微波辐射稻壳灰制纳米SiO_2

Research on the Preparation of Nano Silica from Rice Husk Ash with Microwave Treatment

[目的]研究稻壳灰制备纳米SiO2的方法,为稻壳灰综合利用提供参考。[方法]在微波辐射条件下,采用稻壳灰为原料制备出硅酸钠。而后,又以这种硅酸钠为原料,用化学沉淀法制备出纳米SiO2。[结果]研究了焙烧温度、表面活性剂的用量及溶液pH值对纳米SiO2粒径的影响。硅酸的聚合速度与溶液的pH值有很大关系,而聚合速度直接影响到硅酸的分子量,进而影响SiO2的粒径,溶液pH值在5~6最好;焙烧温度对SiO2的粒径及形貌有较大影响,温度高了,团聚多,形貌不好;表面活性剂的用量需达到一定值才可防止粒子团聚。结果表明：在PEG添加量为≥0.15 g时,经过600℃焙烧后,可制备近似球形的纳米SiO2。[结论]利用微波辐射提取稻壳灰中的SiO2,通过化学沉淀法可制备近似球形的纳米SiO2。该方法操作简单,易于工业化,有利于稻谷壳灰的综合利用。

[Objective] The reference for the comprehensive utilization of rice husk ash was provided through the research on the preparing method of the silica nano from rice husk ash.[Method] The sodium silicate was prepared with rice husk ash as raw material under the condition of microwave radiation;and then,the nano silica was prepared with sodium silicate as the raw material by means of the method chemical precipitation.[Results] The effect of the calcination temperature,the amount of surfactant and the pH value of solution on the size of nano-silica particle was researched.The polymerization rate of silicic acid,which directly affected the molecular weight of silicic acid,resulting in the size of silica particle,was great related to the pH value of solution;and the best pH value of solution was 5-6.The size and morphology of silica particle were greatly affected by the calcination temperature;and many more reunites appeared,resulting in the bad shape,if the temperature was a little high.The agglomeration of particle could be prevented unless the amount of surfactant required had been achieved at a certain value.The results showed that the spherical nano-silica could be prepared from rice husk ash when the PEG addition level was ≥ 0.15 g and after it was calcined at 600 ℃.[Conclusion] The silica could be extracted from rice husk ash with the microwave radiation and the spherical nano-silica could be prepared by means of chemical precipitation.The method was simple and easy in its industrialization,and also was conducive to the comprehensive utilization of rice husk ash.