Xukai Li,Weirui Chen,Dongpo Liu,Gaozu Liao,Jing Wang,Yiming Tang,Laisheng Li
Due to its low interfacial electron migration ability and highly hydrophilic, Fe-MCM-41 (FeM) had poor activity and stability during catalytic ozonation . To this end, the secondary metal Zn and Si-F group were introduced into the framework of FeM to create surface potential difference and hydrophobic sites. Comparative characterizations showed that there existed rich acid sites with great potential difference on F-Fe-Zn-MCM-41 (FFeZnM). Additionally, because of the existence of hydrophobic and electron-withdrawing Si-F unit, the electron migration ability, hydrophobicity and acidity of FFeZnM were enhanced. The greater O 3 mass transfer was induced by Si-F group and O 3 was directly activated at Fe and Zn Lewis acid sites into •OH, •O 2 - and 1 O 2 . With •OH acting as main species, FFeZnM/O 3 achieved the superior IBP removal (93.4%, 30 min) and TOC removal (46.6%, 120 min) over those of sole O 3 and F-FeM/O 3 processes, respectively. HCO 3 - , Cl - , NO 3 - and SO 4 2- hindered IBP degradation by FFeZnM/O 3 , but high concentration humic acid (HA) exhibited promotion by forming HA-IBP complex. IBP degradation by FFeZnM/O 3 was enhanced with tap water , river water, and effluent from the secondary sedimentation tank of the sewage plant acting as medium. This study proposed an innovative approach to catalyst design for catalytic ozonation.
Weirui Chen,Yixiang Bao,Xukai Li,Jun Huang,Jinxin Xie,Laisheng Li
Heterogeneous catalytic ozonation had met the bottlenecks when treating low concentration but high toxic pollutants: (i) the low mass transfer efficiency of ozone and pollutants to hydrophilic catalyst; (ii) the negative impact of coexisted water matrixes. Herein, to enhance the mass transfer efficiency of reactants toward hydrophilic Fe-MCM-41 as well as enhance the interfacial reaction, the fluoride planting Fe-MCM-41 (F-Fe-MCM-41) was synthesized and employed as catalyst in catalytic ozonation for nitrobenzene (NB). Both NB and TOC removal were promoted in F-Fe-MCM-41/O 3 with 99.0 % NB removal in 60 min and 88.6 % TOC removal in 120 min, which were superior to the degradation efficiency by O 3 and Fe-MCM-41/O 3 . FTIR, EPR, Mössbauer spectra, 29 Si NMR, 19 F NMR et al verified that the replacement of non-reactive silanols (-Si−OH) of Fe-MCM-41 with Si F groups could enhance its hydrophobicity, Lewis acidity and mass transfer effect. Comparative characterizations, experiments and theoretical calculations verified that interfacial reaction played the major role over liquid phase reaction for NB degradation in F-Fe-MCM-41/O 3 . Moreover, the strengthened interfacial reaction also reduced the OH scavenging effect of water matrix, such as humic acid and carbonate. The interfacial adjustment method proposed in this study provided a novel insight into catalyst design and water treatment process.
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