草酸锌纳米粒子的合成动力学研究

以微乳液和均匀沉淀耦合法制备出纳米草酸锌粒子。为了研究纳米粒子生长的动力学特征，用稀释法求取了该过程所涉及的NP-9／正己醇／正庚烷／硝酸锌溶液微乳液体系的水核半径：检测了草酸二甲酯与硝酸锌的沉淀反应过程中浓度随时间的变化，建立了草酸二甲酯水解的动力学方程。根据微乳液法制备纳米粒子的扩散机理，推导出纳米粒子的粒径与反应时间的关系式，并将计算所得粒径与实验值进行对比。结果表明：NP-9／正己醇／正庚烷／硝酸锌溶液微乳液体系的水核半径在308K和318K分别为186nm和233nm，可以作为制备纳米粒子的微反应器。在有沉淀反应发生时，草酸二甲酯的水解为一级反应；草酸锌纳米粒子粒径的实验值比计算值大15～30倍，其生长的动力学过程可依照碰撞-融合-分裂机理解释。

Studies on the Kinetics of Synthesis of Zinc Oxalate Nanoparticles

Zinc oxalate nanoparticles were synthesized from the coupling route of microemulsion and homogeneous precipitation. To probe in the kinetic features of the growth of zinc oxalate nanoparticles, the radius of the water droplet of NP-9/hexanol/heptane/zinc nitrate solution microemulsion was inspected through diluting method; the variation of the concentration of methyl oxalate with time in the precipitation reaction was tested, and the kinetic equation of the hydrolysis of methyl oxalate was established. According to the diffusion mechanism, the relation of the size of nanoparticles to reaction time was derived, and the calculated size was compared with the experimental one. The results show that the radius of water droplet of NP-9/hexanol/heptane/zinc nitrate solution microemulsion at 308 K and 318 K is 1.86 nm and 2.33 nm respectively, and such microemulsion is a good medium for the synthesis of nanoparticles. When the precipitation reaction of methyl oxalate exists, the hydrolysis of methyl oxalate is a first order reaction. The calculated size of zinc oxalate nanoparticles was 15 to 30 times smaller than the experimental value. The kinetic process of nanoparticle growth mainly followed with the collision-fusion-cleavage mechanism in this work.