冶炼副产物中金银的富集新工艺

甘油在有碱参与的条件下能与三氧化二锑很好地发生反应,生成甘油亚锑酸钠,溶液在一定的碱浓度下保持稳定。氧化铜、氧化铋、氧化铅也能反应生成双金属醇盐,而氧化态的银被还原生成金属银。用甘油、木糖醇等低炭多元醇的强碱水溶液处理复杂的含Au、Ag物料时,贱金属氧化物生成双金属醇盐溶解脱除的同时,Au、Ag等贵金属被富集在渣中。可用电沉积或中和水解的方法从醇盐溶液中回收各种有价金属,并实现甘油等低炭多元醇的循环再生,为处理复杂的含金银物料提供了1种新方法。     

SiO2纳米流体粘度研究

利用醇盐水解法制备了单分散球形SiO2纳米流体,通过改变不同的参数条件控制颗粒尺寸大小,经透射电镜(TEM)和激光粒度仪分析,其粒度结果一致.在此基础上,对不同粒度和浓度条件下流体的粘度进行了试验研究和理论分析,发现在相同浓度的条件下,随着颗粒尺寸的减小,流体粘度递增.同时我们对低浓度下悬浮液粘度计算公式进行了修正,得到了新的实验关联式,修正式与试验值的最大偏差不超过5%.     

锐钛矿型纳米TiO2粉体的纯净制备

以钛酸丁酯为原料,采用可控醇盐水解沉淀法制得TiO2前驱体,450℃恒温煅烧2h后制备出粒径约10nm的纳米TiO2粉体,并与传统溶胶-凝胶法制备的TiO2纳米粉体的形貌、结构、工艺过程进行了对比.结果表明,可控醇盐水解沉淀法可制得纯度高、粒径小且分布范围窄的纳米TiO2粉体,工艺简单,流程最短.该方法的关键是实现了醇盐的可控水解.     

Tuning the morphology of PVDF membranes using inorganic clusters for oil/water separation

Polyvinylidene fluoride (PVDF) membranes with modified membrane morphology were prepared by phase inversion process using iron alkoxide as a novel pore-forming additive (PFA). Higher pure water flux was observed for PVDF/PFA (iron alkoxide) membranes treated with 5% HCl, due to higher porosity produced by the leaching out of the iron alkoxide additive. The untreated membrane containing 0.04% iron alkoxide showed ~99% efficiency oil removal from a surfactant-stabilized oil–water emulsion. After acid treatment, there was a slight decrease in the rejection efficiency (~96.5%); however, this membrane still exhibited the highest emulsion flux. The fouling propensity of the membrane with 0.04 wt % iron alkoxide tested in a crossflow condition decreases indicating a lower amount of oil adsorbed onto the surface and a greater flux recovery ratio. The treated membranes showed appreciable anti-biofouling property when the membranes were challenged with Escherichia coli and Bacillus subtilis obtained from freshwater and/or seawater. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47641.     

Wear behavior and microstructure of alumina-mullite-zirconia composites prepared by a novel method: Coating of zircon powder by aluminum alkoxide

The formation of the mullite phase is the main challenge in the preparation of alumina-mullite-zirconia (AMZ) composites. To overcome this limitation, a novel method based on the coating of zircon powder with aluminum alkoxide was proposed in this study. Reaction sintering of alumina and coated zircon was carried out at 1630 °C for 3 h. The microstructural, physical, mechanical, and tribological properties of samples were compared with the conventional AMZ composites prepared by common mixing of alumina and zircon. The microstructural analysis indicated the higher alumina phase of the sample prepared with the conventional method. On contrary, the samples prepared with the proposed method included higher percentages of mullite phase. In terms of mechanical properties, the conventional AMZ samples performed better. However, due to the beneficial effect of the mullite phase in tribological applications, the samples prepared with this new method show superior wear resistance. Especially, the samples prepared from 30 wt% aluminum alkoxide exhibited the best wear resistance. The delamination and adhesive wear mechanisms govern the wear process.     

Fabrication of Lanthanum Manganese Oxide Thin Films on Yttria-Stabilized Zirconia Substrates by a Chemically Modified Alkoxide Method

Perovskite-type thin films of lanthanum manganese oxide (LaMnO₃) were prepared on yttria (8%) stabilized zirconia substrate by the sol–gel process from an alkoxide solution of lanthanum isopropoxide (La(O- i -C₃H₇)₃) and manganese isopropoxide (Mn(O- i -C₃H₇)₂). The alkoxide solution was chelated with 2-ethyacetoacetate, and further modified with polyethylene glycol (PEG). The obtained LaMnO₃ thin film was transparent and macroscopically crackless. X-ray diffraction, differential thermal analysis–thermogravimetry analysis, and scanning electron microscope observations indicated that single-phase LaMnO₃ thin films with a grain size of 80 to 100 nm are formed when a spin-coated LaMnO₃ gelled film is heated at 600°C for 1 h. The porous and homogeneous grain structure with a grain size of <100 nm can be obtained when the LaMnO₃ gelled film is heated at 600° and 800°C. It was considered that PEG might accelerate the crystallization of the perovskite phase, which indicates that PEG assists the formation of the La-O-Mn frame network during partial hydrolysis and condensation reactions in sol–gel processes.     

Effects of Complex Precursors on Alkoxide-Derived Cordierite Powder

Preparation of chemically homogeneous cordierite powders of submicrometer size was investigated using alkoxide precursors, synthesized from Mg metal, Al(OBu^s)₃, and partially prehydrolyzed Si(OEt)₄. The amount of partial prehydrolysis water in precursor synthesis was changed to study the effects on the hydrolysis products. In the hydrolysis of the diluted solution of the precursor, product morphology was quite sensitive to the precursor, and different morphologies such as gelation, gel precipitation, and powder precipitation were observed. A redispersable powder of submicrometer size was obtained only from the precursor synthesized at a H₂O/Si(OEt)₄ ratio of 1.2. Differences were also observed in minor crystalline phases among calcined hydrolysis products. The alkoxide precursors were characterized using Raman spectroscopy, gas chromatography, and NMR spectroscopy. The differences in hydrolysis products are most likely due to differences in hydrolysis and condensation of different chemical species in precursors.     

Formation of inorganic (TaC,TaN) fibers by thermal decomposition of cellulose acetate–tantalum alkoxide precursor gel fibers

Precursor gel fiber was formed by extruding cellulose acetate spinning solution into Tantalum (Ta) pentaethoxide acetone solution in a coagulation bath. Gel formation must be due to the coordination of Ta to OH and CO groups on the pyranose ring. The resultant precursor gel fiber was converted into carbide (TaC) or nitride (TaN) fibers by pyrolyzing them in Ar, N₂, or NH₃ atmospheres. TaC and TaN fibers can be obtained near theoretical temperatures calculated from thermodynamics data. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4320–4324, 2006     

稀土金属甲醇盐的制备及表征

以碱土金属钙醇盐为烷氧基提供者,与无水稀土乙酸盐(乙酸镧、乙酸镨、乙酸钕、乙酸钐)在芳香族类溶剂体系中60℃回流加热反应6h～8h,合成出稀土金属(La、Pr、Nd、Sm)甲醇盐。样品红外光谱表明,在1035cm-1左右出现了甲氧基与稀土元素键合的C-O-Ln键的特征吸收峰,紫外-可见谱中出现的三价稀土离子的特征吸收峰,进一步证实了样品为稀土甲醇盐。     

三氯化钇-异丙醇加合物合成异丙醇钇的研究

采用Y2 O3 为原料先制得无水YCl3 然后与异丙醇反应生成YCl3·3C3H7OH加合物 ,并采用自制异丙醇钠与之反应制备得到异丙醇钇 ,反应的最佳条件为 80℃回流 3～ 4小时 ,然后静置 12h以便NaCl的分离。在YCl3·6H2 O脱水制备YCl3 的过程中 ,采用醋酸酐脱水法 ,具有方法简单 ,污染小 ,且易于操作等特点