COD, TOC determination using UV spectrophotometry and its application to monitor the potassium hydrogen phthalate degradation by H2 O2 -HCO3 – oxidation system

Abstract

In this study, the COD and TOC in H₂O₂-HCO₃^– oxidation system containing potassium hydrogen phthalate were determined by UV spectrophotometry (260-310 nm). The pH and H₂O₂ concentrations were investigated as factors influencing the absorbance measurements. The obtained standard curves were Abs = (3.10±0.04)x103xCOD - (0.015±0.003) (R2=0.9996) with LOD of 5.1 mg O₂/l and LOQ of 13.6 mg O₂/l, and Abs = (0.008±0.0001)xTOC - (0.015±0.003) (R²=0.9996) with LOD of 1.6 mg/l and LOQ of 5.4 mg/l. The method was applied to monitor the degradation of potassium hydrogen phthalate by the H₂O₂-HCO₃^– oxidation system. The results revealed that the COD and TOC removal efficiencies reached ~85% after 90 minutes of UVC irradiation. The UV spectra and HPLC chromatographs showed that no aromatic compounds were obtained in the degradation products.