| Because of the low removal efficiency of the micropollutants byconventional water treatment processes, much attention are paid to advancedwater treatment technology. Among those technologies, the heterogeneouscatalytic ozonation by transition metal has drew the focus of reaserchers.In this study, iron manganese silicate（FMS） was prepared by sol-gel method,which can enhance the O3and O3/H2O2system to remove the contaminants inwater markedly. The experimental study investigated the removal efficiency ofpCNB and different factors in FMS/O3and FMS/O3/H2O2system. It’s found thatthe removal efficiency of pCNB by FMS was low, while88.6%and98.8%ofpCNB were removed by FMS/O3and FMS/O3/H2O2system in20min respectively.Moreover, the TOC removal efficiency in FMS/O3system was10percent higherthan that in iron silicate（FS）/O3.This is because manganese in FMS increase theLewis acid sites on surface and promote the electron translocation between highand low valence of Fe or Mn, which can enhance the catalytic activity of FMS.As the high oxidation efficiency of FMS/O3/H2O2system, it can be assumed thatLewis acid sites on the surface of FMS can induce free radical chain reaction togenerate reactive species, which can oxidate organic pollutants in water rapidly.In the study of impact factors of FMS/O3and FMS/O3/H2O2system, it wasfound that the removal efficiency of pCNB by FMS/O3system increasedaccording to pH and ozone dosage raising. On the other hand, the oxidationefficiency of FMS/O3/H2O2system was affected by hydrogen peroxide dosage.But the removal efficiency of pCNB was inhibited when the molar ratio ofO3/H2O2was greater than1. Besides, the FMS catalyst can significantly promotethe decomposition of O3and H2O2in water and the bicarbonate alkalinity andtert-butanol can significantly suppress the oxidation efficiency in FMS/O3andFMS/O3/H2O2). So it can be concluded that The FMS can catalyze the O3andO3/H2O2to generate large numbers of hydroxyl radicals which can oxidate pCNBrapidly.In tap water, the removal efficiency of pCNB in FMS/O3and FMS/O3/H2O2system were inhibited in some extent because of the disinfection byproducts andpromise anions in water. In addition, the catalytic activity of FMS decreasedsince the complexation reaction between surface hydroxyl groups of FMS anddissolved silica in water. The concentration of leaching iron and manganese ionswas lower than the national drinking water standards for maximum limits in thecatalytic oxidation system. Moreover, the FMS catalyst showed high catalytic activity even after recycling for several times, indicating FMS catalyst waspractical. |
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