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981.
纳米二氧化锰的制备及其对亚甲基蓝的吸附研究 总被引:1,自引:0,他引:1
利用微乳液还原法,用甲苯还原KMnO4制得纳米MnO2。借助傅立叶红外光谱(FTIR)、扫描电镜(SEM)等手段对其结构性质进行了表征。通过吸附试验研究了溶液pH、煅烧温度、染料初始质量浓度对纳米MnO2吸附亚甲基蓝效果的影响。结果表明,所得纳米MnO2为球型颗粒,其粒径范围为50~80 nm,比表面积大,表面存在大量活性-OH基团,对亚甲基蓝有较强的吸附作用及较强的催化氧化降解能力;在酸性环境下,纳米MnO2对亚甲基蓝的去除能力随pH增大、煅烧温度的升高而呈现减弱趋势。pH=3时,未经煅烧的纳米MnO2对亚甲基蓝去除率高达98.4%,符合Langmuir模型。 相似文献
982.
通过化学复合镀的方法制备成催化材料,TiO2粉末与镍磷合金共沉积在泡沫镍表面上,并通过光、电催化的方法将3价砷(As(III))氧化为5价砷(As(V))进行吸附试验。结果表明,As(III)吸附在7 h后达到平衡,As(V)吸附在5 h后达到平衡;As(III)和As(V)的吸附动力学与拟2级动力学特征相一致。在光催化、电催化和光电催化3种氧化As(III)的方法中,光电催化的效果最好;当As(III)的初始质量浓度为1 mg/L时,使用光电催化方法的除砷率能达到80.76%。 相似文献
983.
984.
软粘土的次固结变形特性 总被引:5,自引:0,他引:5
在笔者所改装的应力式三轴压缩仪和一维压缩仪上,用杜湖、杭州和萧山三种粘土做了一定数量的固结试验。基于这些试验资料的分析,提出了一种新的主、次固结变形划分法,同时还探讨了固结应力和应力比对次固结系数的影响、固结后期的孔隙水压力、高载增量比对次固结变形比例的影响。根据室内外试验资料,分析了主固结阶段的粘滞蠕变效应。结果表明,主固结阶段的粘滞变形很不显著,可忽略不计。 相似文献
985.
曾义根 《南方冶金学院学报》1990,11(4):38-45
使用装有扭矩测试系统的半工业规模棒磨机,研究了磨机给矿粒度和分批作业磨矿机时间对棒磨产品粒度分布及能量消耗的影响;讨论了棒磨机中的粒度选择性磨矿现象. 相似文献
986.
紫穗槐烧碱—蒽醌浆的实验室漂白的研究表明,其白度可达到生产一般书写纸和有光纸的要求。采用常规次氯酸盐单段或次氯酸盐两段漂白,白度能达到66—70°。研究中发现,碱法紫穗槐浆的硬度对漂白的影响最大,当硬度为高锰酸钾值14~16时,其漂率相当于麦草浆的漂率。研究中还发现,选用HA—P(次氯酸盐/酸处理—过氧化氢)法漂白时,也能获得较好的白度。 相似文献
987.
曾一凡 《沈阳工业大学学报》1990,12(4):89-94
本文是单片机氢离子敏场效应管pH计的研制总结。文中论述了把单片机应用于氢离子敏场效应管pH计中的数学模型和实现方法,以及软件、硬件的组成方式等。 相似文献
988.
Isothermal crystallization kinetics and subsequent melting behavior of β‐nucleated isotactic polypropylene/graphene oxide composites with different ordered structure 下载免费PDF全文
Yansong Yu Fangxinyu Zeng Jinyao Chen Jian Kang Feng Yang Ya Cao Ming Xiang 《Polymer International》2018,67(9):1212-1220
The effects of ordered structure on isothermal crystallization kinetics and subsequent melting behavior of β‐nucleated isotactic polypropylene/graphene oxide (iPP/GO) composites were studied using differential scanning calorimetry. The ordered structure status was controlled by tuning the fusion temperature (Tf). The results showed that depending on the variation of crystallization rate, the whole Tf range could be divided into three regions: Region I (Tf > 179 °C), Region II (170 °C ≤ Tf ≤ 179 °C) and Region III (Tf < 170 °C). As Tf decreased from Region I to Region III, the crystallization rate would increase substantially at two transition points, due to the variation of the ordered structure status. Calculation of Avrami exponent n indicated that the ordered structure induced the formation of two‐dimensional growing crystallites rather than three‐dimensional growing crystallites. Moreover, in the case of isothermal crystallization, the ordered structure effect (OSE) can also greatly increase the relative content of β‐phase (βc). In Region II, OSE took place, resulting in evident increase of βc, achieving 92.4% at maximum. The variation of the isothermal crystallization temperature (Tiso) had little influence on the Tf range (Region II) of the OSE. The higher Tf in Region II was more favorable for the formation of higher βc. The ordered structure was favorable for the improvement of the nucleating efficiency of β‐nucleating agent (β‐NE), and was more effective for the improvement of lower β‐NE. © 2018 Society of Chemical Industry 相似文献
989.
Hanqin Liang Yongfeng Xia Kaihui Zuo Dongxu Yao Jinwei Yin Yuping Zeng 《International Journal of Applied Ceramic Technology》2018,15(3):653-659
Si3N4 ceramics with different BaTiO3 contents have been fabricated by pressureless sintering in a N2 atmosphere at 1680°C for 2 h. Al2O3 and Nd2O3 were used as sintering additives to promote the densification of Si3N4 ceramics. The effect of BaTiO3 addition on the densification, mechanical properties, phase compositions, microstructure, and dielectric properties of Si3N4 ceramics was investigated. The relative density and flexural strength of Si3N4 ceramics increased with the addition of BaTiO3 up to 15 wt% and then decreased, while the dielectric constant increased continuously as the BaTiO3 contents increased. The dielectric constant of Si3N4 ceramics can be tailored in the range from 8.42 to 12.96 by the addition of 5 wt%‐20 wt% BaTiO3. Meanwhile, these Si3N4 ceramics all had flexural strength higher than 500 MPa. 相似文献
990.
Assessment of conversion efficiency of Cr4+ ions by aliovalent cation additives in Cr:YAG ceramic for edge cladding 下载免费PDF全文
Xingtao Chen Yiquan Wu Zhongwen Lu Nian Wei Jianqi Qi Yanli Shi Tengfei Hua Qiang Zeng Wang Guo Tiecheng Lu 《Journal of the American Ceramic Society》2018,101(11):5098-5109
0.25at.% Cr:YAG ceramics were successfully fabricated as the edge cladding of Yb:YAG transparent ceramic slabs through vacuum sintering of co‐precipitated powders, using oxide additives to introduce different cations. The effects of various cation additives (Si4+, Ca2+, and Si4+ + Ca2+) on the conversion efficiency of Cr4+ ions and optical characteristics of the Cr:YAG edge cladding were investigated. Measurements of the absorption spectra of the Cr:YAG ceramics without any additives revealed 2 absorption bands centered at 430 nm and 600 nm, which imparted the sample with a green color. The introduction of only Si4+‐bearing additive did not promote the transition of Cr ions from the 3+ to 4+ state. Theoretical analysis and experimentation revealed that the addition of CaO not only enhanced the microstructure and improved the transmittance of the Cr:YAG ceramic, but also introduced vacancies that assisted in the formation of Cr4+ ions. It was determined that CaO has the same effect on the conversion efficiency of Cr4+ ions whether it is added as a single additive or in combination with SiO2. The underlying mechanisms by which these aliovalent cation additives influence the formation of Cr4+ ions and affect optical properties are discussed in detail. High quality composite ceramics with Yb:YAG transparent ceramic slabs and dark brown‐colored Cr4+: YAG ceramic edge cladding were achieved through the addition of 0.05 wt.% CaO to the edge cladding, with no interfacial effects between the 2 regions being observed. 相似文献