Abstract
In this work, the degradation of chloroquine (CLQ), an antiviral and antimalarial drug, using electro-Fenton oxidation was investigated. Due to the importance of hydrogen peroxide (H2O2) generation during electro-Fenton oxidation, effects of pH, current density, molecular oxygen (O2) flow rate, and anode material on H2O2 generation were evaluated. H2O2 generation was enhanced by increasing the current density up to 60 mA/cm2 and the O2 flow rate up to 80 mL/min at pH 3.0 and using carbon felt cathode and boron-doped diamond (BDD) anode. Electro-Fenton-BDD oxidation achieved the total CLQ depletion and 92% total organic carbon (TOC) removal. Electro-Fenton-BDD oxidation was more effective than electro-Fenton-Pt and anodic oxidation using Pt and BDD anodes. The efficiency of CLQ depletion by electro-Fenton-BDD oxidation raises by increasing the current density and Fe2+ dose; however it drops with the increase of pH and CLQ concentration. CLQ depletion follows a pseudo-first order kinetics in all the experiments. The identification of CLQ degradation intermediates by chromatography methods confirms the formation of 7-chloro-4-quinolinamine, oxamic, and oxalic acids. Quantitative amounts of chlorides, nitrates, and ammonium ions are released during electro-Fenton oxidation of CLQ. The high efficiency of electro-Fenton oxidation derives from the generation of hydroxyl radicals from the catalytic decomposition of H2O2 by Fe2+ in solution, and the electrogeneration of hydroxyl and sulfates radicals and other strong oxidants (persulfates) from the oxidation of the electrolyte at the surface BDD anode. Electro-Fenton oxidation has the potential to be an alternative method for treating wastewaters contaminated with CLQ and its derivatives.
Highlights
Chloroquine (CLQ), a generic pharmaceutical drug, is recommended as the primary antimalarial prevention drug (Frosch et al, 2011; Lee et al, 2011; Price et al, 2014) and to treat diseases such as amoebic dysentery (Singh et al, 2011, 2013), and rheumatism (Furst, 1996; Howard, 2007; Schrezenmeier and Do€rner, 2020)
This work demonstrates that electro-Fenton oxidation using carbon felt cathode and boron-doped diamond (BDD) anode accomplished the complete removal of chloroquine drug, CLQ, and 92% total organic carbon (TOC) removal under optimized operational conditions (0.05 M Na2SO4, pH 1⁄4 3.0, j 1⁄4 60 mA/cm2, O2 flow rate 1⁄4 80 mL/min, T 1⁄4 25 C, stirring 1⁄4 300 rpm)
The efficiency of electro-Fenton oxidation is in good correlation with the generation of H2O2 by electrochemical reduction of O2 at carbon felt cathode
Summary
Chloroquine (CLQ), a generic pharmaceutical drug, is recommended as the primary antimalarial prevention drug (Frosch et al, 2011; Lee et al, 2011; Price et al, 2014) and to treat diseases such as amoebic dysentery (Singh et al, 2011, 2013), and rheumatism (lupus erythematosus) (Furst, 1996; Howard, 2007; Schrezenmeier and Do€rner, 2020). The emergency authorization use of antimalarial drugs including CLQ requires manufacturing this drug in larger scale to fight COVID-19 that infected millions of people in the planet within few months. Large quantities of wastewaters contaminated with CLQ will be discharged into the environment. CLQ has high potential to being persistent, bioaccumulate, and transfer to living organisms in intensified toxic forms owing to its antiviral and antibacterial characteristics. The high risks of natural water contamination due to the large production and utilization of CLQ, necessitates more attention to limit its hazardous effects on human health and environment (ozone depleting substance, bioaccumulation, and persistence)
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