| Water is a renewable resource,and related to production and social lives.With the rapid development of industrial,the water pollution problem has been a serious threat.Especially,a series of nonbiodegradable or persistent organic compounds adversely affects the quality of human life through food chains or environmental cycles.There are many.methods for degradation of organic contaminants such as Fenton?Fenton-Like?photo-Fenton and electro-Fenton.The pH range of Fenton reaction is very narrow,the catalysts of Fenton-Like are easily contaminated,the cost of photo-Fenton and electro-Fenton reaction with low pH is high.Also the degradation rate and generation rate of hydroxyl radical is low.Thus it is important to look for methods which can efficiently degradate organic contaminants and generate hydroxyl radical with mild conditions.Our previous work has succeeded to transform nitrophenol and DNS acid to aminophenol and DSD acid.We think the iron oxide/Fe(?)system exists electron transfer,and have a "new" Fe(?)*and new electron on the surface of iron oxide.We find that the system is highly selective with fast response rate and may produce iron oxide nanoparticles.According to this,in an open system of Fe3O4/Fe(?),the electron is transfered to H2O2,H2O2 is decomposed to very active·OH,thereby increasing production efficiency of·OH.The main research work and results are summarized as follows:1?The material of Fe3O4 was prepared by the previous method of liquid catalytic phase transformation.It was characterized by XRD?SEM?IR.The results showed that:The material of Fe3O4 is spherical with a particle size of approximately 20nm.2?Methylene blue as pollutants template,we changed some factors such as the reaction temperature,pH value,adding speed,Fe(?)and H2O2 dosage.It showed there was a optimal usage.We also degradated Rhodamine B,phenol,benzoic acid,bisphenol A and other six substances,using UV-vis,HPLC and TOC instruments tracked reduction process of degradation.It showed the degradation of organic contaminants and TOC removal rate can reach about 100%.Compared with Fenton reaction,the degradation efficiency and generation of.OH improved significantly.3?The mechanism was preliminary studied.Using LC-MS to track the intermediate of Rhodamine B and benzoic acid,it showed that the structure of Rhodamine B is complex,and more difficult to degrade with many kinds of intermediate products;the structure of benzoic acid is simple and more easily degraded.Iron oxide after the reaction was characterized by XRD,SEM,IR and recycled.The results showed that the system had electron transfer.After the recycling the degradation was still able to basically reach 100%.Iron oxide/Fe(?)system which can catalyze H2O2 and degradate organic contaminants has many advantages.The condition is mild.At room temperature and pH close under neutral conditions it is able to get dose to 100%of degradation and not selective.Compared with Fenton reaction,the degradation efficiency and generation of·OH improved significantly.and therefore it has good prospects.However,the studies of this paper still have some problems.We studied only Fe3O4and Fe(?)coexisting system,in the future we should study case other iron oxide and Fe(?)syatem.During the reaction,the nascent iron oxide is still needed to study the possibility of sales as pigments.These issues are needed to be worked in the future. |
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