Study On The Treatment Of Wastewater Containing Enriched Benzoic Acid By Fenton Reaction And Reclamation Of Ferric Sludge

Fenton reaction is a kind of advanced oxidation technologies applied widely in wastewater treatment,with the feature of quick response and mild conditions,which applied widely to the treating of harmful industrial organic wastewater,while the costly expenses of disposal ferric sludge,which need a special dispose as hazardous solid waste,has astirct the popularize of Fenton reaction.The disposal methods commonly used are incineration and utilization,lacking of study on the reclamation of ferric sludge,which is the key of cost down the Fenton reaction.This research presents a method of recovering the iron catalyst from the iron hydroxide sludge by high-temperature roasting,and the regenerated catalyst is applied to Fenton reaction again,which could reduce the usage amount of ferrum and lessen ferric sludge.And on this basis a new method to recycle the regenerated catalyst has been proposed using the flocculation function of ferric iron.The method is aimed at increasing the total TOC removal rate,which is not only has economic benefits,but also has the signify environment significance.Benzoic acid is choosen to be the typical pollutant as a kind of common chemical materials and chemical intermediate.This paper aims at the optimization of Fenton reaction in wastewater containing high concentrations of benzoic acid and reclamation of ferric sludge.This study identified the optimum conditions of Fenton reaction in benzoic acid solution,the incidence of conditions are compared at the same time.By adopting orthogonal experiment,it was confirmed that the three crucial effects in incidence order were:original pH>original H₂O₂ concentration>original Fe²⁺dosage.The result of single condition experiments shows the optimum conditions of Fenton reaction dealing with benzoic acid solution are:pH is 3,original H₂O₂ and Fe²⁺concentration are 15mmol/L and 10 mmol/L,with the TOC and benzoic acid removal rate were 62.3%and 64.5%respectively.The research disposes ferric sludge by baking at a high temperature to obtain regenerated catalyst.Conparing the catalytic performance of different catalysts,the catalysts in catalytic performance order were:fresh Fe²⁺catalyst>regenerated catalyst>fresh Fe³⁺catalyst.The research of baking temperature and baking time shows that lengthening baking time and rising baking temperature are in favor of the removal of organic matter adsorbed with iron sludge.The best optimum baking condition of the regenerated catalyst is on 350?for 30min,with the TOC removal rate at 61.8%when reused to Fenton reaction.Adding glucose to ferric sludge may raise the rate of Fe²⁺in regenerated catalyst.When the baking condition is 350?30min,the TOC removal rate of Fenton reaction comes up to 62.1%at the recruitant of n?glucose?/n(Fe²⁺)=0.12.The catalytic performance of regenerated catalyst dose not show a clear change in 8 times of recycle.Fe³⁺puts up a satisfactory absorbing effect with organic pollutant in wastewater,which holds an important status in the removal process in Fenton.The maximum of TOC removal rate occurs at FeCl3 dosage 15mg/L,when the concentration of benzoic acid is 2g/L,the optimum absorbing time is 30 min.This study designs a kind of Fenton-flocculation circulation method,which adds a flocculation process as pretreatment to reduce the load of pollutant in Fenton.The sediment could be baked with ferric sludge to be regenerated as catalyst.The method puts up a TOC removal rate as 75.8%at a benzoinc acid concentration at 2g/L,better than which in traditional Fenton process.