Degradation of hydroxychloroquine by electrochemical advanced oxidation processes

Nasr Bensalah

Sondos Midassi

Mohammad Ahmad

Ahmed Bedoui

^{Department of Chemistry and Earth Sciences, College of Arts and Science, Qatar University, PO Box 2713 Doha, Qatar}

^{Department of Chemistry, Faculty of Sciences of Gabes, University of Gabes, Gabes 6072, Tunisia}

^{Central Laboratories Unit, Qatar University, PO Box 2713 Doha, Qatar}

Nasr Bensalah: aq.ude.uq@halasneb.rsan

^{Corresponding author.}aq.ude.uq@halasneb.rsan

Received 2020 Apr 13; Revised 2020 Jul 10; Accepted 2020 Jul 12.

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In this work, the degradation of hydroxychloroquine (HCQ) drug in aqueous solution by electrochemical advanced oxidation processes including electrochemical oxidation (EO) using boron doped diamond (BDD) and its combination with UV irradiation (photo-assisted electrochemical oxidation, PEO) and sonication (sono-assisted electrochemical oxidation, SEO) was investigated. EO using BDD anode achieved the complete depletion of HCQ from aqueous solutions in regardless of HCQ concentration, current density, and initial pH value. The decay of HCQ was more rapid than total organic carbon (TOC) indicating that the degradation of HCQ by EO using BDD anode involves successive steps leading to the formation of organic intermediates that end to mineralize. Furthermore, the results demonstrated the release chloride (Cl^{) ions at the first stages of HCQ degradation. In addition, the organic nitrogen was converted mainly into NO}₃^{and NH}₄^{and small amounts of volatile nitrogen species (NH}₃ and NO_x). Chromatography analysis confirmed the formation of 7-chloro-4-quinolinamine (CQLA), oxamic and oxalic acids as intermediates of HCQ degradation by EO using BDD anode. The combination of EO with UV irradiation or sonication enhances the kinetics and the efficacy of HCQ oxidation. PEO requires the lowest energy consumption (EC) of 63 kWh/m^{showing its cost-effectiveness. PEO has the potential to be an excellent alternative method for the treatment of wastewaters contaminated with HCQ drug and its derivatives.}

Experimental set up used for the treatment of HCQ aqueous solution by EAOPs.

Changes of [HCQ]/[HCQ]₀ with time during electrochemical oxidation of HCQ in aqueous solution using BDD anode at different HCQ concentrations; inset: Changes of pseudo-first order rate constant with HCQ concentration. Operating conditions: 0.05 M Na₂SO₄, j = 20 mA/cm^{; initial pH = 7.1; T = 25 °C.}Changes of HCQ concentration with applied electric charge during electrochemical oxidation of HCQ in aqueous solution using BDD anode at different current densities. Operating conditions: 0.05 M Na₂SO₄, [HCQ]₀ = 250 mg/L; initial pH = 7.1; T = 25 °C.Changes of: (a) % HCQ removal (measured after 1 h) with the initial pH, (b) pH with time during electrochemical oxidation of HCQ in aqueous solution using BDD anode at different initial pH values. Operating conditions: 0.05 M Na₂SO₄, [HCQ]₀ = 250 mg/L; j = 20 mA/cm^{; T = 25 °C.}Changes of: (a) HCQ and TOC, (b) released ions, (d) organic intermediates, with the applied electric charge, (c) HPLC chromatograms of samples withdrawn at t = 0 min and t = 30 min during electrochemical oxidation of HCQ in aqueous solution using BDD anode. Operating conditions: 0.05 M Na₂SO₄, [HCQ]₀ = 250 mg/L; j = 20 mA/cm^{; initial pH = 7.1; T = 25 °C.}

Simple mechanism of HCQ degradation by electrogenerated oxidants using BDD anodes.

Changes of: (a) HCQ, (b) TOC with time and (c) OAMA, (d) OAA with the applied electric charge during EO, SEO, PEO of HCQ in aqueous solution using BDD anode. Operating conditions: 0.05 M Na₂SO₄, [HCQ]₀ = 250 mg/L; j = 20 mA/cm^{; initial pH = 7.1; T = 25 °C.}Energy consumption during EO, SEO, PEO of HCQ using BDD anode in aqueous solutions. Operating conditions: 0.05 M Na₂SO₄, [HCQ]₀ = 250 mg/L; j = 20 mA/cm^{; initial pH = 7.1; T = 25 °C, Sonication power: 8.5 W, UV-irradiation: λ = 254 nm, 15 W.}

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Declaration of Competing Interest

Footnotes

^{Supplementary data to this article can be found online at}https://doi.org/10.1016/j.cej.2020.126279.

Footnotes

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