Cytostatic drug removal using electrochemical oxidation with BDD electrode: Degradation pathway and toxicity

• Published in: Water research (Oxford) 2018-11, Vol.144, p.235-245
• Main Authors: Siedlecka, Ewa Maria, Ofiarska, Aleksandra, Borzyszkowska, Agnieszka Fiszka, Białk-Bielińska, Anna, Stepnowski, Piotr, Pieczyńska, Aleksandra
• Format: Article
• Language: English
• Subjects: Anticancer drug; Araceae - drug effects; Boron - chemistry; Cytostatic Agents - chemistry; Cytostatic Agents - toxicity; Degradation pathway; Diamond - chemistry; Eco-toxicity; Electrochemical oxidation; Electrochemical Techniques - instrumentation; Electrochemical Techniques - methods; Electrodes; Electrolysis; Hydrogen-Ion Concentration; Hydroxyl Radical - chemistry; Oxidation-Reduction; Spectrometry, Mass, Electrospray Ionization; Temperature; Toxicity Tests - methods; Waste Disposal, Fluid - methods; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - toxicity
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2018.07.035

In the presented study, electrochemical oxidation of five anticancer drugs (5-fluorouracil (5-FU), ifosfamide (IF), cyclophosphamide (CF), methotrexate (MTX), imatinib (IMB)) using boron doped diamond (BDD) electrode was investigated. In the first step the operating parameters of electrolysis were optimized. Studies have demonstrated a significant influence of applying current density, temperature, pH of solution and initial concentration of 5-FU on the process efficiency. A comparison of the decomposition rate of all the tested drugs showed a decrease in the pseudo-first order rate constants in the following order: k(IMB) > k(MTX) > k(CF) ≈ k(IF) > k(5-FU). Mineralization current efficiency (MCE) was determined for all the drugs based on the removal amount of total organic carbon (TOC) and their values decreased in the same order as values of drug degradation rate k. Based on the identified degradation products, electrochemical oxidation pathways of the decomposed drugs were proposed. In the case of CF, IF and 5-FU the degradation process occurred mainly through ketonization, hydroxylation and dehalogenation, while MTX and IMB were decomposed by attack of hydroxyl radicals on benzyl position in parent compounds. An important part of the research was the evaluation of eco-toxicity of electrochemically treated drug solutions against Lemna minor. Toxicity of initial 5-FU and MTX solutions towards L. minor were observed but after electrochemical treatment its toxicity decreased. The opposite trend was observed for CF and IF. In this case no significant toxicity was observed for the initial solutions of these drugs, while after electrochemical treatment an increase in growth inhibition of L. minor was found. [Display omitted] •New data of electrochemical oxidation of five anticancer drugs were obtained.•CF, IF and 5-FU were more resistant to electrochemical oxidation than MTX and IMB.•Effect of current density, temperature, pH, concentration of drug were determined.•The degradation pathways for five anticancer drugs were proposed.•Toxicity of 5-FU and MTX towards L. minor decreased with degradation process.