-NZVI were characterized by infrared spectroscopy(FTIR),scanning electron microscope(SEM),X-ray diffraction(XRD),Brunauer–Emmett–Teller(BET),and zeta potential(ζ).The interpretation of the results demonstrated that the polyphenol and other antioxidants in green tea waste can be used as reduction and capping agents in NZVI synthesis,with silty clay an adequate support.Additionally,the experiments were carried out to explore phenol adsorption by NZVI and SC-NZVI.To determine the optimum conditions,the impact of diverse experimental factors(i.e.,initial pH,adsorbent dose,temperature,and concentration of phenol)was studied.Langmuir,Freundlich,and Tempkin isotherms were used as representatives of adsorption equilibrium.The obtained results indicated that the adsorption processes for both NZVI and SC-NZVI well fitted by the Freundlich isotherm model.The appropriateness of pseudofirstorder and pseudosecondorder kinetics was investigated.The experimental kinetics data were good explained by the second-order model.The thermodynamic parameters(ΔH0,ΔS0,andΔG0)for NZVI and SC-NZVI were determined.The maximum removal rates of phenol at optimum conditions,when adsorbed onto NZVI and SC-NZVI,were found to be 94.8%and 90.1%,respectively.展开更多
Knowledge on corrosion behaviors and kinetics of nanoscale zero-valent iron(nZVI)in aquatic environment is particularly significant for understanding the reactivity,longevity and stability of nZVI,as well as providing...Knowledge on corrosion behaviors and kinetics of nanoscale zero-valent iron(nZVI)in aquatic environment is particularly significant for understanding the reactivity,longevity and stability of nZVI,as well as providing theoretical guidance for developing a cost-effective nZVI-based technology and designing large-scale applications.Herein,this review gives a holistic overview on the corrosion behaviors and kinetics of nZVI in water.Firstly,Eh-pH diagram is introduced to predict the thermodynamics trend of iron corrosion.The morphological,structural,and compositional evolution of(modified-)nZVI under different environmental conditions,assisted with microscopic and spectroscopic evidence,is then summarized.Afterwards,common analytical methods and characterization technologies are categorized to establish time-resolved corrosion kinetics of nZVI in water.Specifically,stable models for calculating the corrosion rate constant of nZVI as well as electrochemical methods for monitoring the redox reaction are discussed,emphasizing their capabilities in studying the dynamic iron corrosion processes.Finally,in the future,more efforts are encouraged to study the corrosion behaviors of nZVI in long-term practical application and further build nanoparticles with precisely tailored properties.We expect that our work can deepen the understanding of the nZVI chemistry in aquatic environment.展开更多
In this study, novel core-shell SiO<sub>2</sub>-coated iron nanoparticles (SiO<sub>2</sub>-nZVI) were synthesized using a one-step Stoeber method. The Malachite green degradation abilities of t...In this study, novel core-shell SiO<sub>2</sub>-coated iron nanoparticles (SiO<sub>2</sub>-nZVI) were synthesized using a one-step Stoeber method. The Malachite green degradation abilities of the nanoparticles were investigated. The effects of ethanol/distilled water volume ratio, presence and absence of PEG, tetraethyl orthosilicate (TEOS) dosage, and hydrolysis time used in the nanoparticles preparation process were investigated. The results indicated that the SiO<sub>2</sub>-coated iron nanoparticles had the highest reduction activity when the particles synthesized with ethanol/H<sub>2</sub>O ratio of 2:1, PEG of 0.15 ml, TEOS of 0.5 ml and the reaction time was 4 h. The SiO<sub>2</sub>-nZVI nanoparticles were characterized using Transmission Electron Microscopy (TEM), Energy Dispersive Spectrometry (EDS) and powder X-Ray Diffraction (XRD). The results showed that the average particles diameter of the SiO<sub>2</sub>-nZVI was 20 - 30 nm. The thickness of the outside SiO<sub>2</sub> film is consistent and approximately 10 nm. The results indicated that the nanoparticles coated completely with a transparent SiO<sub>2</sub>-film. Such nanoparticles could have wide applications in dye decolorization.展开更多
ZVI/nZVI凭借其优异的污染物去除性能以及在环境修复中的其他优点,引起了国内外研究人员的极大关注。基于中国知网和Web of Science核心合集数据库中英文文献数据,对国内外微生物协同零价铁(ZVI)/纳米零价铁(nZVI)的相关文献进行年代分...ZVI/nZVI凭借其优异的污染物去除性能以及在环境修复中的其他优点,引起了国内外研究人员的极大关注。基于中国知网和Web of Science核心合集数据库中英文文献数据,对国内外微生物协同零价铁(ZVI)/纳米零价铁(nZVI)的相关文献进行年代分布、期刊分布、关键词共现、时间演进及突现等方面的文献计量分析。结果显示,年度论文总数的增长趋势可分为3个阶段。中国是这一领域最活跃的国家,Journal of Hazardous Materials是出版物数量最多的期刊。有关ZVI与微生物的研究重点是甲烷生产、厌氧消化、脱氯作用;微生物协同nZVI的研究集中于微生物群落、修复、生物毒性、生物炭。关键词的时间演进图谱将其分为9种聚类,关键词的突现分析表明细胞分子水平的机理研究和零价铁生物毒性的创新可能是未来的研究方向。展开更多
Nanoscale zero-valent iron （nZVI） possesses unique chemistry and capability for the separation and transformation of a growing number of environmental contaminants. A nZVI particle consists of two nanoscale componen...Nanoscale zero-valent iron （nZVI） possesses unique chemistry and capability for the separation and transformation of a growing number of environmental contaminants. A nZVI particle consists of two nanoscale components, an iron （oxyhydr）oxides shell and a metallic iron core. This classical ＂core-shell＂ structure offers nZVI with unique and multifaceted reactivity of sorption, complexation, reduction and precipita- tion due to its strong small particle size for engineering deployment, large surface area, abundant reactive sites and electron-donating capacity for enhanced chemical activity. For over two decades, research has been steadily expanding our understanding on the reaction mechanisms and engineering performance of nZVI for soil and groundwater remediation, and more recently for wastewater treatment.展开更多
Risk associated with heavy metals in soil has been received widespread attention.In this study,a porous biochar supported nanoscale zero-valent iron(BC-nZVI)was applied to immobilize cadmium(Cd)and lead(Pb)in clayey s...Risk associated with heavy metals in soil has been received widespread attention.In this study,a porous biochar supported nanoscale zero-valent iron(BC-nZVI)was applied to immobilize cadmium(Cd)and lead(Pb)in clayey soil.Experiment results indicated that the immobilization of Cd or Pb by BC-nZVI process was better than that of BC or nZVI process,and about 80%of heavy metals immobilization was obtained in BC-nZVI process.Addition of BC-nZVI could increase soil pH and organic matter(SOM).Cd or Pb immobilization was inhibited with coexisting organic compound 2,4-dichlorophenol(2,4-DCP),but 2,4-DCP could be removed in a simultaneous manner with Cd or Pb immobilization at low concentration levels.Simultaneous immobilization of Cd and Pb was achieved in BC-nZVI process,and both Cd and Pb availability significantly decreased.Stable Cd species inculding Cd(OH)_(2),CdCO_(3)and CdO were formed,whereas stable Pb species such as PbCO_(3),PbO and Pb(OH)_(2)were produced with BC-nZVI treatment.Simultaneous immobilization mechanism of Cd and Pb in soil by BC-nZVI was thereby proposed.This study well demonstrates that BC-nZVI has been emerged as a potential technology for the remediation of multiple heavy metals in soil.展开更多
The addition of nano zero-valent iron(nZVI)is a promising technology for the in situ remediation of soil.Unfortunately,the mobility and,consequently,the reactivity of nZVI particles in contaminated areas decrease due ...The addition of nano zero-valent iron(nZVI)is a promising technology for the in situ remediation of soil.Unfortunately,the mobility and,consequently,the reactivity of nZVI particles in contaminated areas decrease due to their rapid aggregation.In this study,we determined how nZVI particles can be stabilized using different types of biochar(BC)as a support(BC@nZVI).In addition,we investigated the transport behavior of the synthesized BC@nZVI particles in a column filled with porous media and their effectiveness in the removal of BDE209(decabromodiphenyl ether)from soil.The characterization results of N2 Brunauer-Emmett-Teller(BET)surface area analyses,scanning electron microscopy(SEM),X-ray diffraction(XRD)and Fourier transform infrared spectroscopy(FTIR)indicated that nZVI was successfully loaded into the BC.The sedimentation test results and the experimental breakthrough curves indicated that all of the BC@nZVI composites manifested better stability and mobility than did the bare-nZVI particles,and the transport capacity of the particles increased with increasing flow velocity and porous medium size.Furthermore,the maximum concentrations of the column effluent for bagasse-BC@nZVI(B-BC@nZVI)were 19%,37%and 48%higher than those for rice straw-BC@nZVI(R-BC@nZVI),wood chips-BC@nZVI(W-BC@nZVI)and corn stalks-BC@nZVI(C-BC@nZVI),respectively.A similar order was found for the removal and debromination efficiency of decabromodiphenyl ether(BDE209)by the aforementioned particles.Overall,the attachment of nZVI particles to BC significantly increased the reactivity,stability and mobility of B-BC@nZVI yielded,and nZVI the best performance.展开更多
Solid phase reactions of Cr（Ⅵ） with Fe（0） were investigated with spherical-aberration-corrected scanning transmission electron microscopy（Cs-STEM） integrated with X-ray energy-dispersive spectroscopy（XEDS）. N...Solid phase reactions of Cr（Ⅵ） with Fe（0） were investigated with spherical-aberration-corrected scanning transmission electron microscopy（Cs-STEM） integrated with X-ray energy-dispersive spectroscopy（XEDS）. Near-atomic resolution elemental mappings of Cr（Ⅵ）–Fe（0） reactions were acquired. Experimental results show that rate and extent of Cr（Ⅵ） encapsulation are strongly dependent on the initial concentration of Cr（Ⅵ） in solution. Low Cr loading in nZⅥ（〈1.0 wt%） promotes the electrochemical oxidation and continuous corrosion of n ZⅥ while high Cr loading（〉1.0 wt%） can quickly shut down the Cr uptake. With the progress of iron oxidation and dissolution, elements of Cr and O counter-diffuse into the nanoparticles and accumulate in the core region at low levels of Cr（Ⅵ）（e.g., 〈 10 mg/L）. Whereas the reacted n ZⅥ is quickly coated with a newly-formed layer of 2–4 nm in the presence of concentrated Cr（Ⅵ）（e.g., 〉 100 mg/L）. The passivation structure is stable over a wide range of pH unless pH is low enough to dissolve the passivation layer. X-ray photoelectron spectroscopy（XPS） depth profiling reconfirms that the composition of the newly-formed surface layer consists of Fe（Ⅲ）–Cr（Ⅲ）（oxy）hydroxides with Cr（Ⅵ） adsorbed on the outside surface. The insoluble and insulating Fe（Ⅲ）–Cr（Ⅲ）（oxy）hydroxide layer can completely cover the n ZⅥ surface above the critical Cr loading and shield the electron transfer. Thus, the fast passivation of nZⅥ in high Cr（Ⅵ） solution is detrimental to the performance of nZⅥ for Cr（Ⅵ） treatment and remediation.展开更多
Arsenic(As)and antimony(Sb)are usually coexistent in mine wastes and pose a great threat to human health.The As immobilization by nano zero-valent iron(n ZVI)is promising,however,the stabilization for co-occurring As ...Arsenic(As)and antimony(Sb)are usually coexistent in mine wastes and pose a great threat to human health.The As immobilization by nano zero-valent iron(n ZVI)is promising,however,the stabilization for co-occurring As and Sb is not known.Herein,the immobilization and transformation of As and Sb in n ZVI-treated sediments were evaluated using complementary leaching experiments and characterization techniques.Raw sediment samples from a gold-antimony deposit revealed the co-existence of ultrahigh As and Sb at 50.3 and 14.9 g/kg,respectively.Leaching results show that As was more efficiently stabilized by n ZVI than Sb,which was primarily due to the soluble fraction that was readily absorbed by n ZVI of As was higher.As the n ZVI treatment proceeds,the oxidation and reduction of As and Sb occur simultaneously as evidenced by XPS analysis.The primary oxidant,hydroxyl radicals,was detected by EPR studies,proving the occurrence of n ZVI induced Fenton reaction.This study sheds light on differences in the interaction and immobilization of n ZVI with Sb and As in co-contaminated sediments.展开更多
Integrating nanoscale zero-valent iron(nZVI) with biological treatment processes holds the promise of inheriting significant advantages from both environmental nano-and biotechnologies. nZVI and microbes can perform i...Integrating nanoscale zero-valent iron(nZVI) with biological treatment processes holds the promise of inheriting significant advantages from both environmental nano-and biotechnologies. nZVI and microbes can perform in coalition in direct contact and act simultaneously, or be maintained in separate reactors and operated sequentially. Both modes can generate enhanced performance for wastewater treatment and environmental remediation. nZVI scavenges and eliminates toxic metals, and enhances biodegradability of some recalcitrant contaminants while bioprocesses serve to mineralize organic compounds and further remove impurities from wastewater. This has been demonstrated in a number of recent works that nZVI can substantially augment the performance of conventional biological treatment for wastewaters from textile and nonferrous metal industries. Our recent laboratory and field tests show that COD of the industrial effluents can be reduced to a record-low of 50 ppm. Recent literature on the theory and applications of the nZVI-bio system is highlighted in this mini review.展开更多
Nitroaromatic explosives are major pollutants produced during wars that cause serious environmental and health problems. The removal of a typical nitroaromatic explosive, 2,4,6-trinitrotoluene(TNT), from aqueous solut...Nitroaromatic explosives are major pollutants produced during wars that cause serious environmental and health problems. The removal of a typical nitroaromatic explosive, 2,4,6-trinitrotoluene(TNT), from aqueous solution, was conducted using a new recyclable magnetic nano-adsorbent(Fe@SiO_(2) –NH_(2)). This adsorbent was prepared by grafting amino groups onto Fe@SiO_(2) particles with a well-defined core-shell structure and demonstrated monodispersity in solution. The removal performance of the nano-adsorbent towards TNT was found to be 2.57 and 4.92 times higher than that towards two analogous explosives, 2,4-dinitrotoluene(2,4-DNT) and 2-nitrotoluene(2-NT), respectively, under neutral conditions. The difference in the removal performance among the three compounds was further compared in terms of the effects of different conditions(pH value, ionic strength, humic acid concentration, adsorbent modification degree and dosage, etc.) and the electrostatic potential distributions of the three compounds. The most significant elevation is owing to modification of amino on Fe@SiO_(2) which made a 20.7% increase in adsorption efficiency of TNT. The experimental data were well fit by the pseudo-second-order kinetic model and the Freundlich adsorption isotherm model, indicating multilayer adsorption on a heterogeneous surface. The experimental results and theoretical considerations show that the interactions between Fe@SiO_(2) –NH_(2) NPs and TNT correspond to dipole-dipole and hydrophobic interactions. These interactions should be considered in the design of an adsorbent. Furthermore, the adaptability to aqueous environment and excellent regeneration capacity of Fe@SiO_(2) –NH_(2) NPs makes these remediation materials promising for applications.展开更多
Nanoscale zero-valent iron(nZVI)supported on D001 resin(D001-nZVI)was synthesized for adsorption of high solubility and mobility radionuclide^99Tc.Re(VII),a chemical substitute for^99Tc,was utilized in batch experimen...Nanoscale zero-valent iron(nZVI)supported on D001 resin(D001-nZVI)was synthesized for adsorption of high solubility and mobility radionuclide^99Tc.Re(VII),a chemical substitute for^99Tc,was utilized in batch experiments to investigate the feasibility and adsorption mechanism toward Tc(VII).Factors(pH,resin dose)affecting Re(VII)adsorption were studied.The high adsorption efficiency of Re(VII)at pH=3 and the solid-liquid ratio of 20 g/L.X-ray diffraction patterns revealed the reduction of ReO^?4 into ReO2 immobilized in D001-nZVI.Based on the optimum conditions of Re(VII)adsorption,the removal experiments of Tc(VII)were conducted where the adsorption efficiency of Tc(VII)can reach 94%.Column experiments showed that the Thomas model gave a good fit to the adsorption process of Re(VII)and the maximum dynamic adsorption capacity was 0.2910 mg/g.展开更多
文摘This study addresses the synthesis of nanoscale zero-valent iron(n ZVI) in the presence of natural bentonite(B-n ZVI) using green tea extract. The natural bentonite and B-n ZVI were then applied for the removal of phosphorus from aqueous solutions at various concentrations, p H levels and contact time. The desorption of phosphorus(P) from adsorbents was done immediately after sorption at the maximum initial concentration using the successive dilution method. The characterization of FTIR, SEM, and XRD indicated that n ZVI was successfully loaded to the surface of natural bentonite. The sorption of phosphorus on B-n ZVI was observed to be p H-dependent, with maximum phosphorus removal occurring at the p H range of 2 to 5. The results demonstrate that the maximum sorption capacities of natural bentonite and B-n ZVI were 4.61 and 27.63 mg·g^(-1), respectively.Langmuir, Freundlich, and Redlich–Peterson models properly described the sorption isotherm data. For either adsorbent, desorption isotherms did not coincide with their corresponding sorption isotherms, suggesting the occurrence of irreversibility and hysteresis. The average percentages of retained phosphorus released from natural bentonite and B-n ZVI were 80% and 9%, respectively. The results indicated that sorption kinetics was best described by the pseudo-second-order model. The present study suggests that B-n ZVI could be used as a suitable adsorbent for the removal of phosphorus from aqueous solutions.
基金the National Natural Science Foundation of China(42077176,41601514)Shanghai“Science and Technology Innovation Action Plan”Project(19230742400,19ZR1459300)+1 种基金Shanghai Peak Discipline Project(0200121005/053,2019010202)State Key Laboratory of Petroleum Pollution Control(PPC2016019)。
文摘Diclofenac(DCF)is one of the most frequently detected pharmaceuticals in groundwater,posing a great threat to the environment and human health due to its toxicity.To mitigate the DCF contamination,experiments on DCF degradation by the combined process of zero-valent iron nanoparticles(nZVI)and nano calcium peroxide(nCaO_(2))were performed.A batch experiment was conducted to examine the influence of the adding dosages of both nZVI and nCaO_(2)nanoparticles and pH value on the DCF removal.In the meantime,the continuous-flow experiment was done to explore the sustainability of the DCF degradation by jointly adding nZVI/nCaO_(2)nanoparticles in the reaction system.The results show that the nZVI/nCaO_(2)can effectively remove the DCF in the batch test with only 0.05 g/L nZVI and 0.2 g/L nCaO_(2)added,resulting in a removal rate of greater than 90%in a 2-hour reaction with an initial pH of 5.The degradation rate of DCF was positively correlated with the dosage of nCaO_(2),and negatively correlated with both nZVI dosage and the initial pH value.The order of significance of the three factors is identified as pH value>nZVI dosage>nCaO_(2)dosage.In the continuous-flow reaction system,the DCF removal rates remained above 75%within 150 minutes at the pH of 5,with the applied dosages of 0.5 g/L for nZVI and 1.0 g/L for nCaO_(2).These results provide a theoretical basis for the nZVI/nCaO_(2)application to remove DCF in groundwater.
基金This study was supported by the State Key Laboratory of Petroleum and Petrochemical Contaminant Control and Treatment,the Open Project(Authorization:PPC2019021)the Research and Promotion Project of Key Technologies for Safety and Environmental Protection of CNPC(2017D-4013)the PetroChina Technology Innovation Fund Research Project(Authorization:2017D-5007-0601,2018D-5007-0605).
文摘Considering the need for efficiently and rapidly treating oily wastewater while preventing secondary pollution,the nanoscale zero-valent iron(nZVI)was supported on biochar prepared by using a spent mushroom substrate(SMS),to produce an iron-carbon composite(SMS-nZVI).The ability of the SMS-nZVI to treat wastewater containing high concentration of oil was then comprehensively evaluated.The morphology,structure,and other properties of the composite were characterized by using scanning electron microscopy,transmission electron microscopy,the Brunauer-Emmett-Teller nitrogen sorption analysis,and the Fourier transform infrared spectroscopy.The results show that the biochar prepared by using the SMS can effectively prevent the agglomeration of nZVI and increase the overall specific surface area,thereby enhancing the absorption of petroleum by the composite.Experiments reveal that compared with the SMS and nZVI,the SMS-nZVI composite removes petroleum faster and more efficiently from wastewater.Under optimized conditions involving an nZVI to biochar mass ratio of 1:5 and a pH value of 4,the efficiency for removal of petroleum from wastewater with an initial petroleum concentration of 1000 mg/L could reach 95%within 5 h.Based on a natural aging treatment involving exposure to air for 30 d,the SMS-nZVI composite retained an oil removal rate of higher than 62%,and this result could highlight its stability for practical applications.
文摘The present research investigated a novel route for the synthesis of nanoparticle zero-valent iron(NZVI)utilizing an aqueous extract of green tea waste as a reductant with ferric chloride.Also,the supported nanoparticle zerovalent iron was synthesized using natural silty clay as a support material(SC-NZVI).The NZVI and SC-NZVI were characterized by infrared spectroscopy(FTIR),scanning electron microscope(SEM),X-ray diffraction(XRD),Brunauer–Emmett–Teller(BET),and zeta potential(ζ).The interpretation of the results demonstrated that the polyphenol and other antioxidants in green tea waste can be used as reduction and capping agents in NZVI synthesis,with silty clay an adequate support.Additionally,the experiments were carried out to explore phenol adsorption by NZVI and SC-NZVI.To determine the optimum conditions,the impact of diverse experimental factors(i.e.,initial pH,adsorbent dose,temperature,and concentration of phenol)was studied.Langmuir,Freundlich,and Tempkin isotherms were used as representatives of adsorption equilibrium.The obtained results indicated that the adsorption processes for both NZVI and SC-NZVI well fitted by the Freundlich isotherm model.The appropriateness of pseudofirstorder and pseudosecondorder kinetics was investigated.The experimental kinetics data were good explained by the second-order model.The thermodynamic parameters(ΔH0,ΔS0,andΔG0)for NZVI and SC-NZVI were determined.The maximum removal rates of phenol at optimum conditions,when adsorbed onto NZVI and SC-NZVI,were found to be 94.8%and 90.1%,respectively.
基金supported by the National Natural Science Foundation of China (No.52200184)the Fundamental Research Funds for Central Universities (No.12060096014)。
文摘Knowledge on corrosion behaviors and kinetics of nanoscale zero-valent iron(nZVI)in aquatic environment is particularly significant for understanding the reactivity,longevity and stability of nZVI,as well as providing theoretical guidance for developing a cost-effective nZVI-based technology and designing large-scale applications.Herein,this review gives a holistic overview on the corrosion behaviors and kinetics of nZVI in water.Firstly,Eh-pH diagram is introduced to predict the thermodynamics trend of iron corrosion.The morphological,structural,and compositional evolution of(modified-)nZVI under different environmental conditions,assisted with microscopic and spectroscopic evidence,is then summarized.Afterwards,common analytical methods and characterization technologies are categorized to establish time-resolved corrosion kinetics of nZVI in water.Specifically,stable models for calculating the corrosion rate constant of nZVI as well as electrochemical methods for monitoring the redox reaction are discussed,emphasizing their capabilities in studying the dynamic iron corrosion processes.Finally,in the future,more efforts are encouraged to study the corrosion behaviors of nZVI in long-term practical application and further build nanoparticles with precisely tailored properties.We expect that our work can deepen the understanding of the nZVI chemistry in aquatic environment.
文摘In this study, novel core-shell SiO<sub>2</sub>-coated iron nanoparticles (SiO<sub>2</sub>-nZVI) were synthesized using a one-step Stoeber method. The Malachite green degradation abilities of the nanoparticles were investigated. The effects of ethanol/distilled water volume ratio, presence and absence of PEG, tetraethyl orthosilicate (TEOS) dosage, and hydrolysis time used in the nanoparticles preparation process were investigated. The results indicated that the SiO<sub>2</sub>-coated iron nanoparticles had the highest reduction activity when the particles synthesized with ethanol/H<sub>2</sub>O ratio of 2:1, PEG of 0.15 ml, TEOS of 0.5 ml and the reaction time was 4 h. The SiO<sub>2</sub>-nZVI nanoparticles were characterized using Transmission Electron Microscopy (TEM), Energy Dispersive Spectrometry (EDS) and powder X-Ray Diffraction (XRD). The results showed that the average particles diameter of the SiO<sub>2</sub>-nZVI was 20 - 30 nm. The thickness of the outside SiO<sub>2</sub> film is consistent and approximately 10 nm. The results indicated that the nanoparticles coated completely with a transparent SiO<sub>2</sub>-film. Such nanoparticles could have wide applications in dye decolorization.
文摘ZVI/nZVI凭借其优异的污染物去除性能以及在环境修复中的其他优点,引起了国内外研究人员的极大关注。基于中国知网和Web of Science核心合集数据库中英文文献数据,对国内外微生物协同零价铁(ZVI)/纳米零价铁(nZVI)的相关文献进行年代分布、期刊分布、关键词共现、时间演进及突现等方面的文献计量分析。结果显示,年度论文总数的增长趋势可分为3个阶段。中国是这一领域最活跃的国家,Journal of Hazardous Materials是出版物数量最多的期刊。有关ZVI与微生物的研究重点是甲烷生产、厌氧消化、脱氯作用;微生物协同nZVI的研究集中于微生物群落、修复、生物毒性、生物炭。关键词的时间演进图谱将其分为9种聚类,关键词的突现分析表明细胞分子水平的机理研究和零价铁生物毒性的创新可能是未来的研究方向。
基金supported by the National Natural Science Foundation of China (Nos. 51578398 and 41772243)the National Postdoctoral Program for Innovative Talents (No. BX201700172)
文摘Nanoscale zero-valent iron （nZVI） possesses unique chemistry and capability for the separation and transformation of a growing number of environmental contaminants. A nZVI particle consists of two nanoscale components, an iron （oxyhydr）oxides shell and a metallic iron core. This classical ＂core-shell＂ structure offers nZVI with unique and multifaceted reactivity of sorption, complexation, reduction and precipita- tion due to its strong small particle size for engineering deployment, large surface area, abundant reactive sites and electron-donating capacity for enhanced chemical activity. For over two decades, research has been steadily expanding our understanding on the reaction mechanisms and engineering performance of nZVI for soil and groundwater remediation, and more recently for wastewater treatment.
基金supported by the Special project in key areas of Guangdong Province Ordinary Universities (No. 2020ZDZX1003)the Guangdong Provincial Key R&D Programme (No. 2020B1111350002)+4 种基金the Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme (2018)the research project and development plan for key areas of Guangdong Province (No. 2020B0202080002)the Project of Educational Commission of Guangdong Province of China (No. 2019KTSCX067)the Guangdong Provincial Special Fund for Modern Agriculture Industry Technology Innovation Teams (No. 2019KJ140)the National Natural Science Foundation of China (No. 21407155).
文摘Risk associated with heavy metals in soil has been received widespread attention.In this study,a porous biochar supported nanoscale zero-valent iron(BC-nZVI)was applied to immobilize cadmium(Cd)and lead(Pb)in clayey soil.Experiment results indicated that the immobilization of Cd or Pb by BC-nZVI process was better than that of BC or nZVI process,and about 80%of heavy metals immobilization was obtained in BC-nZVI process.Addition of BC-nZVI could increase soil pH and organic matter(SOM).Cd or Pb immobilization was inhibited with coexisting organic compound 2,4-dichlorophenol(2,4-DCP),but 2,4-DCP could be removed in a simultaneous manner with Cd or Pb immobilization at low concentration levels.Simultaneous immobilization of Cd and Pb was achieved in BC-nZVI process,and both Cd and Pb availability significantly decreased.Stable Cd species inculding Cd(OH)_(2),CdCO_(3)and CdO were formed,whereas stable Pb species such as PbCO_(3),PbO and Pb(OH)_(2)were produced with BC-nZVI treatment.Simultaneous immobilization mechanism of Cd and Pb in soil by BC-nZVI was thereby proposed.This study well demonstrates that BC-nZVI has been emerged as a potential technology for the remediation of multiple heavy metals in soil.
基金The National Key Research and Development Program of China(2018YFC1802802)the Guangdong Technology Research Center for Ecological Management and Remediation of Water Systems(2014B090904077).
文摘The addition of nano zero-valent iron(nZVI)is a promising technology for the in situ remediation of soil.Unfortunately,the mobility and,consequently,the reactivity of nZVI particles in contaminated areas decrease due to their rapid aggregation.In this study,we determined how nZVI particles can be stabilized using different types of biochar(BC)as a support(BC@nZVI).In addition,we investigated the transport behavior of the synthesized BC@nZVI particles in a column filled with porous media and their effectiveness in the removal of BDE209(decabromodiphenyl ether)from soil.The characterization results of N2 Brunauer-Emmett-Teller(BET)surface area analyses,scanning electron microscopy(SEM),X-ray diffraction(XRD)and Fourier transform infrared spectroscopy(FTIR)indicated that nZVI was successfully loaded into the BC.The sedimentation test results and the experimental breakthrough curves indicated that all of the BC@nZVI composites manifested better stability and mobility than did the bare-nZVI particles,and the transport capacity of the particles increased with increasing flow velocity and porous medium size.Furthermore,the maximum concentrations of the column effluent for bagasse-BC@nZVI(B-BC@nZVI)were 19%,37%and 48%higher than those for rice straw-BC@nZVI(R-BC@nZVI),wood chips-BC@nZVI(W-BC@nZVI)and corn stalks-BC@nZVI(C-BC@nZVI),respectively.A similar order was found for the removal and debromination efficiency of decabromodiphenyl ether(BDE209)by the aforementioned particles.Overall,the attachment of nZVI particles to BC significantly increased the reactivity,stability and mobility of B-BC@nZVI yielded,and nZVI the best performance.
基金supported by the National Natural Science Foundation of China(Nos.21677107,51578398)the Fundamental Research Funds for the Central Universities(No.0400219363)
文摘Solid phase reactions of Cr（Ⅵ） with Fe（0） were investigated with spherical-aberration-corrected scanning transmission electron microscopy（Cs-STEM） integrated with X-ray energy-dispersive spectroscopy（XEDS）. Near-atomic resolution elemental mappings of Cr（Ⅵ）–Fe（0） reactions were acquired. Experimental results show that rate and extent of Cr（Ⅵ） encapsulation are strongly dependent on the initial concentration of Cr（Ⅵ） in solution. Low Cr loading in nZⅥ（〈1.0 wt%） promotes the electrochemical oxidation and continuous corrosion of n ZⅥ while high Cr loading（〉1.0 wt%） can quickly shut down the Cr uptake. With the progress of iron oxidation and dissolution, elements of Cr and O counter-diffuse into the nanoparticles and accumulate in the core region at low levels of Cr（Ⅵ）（e.g., 〈 10 mg/L）. Whereas the reacted n ZⅥ is quickly coated with a newly-formed layer of 2–4 nm in the presence of concentrated Cr（Ⅵ）（e.g., 〉 100 mg/L）. The passivation structure is stable over a wide range of pH unless pH is low enough to dissolve the passivation layer. X-ray photoelectron spectroscopy（XPS） depth profiling reconfirms that the composition of the newly-formed surface layer consists of Fe（Ⅲ）–Cr（Ⅲ）（oxy）hydroxides with Cr（Ⅵ） adsorbed on the outside surface. The insoluble and insulating Fe（Ⅲ）–Cr（Ⅲ）（oxy）hydroxide layer can completely cover the n ZⅥ surface above the critical Cr loading and shield the electron transfer. Thus, the fast passivation of nZⅥ in high Cr（Ⅵ） solution is detrimental to the performance of nZⅥ for Cr（Ⅵ） treatment and remediation.
基金financial This work was supported by the National Key Basic Research Program of China(No.2020YFC1807800)the National Natural Science Foundation of China(Nos,41877378 and 42077299)the Major Program of Shandong Natural Science Foundation,China(No.ZR2020ZD34)。
文摘Arsenic(As)and antimony(Sb)are usually coexistent in mine wastes and pose a great threat to human health.The As immobilization by nano zero-valent iron(n ZVI)is promising,however,the stabilization for co-occurring As and Sb is not known.Herein,the immobilization and transformation of As and Sb in n ZVI-treated sediments were evaluated using complementary leaching experiments and characterization techniques.Raw sediment samples from a gold-antimony deposit revealed the co-existence of ultrahigh As and Sb at 50.3 and 14.9 g/kg,respectively.Leaching results show that As was more efficiently stabilized by n ZVI than Sb,which was primarily due to the soluble fraction that was readily absorbed by n ZVI of As was higher.As the n ZVI treatment proceeds,the oxidation and reduction of As and Sb occur simultaneously as evidenced by XPS analysis.The primary oxidant,hydroxyl radicals,was detected by EPR studies,proving the occurrence of n ZVI induced Fenton reaction.This study sheds light on differences in the interaction and immobilization of n ZVI with Sb and As in co-contaminated sediments.
基金supported by the Research and Development Program of Guangdong Province (No. 2020B0202080001)by the China Postdoctoral Science Foundation (No. 2019M651583)+1 种基金by the Education Commission of Shanghai (No. 0400106005)by the National Science Foundation of China (Nos. 21277102, 21003151)。
文摘Integrating nanoscale zero-valent iron(nZVI) with biological treatment processes holds the promise of inheriting significant advantages from both environmental nano-and biotechnologies. nZVI and microbes can perform in coalition in direct contact and act simultaneously, or be maintained in separate reactors and operated sequentially. Both modes can generate enhanced performance for wastewater treatment and environmental remediation. nZVI scavenges and eliminates toxic metals, and enhances biodegradability of some recalcitrant contaminants while bioprocesses serve to mineralize organic compounds and further remove impurities from wastewater. This has been demonstrated in a number of recent works that nZVI can substantially augment the performance of conventional biological treatment for wastewaters from textile and nonferrous metal industries. Our recent laboratory and field tests show that COD of the industrial effluents can be reduced to a record-low of 50 ppm. Recent literature on the theory and applications of the nZVI-bio system is highlighted in this mini review.
基金supported by the National Natural Science Foundation of China(No.21677177)the Science Foundation of China University of Petroleum-Beijing(No.2462020XKJS04)+1 种基金the Beijing Municipal Science&Technology Commission(No.Z181100005318002)the China Postdoctoral Science Foundation(No.2018M631491)。
文摘Nitroaromatic explosives are major pollutants produced during wars that cause serious environmental and health problems. The removal of a typical nitroaromatic explosive, 2,4,6-trinitrotoluene(TNT), from aqueous solution, was conducted using a new recyclable magnetic nano-adsorbent(Fe@SiO_(2) –NH_(2)). This adsorbent was prepared by grafting amino groups onto Fe@SiO_(2) particles with a well-defined core-shell structure and demonstrated monodispersity in solution. The removal performance of the nano-adsorbent towards TNT was found to be 2.57 and 4.92 times higher than that towards two analogous explosives, 2,4-dinitrotoluene(2,4-DNT) and 2-nitrotoluene(2-NT), respectively, under neutral conditions. The difference in the removal performance among the three compounds was further compared in terms of the effects of different conditions(pH value, ionic strength, humic acid concentration, adsorbent modification degree and dosage, etc.) and the electrostatic potential distributions of the three compounds. The most significant elevation is owing to modification of amino on Fe@SiO_(2) which made a 20.7% increase in adsorption efficiency of TNT. The experimental data were well fit by the pseudo-second-order kinetic model and the Freundlich adsorption isotherm model, indicating multilayer adsorption on a heterogeneous surface. The experimental results and theoretical considerations show that the interactions between Fe@SiO_(2) –NH_(2) NPs and TNT correspond to dipole-dipole and hydrophobic interactions. These interactions should be considered in the design of an adsorbent. Furthermore, the adaptability to aqueous environment and excellent regeneration capacity of Fe@SiO_(2) –NH_(2) NPs makes these remediation materials promising for applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.11675103 and 91226111).
文摘Nanoscale zero-valent iron(nZVI)supported on D001 resin(D001-nZVI)was synthesized for adsorption of high solubility and mobility radionuclide^99Tc.Re(VII),a chemical substitute for^99Tc,was utilized in batch experiments to investigate the feasibility and adsorption mechanism toward Tc(VII).Factors(pH,resin dose)affecting Re(VII)adsorption were studied.The high adsorption efficiency of Re(VII)at pH=3 and the solid-liquid ratio of 20 g/L.X-ray diffraction patterns revealed the reduction of ReO^?4 into ReO2 immobilized in D001-nZVI.Based on the optimum conditions of Re(VII)adsorption,the removal experiments of Tc(VII)were conducted where the adsorption efficiency of Tc(VII)can reach 94%.Column experiments showed that the Thomas model gave a good fit to the adsorption process of Re(VII)and the maximum dynamic adsorption capacity was 0.2910 mg/g.
