Role of SiF groups in enhancing interfacial reaction of Fe-MCM-41 for pollutant removal with ozone

Abstract 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/O3 with 99.0 % NB removal in 60 min and 88.6 % TOC removal in 120 min, which were superior to the degradation efficiency by O3 and Fe-MCM-41/O3. FTIR, EPR, Mossbauer spectra, 29Si NMR, 19F 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/O3. 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.