Degradation Kinetics and Pathways of Isopropyl Alcohol by Microwave-Assisted Oxidation Process
Quynh Thi Phuong Tran, Yi-Hsueh Chuang, Steve Tan, Chi-Hsu Hsieh, Tung-Yu Yang, Hsin-hsin Tung
Abstract
Isopropyl alcohol (IPA) is a significant pollutant in the wastewater of semiconductor manufacturing industry. This study investigated the degradation of IPA in the microwave (MW)-assisted oxidation process using hydrogen peroxide (H2O2) as the oxidant. Complete elimination of IPA was noted in the MW/H2O2 system within 90 min of irradiation. In comparison, only 4.8, 6.1, and 68.2% of IPA, respectively, was removed in MW irradiation alone, H2O2 oxidation, and the system using the combination of thermal (TH) and H2O2. The degradation kinetics of IPA followed the pseudo-first-order in MW/H2O2 and TH/H2O2 systems, whereas the pseudo-zero-order reaction kinetics was observed in others. The degradation rates increased on increasing the hydrogen peroxide dose to a certain level. An excess H2O2 would trap the hydroxyl radicals (•OH) to form weaker radicals that inhibit IPA oxidation. A series of degradation intermediates were identified and quantified corresponding to acetone and short-chain organic acids. Finally, the degradation pathways of IPA were proposed and validated by the total organic carbon mass balance.