ADVANCED OXIDATION OF ACETAMINOPHEN IN WATER BY THE UV/H2O2PROCESS

FLORES MARINA; LESCANO MAIA; PASSALIA CLAUDIO; BRANDI RODOLFO; LABAS MARISOL

Praga

Congreso; EAAOP 5th Environmental Applications of Advanced Oxidation Processes; 2017

In the last decade, pharmaceuticals have been reported in the water cycle were some types of them may not be completely removed employing sewage treatments, leading to the subsequent pollution of aquatic ecosystems. Derived from data found in literature, the analgesic acetaminophen (AP) was selected for this study [1].The aim of this work is to evaluate the effectiveness of the UV/H2O2 process and study the preliminary kinetics for acetaminophen (AP) degradation in water. The main variables were studied: hydrogen peroxide (HP) concentration (0 ? 650 mg L-1) and radiation level (0 ? 100%) at constant pollutant concentration (20 mg L -1) in order to find the optimum work conditions. In addition, toxicity tests were performed during the experiments.Experimental runs were carried out in a well-stirred, annular batch reactor with a total reaction volume of 2000 cm3 and with a UV germicidal lamp (Phillips TUV 15 W emitting at 254 nm) on its central axis. The reactor has provisions for sampling, pH and temperature measurements. AP concentration was analysed by HPLC (Waters) equipped with an UV-Vis detector (λ=243 nm). The H2O2 concentration was analyzed with a spectrometric method at 350 nm employing a Boeco S-22 Spectrometer. pH was controlled with HI 88127 Hanna pHmeter. Total Organic Carbon (TOC) was measured with a Shimadzu TOC-5000A analyzer. Acute toxicity of AP was evaluated using a freshwater organism: Daphnia magna. Letal Concentration, LC50, and their respective 95% confidence limits were calculated during the process.Initially, optimum conditions were studied. It is well known that for organic pollutants, there is an optimum concentration ratio between the hydrogen peroxide and the organic substance [2]. Results have shown that there is an optimum condition for the process employing 250 mg L -1 of the oxidant. AP concentration is not detected at t= 20 minutes and TOC conversion reaches values of 13%. In 3 hours this value raise up to 72%. It can be seen that AP has a lineal rate of degradation (zero order kinetics). Then, employing the optimum condition found, experiences were carried out by varying the radiation level. It can be observed that the rate constant for AP degradation increases linearly with the radiation level and has a behaviour of first order kinetics. The linear dependence is useful in the development of the kinetic model for future purpouses. Toxicity evolution throughout the degradation process was checked on Daphnia manga indicating that the toxicity was significantly reduced after the treatment.The results revealed that UV/H2O2 exhibited high removal efficiency of AP. It can be concluded that the process is effective and feasible for AP mineralization in short time and may be use for water treatment. The small remnant toxicity confirms the capability of the UV/H2O2 process to detoxify contaminated waters.