从稻草NaOH预处理液中制取低比表面积SiO_2微球

Preparation of Low Specific Surface Area SiO_2 Microsphere from NaOH-Pretreatment Liquor of Rice Straw

利用化学沉淀法从稻草NaOH预处理液中制取粒径分布均匀的低比表面积SiO_2微球。制取过程包括预处理液的稀释、盐酸溶液滴定沉出SiO_2微球、SiO_2微球煅烧3个步骤。结果表明:当稀释后的预处理液pH值调为8时,预处理液、水、乙醇的体积比决定了SiO_2微球的粒径分布,盐酸溶液的滴加速率决定了SiO_2微球的粒径大小和比表面积。最优制备条件:预处理液、水、乙醇的体积比为1∶1.5∶1,盐酸溶液的滴定速率为3mL/min。在该条件下制取的SiO_2微球平均直径约为485nm,比表面积为8.23m2/g,呈现出介孔无定形结构。

Low specific surface area SiO2 microspheres with narrow size distribution were prepared from NaOH-pretreatment liquor of rice straw with a facile precipitation process, in which three steps including the dilution of NaOH-pretreatment liquor （PTL）, the precipitation of SiO2 microspheres with HCl solution and calcination process were involved orderly. When the pH value of diluted extract is tuned to 8, the particle size distribution of the resulted silica microspheres is depended on the volume ratio of extract, water and ethanol, meanwhile, the size and the specific surface area of them are affected predominantly by the dripping rate of HCl solution. The synthesized SiO2 micro- spheres with internal mesopores have an amorphous structure with diameters of approximately 485 nm and a specific surface area of 8.23 m2/g under the optimized synthesis conditions with a volume ratio of 1 ： 1.5 ： 1 for extract/wa- ter/ethanol and HCl solution dripping rate of 3 mL/min.