Assessment of graphite electrode on the removal of anticancer drug cytarabine via indirect electrochemical oxidation process: Kinetics & pathway study.

In this paper degradation of cytarabine drug has been studied through electrochemical oxidation process by using graphite electrode. The performance of graphite electrode on the degradation of cytarabine was evaluated by investigating the effects of key parameters: pH (3-9), current density (5-20 mA cm-2) and initial pollutant concentration (5-50 mg L-1) with 0.05 M NaCl as supporting electrolyte. Highest removal efficiency (98%) for 20 mg L-1 of initial cytarabine solution was attained within 60 min electrolysis at 10 mA cm-2. The increase in degradation rate of cytarabine was possibly because of the active chlorine species originated at anode during the electrolysis. Further, efficiency of the graphite electrodes was compared with a metal electrode (copper) and results showed that the cytarabine degradation was facilitated by the in-situ generated OH radicals. However, only 82% of cytarabine was removed after 60 min of reaction time at 15 mA cm-2. The scum of Cu2+ ions deposited on the anode surface inhibit the mass transfer among the cytarabine molecules and generated hydroxyl radicals. The kinetic study also suggests faster reaction rate at graphite (0.12 min-1) than copper (0.05 min-1) electrode. The increase in electrolyte concentration enhanced the degradation rate and decreased the energy consumption from 3.66 to 0.66 kWh m-3. Cytosine was identified as the major transformation product from the UV-Vis spectral analysis and LC-MS analysis. Further, total organic carbon analysis depicts that only 60% of the parent molecule was mineralized. Hence, graphite was found to be an efficient anode material as compared to copper for cytarabine degradation.