Fabrication of 3D structures via direct ink writing of kaolin/graphene oxide composite suspensions at ambient temperature

Kaolin/graphene oxide composite has been widely utilized in aero-space and architectural engineering applications due to its excellent mechanical property. Direct ink writing (DIW) is a freeform rapid prototyping technology that could be used to accurately fabricate the resulting size with complex shapes. In this study, we reported the DIW of kaolin/graphene oxide (GO) composite suspensions (KGCS) to assemble 3D structures at ambient temperature for the first time. The effects of GO on the chemical constitution and microstructure of kaolin suspensions were investigated. Rheology was characterized to ensure printability of KGCS. The addition of GO in kaolin suspensions quickened a flocculation structure, which dramatically changed their rheology properties. The DIW of 3D structures from the optimal KGCS sample maintained their initial shape without spreading. The flexural and compressive strengths of the dried optimal KGCS samples were obviously enhanced due to the improvement and reduction of the micro-defects compared from cured kaolin matrix.     

Properties of paper coated with kaolin: The influence of the rheological modifier

The first part of this paper analyses the influence of the molecular weight and concentration of carboxymethyl cellulose (CMC) and of kaolin concentration on rheology of the coating colours and on paper properties coated with ultra lightweight coatings (ULWC). In the second part, relationships between the rheological characteristics of the coating colour formulations and coated paper surface quality was also studied.New indexes on paper roughness at micro-scale are presented (RZI and SRI). In general, they show good correlation with sheet gloss. A new gloss index (SGI) is presented, accounting for the contribution of gloss from machine direction (MD) and cross direction (CD). Porosimetry was used to access microstructural characteristics in order to correlate them with light scattering and gloss properties. The former property is closely related to Hg intrusion volume of the coated layer while gloss is related to surface porosity with pore diameters in the range of 7–15 μm as measured by Hg intrusion volume.     

高岭土在碳热还原氮化过程中的相变

系统研究了苏州高岭土碳热还原氮化合成SiAlON过程在不同温度下的相变。对试样的XRD、SEM以及EDXA分析结果表明 ,1 30 0℃之前 ,试样中没有氮化物生成 ,物相为莫来石、石英和方石英 ;1 30 0℃时 ,高岭土开始发生氮化反应 ,生成过渡型SiAlON和β SiAlON。此时 ,石英和方石英相基本消失 ;1 4 0 0℃时 ,过渡型SiAlON、β SiAlON和X SiAlON三相共存 ,β SiAlON有所增多并有少量刚玉相生成 ;从 1 4 50℃到 1 550℃ ,Z值为 3的β SiAlON成为惟一的氮化产物 ,与少量SiC和刚玉相并存。莫来石在 1 50 0℃时完全消失     

高岭土熟料对焙烧后石膏混合科组织及性能的影响

本丈对以高岭土熟料为填料的石膏混合料作了一系列试验研究。用扫描电镜观察了不同焙烧温度下,试样断口显微结构的变化过程;探索了焙烧温度对石膏混合料抗弯强度、线收缩率的影响;揭示了显微结构与性能之间的内在联系;搞清了随着焙烧温度升高,高岭土填料在改善石膏混合料性能方面的作用机理。关键词:石膏型填料高岭土熟料焙烧性能     

煅烧高岭土吸附Pb^2＋／SDBS／PNP三元共存污染物的研究

对比Pb^2＋,SDBS,PNP单元和三元复合后在煅烧高岭土上的吸附,探讨了在不同投加量、吸附时间、pH值下三元共存在煅烧高岭土上的吸附影响．结果表明：Pb2＋单元去除率为94．71％,三元复合后为85．50％;SDBS单元去除率为75．36％,三元复合去除率为84．04％;PNP单元去除率和三元复合去除率分别为64．24％,55．57％．表明三元复合对Pb2＋和SDBS的去除产生拮抗效应,而三元复合对PNP起到增强吸附的作用．由IR红外分析可知煅烧高岭土吸附三元复合污染物并没有引起结构的改变,吸附过程为物理吸附．     

Ovicidal,larvicidal and insecticidal activity of strains of Beauveria bassiana (Balsamo) Vuillemin against the cigarette beetle,Lasioderma serricorne Fabricius (Coleoptera: Anobiidae), on rice grain

Seven strains of Beauveria bassiana were evaluated for their effects on the eggs of Lasioderma serricorne under laboratory conditions. Strains were applied at a single dose of 0.03 g conidia kg⁻¹ of grain = 2 × 10⁹ conidia g⁻¹ of kaolin kg⁻¹ of grain. All strains were pathogenic on the eggs of L. serricorne. Two strains, MS-8, and 7284, caused the highest levels of egg mortality. These two strains were then formulated at a fixed dose of 0.03 g conidia, with kaolin as an active carrier, at doses of 0.0, 0.5 g, 1 g, 2 g and 3 g of kaolin kg⁻¹ of grain. These powder formulations were evaluated for their effects on adult mortality, larval mortality, number of adults emerged, level of grain damaged and level of weight loss on rice grains. The highest levels of adult mortality and larval mortality were caused by Strain MS-8 at a kaolin dose of 3 g kg⁻¹. It also caused the lowest levels of adult emerged (10%), grain damaged (1.07%) and weight loss (0.55%). When unformulated, the same dose of conidia performed poorly for the same parameters (64%; 20.2%; 3.37%). The highest levels of grain damaged (27%) and weight loss (6.04%) were observed in the untreated control (UTC). Observations made with a scanning electron microscope (SEM) showed that unformulated conidia clumped together whereas conidia formulated in kaolin remained as discrete conidia.     

Biodiesel production by esterification of oleic acid over zeolite Y prepared from kaolin

Zeolite Y, with a Si/Al ratio 3.1, was prepared using Iraqi kaolin and tested as a catalyst in the liquid-phase esterification of oleic acid (a simulated free fatty acid frequently used as a model reaction for biodiesel production). XRD confirmed the presence of the characteristic faujasite structure of zeolite Y, and further analysis was conducted using BET adsorption, FTIR spectroscopy, XRF, DLS particle size and SEM. A range of experimental conditions were employed to study the reaction; alcohol/oleic acid molar ratio, temperature, and catalyst mass loading. The optimum conditions for the reaction were observed at 70 °C, 5 wt% catalyst loading and 6:1 ethanol to oleic acid molar ratio. The oleic acid conversion using the zeolite prepared from kaolin was 85% after 60 min, while the corresponding value for a commercial sample of HY zeolite was 76%. Our findings show that low Si/Al ratio zeolite Y is a suitable catalyst for esterification, which is in contrast to the widespread view of the unsuitability of zeolites, in general, for such applications.     

Cobalt loaded organic acid modified kaolin clay for the enhanced catalytic activity of hydrogen release via hydrolysis of sodium borohydride

Inorganic acids such as hydrochloric acid (HCl), nitric acid (HNO₃) and sulphuric acid (H₂SO₄) are generally used in the acid modification of clays. Here, CoB catalyst was synthesized on the acetic acid-activated kaolin support material (CH₃COOH -kaolin- CoB) with an alternative approach. This prepared catalyst, firstly, was used to catalyze the hydrolysis of NaBH₄ (NaBH₄-HR). The structure of the raw kaolin, kaolin-CH₃COOH, and CH₃COOH-kaolin-CoB samples were characterized by X-ray diffraction spectroscopy (XRD), Fourier transforms infrared spectroscopy (FTIR), scanning electron microscope (SEM), and nitrogen adsorption. At the same time, this catalyst performance was examined by Co loading, NaBH₄ concentration, NaOH concentration, temperature and reusability parameters. The end times of this hydrolysis reaction using raw kaolin-CoB and CH₃COOH-kaolin-CoB were found to be approximately 140 and 245 min, respectively. The maximum hydrogen generation rates (HGRs) obtained at temperatures 30 °C and 50 °C were 1533 and 3400 mL/min/g_catalyst, respectively. At the same time, the activation energy was found to be 49.41 kJ/mol.     

对武安高岭土除铁工艺研究

河北武安硬质高岭土粉含Fe2O31.23%，经高梯度磁选后降至0.77%，再用Na2S2O3进行还原溶解后降至0.62%，白度提高了13％，本文介绍了流程及条件试验过程和结果。     

我国高岭土精选新工艺述评

本文重点从下列几个方面介绍和分析了我国高岭土精选加工工艺的最新进展：（1）景德镇陶瓷原料──高岭土和瓷石──精选试验线（500t／a）工艺流程的研究；（2）福建龙岩某矿可生产多种不同档次高岭土产品的复合工艺流程；（3）高岭土干法加工过程中粉体密相脉冲输送的基本原理和基本流程；（4）由美国设计的湛江年产13万t高岭土项目精选工艺的基本特点和先进装备。