Arsenic(As)contamination of groundwater is a serious global issue requiring effective and sustainable remediation strategies.For long-term As immobilization,this study explores the potential of in-situ magnetite preci...Arsenic(As)contamination of groundwater is a serious global issue requiring effective and sustainable remediation strategies.For long-term As immobilization,this study explores the potential of in-situ magnetite precipitation,induced by anaerobic nitrate-reducing Fe(II)-oxidizing(NRFO)bacteria.A nitrate-intercalated layered double hydroxide(NO_(3)^(-)MgFe LDH)was introduced to provide nitrate as an electron acceptor for Fe(II)bio-oxidation and serve as an iron-based precursor in magnetite formation.The experimental results showed that NO_(3)^(-)MgFe LDH was transformed into green rust(GR)in the presence of Fe(II)and HCO_(3)^(-).Meanwhile,0.5 g/L of NO_(3)^(-)MgFe LDH released cumulatively about 1.21 mM of nitrate within 12 h,promoting the transformation of GR into magnetite induced by Acidovorax sp.BoFeN1.As a result,the aqueous As concentration decreased from 2 mg/L to<0.008 mg/L,with approximately 70%of As confined in recalcitrant Fe oxides,suggesting high potential for long-term As immobilization.Environmental factors influenced the transformation process:a lower Fe(II)concentration(0.5 mM)delayed GR formation,while varying HCO_(3)^(-)concentrations(2.5-10 mM)had minimal effect.Subsequently,an elevated As level(5 mg/L)inhibited the bio-formation of magnetite,leading to lepidocrocite as the dominant mineral phase.Given the stability of magnetite,this study provides a cost-effective and environmentally friendly strategy for the durable in-situ remediation of As-contaminated groundwater.展开更多
A series of Ni-based catalysts were prepared via structural topological transformation from the Ni@Al_(2)O_(3)layered double hydroxides(LDHs)precursors,and applied for the deep catalytic hydrogenation saturation of py...A series of Ni-based catalysts were prepared via structural topological transformation from the Ni@Al_(2)O_(3)layered double hydroxides(LDHs)precursors,and applied for the deep catalytic hydrogenation saturation of pyrene in a high-pressure reactor.The pore structures,active species dispersion,surface morphology,amount and type of acid of the prepared catalysts were characterized by BET,XRD,SEM,TEM,XPS,SEM,NH_(3)-TPD and Py-IR.We studied the influence of physicochemical properties of Ni-based catalysts on the regularity and mechanism of deep hydrogenation of pyrene.Meanwhile,the synergy between Ni and Mo,and the interaction between active metals and support were discussed to further reveal the constitutive relationship during the hydrogenation reaction of pyrene.The results of the evaluation of the catalytic hydrogenation of pyrene show that the as-prepared NiMo mixed metal oxide(MMO)catalyst showed excellent catalytic activity:~95%pyrene conversion,90.12%for the selectivity of deep hydrogenation products(hexahydropyrene,decahydropyrene and hexadecahydropyrene).It was expected that the successfully preparation and utilization of NiMo-MMO catalyst could provide a theoretical basis for the design of this kind of catalysts for deep catalytic hydrogenation of polycyclic aromatic hydrocarbons(PAHs).展开更多
基金Project(2023YFC3207000)supported by the National Key Research and Development Program of ChinaProject(2024RC1008)supported by the Science&Technology Innovation Program of Hunan Province,China。
文摘Arsenic(As)contamination of groundwater is a serious global issue requiring effective and sustainable remediation strategies.For long-term As immobilization,this study explores the potential of in-situ magnetite precipitation,induced by anaerobic nitrate-reducing Fe(II)-oxidizing(NRFO)bacteria.A nitrate-intercalated layered double hydroxide(NO_(3)^(-)MgFe LDH)was introduced to provide nitrate as an electron acceptor for Fe(II)bio-oxidation and serve as an iron-based precursor in magnetite formation.The experimental results showed that NO_(3)^(-)MgFe LDH was transformed into green rust(GR)in the presence of Fe(II)and HCO_(3)^(-).Meanwhile,0.5 g/L of NO_(3)^(-)MgFe LDH released cumulatively about 1.21 mM of nitrate within 12 h,promoting the transformation of GR into magnetite induced by Acidovorax sp.BoFeN1.As a result,the aqueous As concentration decreased from 2 mg/L to<0.008 mg/L,with approximately 70%of As confined in recalcitrant Fe oxides,suggesting high potential for long-term As immobilization.Environmental factors influenced the transformation process:a lower Fe(II)concentration(0.5 mM)delayed GR formation,while varying HCO_(3)^(-)concentrations(2.5-10 mM)had minimal effect.Subsequently,an elevated As level(5 mg/L)inhibited the bio-formation of magnetite,leading to lepidocrocite as the dominant mineral phase.Given the stability of magnetite,this study provides a cost-effective and environmentally friendly strategy for the durable in-situ remediation of As-contaminated groundwater.
基金supported by the National Natural Science Foundation of China(21536009)Science and Technology Plan Projects of Shaanxi Province(2017ZDCXL-GY-10-03)+1 种基金National Natural Science Foundation of China(22008198)the Special Scientific Research Plan Project of Education Ministry of Shaanxi Province,China(19JK0854).
文摘A series of Ni-based catalysts were prepared via structural topological transformation from the Ni@Al_(2)O_(3)layered double hydroxides(LDHs)precursors,and applied for the deep catalytic hydrogenation saturation of pyrene in a high-pressure reactor.The pore structures,active species dispersion,surface morphology,amount and type of acid of the prepared catalysts were characterized by BET,XRD,SEM,TEM,XPS,SEM,NH_(3)-TPD and Py-IR.We studied the influence of physicochemical properties of Ni-based catalysts on the regularity and mechanism of deep hydrogenation of pyrene.Meanwhile,the synergy between Ni and Mo,and the interaction between active metals and support were discussed to further reveal the constitutive relationship during the hydrogenation reaction of pyrene.The results of the evaluation of the catalytic hydrogenation of pyrene show that the as-prepared NiMo mixed metal oxide(MMO)catalyst showed excellent catalytic activity:~95%pyrene conversion,90.12%for the selectivity of deep hydrogenation products(hexahydropyrene,decahydropyrene and hexadecahydropyrene).It was expected that the successfully preparation and utilization of NiMo-MMO catalyst could provide a theoretical basis for the design of this kind of catalysts for deep catalytic hydrogenation of polycyclic aromatic hydrocarbons(PAHs).
