水稻秸秆生物炭制备硅酸钠及白炭黑工艺研究

Research on preparation of sodium silicate and silica technology from rice straw biochar

为有效利用水稻秸秆富硅特性并解决水稻秸秆资源化利用问题,以水稻秸秆生物炭为原料,利用碱溶酸沉方法制备硅酸钠溶液并进一步生产白炭黑。通过单因素试验及中心组合设计响应面法分析硅酸钠溶液及白炭黑最佳制备条件。结果表明,在NaOH溶液浓度2 mol·L^(-1)、液料比7 mL·g^(-1)、反应温度90℃、反应时间4 h条件下水稻秸秆生物炭制得硅酸钠模数为0.69,SiO_(2)溶出率为61.3%;在反应温度80℃、硫酸溶液浓度11%、反应终点pH 9,陈化时间2 h条件下制备的白炭黑纯度为94.68%。通过X射线衍射及红外光谱分析发现制备的白炭黑为无定形水合二氧化硅结构。优化水稻秸秆生物炭制备硅酸钠以及进一步生产白炭黑最佳反应条件,对水稻秸秆高效循环利用具有较高参考价值,为低模数稻秆基硅酸钠制备高纯度白炭黑提供理论依据和技术支撑,对水稻秸秆资源化利用具有积极作用。

In order to effectively utilize the silicon-rich property of rice straw and solve the problem of resource utilization of rice straw,rice straw biochar as raw material,with the method of alkali extraction and acid precipitation to make sodium silicate was used solution,and further produce the silica.Through single factor experiment,central composite design and the response surface methodology,the optimal conditions for the preparation of sodium silicate solution and silica were analyzed.The results showed that under the conditions of concentration of NaOH was 2 mol·L^(-1),liquidsolid ratio was 7 mL·g^(-1),reaction temperature was 90℃,and reaction time was 4 h,the modulus of sodium silicate prepared from rice straw biochar was 0.69,and the dissolution rate of SiO_(2) was 61.3%;the purity quotient of silica was 94.68%,under the preparation conditions of reaction temperature was 80℃,concentration of sulfuric acid was 11%,terminal pH of reaction was 9,and aging time was 2 h.Through the analysis of X-ray diffraction and infrared spectrum,it was found that the prepared silica was of amorphous hydrated silica structure.The optimization of the optimal reaction conditions for the preparation of sodium silicate from rice straw biochar and the further production of silica had a higher reference value for the efficient cyclic utilization of rice straw.And it provided theoretical foundation and technical supports for the preparation of high-purity silica with low modulus rice straw-based sodium silicate,which also plays positive effect for the resource utilization of rice straw.