磁改性海泡石催化过二硫酸盐降解双酚A

为有效去除水中内分泌干扰物,采用共沉淀法合成海泡石负载纳米Fe_3O_4催化剂,催化过二硫酸盐去除水中双酚A(BPA).通过X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电镜(SEM)、透射电镜(TEM)、氮气吸脱附仪等对催化剂进行表征,考察不同温度和溶液pH对催化剂吸附性能的影响,研究催化剂和过硫酸盐投量对BPA去除效果的影响.结果表明,高比表面积的催化剂可对BPA有效吸附,平衡吸附量随着温度升高而降低,室温下可达11.6 mg/g.当催化剂投量为2 g/L、过硫酸钾(PDS)投量为4 000 mg/L、溶液pH为5时,体系可在20 min内完全降解30 mg/L的BPA.催化剂可通过外加磁场进行回收,且重复使用5次之后,60 min降解率仅下降了2.7%.机理推断认为体系内BPA的降解过程由吸附-氧化耦合反应实现,被吸附的BPA分子可在催化剂表面被生成的自由基原位降解.本研究首次将磁改性海泡石作为催化过硫酸盐的高级氧化体系催化剂使用,并认为吸附-氧化耦合式的降解途径可以有效提高自由基利用率,为去除水中痕量有机污染物的催化氧化体系设计提供了新的思路和方向.

Degradation of bisphenol A by persulfate catalyzed with magnetic-modified sepiolite

To effectively remove the endocrine disturbing chemicals in water, nano Fe₃O₄ supported on the sepiolite was prepared by the method of co-precipitation to catalyze persulfate for bisphenol A (BPA) removal. The catalyst was characterized by XRD, XPS, SEM, TEM, and N₂ sorption experiments. The adsorption capacity toward BPA was studied with different solution pH values and temperatures, and effects of catalyst and persulfate doses on BPA removal efficiency were investigated. Results show that the catalyst with high specific surface area could effectively adsorb BPA, and the equilibrium absorption amount decreased with the increase of temperature, which could reach 11.6 mg/g at room temperature. The BPA (30 mg/L) could be degraded completely within 20 minutes with the catalyst dose of 2 g/L, PDS dose of 4 000 mg/L, and solution pH of 5. The catalyst could be recycled by external magnetic field, and the removal efficiency within 60 minutes decreased only 2.7% after 5 times of recycle. The BPA degradation was accomplished by a coupled process of adsorption and oxidation, and the adsorbed BPA molecular could be oxidized in-situ on the catalyst surface, where the radicals were produced. In this study, the magnetic-modified sepiolite was applied as persulfate activator in the advanced oxidation process for the first time. The coupled process of adsorption and oxidation was considered beneficial to increase the radical efficiency, which could provide a new avenue for trace-level contaminants removal from the point of catalytic oxidation system design.