Study On Preparation And Properties Of Loaded Photo-catalytic Materials Based On Iron Hydroxide

Photo-catalytic technology can be applied to environmental problems such as organic pollutants in water treatment,which has an important application prospect.Iron hydroxides are used as a common photocatalyst because of their excellent light stability,safe and non-toxic properties.But sometimes its low catalytic efficiency limits its application.In this paper,iron hydroxide was assembled on various carriers,and the composite catalyst materials based on iron hydroxide were prepared by different methods,and the properties of various materials were studied.FeOOH/SBA-15 and Ag/FeOOH/SBA-15 photo-catalysts were prepared by using mesoporous SBA-15 as the carrier.Their structures were characterized by XRD,TEM and XPS.The results showed that the prepared iron hydroxide is goethite and Ag was zero-valent silver.N2 adsorption-desorption technology test results showed that FeOOH and Ag had partially occupied the SBA-15 pores.According to the results of UV-Vis spectrophotometry,Ag/Fe OOH/SBA-15 had better response than FeOOH/SBA-15 in visible light.The experimental results showed that Ag/FeOOH/SBA-15 had better photocatalytic effect than FeOOH/SBA-15.The photocatalytic mechanism of phenol was determined by analyzing the residual pH and TOC of phenol at different times.The phenol was first degraded to intermediate products,and then converted to CO₂ and H₂O.The FeOOH/AC catalyst was prepared by using activated carbon as the carrier,and Ag/FeOOH/AC was prepared by light precipitation reduction method,and its structural properties were characterized.The effect of two kinds of naphthalene on the removal of naphthalene organic wastewater was studied.The results showed that the loaded Ag can increase the catalytic performance of the material,and the two materials could be reused for several times.With the analysis of GC-MS,the photo-catalytic mechanism of naphthalene was determined with the intermediate product of naphthoquinone,and then the small molecular organic compounds such as toluene were produced and finally mineralized to CO₂ and H₂O.The new Ag/FeOOH/mmt and FeOOH/ZnO/mmt photocatalytic materials were prepared by montmorillonite（mmt）as the carrier.Properties of the materials on the surface of montmorillonite were determined by XRD and TEM.FeOOH/mmt was used as the comparative material to study the removal effect of the two materials on pentachlorophenol.The reaction mechanism of pentachlorophenol in the photocatalytic process was divided into three steps: first,the active groups attack the substitution of chlorine,so that C-Cl was cut off;second,the intermediate products with aromatic ketones was appreared,benzene ring is open;third,the final products of a number of small molecular substances were appeared such as H₂O,CO₂,HCl and so on.The catalytic effect of Ag/FeOOH/AC,Ag/FeOOH/SBA-15 and Ag/FeOOH/mmt on the same organic matter was studied.The catalyst had the better the catalytic propertie with the larger the specific surface area.Also,the light transmission of and the material affect the catalytic propertie.The effects of the molecular size of the organic pollutants were investigated by using Ag/FeOOH/AC as the catalyst.The organic pollutants with larger molecules,with more chlorine substituents were not conducive to degrate.According to the catalytic performance of Ag/FeOOH/mmt and FeOOH/ZnO/mmt,semiconductor compound was better than noble metal.The results of free radical capture experiments showed that the holes and superoxide radicals played an important role in the degradation of organic pollutants compared with hydroxyl radicals.Combined with the principle of precious metal deposition and semiconductor recombination,the mechanism of the material in the photocatalytic reaction is discussed.