Oxidation of 2,6-dimethylaniline by fluidized-bed fention process

Abstract

Fenton reaction is a process among advanced oxidation processes (AOPs) by using hydrogen peroxide and ferrous ion as Fenton’s reagent to generate hydroxyl radicals (•OH) which is more effective to oxidize organics. The disadvantage of Fenton process is that it produces large amount of sludge. Fluidized-bed Fenton process is an alternative process to decrease iron sludge by using carriers to let iron crystallized on the surface of carrier. In this study, target compound is 2,6-dimethylaniline which is carcinogen and difficult to be degraded because of aromatic benzene with amine and 2 methyl groups. First, comparable carriers were investigated by degradation of 2,6-dimethylaniline, total iron, and ferrous ion. Efficiency of 2,6-dimethylaniline removal by using alumina dioxide was 99.13% and pH value change from 2 to 3.5 that it was different from gravel carriers. The Ca element in gravel carriers had affected pH value to change from pH 2 to 5 because carbonate in gravels dissolved in acid solution to carbon dioxide that tended to make up the alkalinity in the system. With examining the effect of pH, it was found that pH 3 was the optimum value to remove not only 2,6-dimethylaniline to 96.04% within first 5 minutes and 100% in 150 minutes, but also total iron and ferrous ion concentration. Moreover, the kinetic study was investigated by varying ferrous ion, hydrogen peroxide and 2,6-dimethylaniline concentrations. The calculation was examined from pseudo-second order in 5 minutes and the kinetics equation is proposed as followings: The optimum concentration of ferrous ion and hydrogen peroxide concentrations to degrade 1 mM of 2,6-dimethylaniline at pH 3 were 2.5 mM and 10 mM, respectively. When using this condition to compare between fluidized-bed Fenton and Fenton processes in 150 minutes, the efficiency of 2,6-dimethylaniline removal were 100% and 88.54%, respectively. Therefore, fluidized-bed Fenton process is superior to Fenton process.