Degradation Of Organic Pollutant By Photocatalyticreaction Of Fe(?)-EDDS System Under UV Irradiation

Photocatalytic oxidation technology is characterized with simple operation,no secondary pollution,fast degradation and high efficient.The Fe(?)-carboxylate system,a kind of common homogeneous photocatalytic system,is widely concerned and researched because of its excellent photocatalytic performance.As a metal chelators,Ethylenediamine disuccinic acid(abbreviated as EDDS)has good biodegradability properties and similar properties with polycarboxylic acid,which can combine with Fe(?)to form a stable chelate.The complex is easily photolyzed with a wide p H range.In this paper,the degradation of brilliant red X-3B and methylparaben in Fe(?)-EDDS complexes under UV irradiation was studied.The main works in this paper can be summarized as follows:(1)Fe(?)-EDDS complexes have a good response to ultraviolet light,under ultraviolet irradiation the system generates ·OH and H2O2.The p H value of the solution,Fe(?)concentration,EDDS concentration have a certain influence on the ·OHyield of the system,when Fe(?)-EDDS complex systems at lower p H conditions its have a higher light activity.With the increase of Fe(?),and EDDS,the · OH yield also increase.(2)Due to the stability of Fe(?)-EDDS complex system,the reaction can be carried out at a p H in the range of 3.0-9.0.When p H value = 3,the effect of degradation is relatively better,while photoreduction in Fe(?)-EDDS system was not obviously dependent on p H values from 5.0 to 9.0 The photooxidation of reactive brilliant red X-3B followed the pseudo first order reaction kinetics.During the photooxidation,·OH and O2-· have been produced and obviously promoted the oxidation of reactive brilliant red X-3B.The ultraviolet absorption,UV-vis,FT-IR spectra and GC-MS analysis proved that the structure of reactive brilliant red X-3B was destroyed by the photooxidation process.Through the curve of the response surface method analys Fe(?)=0.08 mmol/L,EDDS=0.18 mmol/L,p H=5.6 is the optimal conditions.(3)The photodegradation of methylparaben can be carried out during a wide p H value,methylparaben photoreduction at low p H is relatively better.Increase the concentration of both Fe(?)and EDDS can improve the degradation.Under experimental condition,the photoreaction of methylparaben followed the pseudo first order reaction kinetics.During the photooxidation,·OH have been produced and obviously promote the oxidation of methylparaben.Through the curve of the response surface method analys Fe(?)= 0.12mmol/L,EDDS =0.16mmol/L,p H= 4.18 is the optimal conditions.The GC-MS analysis proved that the structure of methylparaben was destroyed by the photooxidation rocess.Fe(?)-EDDS system of photooxidationgenerate hydroxyl free radicals,destroyed the benzene ring and oxidation into small molecule acids.