均匀沉淀法制备纳米氧化镁工艺研究

Study on Preparation of Nanometer MgO by Homogeneous Precipitation Method

以氯化镁为原料,尿素为沉淀剂,聚乙二醇辛基苯基醚(OP-10)为表面活性剂,采用均匀沉淀法制备了纳米氧化镁。考察了镁离子浓度、反应物配比、反应温度、煅烧温度、煅烧时间对氧化镁粒径的影响。采用热重分析仪对前驱体氢氧化镁进行了表征,采用X射线衍射仪和扫描电镜对氧化镁进行了表征。结果表明,在镁离子的浓度为1.5mol/L;反应物配比为4:1;反应温度为110℃;煅烧温度为500℃;煅烧时间为3h时,所得氧化镁粒径最小,为18nm,且粒径分布均匀,晶型为立方晶系。

The content of chemical component on Bambusa chungii SCMP fiber surface before and after enzyme pre- treatment was investigated by X - ray photoelectron spectroscopy, and the reason of the improvement of bleaehabili- ty and brightness stability of SCMP pretreated by enzyme was also discussed. From analysis results, the ratio of O/ C of untreated SCMP fiber surface was 0.40, and 57.45 % and 7.57 % of fiber surface were covered by lignin and extractives. After lipase and pectinase pretreatment, the ratio of O/C of fiber surface was 0.43 and 0.41, 66.40 % and 68.10% of fiber surface were covered by lignin, and 3.05% and 2.03% were extractives, respectively. Af- ter lacease - mediator pretreatment, the ratio of O/C was 0.24, and almost all of fiber surface was covered by lig- nin. The result showed that enzyme pretreatment would remove part of extractives and more lignin would be ex- posed, which was the reason why enzyme pretreatment could improve the bleachability and brightness stability of SCMP.