介孔yolk-shell型Co_3O_4@mSiO_2纳米反应器降解水中的苯酚

Phenol degradation by mesoporous yolk-shell Co_3O_4@mSiO_2 nanoreactors

本文分别采用双溶液注射法和选择性刻蚀法合成了单核和多核两种介孔yolk-shell型Co_3O_4@mSiO_2(介孔Si O2)纳米反应器.并对比了两种纳米反应器和纳米Co_3O_4颗粒催化过一硫酸氢钾(KHSO_5)去除水中苯酚的效果.结果显示,两种纳米反应器催化KHSO_5降解苯酚的效率在相同反应条件下分别比纳米Co_3O_4颗粒提高18.8%和26.7%,说明多核型纳米反应器催化性能更好.进一步研究pH值、KHSO_5与苯酚物质的量之比n_(KHSO_5)∶n_(C_6H_6O)和材料投加量m_(cata)对苯酚降解的影响,发现多核型纳米反应器的最佳反应条件为pH=7,n_(KHSO_5)∶n_(C_6H_6O)=10∶1,m_(cata)=0.8 g·L^(-1).最后,结合催化活性和吸附实验,以及XRD、XPS、STEM、BET等手段,分析了纳米反应器的形貌、结构、元素形态和比表面积,并推断反应机理.结果显示,纳米反应器的主体结构为均匀分散的SiO_2中空微球,粒径约为300 nm,表面布满介孔,并拥有极大的比表面积,能有效吸附水中的苯酚并将其富集于纳米反应器中,同时mSiO_2微球中形成的Co_3O_4内核催化KHSO_5产生硫酸根自由基(SO_4^(·-))降解水中的苯酚,纳米反应器的吸附、富集和限域作用强化了苯酚的降解.

In this study,two solvent impregnation-reduction approach and selective etching approach were applied to synthesize two mesoporous nanoreactors, which were called sole yolk-shell Co_3O_4@ mSiO_2 nanoreactor and multi yolk-shell Co_3O_4@ mSiO_2 nanoreactor respectively. The degradation rates of phenol by the two yolk-shell Co_3O_4@ mSiO_2 nanoreactors were compared,which were 18.8% and 26.7% higher than nano Co_3O_4 particles respectively,demonstrating better catalytic performance of multi yolk-shell Co_3O_4@ mSiO_2 nanoreactor. Optimum degradation condition was investigated,and it was p H = 7,n_（KHSO_5）∶ n_（C_6H_6O）= 10 ∶ 1,m_（cata）= 0. 8 g·L^（-1） for multi yolk-shell Co_3O_4@ mSiO_2 nanoreactor. Besides,the results of catalysis experiments,adsorption experiments and the results of XRD,XPS,STEM,BET analysis were combined to characterize the structure,element valences,specific surface area and morphology of the synthesized nanoreactors,as well as toinfer the degradation mechanism. The two nanoreactors were evenly dispersed with about 300 nm particle diameter. The surfaces were full of mesoporous structures. Phenol could be effectively adsorbed and enriched in nanoreactors,and Co_3O_4 core catalyzed KHSO_5 to produce SO_4^（·-）,which degraded phenol. The adsorption,enrichment and nano-confined effect enhance the degradation of phenol.