纳米级Pd/Fe@SiO2复合颗粒对2,4-DCP的还原脱氯研究

Reductive dechlorination of 2,4-DCP by Pd/Fe@SiO2 nanocomposites

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.

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.