| In recent years,with the development of intensive breeding mode,the widespresd use of phenylarsonic acid feed additives has threatened the safety of human life and the ecological environment.Therefore,the exploration of efficient method for the removal of phenylarsonic acid has become a major research focus of researchers.Among various removal methods,Fenton has attracted great attention because of its ability to generate highly reactive aselective free radicals.However,traditional Fenton has disadvantages such as high demand for H2O2,harsh degradation conditions and metal sludge generation.Therefore,it is urgent to develop an effective Fenton system to apply to the removal of phenylarsonic acid.In this sudy,resorcinol-formaldehyde resins(RF)with good simulated solar response ability were prepared.At the same time,iron-based catalysts(such as Fe(Ⅱ),FeS2,ect.)were used to construct an efficient Fenton system which can produce H2O2 in suit,and ROX degaradation mechanism in photo synegry system(Fe(Ⅱ)/RF and FeS2-RF)was studied.At the same time,factors influencing the degradation of ROX in different systems were thoroughly studied.The research contents and conclusions of this paper are as follows:1.In photo synegry Fe(Ⅱ)/RF system,the effects of various physical and chemical factors on the degradation of ROX were studied.The results showed that:18 μmol was the optimal dosage of Fe(Ⅱ);The concentration of H2O2 and Fe(Ⅱ)determines the ROX degradation efficiency,so light and Fe(Ⅱ)have a great influence on the degradation ability of the system,while O2 is the necessary factor for the conversion of As(Ⅲ)to As(Ⅴ).When the solution pH is 4.7,the ROX degradation efficiency is the highest.It was found that·O2-,·OH,e-and h+were reactive radicals,·O2-and h+are the main reactive radicals.Through HPLC/MS-MS identification of intermediate products,it was found that the intermediate products mainly included 2-nitrohydroquinone,2-nitrobenzene,2-hydroxy-3,2’-dinitro-diphenyl arsenic ether or 3,3’-dinitro-2,2’-dihydroxy phenylarsonic acid(isomers).These intermediate products would generate CO2 and H2O during further oxidation.Finally,the system has a broad spectrum of pollutant removal,and can achieve good degradation of pollutants and high TOC removal efficiency for various emering organic contaminants(EOCs)within 60 min.2.In photo synegry system(FeS2-RF),we invistigated the influence of various factors on the degradation of ROX,it is found that:2.0%FeS2-RF has the best degradation efficiency for ROX among various catalysts,and the system has recycling ability.When pH=2.8,the system has the best ROX degradation ability,but with the increase of pH,the ROX degradation efficiency is constantly decreasing because the ionization of FeS2 is inhabited.At the same time,in the ion influence experiment,only HCO3-inhibits the degradation of ROX in this system,resulting in low removal efficiency.The common cation has little effect on the degradation effect of the system.The higher the concentration of humic acid,the deeper the effect on the degradation efficiency of the system,which is not conducive to the degradation of ROX;Finally,through EPR and free radical scavenging experiment,it was found that·O2,·OH and e-were the main reactive radicals.·OH was the main reactive radical.Through HPLC/MS-MS,we found intermediate products such as 2-nitro hydroquinone,2-nitrobenzene quinone 2-hydroxy-3,2 ’-2 nitro-arsenic diphenyl ether or 3,3’ nitro-2,2 ’-dihydroxy phenyl arsonic acid(both isomers),and they would be transferred into CO2 and H2O in further oxidation process. |
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