The Investigation of the Catechol Removal from Aqueous Solutions by the Oxidation Process with Ozone and Identification of Its Intermediate Products

Water and wastewater resources contamination, caused by the wastewater discharged from industries, is considered a major threat to human and environment health. Catechol is one of the usual phenolic compounds in wastewater of various industries such as oil and petrochemicals, plastics, resins, and etc, which is highly toxic and resistant to degradation. Therefore, the purpose of this study was to determine the intermediate compounds and mineralization of catechol in oxidation process with ozone.
Material and This study was a laboratory research which investigated the effect of variables such as solution pH (2-10), reaction time (0-60 min), initial concentration of catechol (50-1000 mg/l),and radical scavenger on the efficiency of ozonation process. The residual concentration of catechol was measured by HPLC at 275 nm. Also mineralization and degradation of catechol were determined by TOC (Total Organic Carbon) and COD (Chemical Oxygen Demand) tests. Intermediate compounds of ozonation process were measured by GC/MS and were presented as tables and graphs.
Optimum pH for ozonation process was 10. The maximum process efficiency at pH 10 and the contact time of 60 min was 96.20%. Kinetics of catechol degradation followed the first order model. The TOC and COD removal after the contact time of 60 minutes were determined about 78% and 84.4%, respectively. Radical scavenger of tert-butanol (1gr) and sulfate (1gr) reduced the removal efficiency of catechol 12.61% and 0.13%, respectively.
The results showed that the removal of catechol in the optimum condition such as alkaline pH has better efficiency due to the production of hydroxyl radicals. As a result, it seems ozonation process is an effective method for degradation and mineralization of catechol from industrial wastewater.