【摘要】 为有效抑制纳米级Pd/Fe颗粒的团聚和钝化及改善其表面特性,将纳米SiO₂包覆在Pd/Fe颗粒表面,超声波辐照下液相还原法制备纳米级Pd/Fe@SiO₂复合颗粒,采用TEM、SEM、XRD、EDX及BET表征其物性,以2,4-二氯苯酚（2,4-DCP）为目标污染物,探究其对2,4-DCP的还原脱氯影响因素、降解机理和动力学,结果表明:制备的纳米级颗粒粒径均匀、分散性好,比表面积大;体系中纳米级Pd/Fe投加量、钯化率、TEOS投加量、反应温度及溶液初始pH均会对2,4-DCP的降解效果产生明显影响;并推测出纳米级Pd/Fe@SiO₂复合颗粒对2,4-DCP的降解机理即快速吸附—逐步脱氯—最终脱附释放,其降解符合拟一级动力学关系.更多还原

【Abstract】 To inhibit the agglomeration and passivation of Pd/Fe nanoparticles and improve its surface properties, nano-SiO₂ coated Pd/Fe particles（Pd/Fe@SiO₂ nanocomposites） were prepared via a facile liquid phase reductive method with the aid of ultrasound irradiation, and were characterized by TEM, SEM, XRD, EDX, and BET. Thereafter, the catalytic performance of Pd/Fe@SiO₂ was checked using the model reaction of 2,4-dichlorophenol（2,4-DCP） dechlorination, wherein the influential factors, degradation kinetics, and reaction mechanism were investigated. It can be found that: 1) the highly dispersed, with uniform size and large surface area of Pd/Fe@SiO₂ catalyst could be accounted for the superior activity of 2,4-DCP dechlorination; 2) several factors such as Pd/Fe nanoparticles dosage, palladium content, TEOS dosage, reaction temperature and initial pH significantly affect the degradation of 2,4-DCP; 3) the degradation of 2,4-DCP by Pd/Fe@SiO₂ nanocomposites is rapid adsorption—gradual dechlorination—final desorption. following pseudo-first-order kinetics.更多还原