| Summary: | 碩士 === 國立屏東科技大學 === 環境工程與科學系所 === 96 === The catalyst used for traditional Fenton oxidation process is the ferrous ion form under acidic solution pHs. However, during the Fenton reaction, Fe hydroox precipitates form and the oxidation efficiency is significantly reduce. Also the Fenton reaction must be carried out under the acidic environment so it is not feasible for the soil and groundwater remediation. One of the Fenton-like process (also called the modified Fenton reaction) is the use of organic acid or chelate complexed with Fe (II) or Fe (III) as a new catalyst. A Fe (III)-organic acid A complex (named the Fe (III) complex A), developed in our previous batch study, has shown that the Fe (III) complex A can keep the iron ion exist stably in the solution and therefore maintain the oxidation efficiency.
This study continue to test the transport and catalysis of Fenton-like oxidation of benzene and toluene by the developed Fe (III) complex A in soil columns, using the optimum Fenton-like reaction condition found previously. First the results in batch experiments found that more toluene was removed by the Fenton-like oxidation catalyzed by Fe (III) complex A at 0.5% and 1% H2O2 than benzene. More toulene degradation ocuurred by the repeated H2O2 dose. The results in the column tests revealed that the Fe (III) complex A solution at Fe (III) : organic acid (A) molar ratio = 1 : 2 and 1 : 5 can transport over 120 cm. By contrast, the Fe (III) complex A solution at Fe (III) : organic acid (A) molar ratio = 1 : 1 (Fe = 2 mM) only transported less than 80 cm. Thus, it was concluded that using a lower Fe (III) concentration, with elevated organic acid A concentration can increase the Fe (III) transport distance. The gas production in soil column from the Fenton-like decay of 2% H2O2 catalyzed by the Fe (III) complex A at M/M ratio = 1 : 2 (Fe = 0.5 mM) was less than that by M/M ratio of 1: 5. The Fenton-like reaction catalyzed by the studied Fe (III) complex A at Fe (III): organic acid A molar ratio = 1 : 2 can successfully catalyze H2O2 and oxidize benzene and toluene in soil column. It was found that the Fe (III) complex A also acted as a co-solvent during transport which enhanced benzene and toluene movement in soil columns.
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