Microreactors are increasingly used for green and safe chemical processes owing to their benefits of superior mass and heat transfer,increased yield,safety,and simplicity of control.However,immobilizing catalysts in m...Microreactors are increasingly used for green and safe chemical processes owing to their benefits of superior mass and heat transfer,increased yield,safety,and simplicity of control.However,immobilizing catalysts in microreactors remains challenging.In this investigation,a technique for creating Cu_(2)O/montmorillonite catalyst coating,using electrostatic attraction for layer-by-layer self-assembly,was proposed.The montmorillonite film's morphology and thickness could be efficiently regulated by adjusting the degree of exfoliation and surface charge of montmorillonite,alongside layer-by-layer coating times.The Cu_(2)O nanoparticles were immobilized using the flow deposition approach.The resulting Cu_(2)O@montmorillonite-film-coated capillary microreactor successfully transformed glycerol into dihydroxyacetone.The conversion of glycerol and product selectivity could be controlled by adjusting the molar ratio of reactants,temperature,residence time,and Cu_(2)O loading.The maximum glycerol conversion observed was 47.6%,with a 27%selectivity toward dihydroxyacetone.The study presents a technique for immobilizing montmorillonite-based catalyst coatings in capillary tubing,which can serve as a foundation for the future application of microreactors in glycerol conversion.展开更多
TiO2 and montmorillonite composite photocatalysts were prepared and applied in degrading γ-hexachlorocyclohexane （γ-HCH） in soils. After being spiked with γ-HCH, soil samples loaded with the composite photocataly...TiO2 and montmorillonite composite photocatalysts were prepared and applied in degrading γ-hexachlorocyclohexane （γ-HCH） in soils. After being spiked with γ-HCH, soil samples loaded with the composite photocatalysts were exposed to UV-light irradiation. The results indicated that the photocatalytic activities of the composite photocatalysts varied with the content of TiO2 in the order of 10%〈70%〈50% 〈30%, Moreover, the photocatalytic activity of the composite photocatalysts with TiO2 content 30% was higher than that of the pure P25 with the same mass of TiO2. The strong adsorption capacity of the composite photocatalysts and quantum size effect may contribute to its increased photocatalytic activities. In addition, effect of dosage of composite photocatalysts and soil pH on γ-HCH photodegradation was investigated. Pentachlorocyclohexene, trichlorocyclohexene, and dichlorobenzene were detected as photodegradation intermediates, which were gradually degraded with the photodegradation evolution.展开更多
Zn-montmorillonites（Zn-MMTs） as antibacterial compounds were prepared by an ion-exchange reaction. The reaction time, initial pH value and molar ratios of CEC influencing zinc content in Zn-MMTs were investigated, a...Zn-montmorillonites（Zn-MMTs） as antibacterial compounds were prepared by an ion-exchange reaction. The reaction time, initial pH value and molar ratios of CEC influencing zinc content in Zn-MMTs were investigated, and Zn-MMTs were characterized by means of EDX, XRD, XPS, and SEM. The results of bacterial growth tests were confirmed by determination of the minimum inhibition concentrations （MICs） and minimum bactericidal concentrations （MBCs）. The experimental results show that the zinc is confirmed as bivalent zinc state, the d001 basal spacing of Zn-MMTs is enlarged with the enhancement of the zinc content, and the particles of Zn-MMTs are formed with irregular shape. Moreover, the antibacterial activity of Zn-MMTs increases with increasing the zinc content, and Zn-MMT-3 containing 6.76 mass% of zinc exhibits optimum antibacterial activity against Escherichia coli and Staphylococcus aureus.展开更多
A new composite antibacterial material ZnO/Cu^(2+)-Chitosan/Montmorillonite (ZCCM) was prepared with montmorillonite as carrier,Zn(Ac)_(2)·2H_(2)O,Cu(NO_(3))_(2)·3H_(2)O and chitosan as raw materials.ZCCM wa...A new composite antibacterial material ZnO/Cu^(2+)-Chitosan/Montmorillonite (ZCCM) was prepared with montmorillonite as carrier,Zn(Ac)_(2)·2H_(2)O,Cu(NO_(3))_(2)·3H_(2)O and chitosan as raw materials.ZCCM was characterized by X-ray diffraction,nitrogen physical adsorption,scanning electron microscopy and energy dispersion spectrometry.The antibacterial activity of ZCCM against Escherichia coli,Salmonella typhimurium,and Staphylococcus aureus was evaluated by minimal inhibitory concentration,minimum bactericidal concentration and the influence of growth curves.ZCCM displays excellent antibacterial activity which is higher than ZnO-Montmorillonite,Cu^(2+)-Montmorillonite and ZnO/Cu^(2+)-Montmorillonite.In addition,the antibacterial mechanism of ZCCM was investigated by analyzing bacterial morphology,integrity of cell membrane,lipid peroxidation and the effect of histidine on antibacterial activity of materials.It is found that cell morphologies of bacteria are damaged and bacterial cells are shrunken.With the increase of cell membrane permeability,the intracellular dissolved matters leak continuously.What’s more,the reactive oxygen species are generated and biomacromolecules are oxidized.展开更多
Organomontmorillonites （organo-MMT） were synthesized by means of montmorillonites （MMT） modified with a series of 2-methacryloyloxy ethyl alkyl dimethyl ammonium bromide （MAAB） having different alkyl chain lengt...Organomontmorillonites （organo-MMT） were synthesized by means of montmorillonites （MMT） modified with a series of 2-methacryloyloxy ethyl alkyl dimethyl ammonium bromide （MAAB） having different alkyl chain lengths as cationic surfactants through a cationic exchanging reaction, and were characterized by FTIR, TG, elemental analysis, and XRD. The microenvironment of the organic interlayer such as the orientation and arrangement of the alkyl chains of MAAB, as well as the properties of nanocomposite hydrogels, were also investigated. The amount of organic components absorbed on interlayer and the basal spacing of organo-MMT both increase with the increasing of alkyl length of MAAB. When carbon number of alkyl chain is in the region of 8 to 14, the alkyl chains between layers would adopt a disordered gauche conformation; while the carbon number is 16, an ordered all-trans conformation with a vertical orientation would be found together with the disordered gauche conformation according to the results of XRD and FTIR. Due to the difference of microenvironment of organic interlayer, the Young＇s moduli of the nanocomposite hydrogels increased as the alkyl chains of MAAB became longer.展开更多
The hydrated-titanium-oxide/montmorillonite composite samples were prepared using a hydrolysation- intercalation composite method by controlling the amount of TiOSO4·2H2O. The TiO2/montmorillonite composite sampl...The hydrated-titanium-oxide/montmorillonite composite samples were prepared using a hydrolysation- intercalation composite method by controlling the amount of TiOSO4·2H2O. The TiO2/montmorillonite composite samples were got after calculated at 700℃ and 1100 ℃. The results show that: when the value of Ti/montmorillonite is 12.5 mmol/g, the c axis of hydrated-titanium-oxide/ montmorillonite composite sample began to disorder, moreover, the crystal size of anatase is just 13.4nm in the TiO2/montmorillonite composite sample calculated at 700 ℃, and after calculated at 1100 ℃, the crystal size of anatase is 55.8 nm, and the relative content of anatase reaches the highest (55.7%). Compared with pure TiO2 nano-particle sample, TiO2/montmorillonite composite sample has a higher phase transition temperature from anatase phase to rutile phase and smaller crystal size of TiO2. Montmorillonite structure layer has a significant blocking effect on TiO2 phase transformation and grain growth, and the blocking effect reaches saturation when the value of Ti/montmorillonite is 12.5 mmol/g.展开更多
The liquid phase ring-opening of octamethylcy-clotetrasiloxane （D4） was investigated over Pt-H2SO4/Zr- montmorillonite catalyst. Montmorillonite （Mt）, Zr-Mt, H2SO4/Mt, H2SO4/Zr-Mt and Pt-H2SO4/Zr-Mt were also dete...The liquid phase ring-opening of octamethylcy-clotetrasiloxane （D4） was investigated over Pt-H2SO4/Zr- montmorillonite catalyst. Montmorillonite （Mt）, Zr-Mt, H2SO4/Mt, H2SO4/Zr-Mt and Pt-H2SO4/Zr-Mt were also detected for evaluation. The catalysts were characterized by X-ray fluorescence, X-ray diffraction, nitrogen adsorption-desorption, NH3-TPD and pyridine-FTIR measurements. In comparison to activate clay which is used in the industry of catalyst, Zr-Mt catalyst displayed stronger acidity and more excellent catalytic activity in the polymerization of D4, polymethylhydrosiloxane （DH） and hexamethyldisiloxane （MM） to low-hydro sili- cone oil. Relative to Zr-Mt, the acidity of H2SO4/Zr-Mt was noticeably improved and the catalyst exhibited a higher capability of ring-opening of D4 conversion and yield of low-hydro silicone oil. To enhance the stability of H2SO4/Zr-Mt catalyst, a small amount of metals （Pt） was doped. The nitrogen adsorption-desorption results indicated that pore textural parameters of the Pt-H2SO4/Zr-Mt had not changed with larger specific surface area. Compared with H2SO4/Zr-Mt, the total acidity of Pt-H2SO4-Zr/Mt catalyst retained, but the content of the Bransted acid increased and the content of the Lewis acid decreased. The Pt-H2SO4-Zr/Mt catalyst displayed higher catalyst reproducibility. After 40 h reaction of polymerization, the yield of low-hydro silicone oil decreased from 93% to 42% over H2SO4/Zr-Mt catalyst, while the yield of low-hydro silicone oil reduced from 93% to 78% over Pt-H2SO4/Zr-Mt catalyst. A sharp decrease in catalytic activity after 35 h of Pt-H2SO4/Zr-Mt catalyst was detected. Furthermore, Pt-H2SO4/Zr-Mt was completely regenerated under appropriate condition and appeared good repeatability in the D4, DH and MM to low-hydro silicone oil.展开更多
Lead adsorption of zinc oxide-coated ACOR montmorillonite was investigated in batches and under reducing conditions at ambient temperature. The presence of zinc oxide coating significantly enhanced the adsorption of P...Lead adsorption of zinc oxide-coated ACOR montmorillonite was investigated in batches and under reducing conditions at ambient temperature. The presence of zinc oxide coating significantly enhanced the adsorption of Pb^(2+) ions by ACOR montmorillonite. Characterization of adsorbents involved the use of X-ray diffraction, sodium saturation techniques, coulter laser analysis, scanning electron microscopy, and electron dispersive spectroscopy.Synthesis involved the trimetric process, activation of the ACOR montmorillonite and reacting of the same with zinc nitrate to produce a zinc oxide composite solid at 450 °C.The reaction mechanism indicated less than one proton coefficient, and higher mass transfer rates, when compared with bare montmorillonite. Intraparticle diffusion was higher than the value recorded for the bare montmorillonite. Reactions based on initial Pb^(2+) concentration indicated that coated montmorillonite gradually became saturated as the concentration was increased. Reactions based on solid concentration demonstrated a complex change in the capacity of adsorption over different Pb^(2+) concentrations(10–40 mg L^(-1)) and solid concentrations(2–10 g L^(-1)). The specific surface area reduction, particle size increase, mineral aggregation, and concentration gradient effect controlled the complex changes in adsorption.展开更多
基金support from the National Natural Science Foundation of China(2207213641672033)+2 种基金the research grants from Engineering Research Center of Non-metallic Minerals of Zhejiang Province(ZD2023K01)the projects from Qing Yang Institute for Industrial Minerals(KYYHX-20220336KYY-HX-20170557).
文摘Microreactors are increasingly used for green and safe chemical processes owing to their benefits of superior mass and heat transfer,increased yield,safety,and simplicity of control.However,immobilizing catalysts in microreactors remains challenging.In this investigation,a technique for creating Cu_(2)O/montmorillonite catalyst coating,using electrostatic attraction for layer-by-layer self-assembly,was proposed.The montmorillonite film's morphology and thickness could be efficiently regulated by adjusting the degree of exfoliation and surface charge of montmorillonite,alongside layer-by-layer coating times.The Cu_(2)O nanoparticles were immobilized using the flow deposition approach.The resulting Cu_(2)O@montmorillonite-film-coated capillary microreactor successfully transformed glycerol into dihydroxyacetone.The conversion of glycerol and product selectivity could be controlled by adjusting the molar ratio of reactants,temperature,residence time,and Cu_(2)O loading.The maximum glycerol conversion observed was 47.6%,with a 27%selectivity toward dihydroxyacetone.The study presents a technique for immobilizing montmorillonite-based catalyst coatings in capillary tubing,which can serve as a foundation for the future application of microreactors in glycerol conversion.
基金Project supported by the National Natural Science Foundation of China(No. 29977003, 20507011)the State Ministry of Education of China(No. 00028)
文摘TiO2 and montmorillonite composite photocatalysts were prepared and applied in degrading γ-hexachlorocyclohexane （γ-HCH） in soils. After being spiked with γ-HCH, soil samples loaded with the composite photocatalysts were exposed to UV-light irradiation. The results indicated that the photocatalytic activities of the composite photocatalysts varied with the content of TiO2 in the order of 10%〈70%〈50% 〈30%, Moreover, the photocatalytic activity of the composite photocatalysts with TiO2 content 30% was higher than that of the pure P25 with the same mass of TiO2. The strong adsorption capacity of the composite photocatalysts and quantum size effect may contribute to its increased photocatalytic activities. In addition, effect of dosage of composite photocatalysts and soil pH on γ-HCH photodegradation was investigated. Pentachlorocyclohexene, trichlorocyclohexene, and dichlorobenzene were detected as photodegradation intermediates, which were gradually degraded with the photodegradation evolution.
基金Funded by the National Natural Science Foundation of China (Nos. 20676049, 20871058 and 20971028)the Foundation of Enter-prise-University-Research Institute Cooperation from Guangdong Province and Ministry of Education of China (Nos. 2007B090400105 and2008A010500005)the Open Fundation of Guangdong Provincial Key Laboratory of Applied Microbiology (No. SWKF200704)
文摘Zn-montmorillonites（Zn-MMTs） as antibacterial compounds were prepared by an ion-exchange reaction. The reaction time, initial pH value and molar ratios of CEC influencing zinc content in Zn-MMTs were investigated, and Zn-MMTs were characterized by means of EDX, XRD, XPS, and SEM. The results of bacterial growth tests were confirmed by determination of the minimum inhibition concentrations （MICs） and minimum bactericidal concentrations （MBCs）. The experimental results show that the zinc is confirmed as bivalent zinc state, the d001 basal spacing of Zn-MMTs is enlarged with the enhancement of the zinc content, and the particles of Zn-MMTs are formed with irregular shape. Moreover, the antibacterial activity of Zn-MMTs increases with increasing the zinc content, and Zn-MMT-3 containing 6.76 mass% of zinc exhibits optimum antibacterial activity against Escherichia coli and Staphylococcus aureus.
基金Funded by the Natural Science Foundation of Ningxia(No. 2019AAC03019)the National Natural Science Foundation of China(No. 51564043)。
文摘A new composite antibacterial material ZnO/Cu^(2+)-Chitosan/Montmorillonite (ZCCM) was prepared with montmorillonite as carrier,Zn(Ac)_(2)·2H_(2)O,Cu(NO_(3))_(2)·3H_(2)O and chitosan as raw materials.ZCCM was characterized by X-ray diffraction,nitrogen physical adsorption,scanning electron microscopy and energy dispersion spectrometry.The antibacterial activity of ZCCM against Escherichia coli,Salmonella typhimurium,and Staphylococcus aureus was evaluated by minimal inhibitory concentration,minimum bactericidal concentration and the influence of growth curves.ZCCM displays excellent antibacterial activity which is higher than ZnO-Montmorillonite,Cu^(2+)-Montmorillonite and ZnO/Cu^(2+)-Montmorillonite.In addition,the antibacterial mechanism of ZCCM was investigated by analyzing bacterial morphology,integrity of cell membrane,lipid peroxidation and the effect of histidine on antibacterial activity of materials.It is found that cell morphologies of bacteria are damaged and bacterial cells are shrunken.With the increase of cell membrane permeability,the intracellular dissolved matters leak continuously.What’s more,the reactive oxygen species are generated and biomacromolecules are oxidized.
文摘Organomontmorillonites （organo-MMT） were synthesized by means of montmorillonites （MMT） modified with a series of 2-methacryloyloxy ethyl alkyl dimethyl ammonium bromide （MAAB） having different alkyl chain lengths as cationic surfactants through a cationic exchanging reaction, and were characterized by FTIR, TG, elemental analysis, and XRD. The microenvironment of the organic interlayer such as the orientation and arrangement of the alkyl chains of MAAB, as well as the properties of nanocomposite hydrogels, were also investigated. The amount of organic components absorbed on interlayer and the basal spacing of organo-MMT both increase with the increasing of alkyl length of MAAB. When carbon number of alkyl chain is in the region of 8 to 14, the alkyl chains between layers would adopt a disordered gauche conformation; while the carbon number is 16, an ordered all-trans conformation with a vertical orientation would be found together with the disordered gauche conformation according to the results of XRD and FTIR. Due to the difference of microenvironment of organic interlayer, the Young＇s moduli of the nanocomposite hydrogels increased as the alkyl chains of MAAB became longer.
文摘The hydrated-titanium-oxide/montmorillonite composite samples were prepared using a hydrolysation- intercalation composite method by controlling the amount of TiOSO4·2H2O. The TiO2/montmorillonite composite samples were got after calculated at 700℃ and 1100 ℃. The results show that: when the value of Ti/montmorillonite is 12.5 mmol/g, the c axis of hydrated-titanium-oxide/ montmorillonite composite sample began to disorder, moreover, the crystal size of anatase is just 13.4nm in the TiO2/montmorillonite composite sample calculated at 700 ℃, and after calculated at 1100 ℃, the crystal size of anatase is 55.8 nm, and the relative content of anatase reaches the highest (55.7%). Compared with pure TiO2 nano-particle sample, TiO2/montmorillonite composite sample has a higher phase transition temperature from anatase phase to rutile phase and smaller crystal size of TiO2. Montmorillonite structure layer has a significant blocking effect on TiO2 phase transformation and grain growth, and the blocking effect reaches saturation when the value of Ti/montmorillonite is 12.5 mmol/g.
基金Supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘The liquid phase ring-opening of octamethylcy-clotetrasiloxane （D4） was investigated over Pt-H2SO4/Zr- montmorillonite catalyst. Montmorillonite （Mt）, Zr-Mt, H2SO4/Mt, H2SO4/Zr-Mt and Pt-H2SO4/Zr-Mt were also detected for evaluation. The catalysts were characterized by X-ray fluorescence, X-ray diffraction, nitrogen adsorption-desorption, NH3-TPD and pyridine-FTIR measurements. In comparison to activate clay which is used in the industry of catalyst, Zr-Mt catalyst displayed stronger acidity and more excellent catalytic activity in the polymerization of D4, polymethylhydrosiloxane （DH） and hexamethyldisiloxane （MM） to low-hydro sili- cone oil. Relative to Zr-Mt, the acidity of H2SO4/Zr-Mt was noticeably improved and the catalyst exhibited a higher capability of ring-opening of D4 conversion and yield of low-hydro silicone oil. To enhance the stability of H2SO4/Zr-Mt catalyst, a small amount of metals （Pt） was doped. The nitrogen adsorption-desorption results indicated that pore textural parameters of the Pt-H2SO4/Zr-Mt had not changed with larger specific surface area. Compared with H2SO4/Zr-Mt, the total acidity of Pt-H2SO4-Zr/Mt catalyst retained, but the content of the Bransted acid increased and the content of the Lewis acid decreased. The Pt-H2SO4-Zr/Mt catalyst displayed higher catalyst reproducibility. After 40 h reaction of polymerization, the yield of low-hydro silicone oil decreased from 93% to 42% over H2SO4/Zr-Mt catalyst, while the yield of low-hydro silicone oil reduced from 93% to 78% over Pt-H2SO4/Zr-Mt catalyst. A sharp decrease in catalytic activity after 35 h of Pt-H2SO4/Zr-Mt catalyst was detected. Furthermore, Pt-H2SO4/Zr-Mt was completely regenerated under appropriate condition and appeared good repeatability in the D4, DH and MM to low-hydro silicone oil.
基金the Niger Delta University for the usual research allowances provided for the running of research projects
文摘Lead adsorption of zinc oxide-coated ACOR montmorillonite was investigated in batches and under reducing conditions at ambient temperature. The presence of zinc oxide coating significantly enhanced the adsorption of Pb^(2+) ions by ACOR montmorillonite. Characterization of adsorbents involved the use of X-ray diffraction, sodium saturation techniques, coulter laser analysis, scanning electron microscopy, and electron dispersive spectroscopy.Synthesis involved the trimetric process, activation of the ACOR montmorillonite and reacting of the same with zinc nitrate to produce a zinc oxide composite solid at 450 °C.The reaction mechanism indicated less than one proton coefficient, and higher mass transfer rates, when compared with bare montmorillonite. Intraparticle diffusion was higher than the value recorded for the bare montmorillonite. Reactions based on initial Pb^(2+) concentration indicated that coated montmorillonite gradually became saturated as the concentration was increased. Reactions based on solid concentration demonstrated a complex change in the capacity of adsorption over different Pb^(2+) concentrations(10–40 mg L^(-1)) and solid concentrations(2–10 g L^(-1)). The specific surface area reduction, particle size increase, mineral aggregation, and concentration gradient effect controlled the complex changes in adsorption.
