Study Of Powder Activated Carbon Effect On Oxidation Of Fenton Reaction

The oxidation of Fenton reaction has been widely used in the degradation ofpersistent organic pollutants due to Fenton reaction can degrade most of the pollutantsinto harmless or biodegradable products, and residual reagents of the reaction withoutharm to the environment, more importantly, the cost of Fenton reagents are relativelylow.The biggest drawback of application of Fenton reagent is that hydroxyl radicalsare vulnerable to react with non-pollutants, which for in situ soil pollution andgroundwater contamination on the application of the Fenton reaction has been greatlyrestricted.Hydroxyl radical is kind of very powerful oxidant, which can react with most ofthe organic compounds and many inorganic chemicals. Therefore, the oxidation ofFenton reaction is inefficient in practical applications sometimes.In this study, for this shortcoming of non-selective oxidation of hydroxyl radicals,activated carbon may overcome it. Because of the organic matter and ferrous ions inthe solution could be absorbed by the activated carbon. So when the hydrogenperoxide reacted with the ferrous ions which absorbed on the activated carbon, thehydroxyl radicals generated in a pollutant concentrated circumstance. According tothe chemical collision theory, the possibility of reaction between the hydroxyl radicalsand organic compounds likely to be greatly increased in a pollutant concentratedcircumstance, thus from the overall, the efficiency of oxidation of Fenton reaction canbe improved.To achieve the purpose of improving oxidation efficiency of Fenton reaction,powder activated carbon was added in Fenton reaction system. The experiment resultsshowed that the powder activated carbon can improve the oxidation efficiency ofFenton reaction. Compared with Fenton system which oxidized phenol, the CODremoval growth of PAC (Powder Activated Carbon, PAC)-Fenton system was higherthan the COD removal of PAC adsorption system which only adsorbed phenol whenthe ferrous concentration was higher than0.050mM as well as the dosage of PAC was0.15g/L. When the ferrous concentration was1.0mM, the COD removal growth was 14.8%that higher than the phenol adsorption of PAC system which COD removal wasonly11.0%. The point should be mentioned was that the pollutants adsorbed by PACin PAC-Fenton system were different from in PAC system. The phenol in PAC-Fentonsystem was degraded into intermediate products which molecular weight is lower thanthe phenol.To further prove the role of activated carbon on the oxidation of Fenton reaction,the activated carbon was modified by concentrated nitric acid. The results show thatthe modified activated carbon for enhancing the efficiency of Fenton oxidationreaction is very obvious. The COD removal growth of MPAC (Modified PowderActivated Carbon, MPAC)-Fenton system can reach more than20.5%.