Study On The Degradation Of Organic Pollutants In Water By Fenton-like Reaction In The Presence Of Chelate

Fenton/Fenton-like oxidation process has been widely used in wastewater pretreatment and advanced treatment. However, the Fenton/Fenton-like oxidation process has some disadvantages such as low suitable p H value, the conversion rate from Fe(III) to Fe(II) is low, and the low utilization rate of Fe(II). Ethylenediaminetetraacetic acid(EDTA), Nitrilotriacetic acid(NTA) can form complexes with Fe3+/Fe2+ which is stable in neutral or weak alkaline aqueous solution and can ensure the concentration of soluble Fe(III)/Fe(II). Heterocyclic aromatic derivatives represent atrazine( AT) and benzene ring arene derivatives on behalf of nitrobenzene(NB) as ordinary organic chemical raw materials and chemical products, production wastewater, Fenton/Fenton-like oxidation process is an ideal method for degradation of them. In this study, wastewater has been composed with NTA, EDTA, NB or AT, Fe2(SO4)3 and H2O2 was composed to Fenton-like system to research the effects of different chelate on the degradation of organic compounds by Fenton-like reaction and the effcts of the degradation of different organic compound.The results of the experiment of the degradaiton of AT by Fenton-like with chelate indicate:(1) the presence of complexing agent to improve the p H value of Fenton-like reaction, in p H=7 or 9, the degradation efficiency of AT is higher obvious compared to Fenton-like reaction with no chelate.(2) In the presence of EDTA and NTA, the degradation efficiency of AT increased with the increase of p H value at p H=3~9. This is due to the structure of Fe(III) complex has chaged with the increase of the p H value, which makes it easier to be more complex with hydrogen peroxide. And H2O2 degradation easier in the high p H value.(3) Becaues of the difference of shape distribution with p H and space structure of between FeIIIEDTA and FeIIINTA the efficienvy of Fenton-like with NTA is better than which with EDTA on the degradation of AT.(4) The initial concentration of hydrogen peroxide has different effects on Fenton EDTA and NTA Fenton-like system.(5) The increase of the concentration of tert butyl alcohol in the reaction system prevent the degradation of AT obviously, which indicates that the main active species of EDTA and NTA in the presence of Fenton-like degradation of organic compounds are hydroxyl radicals.(6) FeIIINTA and FeIIIEDTA in the process of degradation of the AT themselves are decomposed, FeIIIEDTA can be decomposed into FeIIINTA, will speed up the reaction rate.The effects of NTA on the degradation of differe nt organic compounds by Fenton-like reaction showed that:(1) Because of the efficiency of intermediate product of NB and the structure difference, the influence of p H value on AT is higher,(2) for the degradation of AT and NB, the effects of the other factors except the initial concentration of NTA were similar;(3) the d egradation of NB was the same as that of the intermediate products of the degrad ation of nitrobenzene by Fenton-like reaction degradation.(4) intermediate product from the decomposition of NB has no obvious self catalysis effection on the reaction of Fenton-like, which indicates that the NTA has hindered the contact between Fe(III) and intermediate products.