土壤铁锰氧化物形态测定及吸附Sb(Ⅲ)的主控因子研究

研究影响土壤吸附Sb(Ⅲ)的主控因子对土壤锑污染的评价、预警及修复具有重要意义。本文采用化学法、电感耦合等离子体发射光谱法和原子荧光光谱法测定了10个不同地区土壤的理化性质和机械组成、主要化学组成,采用原子吸收光谱法测定了土壤铁锰氧化物的不同形态以及土壤对Sb(Ⅲ)的饱和吸附容量,并开展了土壤对Sb(Ⅲ)的饱和吸附容量和土壤理化性质、机械组成、铁锰氧化物及其形态的相关性分析、主成分分析和因子分析。在研究土壤吸附Sb(Ⅲ)的影响因素基础上,进一步研究其主控因子。结果表明,10个不同性质的土壤对Sb(Ⅲ)饱和吸附容量介于0.63~3.98mg/g之间,与土壤类型有关,其大小顺序为:红壤>棕壤>黄壤>褐土>沙土。土壤对Sb(Ⅲ)饱和吸附容量与阳离子交换容量(CEC)、氧化铁总量、无定形铁含量呈极显著正相关,与游离铁含量、无定形锰含量以及游离锰含量呈显著正相关。主成分分析和因子分析结果表明土壤中6个因子是影响土壤吸附Sb(Ⅲ)的主控因子,影响力大小为:氧化铁总量>CEC>无定形铁含量>游离铁含量>无定形锰含量>游离锰含量。铁锰氧化物及其形态显著影响土壤吸附Sb(Ⅲ)。

蛋壳膜电解质栅控氧化物神经形态晶体管

近年来,神经形态器件的研究受到了人们的广泛关注,正在成为人工智能技术发展的重要分支.与此同时,天然生物材料具有可降解性、良好的生物相容性、无毒性等多种优势,在新型便携式智能系统中有重要应用价值.本文采用蛋壳膜(ESM)作为电解质,具有极高的室温质子电导率(~6.4×10^(-3) S/cm)和极高的室温双电层电容(~2.8μF/cm^(2)),因此其具有极强的界面双电层静电调控能力.以此为基础,研制了氧化铟锡双电层晶体管,器件具有优异的电学特性.基于ESM独特的界面双电层调控特性,在器件上实现了一些重要仿生突触塑性行为,如兴奋性突触后电流、双脉冲易化和突触滤波.通过施加突触刺激,实现了器件的多重突触权重更新.在此基础上采用人工神经网络实现了手写数字的模式识别,最佳识别精度约高达92.59%.因此,提出的ESM栅控氧化物神经形态晶体管在低成本生物可降解神经形态系统中有一定的应用潜力.

明胶/羧化壳聚糖栅控氧化物神经形态晶体管

模仿大脑感知信息处理方式对于仿生智能感知系统的设计具有重要意义,而采用具有生物相容性和生物可降解特性的功能材料构建环境友好型神经形态器件是突触电子学研究的重要内容。本研究采用明胶/羧化壳聚糖(GEL/C-CS)复合电解质薄膜作为栅介质制作氧化物神经形态晶体管,模仿了不同湿度下的突触响应行为,包括兴奋性突触后电流和双脉冲易化。基于不同刺激数量下的突触塑性行为,提出了一种触觉对物体识别程度的量化处理方式。进一步搭建人工神经网络,实现了对MNIST手写数字的识别,识别精度达90%以上。这种GEL/C-CS栅控神经形态器件对仿生智能感知和脑启发神经形态系统的设计具有一定的参考价值。

变质处理对复相耐磨铸钢硫氧化物夹杂形态的影响

在实验和检验分析的基础上 ,探讨了变质处理对复相耐磨铸钢中硫氧化物夹杂形态的影响。研究结果表明 ,复相耐磨钢中硫氧化物形态与钢中残余镁含量。

RH精炼过程中含钛超低碳钢的氧化物夹杂组成和形态变化

在含钛超低碳水中，脱氧前的夹杂物主要组成为Fe—Mn—O，添加Al3min后，夹杂物改变成粒状和球形Al2O3。添加A17—10min后，形成簇状Al2O3，其由粒状和直径为1—2μm的球形颗粒组成。添加钛铁合金3min后，形成Al2O3·TiOx夹杂物，其中Ti／（A1＋Ti）介于0．15和0．30之间，由于在富[Ti]和低[A1]区域，形成的簇状Al2O3·TiOx存在于钛铁粒子和簇状A1203周围。当酸溶铝超过0．035％，而钛低于0．08％时，很难形成Ti305，在复杂液相夹杂物中的Ti3O5活度明显随酸溶铝的减少而增加，并随钛含量的增加而增加。

广东省赤红壤区土壤团聚体有机碳和铁氧化物特征及稳定性

通过野外采样和室内分析相结合,以广东省赤红壤区花岗岩(G)、第四纪红土(Q)和砂页岩(S)母质发育的林地(FL)、水田(PF)和旱地(UL)土壤为研究对象,分析了土壤团聚体有机碳及其组分和不同形态铁氧化物含量,探究了其对土壤团聚体稳定性的影响及贡献。结果显示:(1)3种母质发育的3种利用方式土壤团聚体均以>0.25 mm为主,2~5 mm团聚体以花岗岩母质发育林地土壤最高(58.51%),0.25~2 mm团聚体以花岗岩(62.93%)和第四纪红土(59.21%)母质发育水田和旱地土壤最高;土壤团聚体平均重量直径(MWD)和几何平均直径(GMD)以砂页岩母质发育林地土壤最高;(2)3种母质发育林地土壤团聚体有机碳及其组分主要分布在2~5 mm粒径中,水田和旱地土壤团聚体有机碳及其组分主要分布在<0.053 mm粒径中;3种母质发育林地土壤团聚体铁氧化物含量主要分布在<0.053,0.25~2 mm粒径中,水田和旱地土壤团聚体铁氧化物含量主要分布在<0.053 mm粒径中。(3)相关分析和主成分分析表明,MWD、GMD与团聚体HAC、HAC/FAC、Fe fr和Fe co呈显著相关(P<0.05);不同母质和利用方式以砂页岩母质发育的林地土壤团聚体胶结能力最好。研究表明,不同母质和利用方式土壤团聚体HAC、HAC/FAC、Fe fr和Fe co含量分布差异显著,进而影响了土壤团聚体分布和稳定性,同时砂页岩母质发育的林地土壤团聚体结构较稳定。

水分及活性有机碳驱动下水稻土中铁形态的变化

【目的】铁氧化物是水稻土中活性较高、最常见的氧化物之一,其形态易随着环境的变化而转变。水稻土中水分条件和有机质含量是影响铁氧化物转化的两个重要因素,探究土壤水分条件变化和外源活性有机碳添加条件下水稻土铁氧化物的形态变化,旨在加深对水稻土铁循环的理解。【方法】采用室内培养试验,供试水稻土采自辽宁省沈阳市沈河区。试验设置干湿交替(AWD)、持续淹水(F)和落干(FC)3种水分条件,每个水分条件下设置添加葡萄糖(+C)和不添加葡萄糖(−C)两个处理,在黑暗条件下25℃恒温培养80天。取样测定了土壤铁还原率、游离态氧化铁、络合态氧化铁、无定形态氧化铁含量,以及土壤pH和氧化还原电位(Eh)。【结果】培养80天后,土壤中无定形铁含量在持续淹水条件下增幅最大,不添加和添加葡萄糖处理分别比培养初始期增加了1.16g/kg和1.33 g/kg;在干湿交替和落干条件下,不添加葡萄糖处理的游离态铁含量分别较培养初期增长了20.57%和15.90%;在干湿交替、持续淹水、落干条件下,添加葡萄糖处理的络合态铁含量均有所增加,增幅分别为68.66%、16.09%、17.89%。土壤Eh与无定形铁、络合铁含量呈极显著负相关,与游离铁含量呈显著正相关。【结论】外源活性有机碳的添加促进了铁氧化物的络合,在干湿交替条件下,铁的络合度显著增加了75%。淹水降低土壤Eh,有利于游离态铁向络合态和无定形态转化,提高铁的活性。不论是否添加外源碳,淹水条件下土壤铁的活化度均较高,分别达到0.46和0.47。反复干湿交替促进土壤中非结晶态铁氧化物向结晶态转变,落干再淹水可显著提高铁还原率,添加外源活性有机碳后铁还原率提升更为显著,有利于提高土壤中有效铁含量。

Synthesis of Biomorphic ZrO2-CeO2 Nanostructures by Silkworm Silk Template

A simple and green technique has been developed to prepare hierarchical biomorphic ZrO2- CeO2, using silkworm silk as the template. Different from traditional immersion technics, the whole synthesis process depends more on the restriction or direction functions of the silkworm silk template. The analytic results showed that ZrO2-CeO2 exhibited a well-crystallized hierarchically interwoven hollow fiber structure with 16-28 μm in diameter. The grain size of the sample calcined at 800 ℃ was about 14 nm. Consequently, the interwoven meshwork at three dimensions is formed due to the direction of biotemplate. The action mechanism is summarily discussed here. It may bring the biomorphic ZrO2-CeO2 nanomaterials with hierarchical interwoven structures to more applications, such as catalysts.

Preparation of tetrapod-like ZnO whiskers from waste hot dipping zinc

Large and uniform tetrapod-like ZnO whiskers （T-ZnO） were prepared from waste hot dipping zinc by vapor oxidation and examined by means of X-ray diffraction and ICP-AES analysis and scanning electron microscope. The products are pure hexagonal wurtzite crystals with tetrapod shape and edge size of center body 56 μm and needle length of 100130 μm. The size and shape of ZnO particles are fully controlled by the growth conditions and T-ZnO can be obtained only at 8501 000 ℃ and total gas flow rate ranging from 40 to 250 L·h-1 in which the size of the T-ZnO particles varies slightly with temperature. The process of the formation of T-ZnO is that T-ZnO may nucleate at the initial stage with a complete tetrapod shape and develop to the large size, but not the process of （preferential） growth of octahedral nuclei and subsequent growth of the needles. The experiment presents a new method to prepare T-ZnO economically by using the waste hot dipping zinc.

Relationship Between Iron Oxides and Surface Charge Characteristics in Soils

The relationship between iron oxides and surface charge characteristics in variable charge soils ( latosol and red earth ) was studied in following three ways. ( 1 ) Remove free iron oxides ( Fed ) and amorphous iron oxides ( Feo ) from the soils with sodium dithionite and acid ammonium oxalate solution respectively. ( 2 ) Add 2% glucose ( on the basis of air-dry soil weight ) to soils and incubate under submerged condition to activate iron oxides, and then the mixtures are dehydrated and air-dried to age iron oxides. ( 3 ) Precipitate various crystalline forms of iron oxides onto kaolinite. The results showed that free iron oxides ( Fed ) were the chief carrier of variable positive charges. Of which crystalline iron oxides ( Fed-Feo ) presented mainly as discrete particles in the soils and could only play a role of the carrier of positive charges, and did little influence on negative charges. Whereas the amorphous iron oxides ( Feo ) , which presented mainly as a coating with a large specific surface area, not only had positive charges, but also blocked the negative charge sites in soils. Submerged incubation activated iron oxides in the soils, and increased the amount of amorphous iron oxides and the degree of activation of iron oxide, which resulted in the increase of positive and negative charges of soils. Dehydration and air-dry aged iron oxides in soils and decreased the amount of amorphous iron oxides and the degree of activation of iron oxide, and also led to the decrease of positive and negative charges. Both the submerged incubation and the dehydration and air-dry had no significant influence on net charges. Precipitation of iron oxides onto kaolinite markedly increased positive charges and decreased negative charges. Amorphous iron oxide having a larger surface area contributed more positive charge sites and blocked more negative charge sites in kaolinite than crystalline goethite.

Synthesis of butterfly-like BiVO4/RGO nanocomposites and their photocatalytic activities

A simple and high efficient method was proposed for the synthesis of uniform three dimensional （3D） BiVO4/reduced graphene oxide （RGO） nanocomposite photocatalyst by adopting the microwave assistant and using Bi （NO3）3·5H2O, graphene oxide （GO） and NH4VO3 as precursor. The as-obtained composites were well characterized with the aid of various techniques to study the morphology, structure, composition, optimal and electrical property. In the as-obtained composites, the GO sheets were fully reduced into RGO, and monoclinic structure BiVO4 crystallized completely into butterfly-like BiVO4 lamellas and well bonded with the RGO lamellas. The length and the width of the butterfly-like BiVO4 particle were about 1.5 μm, and the thickness of the flake was about 20 nm. Photocatalytic performances of BiVO4/RGO composite and pure BiVO4 particle have been evaluated by investigating the reduction of Cr（VI） ion-contained wastewater under simulated solar light irradiation, where the BiVO4/RGO composite displayed enhanced photocatalytic activity. It is found that the pseudo-first-order rate constants （k） for the photocatalytic reduction of Cr （VI） by BiVO4/RGO composite was about 4 times as high as that of the pure BiVO4. The present work suggested that the combination of BiVO4 and RGO displayed a remarkable synergistic effect, which led to enhanced photo-catalytic activity on Cr（VI） reduction.

Synthesis of ordered mesoporous manganese titanium composite oxide catalyst for catalytic ozonation

In this account,highly ordered mesoporous MnO_x/TiO_2composite catalysts with efficient catalytic ozonation of phenol degradation were synthesized by the sol–gel method.The surface morphology and properties of the catalysts were characterized by several analytical methods,including SEM,TEM,BET,XRD,FTIR,and XPS.Interestingly,Mn doping was found to improve the degree of order,and the ordered mesoporous structure was optimized at 3%doping.Meanwhile,MnO_xwas highly dispersed in the ordered mesoporous materials to yield good catalytic ozonation performance.Phenol could completely be degraded in 20 min and mineralized at 79%in 60 min.Thus,the catalyst greatly improved the efficiency of degradation and mineralization of phenol when compared to single O_3or O_3+TiO_2.Finally,the reaction mechanism of the catalyst was discussed and found to conform to pseudo-first-order reaction dynamics.

Synthesis of Three-Dimensional Agaric-like Biomorphic TiO_2 by a Facile Method with Coscinodiscus sp.Frustule

The paper aims to expand the application of natural marine algae. Marine diatoms, which have intricate frustule struc- tures, can serve as bio-template for preparing three-dimensional materials. A simple and effective approach to synthesize the corru- gated agaric-like biomorphic TiO2 templated with frustule of Coscinodiscus sp. is reported. In the sol-gel preparation process, the titania-coating on the frustule is prepared through the deposition and condensation with the aid of acetylacetone （acac） as a control- ling agent to make the precursor Ti（BuO）4 hydrolyze slowly. The as-prepared titania-coated frustule and biomorphic TiOz is charac- terized by scanning electron microscopy （SEM） attached with energy dispersive X-ray spectrometer （EMAX） and X-ray diffraction （XRD）. The microstructure of the corresponding titania nanoparticles appears to be sphere with the diameters distributed around 10-20nm. The templating process is repeated for three cycles. Subsequently, the three-dimensional freestanding corrugated aga- ric-like biomorphic TiO2 structure is obtained by a selective removal in the NaOH solution. As far as we known, the 3D freestanding corrugated agaric-like biomorphic TiOz with greatly increased surface area is obtained for the first time.

Mineralogical and micromorphological characteristics of Si-Fe-Mn oxyhydroxides from the PACMANUS hydrothermal field, Eastern Manus Basin

The mineralogical and micromorphological characteristics of Si-Fe-Mn oxyhydroxides from the dacite-hosted PACMANUS hydrothermal field were analyzed.The samples are poorly crystallized Si-Fe-Mn oxyhydroxides with minor birnessite, todorokite, nontronite, goethite, and opal-A.There are some microtextures which are rather like fossil microbes such as the filamentous silica and the hollow pipes.Flakes of nontronite crystals are found either forming a honeycomb texture or distrib- uted on the surface of the hollow pipes.Nontronite is the product precipitated from low-temperature hydrothermal fluids, and microbes may play a role in its formation.Si-Fe-Mn oxyhydroxides have two kinds of nuclei: Si-Mn nuclei and Si nuclei, both enveloped by the similar Si-Fe outer layer, existing in the rod-shaped oxyhydroxide and spheroidal oxyhydroxide, respectively.In the Si-Mn nuclei, the concentration of SiO2 is between 39.32 wt% and 86.31 wt%, and MnO concentration is between 4.97 wt% and 27.01 wt%, but Fe2O3 concentration is very low (0.54 wt%-3.43 wt%).In the Si nucleus the concentration of SiO2 is 90.17 wt%, but concentration of MnO and Fe2O3 are low, with 0.06 wt% and 3.47 wt%, respectively.The formation of the Si-Mn nucleus is closely related to microbes, whereas the Si nucleus is of inorganic origin.

Morphology-dependent nanocatalysis on metal oxides

The design and fabrication of solid nanomaterials are the key issues in heterogeneous catalysis to achieve desired performance. Traditionally, the main theme is to reduce the size of the catalyst particles as small as possible for maximizing the number of active sites. In recent years, the rapid advancement in materials science has enabled us to fabricate catalyst particles with tuna- ble morphology. Consequently, both size modulation and morphology control of the catalyst particles can be achieved inde- pendently or synergistically to optimize their catalytic properties. In particular, morphology control of solid catalyst particles at the nanometer level can selectively expose the reactive crystal facets, and thus drastically promote their catalytic performance. In this review, we summarize our recent work on the morphology impact of Co304, CeO2 and Fe203 nanomaterials in catalytic reactions, together with related literature on morphology-dependent nanocatalysis of metal oxides, to demonstrate the importance of tuning the shape of oxide-nanocatalysts for prompting their activity, selectivity and stability, which is a rapidly growing topic in heterogeneous catalysis. The fundamental understanding of the active sites in morphology-tunable oxides that are enclosed by reactive crystal facets is expected to direct the development of highly efficient nanocatalysts.

Surface modification of natural cellulose substances:toward functional materials and applications

Combining various synthetic chemical processes and biological assemblies provides a promising strategy for the design and fabrication of functional materials with tailored structures and properties.The unique multilevel structures and morphologies of natural cellulose substances such as ordinary commercial laboratory filter paper make them ideal platforms for the self-assemblies of various functional guest molecules that are to be deposited on the surfaces of their fine structures,and the resulting composite matters show significant potentials for various applications.The surface sol-gel process was employed to deposit ultrathin metal-oxide(e.g.,titania and zirconia)gel films to coat the cellulose nanofibers in bulk filter papers;thereafter,monolayers of specific guest substrates were immobilized onto the surfaces of the metal-oxide gel films.Highly selective,sensitive,and reversible chemosensors based on the surface modification of filter paper were obtained toward the fluorescence and colorimetric detection of various analytes such as heavy-metal ions,inorganic anions,amino acids,and gases.Cellulosebased composite materials with superhydrophobic,antibacterial,or luminescent properties were fabricated by self-assembly approaches toward practical applications.

Fabrication of ZnO with tunable morphology through a facile treatment of Zn-based coordination polymers

The morphology and structure of zinc oxide(ZnO), one of the important semiconductors, are relevant to its properties and applications. The preparation of ZnO with tunable morphology and desired structure is an attractive topic in the field of material synthesis. This work reports a facile method for the synthesis of Zn O with controllable morphology and crystal orientation using Zn-based coordination polymer particles(Zn-CPP) as precursors. Using hydrothermal method, Zn-CPP with morphologies of microrod, nanoplate, flower-like, arrow-tipped microsheet, and square cylinder were successfully synthesized via the coordination between metal ions Zn2+ and organic ligand 1,4,5,8-naphthalenetetracarboxylic dianhydride in aqueous solution. Subsequent thermal treatment of the Zn-CPP successfully resulted in the formation of porous Zn O with similar morphology to Zn-CPP. It is also found that the Zn O with enhanced(002) orientation could be obtained from Zn-CPP with preferred(002) orientation. This strategy could be extended for the preparation of other metal oxides with desired shape and structure.