Abstract
Experiments using persulfate were conducted at 303-348K under normal N2 pressure to demonstrate the oxidative decomposition of four pharmaceutical products: sulfamethoxazole (SMX), trimethoprim (TMP), theophylline (TPL), and cyclophosphamide (CPA). Time variations in sample concentrations, total organic carbon (TOC) and CO2 were measured by adding persulfate of 120 molar equivalent to pharmaceutical products in 100mg/L aqueous solution in a lab-scale glass reactor.
Results showed that the pharmaceutical products were decomposed effectively by persulfate at lower temperatures. At 333K, the initial sample decomposition rates were CPA > SMX > TPL > TMP, where the CPA decomposition rate was extremely high. For complete mineralization of CPA, and for that of TMP and SMX at 333K, about 90 min and more than 400 min were needed, respectively. By contrast, TPL showed the greatest difficulty mineralizing. Its mineralization ratio was saturated at about 0.9, even after 400 min reaction time. Moreover, the mineralization ratio of SMX increased from about 0.9 to 0.98 with a rise in temperature from 333 to 348K. Nearly all carbons in SMX were converted to CO2 with no generation of CO or volatile organic matter.
