In this study, biosilica of high purity was successfully prepared from marine diatom （Nitzschia closterium and Thalassiosira） biomass using an optimized novel method with acid washing treatment followed by thermal t...In this study, biosilica of high purity was successfully prepared from marine diatom （Nitzschia closterium and Thalassiosira） biomass using an optimized novel method with acid washing treatment followed by thermal treatment of the biomass. The optimal condition of the method was 2% diluted HCl washing and baking at 600℃. The SiO2 contents of N. closterium biosilica and Thalassiosira biosilica were 92.23% and 91.52%, respectively, which were both higher than that of diatomite biosilica. The SiO2 morphologies of both biosilica are typical amorphous silica. Besides, IV. closterium biosilica possessed micropores and fibers with a surface area of 59.81 m^2/g. And Thalassiosira biosilica possessed a mesoporous hierarchical skeleton with a surface area of 9.91 m^2/g. The results suggest that the biosilica samples obtained in this study present highly porous structures. The prepared porous biosilica material possesses great potential to be used as drug delivery carrier, biosensor, biocatalyst as well as adsorbent in the future.展开更多
In several countries, the residual RHA （rice husk ash） has been produced in rice processing industries or in thermoelectric plants that use rice husk to generate heat and/or electrical energy, usually without burnin...In several countries, the residual RHA （rice husk ash） has been produced in rice processing industries or in thermoelectric plants that use rice husk to generate heat and/or electrical energy, usually without burning process control. This causes a reduction in the amorphous silica content of residual RHA, which distinguishes them from the RHA produced according to controlled burning process, which is totally amorphous and considered a highly reactive pozzolan. In this paper, the hydration products and the porous structure of binders paste were studied by replacing, in weight of 5%, 10% and 20% of Portland cement OPC （ordinary Portland cement）, by residual RHAs named A and B, which have high and low content of amorphous silica, respectively, using microstructure evaluation techniques as XRD （X-ray diffraction）, TG （thermogravimetric） tests and MIP （mercury intrusion porosimetry）. A reducing the size of the pores of the pastes was observed according to the increase of content replacement of RHA A and RHA B.展开更多
Fist-sized iron nodules, extensively found on the ground of Western Australia, were investigated by element analysis(XRF, ICP-MS and ICP-AES), electron microscopes, X-ray diffraction and M?ssbauser spectroscopy. Loose...Fist-sized iron nodules, extensively found on the ground of Western Australia, were investigated by element analysis(XRF, ICP-MS and ICP-AES), electron microscopes, X-ray diffraction and M?ssbauser spectroscopy. Loosely-packed pisoidic structures of a few to >10 mm in size were observed in the cross-section of nodules. Chemically, the nodules are majorly made of O, Si, Fe and Al, and share similar REE pattern with the loess sourced Greatford concretions from New Zealand. Angular quartz particles, nano-sized goethite and hematite are found to be the major mineral phases. Other minerals, such as detrital zircon, barite and Ce-containing particles can also be observed but of very low abundance. No detectable carbonate or amorphous silica implies that these nodules have experienced little underground fluid alteration. The quartz particles showing particularly three sections of fractal size-distributions, together with their extensive broken features and conchoidal fractures, strongly suggest in situ fragmentation of the host rock with minimum later dynamic sorting. These observations indicate the genetic environment of those nodules is always close to the surface of the tectonically stable ground since their formation. Because of the similarity of climatic and geological features, the genesis and preservation environment of these nodules in Western Australia may provide clues on the formation of Martian iron concretions.展开更多
Au nanoparticle（Au NP）@SiO2@TDA-Eu nanocomposites were prepared by a two-step process： Au NP@SiO2 nanocomposites were prepared by a modified onepot process. Then the europium coordination polymer was deposited on t...Au nanoparticle（Au NP）@SiO2@TDA-Eu nanocomposites were prepared by a two-step process： Au NP@SiO2 nanocomposites were prepared by a modified onepot process. Then the europium coordination polymer was deposited on the surface of the Au NP@SiO2 by mixing 2,2＇-thiodiacetic acid [S（CH2 COO）2^（2-）, TDA] and Eu（NO3）3·6 H2 O in ethanol via a hydrothermal method. The maximum fluorescent enhancement factor of the nanocomposites was 6.81 at 30 nm thickness of silica between the core of the Au NP and the shell of TDA-Eu. The prepared nanocomposites exhibit more sensitive monitoring of reactive oxygen species.展开更多
基金Supported by the Public Science and Technology Research Funds Projects of Ocean,China(No.201305022)the PhD Start-up Fund of Natural Science Foundation of Guangdong Province,China(No.2014A030310326)
文摘In this study, biosilica of high purity was successfully prepared from marine diatom （Nitzschia closterium and Thalassiosira） biomass using an optimized novel method with acid washing treatment followed by thermal treatment of the biomass. The optimal condition of the method was 2% diluted HCl washing and baking at 600℃. The SiO2 contents of N. closterium biosilica and Thalassiosira biosilica were 92.23% and 91.52%, respectively, which were both higher than that of diatomite biosilica. The SiO2 morphologies of both biosilica are typical amorphous silica. Besides, IV. closterium biosilica possessed micropores and fibers with a surface area of 59.81 m^2/g. And Thalassiosira biosilica possessed a mesoporous hierarchical skeleton with a surface area of 9.91 m^2/g. The results suggest that the biosilica samples obtained in this study present highly porous structures. The prepared porous biosilica material possesses great potential to be used as drug delivery carrier, biosensor, biocatalyst as well as adsorbent in the future.
文摘In several countries, the residual RHA （rice husk ash） has been produced in rice processing industries or in thermoelectric plants that use rice husk to generate heat and/or electrical energy, usually without burning process control. This causes a reduction in the amorphous silica content of residual RHA, which distinguishes them from the RHA produced according to controlled burning process, which is totally amorphous and considered a highly reactive pozzolan. In this paper, the hydration products and the porous structure of binders paste were studied by replacing, in weight of 5%, 10% and 20% of Portland cement OPC （ordinary Portland cement）, by residual RHAs named A and B, which have high and low content of amorphous silica, respectively, using microstructure evaluation techniques as XRD （X-ray diffraction）, TG （thermogravimetric） tests and MIP （mercury intrusion porosimetry）. A reducing the size of the pores of the pastes was observed according to the increase of content replacement of RHA A and RHA B.
基金a General Research Fund (Grant No. HKU 703911P) provided by the Hong Kong Research Grants Council
文摘Fist-sized iron nodules, extensively found on the ground of Western Australia, were investigated by element analysis(XRF, ICP-MS and ICP-AES), electron microscopes, X-ray diffraction and M?ssbauser spectroscopy. Loosely-packed pisoidic structures of a few to >10 mm in size were observed in the cross-section of nodules. Chemically, the nodules are majorly made of O, Si, Fe and Al, and share similar REE pattern with the loess sourced Greatford concretions from New Zealand. Angular quartz particles, nano-sized goethite and hematite are found to be the major mineral phases. Other minerals, such as detrital zircon, barite and Ce-containing particles can also be observed but of very low abundance. No detectable carbonate or amorphous silica implies that these nodules have experienced little underground fluid alteration. The quartz particles showing particularly three sections of fractal size-distributions, together with their extensive broken features and conchoidal fractures, strongly suggest in situ fragmentation of the host rock with minimum later dynamic sorting. These observations indicate the genetic environment of those nodules is always close to the surface of the tectonically stable ground since their formation. Because of the similarity of climatic and geological features, the genesis and preservation environment of these nodules in Western Australia may provide clues on the formation of Martian iron concretions.
基金financially supported by the National Natural Science Foundation of China (51702006 and 21501141)the Doctoral research project (ZK2017027) of Baoji University of Arts and Sciencesthe Education Commission of Shaanxi Province (2015JQ6223,12JS114,14JS092 and 17JS009)
文摘Au nanoparticle（Au NP）@SiO2@TDA-Eu nanocomposites were prepared by a two-step process： Au NP@SiO2 nanocomposites were prepared by a modified onepot process. Then the europium coordination polymer was deposited on the surface of the Au NP@SiO2 by mixing 2,2＇-thiodiacetic acid [S（CH2 COO）2^（2-）, TDA] and Eu（NO3）3·6 H2 O in ethanol via a hydrothermal method. The maximum fluorescent enhancement factor of the nanocomposites was 6.81 at 30 nm thickness of silica between the core of the Au NP and the shell of TDA-Eu. The prepared nanocomposites exhibit more sensitive monitoring of reactive oxygen species.
