Coupling of Photoactive TiO2 and Impressed Magnetic Field for Phenol Highly Efficient Degradation

Abstract

Synergistic effect of nanosized TiO2 and impressed magnetic field (MF) was studied by investigating the photocatalytic degradation of phenol at room temperature. The introducing of MF with relatively high intensity (>0.082 T) has obvious promotion effects on phenol degradation rate (C/C 0), while negative influences of MF on C/C 0 can be observed under low-intensity MF (<0.044 T). The yield of hydroxyl radicals (·OH) in reaction processes increases with the raising of MF intensity initially and reaches the maximum concentration when the magnetic intensity is 0.082 T. The photoinduced carriers initially decrease until the MF intensity reaches at 0.024 T, and then increase with the increasing of MF intensity. The effects of MF on photoinduced carriers can be explained in terms of the Δg mechanism together with the hyperfine coupling mechanism. Low-intensity MF accelerates the recombination of electrons and holes and suppresses the generation of photoinduced carriers, which further restricts the degradation of phenol. In contrast, the presence of high-intensity MF retards the recombination of hydroxyl radicals and thus enhances the production of ·OH radicals. The generation of hydroxyl radicals is the primary factor in determining the phenol degradation process in the high-intensity MF region.