A novel nanofluid of modified carbon black(MCB)nanoparticles was initially developed for enhanced oil recovery(EOR)in low permeability reservoirs.The MCB nanoparticles were obtained via a three-step reaction involving...A novel nanofluid of modified carbon black(MCB)nanoparticles was initially developed for enhanced oil recovery(EOR)in low permeability reservoirs.The MCB nanoparticles were obtained via a three-step reaction involving modification by oxidation,acyl chlorination,and activated grafting.MCB nano-particles were spherically dispersed,with an average size of 72.3 nm.Compared with carbon black(CB)nanoparticles,dispersed MCB nanoparticles can effectively reduce the oil-water interfacial tension(IFT)to 10^(-2)mN/m and change the surface wettability of sand particles.Based on the results of core flooding experiments,the MCB nanoparticles exhibited a better EOR capacity than surfactants and CB nano-particles,and the final oil recovery was significantly increased by 27.27%.The core scanning test showed that the MCB nanoparticles could plug high permeability channels by adsorbing onto the surfaces of sand particles and forming larger aggregates that bridge across pores or throats,resulting in a higher swept volume.The synergistic effects of improved swept volume and oil displacement efficiency were the EOR mechanisms of the MCB nanoparticles.The studies indicate that these MCB nanoparticles have excellent potential for EOR in low permeability reservoirs.展开更多
Glyphosate is a herbicide that has been widely used worldwide and is used in agricultural areas to control weeds and unwanted vegetation.Electrochemical sensors developed from different nanomaterials have high efficie...Glyphosate is a herbicide that has been widely used worldwide and is used in agricultural areas to control weeds and unwanted vegetation.Electrochemical sensors developed from different nanomaterials have high efficiency,excellent cost-benefit,and fast analysis time for detecting traces of environmental pollutants.This study aimed to produce an electrochemical sensor with disposable screen-printed electrodes based on carbon black modified with niobium nanoparticles to determine glyphosate in aqueous solutions.The morphology,structure and electrochemical performance of the sensor were characterized by scanning electron microscopy,energy-dispersive X-ray spectroscopy,X-ray diffraction and cyclic voltammetry.Differential pulse voltammetry in BR buffer solution at pH 5.0 allowed the generation of a method to quantify glyphosate concentration in a linear range of 5.90-172.30μmol/L(1.00-29.13μg/mL),with a limit of detection calculated at 3.07μmol/L(0.52μg/mL).The method efficiently quantified glyphosate in real water samples and showed no interference from K^(+),Na^(+),Ca^(2+),Mg^(2+)ions or thiamethoxam,imidacloprid and carbendazim pesticides.展开更多
Oxidative dehydrogenation of propane with carbon dioxide(CO_(2)-ODP)characterizes the tandem dehydrogenation of propane to propylene with the reduction of the greenhouse gas of CO_(2)to valuable CO.However,the existin...Oxidative dehydrogenation of propane with carbon dioxide(CO_(2)-ODP)characterizes the tandem dehydrogenation of propane to propylene with the reduction of the greenhouse gas of CO_(2)to valuable CO.However,the existing catalyst is limited due to the poor activity and stability,which hinders its industrialization.Herein,we design the finned Zn-MFI zeolite encapsulated noble metal nanoparticles(NPs)as bifunctional catalysts(NPs@Zn-MFI)for CO_(2)-ODP.Characterization results reveal that the Zn2+species are coordinated with the MFI zeolite matrix as isolated cations and the NPs of Pt,Rh,or Rh Pt are highly dispersed in the zeolite crystals.The isolated Zn2+cations are very effective for activating the propane and the small NPs are favorable for activating the CO_(2),which synergistically promote the selective transformation of propane and CO_(2)to propylene and CO.As a result,the optimal 0.25%Rh0.50%Pt@Zn-MFI catalyst shows the best propylene yield,satisfactory CO_(2)conversion,and long-term stability.Moreover,considering the tunable synergetic effects between the isolated cations and NPs,the developed approach offers a general guideline to design more efficient CO_(2)-ODP catalysts,which is validated by the improved performance of the bifunctional catalysts via simply substituting Sn4+cations for Zn2+cations in the MFI zeolite matrix.展开更多
Carbon black supported ultra-high loading silver nanoparticle catalyst (Ag/CB) was prepared by a modified ethylene glycol reduction method, using ethylene glycol as the reducing agent and sodium hydroxide as the pH ad...Carbon black supported ultra-high loading silver nanoparticle catalyst (Ag/CB) was prepared by a modified ethylene glycol reduction method, using ethylene glycol as the reducing agent and sodium hydroxide as the pH adjusting agent. The X-ray diffraction, thermogravimetry and scanning electron microscopy characterizations showed that the Ag nanoparticles crystallized with a face-centered cubic structure and were densely stacked on the CB surface without aggregation, despite such a small average size (ca. 10 nm) and an ultra-high loading mass (392 wt.%). The electrochemical evaluation based on cyclic voltammetry, chronoamperometry and polarization tests revealed that the ultra-high loading Ag/CB catalyst possessed a superior electrocatalytic activity for the oxidation of hydrazine, via a diffusion-limited process and a 4-electron transfer pathway. Moreover, the chronoamperometry response on an electrode modified with this ultra-high loading Ag/CB catalyst exhibited a promising application for determination of hydrazine, due to a broad linear calibration ranging from 50 to 800 μM, a high sensitivity of 0.03795 A/ M and a low detection limit of 3.47 μM.展开更多
通过自组装方式采用一步法制备了锂离子电池硅碳复合电极材料.使用X射线衍射仪(XRD)、透射电子显微镜(TEM)和扫描电子显微镜(SEM)等对样品结构进行表征.结果表明,聚乙烯吡咯烷酮(PVP)包覆的纳米硅颗粒(Si@PVP)均匀嵌入到具有三维网络纳...通过自组装方式采用一步法制备了锂离子电池硅碳复合电极材料.使用X射线衍射仪(XRD)、透射电子显微镜(TEM)和扫描电子显微镜(SEM)等对样品结构进行表征.结果表明,聚乙烯吡咯烷酮(PVP)包覆的纳米硅颗粒(Si@PVP)均匀嵌入到具有三维网络纳米孔结构的导电石墨化炭黑(GCB)骨架中,形成核壳复合型(Si@PVP-GCB)纳米颗粒,既提高了该复合电极材料的导电性能,又改善了材料的机械强度.在纳米级GCB颗粒内部存在的中空石墨环结构和包覆在纳米Si颗粒外面的PVP包覆层都有效缓冲了纳米Si颗粒在充放电过程中较大的体积变化,从而使纳米Si颗粒更加稳定.电化学测试结果表明,Si@PVP-GCB电极材料在电流密度为50 m A/g时,经过100次循环后其可逆容量仍达到545 m A·h/g时,远高于商品化的石墨微球(GMs)电极材料的容量(理论容量为372 m A·h/g).展开更多
基金supported by the National Key R&D Program of China(2018YFA0702400)National Natural Science Foundation of China(5207040347).
文摘A novel nanofluid of modified carbon black(MCB)nanoparticles was initially developed for enhanced oil recovery(EOR)in low permeability reservoirs.The MCB nanoparticles were obtained via a three-step reaction involving modification by oxidation,acyl chlorination,and activated grafting.MCB nano-particles were spherically dispersed,with an average size of 72.3 nm.Compared with carbon black(CB)nanoparticles,dispersed MCB nanoparticles can effectively reduce the oil-water interfacial tension(IFT)to 10^(-2)mN/m and change the surface wettability of sand particles.Based on the results of core flooding experiments,the MCB nanoparticles exhibited a better EOR capacity than surfactants and CB nano-particles,and the final oil recovery was significantly increased by 27.27%.The core scanning test showed that the MCB nanoparticles could plug high permeability channels by adsorbing onto the surfaces of sand particles and forming larger aggregates that bridge across pores or throats,resulting in a higher swept volume.The synergistic effects of improved swept volume and oil displacement efficiency were the EOR mechanisms of the MCB nanoparticles.The studies indicate that these MCB nanoparticles have excellent potential for EOR in low permeability reservoirs.
基金the Coordenacao de Aperfeicoamento de Pessoal de Nível Superior(CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq)Fundacao de Amparo à Pesquisa do Estado do Rio de Janeiro(FAPERJ)(Cincotto Proc.E-26/202.696/2019,Proc.E-26/010.002267/2019 and E-26/210.304/2022)for the financial support
文摘Glyphosate is a herbicide that has been widely used worldwide and is used in agricultural areas to control weeds and unwanted vegetation.Electrochemical sensors developed from different nanomaterials have high efficiency,excellent cost-benefit,and fast analysis time for detecting traces of environmental pollutants.This study aimed to produce an electrochemical sensor with disposable screen-printed electrodes based on carbon black modified with niobium nanoparticles to determine glyphosate in aqueous solutions.The morphology,structure and electrochemical performance of the sensor were characterized by scanning electron microscopy,energy-dispersive X-ray spectroscopy,X-ray diffraction and cyclic voltammetry.Differential pulse voltammetry in BR buffer solution at pH 5.0 allowed the generation of a method to quantify glyphosate concentration in a linear range of 5.90-172.30μmol/L(1.00-29.13μg/mL),with a limit of detection calculated at 3.07μmol/L(0.52μg/mL).The method efficiently quantified glyphosate in real water samples and showed no interference from K^(+),Na^(+),Ca^(2+),Mg^(2+)ions or thiamethoxam,imidacloprid and carbendazim pesticides.
基金supported by the National Natural Science Foundation of China(21902097,21636006 and 21761132025)the China Postdoctoral Science Foundation(2019M653861XB)+1 种基金the Natural Science Foundation of Shaanxi Province(2020JQ-409)the Fundamental Research Funds for the Central Universities(GK201901001 and GK202003035)。
文摘Oxidative dehydrogenation of propane with carbon dioxide(CO_(2)-ODP)characterizes the tandem dehydrogenation of propane to propylene with the reduction of the greenhouse gas of CO_(2)to valuable CO.However,the existing catalyst is limited due to the poor activity and stability,which hinders its industrialization.Herein,we design the finned Zn-MFI zeolite encapsulated noble metal nanoparticles(NPs)as bifunctional catalysts(NPs@Zn-MFI)for CO_(2)-ODP.Characterization results reveal that the Zn2+species are coordinated with the MFI zeolite matrix as isolated cations and the NPs of Pt,Rh,or Rh Pt are highly dispersed in the zeolite crystals.The isolated Zn2+cations are very effective for activating the propane and the small NPs are favorable for activating the CO_(2),which synergistically promote the selective transformation of propane and CO_(2)to propylene and CO.As a result,the optimal 0.25%Rh0.50%Pt@Zn-MFI catalyst shows the best propylene yield,satisfactory CO_(2)conversion,and long-term stability.Moreover,considering the tunable synergetic effects between the isolated cations and NPs,the developed approach offers a general guideline to design more efficient CO_(2)-ODP catalysts,which is validated by the improved performance of the bifunctional catalysts via simply substituting Sn4+cations for Zn2+cations in the MFI zeolite matrix.
基金financially supported by the National Natural Science Foundation for Distinguished Young Scholars (51125007)
文摘Carbon black supported ultra-high loading silver nanoparticle catalyst (Ag/CB) was prepared by a modified ethylene glycol reduction method, using ethylene glycol as the reducing agent and sodium hydroxide as the pH adjusting agent. The X-ray diffraction, thermogravimetry and scanning electron microscopy characterizations showed that the Ag nanoparticles crystallized with a face-centered cubic structure and were densely stacked on the CB surface without aggregation, despite such a small average size (ca. 10 nm) and an ultra-high loading mass (392 wt.%). The electrochemical evaluation based on cyclic voltammetry, chronoamperometry and polarization tests revealed that the ultra-high loading Ag/CB catalyst possessed a superior electrocatalytic activity for the oxidation of hydrazine, via a diffusion-limited process and a 4-electron transfer pathway. Moreover, the chronoamperometry response on an electrode modified with this ultra-high loading Ag/CB catalyst exhibited a promising application for determination of hydrazine, due to a broad linear calibration ranging from 50 to 800 μM, a high sensitivity of 0.03795 A/ M and a low detection limit of 3.47 μM.
文摘通过自组装方式采用一步法制备了锂离子电池硅碳复合电极材料.使用X射线衍射仪(XRD)、透射电子显微镜(TEM)和扫描电子显微镜(SEM)等对样品结构进行表征.结果表明,聚乙烯吡咯烷酮(PVP)包覆的纳米硅颗粒(Si@PVP)均匀嵌入到具有三维网络纳米孔结构的导电石墨化炭黑(GCB)骨架中,形成核壳复合型(Si@PVP-GCB)纳米颗粒,既提高了该复合电极材料的导电性能,又改善了材料的机械强度.在纳米级GCB颗粒内部存在的中空石墨环结构和包覆在纳米Si颗粒外面的PVP包覆层都有效缓冲了纳米Si颗粒在充放电过程中较大的体积变化,从而使纳米Si颗粒更加稳定.电化学测试结果表明,Si@PVP-GCB电极材料在电流密度为50 m A/g时,经过100次循环后其可逆容量仍达到545 m A·h/g时,远高于商品化的石墨微球(GMs)电极材料的容量(理论容量为372 m A·h/g).
