【作者】 李健；

【导师】 牟占军；

【作者基本信息】 内蒙古工业大学 ， 化学工程， 2015， 硕士

【摘要】 白炭黑是一种外表呈白色、质轻、蓬松的非晶质二氧化硅,具有表面多孔结构,组成可用Si O2·n H2O来表示,其中n H2O是以表面羟基形式存在的。白炭黑常用的制备方法包括气相法、沉淀法和硅酸盐矿物分解法。前两种方法的原材料通常为硅酸钠、四氯化硅、正硅酸乙酯,成本都较高,而非金属矿则价廉易得,是一种理想的原材料。高岭土中含有的二氧化硅经高温煅烧可转化为非晶态二氧化硅,因此廉价的高岭土可以作为合成白炭黑的硅源,既降低了生产成本,又实现了高岭土的资源化、精细,提高了其附加价值。本文以高岭土为原料,高温煅烧后可与氢氧化钠溶液反应,绝大多数非晶态二氧化硅与碱液反应而进入溶液中。实验重点考察了高岭土煅烧温度、碱浸反应的碱液浓度、反应温度和反应时间对提硅效果的影响。通过单因素实验研究确定了最佳提硅条件为:煅烧温度:960℃,碱液浓度:20%,反应温度90℃;反应时间90 min。在此工艺条件下,提硅率可达60.50%。然后以提硅液为原料沉淀法制备得到了白炭黑,考察了提硅液中二氧化硅浓度、碳化温度、反应时间及陈化时间等对白炭黑的产率及DBP值的影响,得出最适反应条件:提硅液中二氧化硅浓度为12 g/L,碳化温度为90℃,反应时间为90 min,陈化时间为2 h,在此条件下合成的白炭黑DBP吸油值在2.8 m L/g以上,比表面积达到127.4 m2/g,符合国家标准。同时采用红外光谱、X射线衍射、扫描电镜等分析手段对高岭土及制备白炭黑的组成及形貌进行了表征,通过场发射扫描电镜图可以看出白炭黑粒径大约40~50 nm。以合成的白炭黑为吸附剂,考察了不同条件下,白炭黑对水溶液中钙、镁离子去除能力的影响。白炭黑用量、接触时间和溶液初始浓度对去除效果影响较大,同时反应温度、摇床转速也对钙镁离子的去除有一定的影响。常温下,当钙离子浓度为200 mg/L,白炭黑投加量为4 g/L时,去除率达到94.99%,当镁离子的浓度为100 mg/L时,白炭黑投加量为8 g/L时,去除率才达到62.32%,可见,合成的白炭黑对钙离子的去除能力明显高于镁离子。更多还原

【Abstract】 White carbon black is a kind of white appearance, qualitative light, fluffy, and porous amorphous silica materials. Its composition can be expressed as Si O2·n H2 O, wherein the n H2 O exist in the form of surface hydroxylgroups. There were three processes for preparation of white carbon black, normally includinggas-phase process, precipitation process and dissociation process. The raw materials of the fist two methods are more expensive, and the non-metallic mineral as an ideal raw material is cheaper. Kaolin,which contains a large amount of silica, was used as a silica source for the synthesis of a novel silica material.In this paper, the calcined kaolin was then treated with sodium hydroxide solution. The vast majority of amorphous silica reaction with alkali went into the solution. The effect of the calcination temperature of kaolin, alkali concentration, reaction temperature and reaction time on the silicon dissolution rate was discussed. The optimum synthetic condition is confirmed by orthogonal experiments and the optimum were as follows:calcination temperature of 960 ℃, alkali concentration of 20 %, reaction temperature of90 ℃ and reaction time 90 min. Under the optimum condition, the dissolution rate could arrive at 60.50 %. Then the desilication solution was used as raw material to synthetic silica material by the method of precipitation. The impact of solution concentration,reaction temperature and time, aging time on the preparation of amorphous silica was studied. The optimum synthetic condition were as follows: the concentration of silica in solution of 12 g/L, reaction temperature of 90 ℃, reaction time of 90 min and aging time of 2 h. Silica synthesized under these conditions can conform to the state standards. The oil absorption value and surface area of white carbon black, respectively, reached of over2.8 m L/g and 127.4 m2/g. The characteristics of the white carbon black material was analyzed by Fourier transform infrared(FTIR), X-ray diffraction(XRD) and Field emission scanning electron microscope(FESEM). The spectral results indicated that the particle size of white carbon black materials was 40-50 nm.The study of performance of the white carbon black material in removing calcium and magnesium ions from aqueous solutions showed that the silica material synthesized from kaolin have potential capability to soften the hard water. The mass of adsorbent, the contact time and initial ions concentration have a great effect on calcium and magnesium ions removal, Meanwhile, the reaction temperature and rotate speed have impact oncalcium and magnesium ions removal either. The removal rate of the white carbon black(4 g/L and 8 g/L) in the solution of calcium ions(200 mg/L) and magnesium ions(100mg/L) arrived at 94.99 % and 62.32 %, respectively. The studied white carbon black adsorbents showed a higher selectivity for calcium adsorption compared with magnesium.更多还原