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采用共沉淀法制备了磁性Fe_3O_4纳米粒子(Fe_3O_4 NPs),通过多巴胺(DA)原位氧化聚合的方式,将聚多巴胺(PDA)引入到Fe_3O_4NPs表面,制备了PDA包覆Fe_3O_4纳米粒子(Fe_3O_4@PDA NPs)。通过TEM、XRD、FTIR、XPS对粒子的形貌、结构及组成进行了表征。随后将其作为异相芬顿(Fenton)催化剂用于催化亚甲基蓝(MB)的氧化降解,对该催化剂的催化活性及稳定性进行了考察,探讨了催化反应的机理。结果表明:Fe_3O_4NPs作为催化剂时,,MB 2 h脱除率为26%,而Fe_3O_4@PDA NPs作为催化剂时,30 min,MB的脱除率为99%。具有酚醌单元的PDA可促进Fe~(3+)与Fe~(2+)间的循环,使得Fe_3O_4@PDA NPs较之Fe_3O_4NPs具有更强的催化活性。此外,Fe_3O_4@PDA NPs稳定性良好,可实现2次回收再利用,对活性降低的Fe_3O_4@PDA NPs用NaBH_4处理后,仍具有催化降解MB反应的能力。
Fe_3O_4 nanoparticles (Fe_3O_4 NPs) were prepared by coprecipitation method. PDs were introduced onto the surface of Fe_3O_4NPs via in-situ oxidative polymerization of dopamine (DA) NPs). The morphology, structure and composition of the particles were characterized by TEM, XRD, FTIR and XPS. Subsequently, it was used as a heterogeneous Fenton catalyst to catalyze the oxidative degradation of methylene blue (MB). The catalytic activity and stability of the catalyst were investigated. The mechanism of the catalytic reaction was also discussed. The results showed that the removal rate of MB 2 h was 26% when Fe_3O_4NPs was used as catalyst, and the removal rate of MB was 99% after 30 min using Fe_3O_4 @ PDA NPs as catalyst. PDAs with phenoquinone units promoted the cycling between Fe 3+ and Fe 2+, making the Fe 3+ 4 @ PDA NPs more active than Fe 3+ 4 NPs. In addition, the Fe_3O_4 @ PDA NPs have good stability and can be recycled twice, and the reduced activity of Fe_3O_4 @ PDA NPs with NaBH_4 still has the ability to catalyze the degradation of MB.