Chlorinated organic compounds have been used as solvents, degreasers and washing soulutions in many industries. These compounds are persist when released into the environment and can have adverse effects on human health. Especially trichloroethylene(TCE) that is detected most commonly in drinking water wells and 2,4-dichlorophenol(2,4-D) are highly resistant to biodegradation.
Advanced oxidation processes(AOPs) based on combination of hydrogen peroxide, ozone, ultraviolet rays and iron catalyst have the capability of total destruction of many organic pollutants. Among them, $Fe/H_2O_2$ system that combines hydrogen peroxide and iron ion as a catalyst is superior to others in cost as well as application.
In this study, 1) the pH effect in the solution, 2) optimum dosage of oxidant, 3) optimum dosage of catalyst, 4) the effects of injection patterns of reagents on the removal efficiency were investigated.
The results of this study were as follows :
1) Owing to the reaction with hydroxyl radical as a scavenger, removal efficiency under buffer condition was inferior to that under condition of initial pH. And the TCE and 2,4-D removal were most efficient under condition of initial pH 5.3 and pH 4 respectively.
2) The ratios of optimum dosage of oxidant and catalyst were as follows :
TCE : $H_2O_2$ : $Fe^{2+}$ = 1 : 1 : 1 (ppm)
2,4-D : $H_2O_2$ : $Fe^{2+}$ = 1 : 1 : 0.5 (ppm)
3) Catalytic efficiency concerning oxidation state of iron ion was that iron(II) ion was more effective than iron(III) ion.
4) Batch injection of reagent was the most efficient method, but the total efficiencies of degradation in the limited reaction time were almost same in three patterns.
