Photodegradation Of Nonylphenol Ethoxylate-10 Surfactant By Modified Nano-ZnO Catalysts

Nano-ZnO and Ag/ZnO, Fe3+/ZnO and SnO2/ZnO were prepared by ammonia immersion method. The crystal structure, specific surface area, surface composition and spectral characteristic were analyzed by X-ray diffraction, N2 adsorption, X-ray photoelectron spectroscopy and diffuse reflectance ultraviolet-visible spectroscopy, respectively. The photocatalytic activity of catalysts for nonylphenol ethoxylates-10 (NPE-10) degradation was studied under the irradiation with ultraviolet light and visible light.The crystal structure of nano-ZnO which was calcined at 300℃for 2h was perfect, and the particle size of ZnO increased and specific surface area decreased with the increasing of calcination temperature.In Ag-modified nano-ZnO, Ag element exists in two forms: Ag0 and Ag+. The particle size of Ag/ZnO increased and its specific surface area decreased with the increase of Ag loading. Compared with the nano-ZnO, the binding energy of Ag3d5/2 in 0.5%Ag/ZnO reduced, but the binding energy of Zn2p and O1s increased; and the contents of adsorbed oxygen and hydroxy oxygen on the surface increased remarkably. The 0.5%Ag/ZnO exhibited red shift in the absorption spectrum, and the resonance absorbing peak of Ag ion appeared in the visible region.In the Fe3+-modified nano-ZnO, Fe element exists in three forms: Fe3+, Fe2+ and Fe0. The particle size of Fe3+/ZnO decreased and its specific surface area increased with the increase of Fe3+ loading because Fe entered the crystal lattice of ZnO superseding Zn. Compared with the nano-ZnO, the binding energy of Fe2p in 0.5% Fe3+/ZnO was reduced, but the binding energy of Zn2p and O1s increased; and the contents of adsorbed oxygen and hydroxy oxygen on the surface increased. The adding of Fe element provided a intermediate energy level between the valance band and the conduction band of ZnO, which can reduced the essential energy of the electron excitation. Thus, it resulted that Fe/ZnO exhibited absorption in the visible region.In the SnO2-modified nano-ZnO composites, Sn element exists in SnO2 crystal with one form: Sn4+. The particle size of SnO2/ZnO decreased and its specific surface area increased with the increase of SnO2 loading because SnO2 had restrained the growing of the ZnO crystal. Compared with the nano-ZnO, the binding energy of Zn2p and O1s in 20% SnO2/ZnO increased, and the content of adsorbed oxygen on the surface increased. The band gap energy of ZnO had been changed and the adsorption of visible light of ZnO was enhanced because of the SnO2 adding.The optimum photocatalytic activity was obtained from 0.5%Ag/ZnO, 0.5%Fe3+/ZnO and 20%SnO2/ZnO, respectively. The extra 26% (40%), 18% (33%) and 20% (45%) degradation rate of NPE-10 could be found under 3h irradiation of ultraviolet (visible light), respectively.