介绍高岭土表面改性方法、改性机理及改性效果的表征,并简介偶联剂改性高岭土在橡胶中的应用.常用的高岭土表面改性方法有煅烧改性和偶联剂改性,表面改性提高了高岭土与有机物基体的相容性和结合力,并改善了其在有机物基体中的分散性;高岭土表面改性效果表征方法主要有沉浮法、活化指数法、有效活化指数法、浊度法、表面润湿法、特征系数法、吸附性法、材料性能测定法.研究表明,表面改性高岭土可部分或全部替代炭黑或白炭黑用作橡胶补强剂.

以钛酸丁酯为原料,以高岭土为载体,采用溶胶-凝胶法制备了铁掺杂TiO2/高岭土复合矿物光催化剂.采用XRD、IR等测试手段对铁掺杂TiO2/高岭土复合矿物光催化剂进行了表征,并通过对偶氮砷Ⅲ的降解反应,考察了其光催化活性,实验结果表明,该复合矿物光催化剂在铁的掺杂量0.75%、被降解溶液的pH值在3.5时,对偶氮砷Ⅲ的脱色率可达到100%.

The distribution characteristic of lead and cadmium in PM 10 was investigated in a fluidized bed incinerator with kaolin as sorbent to control their emissions. The low pressure impactor (LPI) and atomic absorption spectrophotometer (AAS) were used to detect the size distribution of Pb and Cd in flue gas. The scanning electron microscope/X-ray diffraction/energy disperse spectroscopy (SEM/XRD/EDS) was used to observe the surface morphology and element distribution, respectively. More than 90% of particulate Pb and 85% of particulate Cd in flue gas are enriched in submicron particles. The volatilization of Pb is significantly higher than that of Cd. The reactions of Pb and Cd with kaolin powders can induce the eutectic-melt at high temperature, and its amount increases with the temperature rising. The melted kaolin particles conglutinate to larger particles which can shift the metals in flue gas from the fine to coarse particles. The addition of kaolin can effectively absorb submicron Pb and Cd. The best absorption efficiencies are up to 80% and 50% respectively. For submicron Pb absorption, the optimum incineration temperature is 950 ℃. For submicron Cd absorption, the reaction temperature is much higher; the obvious absorption process occurs until 1 000 ℃.

采用流化床焚烧炉进行焚烧实验,研究了烟气中颗粒物形态Pb和Cd的排放规律以及炉内添加高岭土粉末对Pb、Cd排放的影响。用低压冲击器分级采集颗粒物,原子吸收分光光度计检测Pb、Cd浓度,用扫描电镜/X射线衍射/能谱仪观察高岭土吸附重金属前后表面形貌和反应物的种类并检测表面元素分布。结果表明,PM 10 中90%以上的Pb和85%以上的Cd分布在亚微米颗粒物中;在焚烧炉内,Pb比Cd更易于向PM 10 中迁移。高温下高岭土与重金属Pb、Cd蒸气反应而产生共晶融化,随温度升高融化量逐渐增加。共晶融化可以促使颗粒相互黏附,促进亚微米重金属向粗颗粒中迁移。添加高岭土可以有效控制亚微米Pb、Cd排放,对亚微米Pb的最高吸附效率达83%,对亚微米Cd的最高效率达50%。高岭土对Pb吸附效率顺序为950 ℃>1 000 ℃>850 ℃>900 ℃;高岭土与Cd反应所需的温度较高,直至1 000 ℃时才具有明显吸附效果。

As the temperature grows, the melting situation of compounds produced by reaction between Na, Pb compounds and kaolin was investigated in the melting point analyzing furnace. The adsorption experiments of Na, Pb compounds by kaolin in a lab-scale fixed bed reactor were carried out at 800, 1000 and 1200℃, respectively, to study the infiuence of different temperatures, mole ratios of kaolin/metal and Na/Pb on the reaction. The surface morphology, crystal compositions and adsorption efficiency were examined by FSEM. XRD and XRF, respectively. The experimental results showed that at about lOOOoC, melting occurred on the alone Na/kaolin and multiple NalPb/kaolin system and aggravated with presence of both Na and Pb. Moreover, the existance of Na inhibited the reaction between kaolin and Pb compounds, and the inhibition got stronger when more Na was added, or the temperature was increased. However, the effect of Pb on Na capture by kaolin was not observed obviously under the experimental conditions.

使用熔点分析仪考察了高岭土吸附Na、Pb过程中产物及高岭土原样随温度升高的熔融情况，并在管式炉中800℃、l000℃、1200℃下进行了高岭土分别及同时吸附Na、Pb的实验，研究不同温度、不同高岭土／金属摩尔比以及不同碱金属／重金属摩尔比对吸附结果的影响。使用FSEM、XRD和XRF等手段研究产物的形貌、晶体组成以及高岭土对金属的固定率等。结果表明：l000℃是Na／kaolin和Na/Pb/kaolin系统生成产物开始熔融的温度，Na、Pb同时存在时熔融现象加剧；在l000℃时Na的存在抑制了高岭土与Pb的反应，并且Na量越多，温度越高，这种抑制作用越强烈；Pb对高岭土吸附Na的影响并不显著。