Na2SiO3对碱性硫脲溶液选择性溶金的影响

采用电化学方法研究Na2SiO3浓度对碱性硫脲浸金的影响和金及其常见伴生元素银、铜、镍、铁在含有Na2SiO3的碱性硫脲溶液中的电化学行为．研究结果表明：加入Na2SiO3在很大程度上提高了金的溶解电流，Na2SiO3的最佳浓度为0．15mol／L分析不同电势时lgJ与lgc(Na2SiO3)之间的关系可得：在电势为0．42V时，Na2SiO3对碱性硫脲溶液电化学溶金的促进作用最显著，含Na2SiO3的碱性硫脲溶液对金的溶解具有一定的选择性；在电势为0．58V时溶金效果最佳。金、银、镍和铁的阳极电流密度分别为2．49，1．22，1．03和0．09mA／cm^2；而同时加入Na2SiO3；和Na2SO3时碱性硫脲溶液选择性溶金的最佳电势负移至0.42V，对金的选择性溶解更为明显，金、银、铜、镍和铁的溶解电流密度依次为3．83，1．13，0．73，0．14和0．09mA／cm^2，金的溶解电流密度分别是银、铜、镍和铁的3．4，5．2，27．3和42．6倍．     

栲胶法脱硫在合成氨系统中的应用

1栲胶法脱硫反应机理 栲胶法是在碳酸钠（Na2CO3）稀碱液中添加偏钒酸钠（Na2VO3）、氧化栲胶等组成脱硫液,与原料气逆向接触吸收了硫化氢的碱性溶液经再生塔与空气氧化,使溶液再生并浮选出单质硫,溶液循环使用。反应分为4个历程进行。（1）碱性溶液吸收H2S生成HS-：Na2CO3＋H2S=NaHS＋NaHCO3。     

利用灭活啤酒酵母菌吸附溶液中铀的影响因素探讨

初步探讨了啤酒酵母菌吸附铀的特性，考察了溶液pH值、铀的初始浓度等对吸附能力的影响，得出最佳pH值为6．0，结果表明：啤酒酵母菌对铀的吸附量大，由Langmuir吸附模型得出qmax=196．1mg／g，最后研究了铀的解吸，用Na2CO3或NaHCO3解吸效果较好，解吸率分别为87．8％和87．2％。     

均相法制备文石型碳酸钙晶须

在不加入任何结晶控制剂的条件下，采用CaCl2和Na2CO3的稀溶液并加的均相反应法制得了具有较好光滑性和长径比、分布均一的文石型碳酸钙晶须。其最佳工艺条件为：CaCl2与Na2CO3溶液浓度为0．025mol／L，滴加速度为1．20ml／min，滴管直径为3mm，搅拌速度为500r／min。     

稀土修饰电极Pt - TiO2/Eu3+/C对CO电氧化的影响

为研究Pt—TiO2／C电极表面吸附稀土铕离子对CO吸附和氧化的影响,用循环伏安法研究了CO在Pt—TiO2／C,Pt-TiO2／Eu^3 ／C电极上的氧化,发现吸附稀土Eu^3 后,电极表面对CO的吸附明显减弱．CO在电极表面的氧化过电位减小,在酸性溶液中CO的起始氧化电位及氧化峰电位分别负移200mV和210mV;中性溶液中氧化峰电位负移380mV．Eu^3 在电极表面的吸附有利于CO在电极表面的氧化．     

电压对纯钛微弧氧化膜生长特性的影响

在Na2CO3Na2SiO3溶液中,利用单极性脉冲微弧氧化电源在TA2基底上制备了二氧化钛氧化膜.研究了微弧氧化电压对氧化膜生长速率、相组成及表面形貌的影响.结果表明:随着电压的升高,氧化膜的生长速率先增加后减小,表面粗糙度和微孔尺寸逐渐增大,而微孔密度逐渐减小.膜层主要由锐钛矿和金红石相TiO2组成,随着电压的增加,膜层中锐钛矿相TiO2先增加后减少,而金红石相TiO2则逐渐增加并成为主晶相.     

油膜收缩速率的测定方法

为了评价表面活性剂剥离固体表面油膜的能力,提出了采用油膜剥离速率作为评价驱油剂的一项指标,分别研究了油膜在OP类表面活性剂以及Na2CO3溶液中的收缩规律.结果表明油膜在OP-10溶液中收缩的最快,在OP-8和OP-30中的收缩速率相近,在OP-40中的油膜收缩速率最慢;在Na2CO3溶液中只有油膜的厚度发生变化,而油膜的面积并没有变化.通过分析杨氏方程可知,表面活性剂(OP)吸附在水-固界面上降低了水-固界面张力,油膜在水平力的作用下收缩;Na2CO3只改变油-水界面张力,没有降低固-液界面张力,所以油膜没有收缩,而Na2CO3与原油中的酸性物质反应,生成的表面活性物质在油膜表面分布不均匀造成了局部的界面张力梯度,从而出现厚薄不均的现象.     

氮含量和环境温度对316L不锈钢耐腐蚀性的影响

研究低温条件下腐蚀溶液温度以及钢中氮含量对316L奥氏体不锈钢耐腐蚀性能的影响,在1mol／L H2SO4＋0．5mol／L NaCl的腐蚀液中,对氮含量为0．0095％～0．5575％的316L奥氏体不锈钢进行阳极极化曲线及电化学阻抗测量。结果表明,提高氮含量,316L奥氏体不锈钢耐蚀性增强;腐蚀液温度升高,316L奥氏体不锈钢耐蚀性减弱。     

用CaO-Fe2O3-CaF2-Al2O3-Na2CO3熔剂进行铁水预处理脱磷的实验研究

用CaO-Fe2O3-CaF2-A12O3-Na2CO3渣系，不同的(CaO Na2CO3)／Fe2O3，CaF2，Na2CO3含量及以BaO部分代替Cao对铁水预处理脱磷进行了实验研究，结果表明，当脱磷熔剂中(CaO Na2CO3)／Fe2O3为0．8-1．05；CaF2含量达到8％-11％；Na2CO3用量达10％-12％；BaO配入量为10％-17％时都能取得较好脱磷效果。其脱磷率可达80％-85％。     

硫酸盐竹浆高温高压H2O2漂白工艺的研究

通过实验研究了硫酸盐竹浆高温高压过氧化氢漂白工艺．实验结果表明：高温高压过氧化氢漂白在加入4％（质量分数，下同）的H2O2，H2O2／NaOH用量比为1.3，MgSO4用量为0．5％，Na：SiO3用量为3％，控制反应温度为120℃，保温时间为60min，氧压为1．2MPa，浆浓为10％的条件下，漂后浆料白度达79．5％ISO，卡伯值达2．5，粘度为719mL／g．     

Li4SiO4高温吸碳材料的制备及性能研究

以水玻璃、碳酸锂等为原料,利用凝胶-固相反应法制备了硅酸锂高温CO2吸附材料．用差热-热重技术分析了硅酸锂材料合成过程,确定了合成温度范围,并且对恒温状态下硅酸锂吸附CO2的性能进行了研究;利用扫描电子显微镜和X射线粉末衍射技术分别观察和评价了合成材料的表面形貌与结构特征．结果表明,可在700℃、16h煅烧条件下获得纯净的正硅酸锂材料;制备出的材料在700℃下CO2吸附量最大,27min后饱和吸附量可达35％左右,高于700℃则发生CO2脱附反应．     

Microstructures and magnetic properties of [SiO2/FePt]5/Ag thin films

[SiO2/FePt]5/Ag thin films were deposited by RF magnetron sputtering on the glass substrates and post annealing at 550 ℃ for 30 min in vacuum. Vibrating sample magnetometer and X-ray diffraction analyser were applied to study the magnetic properties and microstructures of the films. The results show that without Ag underlayer [SiO2/FePt]5 films deposited onto the glass are FCC disordered; with the addition of Ag underlayer [SiO]FePt]5/Ag films are changed into L10 and （111） mixed texture. The variation of the SiO2 nonmagnetic layer thickness in [SiO2/FePt]5/Ag films indicates that SiO2-doping plays an important role in improving the order parameter and the perpendicular magnetic anisotropy, and reducing the grain size and intergrain interactions. By controlling SiO2 thickness the highly perpendicular magnetic anisotropy can be obtained in the [SiO2 （0.6 nm）/FePt （3 nm）]5/Ag （50 nm） films and highly （001）-oriented films can be obtained in the [SiO2 （2 nm）/FePt （3 nm）]5/Ag （50 nm） films.     

SiO2 Aerogels Prepared with Ambient Pressure Drying and Its Properties

SiO₂ aerogels were produced from tetraethyl orthosilicate (TEOS) as silicon resources, ethanol as solvent and watery HCl or ammonia by sol-gel method and surface modification at ambient pressure. Scanning electronic microscopy,Fourier transform infrared spectrometer (FT-IR),pore size distribution measurement, packing density and some other experiment methods were used to characterize the morphology and pore structure and other properties of the silica aerogels. The results show that the silica aerogels have a typical nano-porous microstructure with hydrophobic property. It was discovered that SiO₂ aerogels have better properties when the preparation condition is as following: the watery HCl concentration is 1%, the aging reagent is CH₃CHOHC₄H₉, the aging time is 20d, the volume concentration of trimethylchlorosilane (TMCS) in hexane is 6% and the surface modification time is 24h.     

Fabrication and characterization of SiO2（f）/Si3N4 composites

A silicon dioxide fiber-reinforced silicon nitride matrix (SiO2/Si3N4) composite used for radomes was prepared by chemi- cal vapor infiltration (CVI) process using the SiCl4-NH3-H2 system. The effects of the process conditions, including infiltration tem- perature, infiltration time, and gas flux were investigated. The energy dispersion spectra (EDS) result showed that the main elements of this composite contained Si, N, and O. The X-ray diffraction (XRD) results indicated that phases of the composite before and after treatment at 1350°C were all amorphous. A little fiber pull-out was observed on the cross section of the composite by scan electron microscope (SEM). As a result, the composite exhibited good thermal stability, but an appropriate interface was necessary between the fiber and the matrix.     

Synthesis of novel CaCO_3/Ag_2CO_3/Ag I/Ag plasmonic photocatalyst with enhanced visible light photocatalytic activity.

In this work, novel Ca CO3/Ag2CO3/Ag I/Ag plasmonic photocatalysts were successfully synthesized by a two-step in situ ion exchange process and their photocatalytic properties were studied. The morphology, crystal structure and optical properties of the as-prepared Ca CO3/Ag2CO3/Ag I/Ag nanocomposites were characterized by transmission electron microscopy(TEM), XRay diffraction(XRD), and UV-vis diffuse reflectance spectroscopy. The photocatalytic activity of the obtained nanocomposites was evaluated by the photodegradation of methyl orange(MO) under visible light irradiation. It was found that the as-prepared Ca CO3/Ag2CO3/Ag I/Ag plasmonic photocatalyst exhibits high visible light photocatalytic activity. With an optimized composition, MO dye can be decomposed by more than 94% within 15 min under visible light irradiation. Moreover, the photocatalytic stability could be greatly improved upon the addition of Na2CO3 into the photocatalytic system. From the proposed photocatalytic mechanism, the strong surface plasmon resonance effect of Ag nanoparticles and the efficient separation of photogenerated electrons and holes can effectively enhance the photocatalytic performance of the Ca CO3/Ag2CO3/ Ag I/Ag composites.     

稻草制浆中硅含量测定方法的改进

采用可见分光光度法测定稻草纤维原料及其亚铵法制浆废液中的硅含量.比较了分析纯Na2SiO3·9H2O和单晶硅标准物工作曲线的线性相关性,探讨了浸提剂种类和浸提温度对测定结果的影响.结果表明,在实验试剂用量范围内,分析纯Na2SiO3·9H2O和单晶硅标准物在680 nm处吸光度与质量浓度呈线性关系,相关系数分别为0.9...     

方铅精矿中脉石成分在Na2CO3熔盐中的 反应行为研究

为探究方铅精矿低温熔盐清洁冶金方法,在热力学分析的基础上,采用XRD分析技术,研究了方铅精矿中主要脉石成分SiO2、CaCO3、MgCO3、Al2O3等与Na2CO3熔盐的反应行为。研究结果表明:SiO2在温度高于1 173 K时会和Na2CO3反应生成Na2SiO3;CaCO3在温度高于923 K时会和Na2CO3结合成Na2Ca(CO3)2,但是其在温度高于1 123 K时又会发生分解;MgCO3在温度为873～1 123 K时会分解为MgO,但MgO不会和Na2CO3发生反应;Al2O3与Na2CO3在温度高于973 K时会发生反应,生成铝酸钠。为降低Na2CO3熔盐的消耗量,低温熔盐炼铅温度宜控制为1 073～1 173 K。     

铝酸钠溶液蒸发过程中的结垢与防垢

以氧化铝生产中种分母液为对象,研究铝酸钠溶液蒸发过程中碳酸钠和硫酸钠等杂质盐的析出行为及其影响因素。采用对比实验法,研究防垢添加剂对减缓铝酸钠溶液蒸发过程中加热面结垢的影响。研究结果表明：随着苛性碱浓度的升高,铝酸钠溶液中碳酸钠和硫酸钠的平衡浓度明显降低：随着温度降低,碳酸钠和硫酸钠的平衡浓度下降;根据实验结果提出铝酸钠溶液中碳酸钠和硫酸钠平衡浓度与氢氧化钠浓度、温度等因素的定量变化关系式：GR-12、GR-3、GR-4等添加剂防垢效果明显,可降低结垢量60％-70％,有效减缓加热面结垢的形成速度,并抑制溶液中硅的析出。     

Formation of Ca3SiO5 prepared by electric and microwave burning

A new method of sintering Ca3SiO5 by the combination of conventional and microwave heating methods was studied. The influence of transitional metal oxides such as Fe2O3, Cr2O3, MnO2, and V2O5 used as the additive of microwave absorption on the microwave-promoted burning of Ca3SiO5 was investigated. The experimental results indicate that the new burning technique is capa-ble of promoting the sintering of Ca3SiO5. At 1200-1300°C in an electric furnace, Ca3SiO5 can be obtained only when the sample is heated in a microwave for 110-240 s, and the free lime content is below 40wt%. Based on the experiments, Fe2O3, Cr2O3, MnO2, and V2O5 can enhance microwave sintering. Amongst them, Cr2O3 is the most effective. The characteristic of the X-ray diffraction peaks of Ca3SiO5 is similar to those of standard Ca3SiO5, but the peaks are wider.