Catalytic ozonation by iron coated pumice for the degradation of natural organic matters

The use of iron-coated pumice (ICP) in heterogeneous catalytic ozonation significantly enhanced the removal efficiency of natural organic matters (NOMs) in water, due to the synergistic effect of hybrid processes when compared to sole ozonation and adsorption. Multiple characterization analyses (BET, TEM, XRD, DLS, FT-IR, and pH(PZC)) were employed for a systematic investigation of the catalyst surface properties. This analysis indicated that the ICP crystal structure was alpha-FeOOH, the surface hydroxyl group of ICP was significantly increased after coating, the particle size of ICP was about 200-250 nm, the BET surface area of ICP was about 10.56 m(2) g(-1), the pH(PZC) value of ICP was about 7.13, and that enhancement by iron loading was observed in the FT-IR spectra. The contribution of surface adsorption, hydroxyl radicals, and sole ozonation to catalytic ozonation was determined as 21.29%, 66.22%, and 12.49%, respectively. The reaction kinetic analysis with tert-Butyl alcohol (TBA) was used as a radical scavenger, confirming that surface ferrous iron loading promoted the role of the hydroxyl radicals. The phosphate was used as an inorganic probe, and significantly inhibited the removal efficiency of catalytic NOM ozonation. This is an indication that the reactions which occur are more dominant in the solution phase.