Study On The Effect Appraisal And Factor Choice Of Fenton Advanced Oxidation Processes At Room Temperature

The complexity of waste water is increasing and its harming to the environment is more and more serious because of the increasing of human activity and the ceaseless change of the environment resources,these object to the ideas of energy saving and emission reduction,environment amicably society and resources economizing society. The Fenton reagent is a unique superiority oxidation technology of kinds of advanced oxidation processes which is used in treating waste water widely and is a hot spot in environmental science and project research.But in the practice,there are high cost and low efficency in present processes because of the influencing of some factors to the Fenton reagent.So we need to analyse these factors and their influencing extents systematically which can do great benefit to the practice.Fenton reagent was selective to the organic compounds with different kinds of hydroxyl such as the hydroxyl type,hydroxyl quantity,the hydroxyl position,the length of the chain and the chain's saturation.The experimental results indicated some concludes:the monohydric phenol hydroxyl can promote the Fenton reaction,but the monohydroxy-alcohol hydroxyl suppress it fiercely;when the hydroxy compounds had the same carbon but the hydroxy quantity,their effects wound unincreased as the hydroxy quantity increasing;to the saturated monohydroxy-alcohol,the suppression became more and more obviously while the carbons of the chain were increasing;the effects of the chain's unsaturation on Fenton reaction were different:the oxidized effects were very well for the hydroxyl compounds with the phenyl but the acyclic unsaturated compounds;when the length of the chain and the hydroxyl quantity were increasing,the suppression descended and the oxidized effects were well.The free radical chain reaction in the Fenton reaction is influenced by many factors,[Fe2+] is required to control in 3mmol/L.In the phenol's system,the availably utilized ratios of H₂O₂ were not only influenced by its concentration but also the COD_Cr of this system.Generally,with the increasing of the COD_Cr, the availably utilized ratios H₂O₂ were increasing.When the COD_Cr was constant and the concentration of H₂O₂ was from 600 to 1800mg/L,there were two peaks of H₂O₂'s availably utilized ratios in one phenol and dual phenol's systems respectively,the former peaks were 11.83 and 12.99gCOD_Cr/gH₂O₂,the latter peaks were 9.01 and 11.95gCOD_Cr/gH₂O₂.In the alcohol's system,the availably utilized ratios of H₂O₂ were influenced by the concentration of H₂O₂ obviously,but not the system's COD_Cr.When the concentration of H₂O₂ was less than 300mg/L, the decomposition rate of H₂O₂ was higher by 1-3 percent in the ethanol than the control system,and the availably utilized ratios were only 0.6gCOD_Cr/gH₂O₂;with the increasing of H₂O₂,its availably utilized ratios tended to 0gCOD_Cr/gH₂O₂.In the system of 1,3 propanediol,the availably utilized ratios of H₂O₂ displayed a "inverted U",with its concentration increasing,when the concentration of H₂O₂ was less than 300mg/L,its availably utilized ratios were only 1.25gCOD_Cr/gH₂O₂; but the availably utilized ratios H₂O₂ could be up to 8.96gCOD_Cr/gH₂O₂ when the concentration H₂O₂ is 300-900mg/L,later it fell rapidly to the level of ethanol.In the mixed system,the availably utilized ratios of H₂O₂ was also influenced obiviously by the proportion of phenol and alcohol,when the proportion of ethanol was less than 60%,the H₂O₂'s availably utilized ratios stabilized in 13.0gCOD_Cr/gH₂O₂;and when its proportion surpassed 60%,it displayed the dosage dependent inhibitory action and the H₂O₂'s availably utilized ratios also tended to near 0gCOD_Cr/gH₂O₂,it was confirmed that this part of H₂O₂ could't be decomposited effectivly for the oxidizition of COD_Cr,consequently,we must pay more attention to it in engineering.The selection of Fenton was expressed by the different hydroxyl radical quantity,and the hydroxyl radical quantity can be obtained by theΔA which was detected in the method based on its reaction with thiazine.the bigger was theΔA,the more was the hydroxyl radical quantity.Under the same experimental condition,ΔAethanol <<ΔA_glycerol,ΔA₍polyvinyl alcohol_,ΔA_phenol andΔA_glycerol <ΔA_{polyvinyl alcohol},ΔA_phenol.We can conclude that ethanol suppressed the oxidation of Fenton fiercely.So the thiazine spectrophotometric analysis can be used as an effective method which estimates the suppression and the extent of suppression of different organic compands.The pulse warming can promote the oxidation effect of Fenton at room temperature,and the more increasing was the frequency,the more obvious was the promotion.