Removal of antibiotic rifampicin from aqueous media by advanced electrochemical oxidation: Role of electrode materials, electrolytes and real water matrices

Antibiotic amoxicillin degradation by electrochemical oxidation process: effects of process parameters and degradation pathway at environmentally relevant concentrations

Amoxicillin (AMX) is a common antibiotic used in both human and veterinary medicine in order to both cure and avoid bacterial infections. Traces of AMX have been found in ground and surface water, urban effluents, water, and wastewater treatment facilities due to its widespread use. The level of hazard and disposal of this class of micropollutants is the reason for concern. Advanced technology is required since conventional wastewater treatment plants are ineffective at eliminating these emerging contaminants. Electrochemical oxidation is a promising method of treating wastewater, which uses electrogenerated radicals to mineralize organic pollutants. This work investigated the detailed process mechanism for AMX degradation utilizing a low-cost, thin, flexible graphite sheet with lower AMX concentrations, initial pH value, voltage, electrolyte concentration, and wastewater matrix. The degradation of AMX by in situ generated hydroxyl radicals is a function of applied voltage and follows pseudo-first-order reaction kinetics. The removal efficiencies of AMX have been achieved up to 99% within 3 h. Moreover, intermediate by-products have been identified using liquid chromatography-mass spectrometry, and a plausible pathway has been proposed. This study could serve as a process reference for controlling AMX wastewater contamination via the electrochemical oxidation technique.

Peroxydisulfate activation by synergized modified AgCuFe2O4@GO nanoparticle electrode with anchored MnO2 in cefixime three-dimensional electrochemical degradation: Optimization and mechanisms

Cefixime (CFX) is a potent antibiotic against gram-positive and gram-negative bacteria that resists degradation and typical removal procedures. This research aimed to synthesize a modified AgCuFe2O4@GO nanoparticle electrode with anchored MnO2 for removing CFX by three-dimensional electrochemical oxidation. The physical and chemical characteristics of the nanocomposite were evaluated using various techniques, including FESEM, XRD, EDS-mapping, FTIR, BET, VSM, and TGA. The analysis found that the AgCuFe2O4@GO with anchored MnO2 nanoparticle electrode has a large specific surface area, acceptable crystal structure, good magnetic characteristics, and a quasi-spherical form. At pH 5, 40 mg/L of CFX concentration, 0.4 g/L of the nanocomposite, 3 cm of electrode interval, 0.12 mM of persulfate electrolyte, and 12.5 mA/cm2 of current density for 40 min, the process reached removal effectiveness of 97.1% for the synthetic sample and 90.7% removal efficiency for the actual sample, while had rate mineralization of 61.8% and 241.1 kWh/g energy consumption. Pseudo-first-order (R2 = 0.997) and Langmuir-Hinshelwood (R2 = 0.769) kinetic experiments provided values of KC = 7.788 mg/L.min and KL-H = 0.011 L/mg, respectively, confirming conformity to these models. The adsorption isotherms demonstrated that the CFX antibiotic complies with the Temkin model with an R2 of 0.959. The particle electrode eliminated 86.1% of the contaminant over five cycles of regeneration and recovery, showcasing outstanding chemical stability. Throughout this process, persulfate functioned as both an oxidizing agent and an electrolyte, so amplifying the production of active radicals that degrade the pollutant and improve removal efficiency. Due to its magnetic properties, chemical stability, reusability, and high efficiency, modified AgCuFe2O4@GO with anchored MnO2 is suggested for purifying industrial and medicinal wastewater.

Proof of Concept for the Organic Electrorefinery Technology with Actual Effluents

This work describes results of a first proof of the concept of electrorefinery with a real waste obtained from a cashew nut factory, and it shows the effect of the current densities of both the anodic oxidation and electrochemically assisted separation processes on the performance of the system. Results obtained demonstrate that electrorefinery is a promising option to minimize the carbon fingerprint, worth studying for increasing the sustainability of the environmental remediation of wastes, because valuable species can be obtained from the destruction of pollutants and recovered within the same integrated process. They also point out that there is still a long way to reach an optimum solution for this technology, but it is worth the effort to be made. Many different carboxylates were detected, but oxalate was the primary product both in the reaction tank and in the recovery tank. The production is almost linear during the electrolysis, with a reaction rate of 23.3 mg C h-1 in the case of oxalate and a separation ration of around 20% in the electrodialysis stage. There is a negligible crossover of aromatic species into the recovery solution, which becomes an important advantage for further processing of the carboxylate solutions in the search to valorize these species in terms of circular economy principles. Energy efficiencies in the range of 0.04-0.21 mg C-carboxylates (Wh)-1 and Coulombic efficiencies in the range 0.92-2.03 mg C-carboxylates (Ah)-1 were obtained in this work. A life cycle assessment indicated carbon dioxide and water footprints as low as 0.31 g of CO2 mg-1 C and 30 mL of H2O mg-1 C recovered in the products obtained, respectively.

Efficient electrochemical removal of ammoniacal nitrogen from livestock wastewater: The role of the electrode material

Wastewater from livestock farms contains high concentrations of suspended solids, organic contaminants, and nitrogen compounds, such as ammoniacal nitrogen. Discharging livestock effluents into water bodies without appropriate treatment leads to severe environmental pollution. Compared to conventional treatment methods, electrochemical oxidation exhibits higher nitrogen removal efficiencies. In the present work, the electrochemical removal of ammoniacal nitrogen from real livestock wastewater was investigated through a lab-scale reactor. Preliminary experiments were carried out to investigate the effects of different anode materials, including boron-doped diamond and iridium/ruthenium-coated titanium, on the total nitrogen removal efficiency using synthetic wastewater. Boron-doped diamond, a well-known non-active electrode, allowed to obtain 63.7 ± 1.21 % of total nitrogen degradation efficiency. However, the iridium/ruthenium-coated titanium electrode, belonging to the class of active anodes, showed a higher performance, achieving 78.8 ± 0.76 % contaminant degradation. Coupling iridium/ruthenium-coated titanium anode with a stainless-steel cathode improved the performance of the system, achieving even 96.2 ± 2.73 % of total nitrogen removal. The optimized cell configuration was used to treat livestock wastewater, resulting in the degradation of 67.0 ± 2.25 % of total nitrogen and 37.3 ± 0.68 % of total organic carbon when sodium chloride was added. At the end of the process, the ammonium content was completely removed, and only 17.7 ± 0.51 % of the initial nitrogen turned into nitrate. The results show that the proposed system is a promising approach to treating livestock wastewater by coupling high contaminant removal efficiencies with low operational costs. Anyway, further studies on process optimization with an emphasis on power requirements and electrode costs need to be carried out.

Hybrid process combining ultrafiltration and electro-oxidation for COD and nonylphenol ethoxylate removal from industrial laundry wastewater

Laundry wastewater is a significant source of nonylphenol ethoxylate (NPEO) at wastewater treatment plants, where its breakdown forms persistent nonylphenol (NP). NP poses risks as an endocrine disruptor in wildlife and humans. This study investigates the degradation of NPEO and COD in industrial laundry wastewater (LWW) using a two-stage process combining ultrafiltration (UF) and electro-oxidation (EO). UF was used to remove suspended solids, while soluble COD (COD0 = 239 ± 6 mg.L-1) and NPEO (NPEO0 = 341 ± 8 μg.L-1) were oxidized by the EO process. Different operating parameters were studied such as current density, electrolysis time, type of cathode and supporting electrolyte concentration. Using an experimental design methodology, the optimal conditions for COD and NPEO3-17 degradation were recorded. This included achieving 97% degradation of NPEO3-17 and 61% degradation of COD, with a total operating cost of 3.65 USD·m-3. These optimal conditions were recorded at a current density of 15 mA cm-2 for a 120-min reaction period in the presence of 4 g·Na2SO4 L-1 using a graphite cathode. The EO process allowed for reaching the guidelines required for water reuse (NPEO <200 μg.L-1, COD <100 mg.L-1) in the initial laundry washing cycles. Furthermore, our results demonstrate that both NP and NPEO compounds, including higher and shorter ethoxylate chains (NPEO3-17), were effectively degraded during the EO process, with removal efficiencies between 94% and 98%. This confirms the EO process's capability to effectively degrade NP, the by-product of NPEO breakdown.

An evaluation of conventional and nature-based technologies for controlling antibiotic-resistant bacteria and antibiotic-resistant genes in wastewater treatment plants

Antibiotic resistance is a globally recognized health concern which leads to longer hospital stays, increased morbidity, increased mortality, and higher medical costs. Understanding how antibiotic resistance persists and exchanges in environmental systems like soil, water, and wastewater are critically important for understanding the emergence of pathogens with new resistance profiles and the subsequent exposure of people who indirectly/directly come in contact with these pathogens. There are concerns about the widespread application of prophylactic antibiotics in the clinical and agriculture sectors, as well as chemicals/detergents used in food and manufacturing industries, especially the quaternary ammonium compounds which have been found responsible for the generation of resistant genes in water and soil. The rates of horizontal gene transfer increase where there is a lack of proper water/wastewater infrastructure, high antibiotic manufacturing industries, or endpoint users - such as hospitals and intensive agriculture. Conventional wastewater treatment technologies are often inefficient in the reduction of ARB/ARGs and provide the perfect combination of conditions for the development of antibiotic resistance. The wastewater discharged from municipal facilities may therefore be enriched with bacterial communities/pathogens and provide a suitable environment (due to the presence of nutrients and other pollutants) to enhance the transfer of antibiotic resistance. However, facilities with tertiary treatment (either traditional/emerging technologies) provide higher rates of reduction. This review provides a synthesis of the current understanding of wastewater treatment and antibiotic resistance, examining the drivers that may accelerate their possible transmission to a different environment, and highlighting the need for tertiary technologies used in treatment plants for the reduction of resistant bacteria/genes.

Construction of p-n-p nano heterojunction through coupling La2O3, (BiO)2CO3 and Ag3PO4 for effective photocatalytic degradation of doxycycline: Insights into mechanism, pathway and intermediate toxicity evaluation

The present work is centred around the development of La2O3/(BiO)2CO3/Ag3PO4 (LBA), a p-n-p nano-heterojunction to photodegrade doxycycline under visible light irradiation. Here, ultrasonication assisted co-precipitation method was employed to synthesize the photocatalyst. The photocatalyst was characterized using different analysis such as SEM, TEM, elemental mapping, XRD, XPS, FTIR, Raman, BET, DRS, PL and EIS which confirmed the successful fabrication of LBA and their excellent ability to refrain the e-/h+ recombination owing to the construction of the heterojunction. LBA was found to degrade DOX by 91.75 % with the high mineralization of 87.23%. The impact of the reaction parameters influencing the photodegradation process including the concentration of the NCs and DOX, pH and the influence of the commonly present anions were studied. The stability and reusability of the LBA was assessed through subjecting it to four cycles of photodegradation of DOX. In addition, the recovered LBA was characterized through XPS and XRD analysis to confirm the particles stability and reusability. The active participation of the photogenerated charges and the reactive oxygen species were identified through the scavenging assay and ESR analysis. Further, GC-MS/MS analysis was performed to put forward a plausible photodegradation pathway. The toxicity of the end products as well as the intermediates was predicted through ECOSAR software.

Electrochemical degradation of favipiravir (anti-viral) drug from aqueous solution: optimization of operating parameters using the response surface method

The aim of the current study is to investigate the efficacy of the electro-Fenton process in the degradation of favipiravir drugs from aqueous solutions, which has increased in use as a result of the COVID-19 pandemic. The Response Surface Methodology (RSM) was developed using a Central Composite Design (CCD) in which five independent variables, including Fe2+ concentration, current density, initial FVP concentration, pH, and reaction time, were coded with high and low levels, and the maximum removal percentage of FVP (97.8%) and COD (91.65%) were determined as responses. In the EF process, 530 mg/L H2O2 was produced in-situ by cathodic reduction of O2 in aqueous solution and thus FVP has been successfully oxidized through hydroxyl radicals. The H2O2/Fe2+ ratio was determined to be 0.51 under optimum conditions. At the end of the experiment, the maximum energy consumption was found to be 2.12 kWh per g COD. The FVP was completely mineralized in a very short time by the EF process, according to the LC-MS/MS examination. The EF process followed the pseudo first-order kinetic model with the rate constants of 0.023, 0.016 and 0.006 1/min for pH 2, 3 and 4, respectively. According to the findings of this study, the electro-Fenton process is an effective method for removing FVP from aqueous solutions. To the authors' knowledge, this is the first study to show the degradation and optimum conditions of FVP in aqueous solution using the electro-Fenton (EF) process.

TiO2/graphene composite nanofibers for efficient photocatalytic degradation of pharmaceutical compounds: Rifampin, Phenazopyridine, Azathioprine

Pharmaceutical wastewater treatment is an essential component of environmental protection and sustainable development. In this study, our aim was to investigate the morphology, characterization, and effectiveness of TiO2/graphene composite nanofiber photocatalysts in the treatment of pharmaceutical wastewater containing three different pharmaceutical groups, such as an antibiotic (rifampin), painkiller (phenazopyridine), and immunosuppressant (azathioprine). Various parameters such as pH, salt concentration, and initial pharmaceutical compound concentration were optimized to achieve maximum degradation kinetics and efficiency. The optimum conditions were determined to be 1.5% graphene content, 30 ppm initial concentration of pharmaceutical compound, pH=5, and a 0.5 g/L photocatalyst dose. The presence of salt slightly decreased the degradation kinetics, but it did not significantly affect the performance of the TiO2/graphene composite nanofibers photocatalyst. At optimum condition, TiO2/1.5% graphene composite nanofibers degraded 50% of phenazopyridine, 86.89% of rifampin, and completely azathioprine. Comparing with phenazopyridine, N heteroatom-rich molecule of azathioprine and hydroxyl-rich molecule of rifampin lead to being susceptible to photocatalytic degradation. The reuse of the photocatalyst in multiple cycles showed consistent performance, indicating its potential for practical and economic applications.

Toxicological aspect of water treated by chlorine-based advanced oxidation processes: A review

As well established in the literature, residual toxicity is an important parameter for evaluating the sanitary and environmental safety of water treatment processes, and this parameter becomes even more crucial when chlorine-based processes are applied for water treatment. Eliminating initial toxicity or preventing its increase after water treatment remains a huge challenge mainly due to the formation of highly toxic disinfection by-products (DBPs) that stem from the degradation of organic contaminants or the interaction of the chlorine-based oxidants with different matrix components. In this review, we present a comprehensive discussion regarding the toxicological aspects of water treated using chlorine-based advanced oxidation processes (AOPs) and the recent findings related to the factors influencing toxicity, and provide directions for future research in the area. The review begins by shedding light on the advances made in the application of free chlorine AOPs and the findings from studies conducted using electrochemical technologies based on free chlorine generation. We then delve into the insights and contributions brought to the fore regarding the application of NH₂Cl- and ClO₂-based treatment processes. Finally, we broaden our discussion by evaluating the toxicological assays and predictive models employed in the study of residual toxicity and provide an overview of the findings reported to date on this subject matter, while giving useful insights and directions for future research on the topic.

A non-steroidal drug "diclofenac" is a substrate for electrochemical degradation process using graphite anode

In the electrochemical degradation process, the elimination of organic pollutants could be enhanced using supporting electrolyte and applied voltage. After degradation of the target organic compound, some by-products are formed. Chlorinated by-products are the main products formed in the presence of sodium chloride. In the present study, an electrochemical oxidation process has been applied to diclofenac (DCF) using graphite as an anode and sodium chloride (NaCl) as a supporting electrolyte. Monitoring the removal of the by-products and elucidating them were provided using HPLC and LC-TOF/MS, respectively. A high removal% of 94% DCF was observed under the conditions: 0.5 g NaCl, 5 V, and 80 min of electrolysis, while the removal% of chemical oxygen demand (COD) was 88% under the same conditions, but 360 min of electrolysis was required. The pseudo-first-order rate constant values were quite varied based on the selected experimental conditions; the rate constants were between 0.0062 and 0.054 min^-1, between 0.0024 and 0.0326 min^-1 under the influence of applied voltage and sodium chloride, respectively. The maximum values of energy consumption were 0.93 and 0.55 Wh/mg using 0.1 g NaCl and 7 V, respectively. Some chlorinated by-products, C₁₃H₁₈Cl₂NO₅, C₁₁H₁₀Cl₃NO₄, and C₁₃H₁₃Cl₅NO₅, were selected and elucidated using LC-TOF/MS.

Modification of Chlorella vulgaris carbon with Fe3O4 nanoparticles for tetracycline elimination from aqueous media

Tetracycline (TTC) is an antibiotic commonly prescribed to treat bacterial infections in animals and humans because of its low toxicity and antibacterial activity. This study focuses on the removal of TTC from an aqueous media using an activated carbon of Chlorella vulgaris modified with Fe3O4 magnetic composite (ACCV/Fe3O4 mc). The isothermal and kinetic models were studied to understand the adsorption mechanism. The Box-Behnken model was used for experimental design, and the main research parameters were ACCV/Fe3O4 mc mass (0.2-0.8 g/L), reaction time (10-60 min), TTC concentration (5-30 mg/L), and pH (3-11). The highest TTC removal rate of 90.47% was obtained at a pH of 7, a time of 60 min, an ACCV/Fe3O4 mc mass of 0.5 g/L, and an antibiotic concentration of 5 mg/L. TTC removal was fitted with the pseudo-second-order and the Langmuir model. The Langmuir adsorption capacity of TTC was computed to be 26.18 mg/g. The results show that the ACCV/Fe3O4 mc adsorbent significantly removes TTC from the aqueous solution.

Closing the loop: Upcycling secondary waste materials into nanoarchitectured carbon composites for the electrochemical degradation of pharmaceuticals

In this study, we demonstrated the application of electrochemical oxidation as a safer and cleaner technology for minimizing the impact of pharmaceuticals in wastewaters, simultaneously mediated by upcycled secondary waste materials (SWMs)-derived electrodes, to further reduce their environmental impact. The modularity, scalability, ease of operation and reliability make electrochemical oxidation an ideal process for the destruction of emerging persistent pollutants; however, their full-scale application is hindered by energy efficiency and the potential release of toxic by-products. Thus, the answer to these issues can be found in the design of tailored multifunctional electrode material. For the first time, SWMs derived from combustion and industrial processes have been employed with the simultaneous dual function of functional fillers, in a polyacrylonitrile fibrous matrix, and as a catalyst for the growth of carbon nanofeatures over the fiber surface, to increase the surface area and charge transfer. Next, the tailored composites were employed as anodes for the electrochemical oxidation of acetaminophen, both in phosphate buffer and in a real wastewater sample. The results suggest that SWMs can substitute costly engineered fillers in carbon-based electrodes and that the absence of reaction by-products (monitored by UHPLC-ESI-MS/MS), together with the low energy consumption, make the tailored fibrous composite electrodes good candidates for the development of safer and cleaner technologies with reduced environmental impact.

Degradation of antibiotics by electrochemical advanced oxidation processes (EAOPs): Performance, mechanisms, and perspectives

Global consumption and discharge of antibiotics have led to the rapid development and spread of bacterial antibiotic resistance. Among treatment strategies, electrochemical advanced oxidation processes (EAOPs) are gaining popularity for treating water/wastewater containing antibiotics due to their high efficiency and easiness of operation. In this review, we summarize various forms of EAOPs that contribute to antibiotic degradation, including common electrochemical oxidation (EO), electrolyte enhanced EO, electro-Fenton (EF) processes, EF-like process, and EAOPs coupling with other processes. Then we assess the performance of various EAOPs in antibiotic degradation and discuss the influence of key factors, including electrode, initial concentration and type of antibiotic, operation conditions, electrolyte, and water quality. We also review mechanisms and degradation pathways of various antibiotics degradation by EAOPs, and address the species and toxicity of intermediates produced during antibiotics treatment. Finally, we highlight challenges and critical research needs to facilitate the application of EAOPs in antibiotic treatment.

State of the Art on Developments of (Bio)Sensors and Analytical Methods for Rifamycin Antibiotics Determination

This review summarizes the literature data reported from 2000 up to the present on the development of various electrochemical (voltammetric, amperometric, potentiometric and photoelectrochemical), optical (UV-Vis and IR) and luminescence (chemiluminescence and fluorescence) methods and the corresponding sensors for rifamycin antibiotics analysis. The discussion is focused mainly on the foremost compound of this class of macrocyclic drugs, namely rifampicin (RIF), which is a first-line antituberculosis agent derived from rifampicin SV (RSV). RIF and RSV also have excellent therapeutic action in the treatment of other bacterial infectious diseases. Due to the side-effects (e.g., prevalence of drug-resistant bacteria, hepatotoxicity) of long-term RIF intake, drug monitoring in patients is of real importance in establishing the optimum RIF dose, and therefore, reliable, rapid and simple methods of analysis are required. Based on the studies published on this topic in the last two decades, the sensing principles, some examples of sensors preparation procedures, as well as the performance characteristics (linear range, limits of detection and quantification) of analytical methods for RIF determination, are compared and correlated, critically emphasizing their benefits and limitations. Examples of spectrometric and electrochemical investigations of RIF interaction with biologically important molecules are also presented.

Contribution of electrolyte in parametric optimization of perfluorooctanoic acid during electro-oxidation: Active chlorinated and sulfonated by-products formation and distribution

The present study investigated the roles of peroxydisulfate (PDS) radicals and sulfate radicals (SO₄^•-) that formed from sulfate (SO₄^2-) during electrochemical oxidation of perfluorooctanoic acid (PFOA). The effect of operating parameters such as different types of electrolytes (NaCl, NaClO₄, and Na₂SO₄), initial pH, current density, dose of electrolyte, and initial concentration of PFOA using electrochemical oxidation for perfluorooctanoic acid (PFOA) decomposition study was investigated. A difference in the removal efficiency with different electrolytes (i.e., Cl^-, ClO₄^-, and SO₄^2-) illustrated an increasing effect of electrooxidation of PFOA in the order of ClO₄^- < Cl^- < SO₄^2-, which suggested that ^•OH induced oxidation and direct e^- transfer reaction continued to play a crucial role in oxidation of PFOA. At the optimum treatment condition of j = 225.2 Am^-2, Na₂SO₄ concentration = 1.5 gL^-1, [PFOA]_o = 50 mgL^-1 and initial pH = 3.8 maximum PFOA removal of 92% and TOC removal of 80% was investigated at 240 min. The formation of three shorter-chain perfluorocarboxylates (i.e., perfluoroheptanoic acid (PFHpA), perfluorohexanoic acid (PFHxA), and perfluoropentanoic acid (PFPeA) and formate (HCOO^-) ions were detected as by-products of PFOA electro-oxidation, showing that the C-C bond first broken in C₇F₁₅ and then mineralized into CO₂, and fluoride ion (F^-). The fluorine recovery as F^- ions and the organic fluorine as the shorter-chain by-products were also obtained. The degradation kinetic has also been studied using the nth-order kinetic model.

Application of electro-Fenton and photoelectro-Fenton processes for the degradation of contaminants in landfill leachate

Worldwide, most solid waste ends its life in landfill sites, which have a significant environmental impact in several respects. In particular, rainfall over landfill sites results in the production of an aqueous leachate containing compounds having low biodegradability, high toxicity, and a high organic load. For this reason, this study aims to investigate the applicability of electro-Fenton (EF) and photoelectro-Fenton (PEF) processes as alternative for treating a local landfill effluent with high organic content (chemical oxygen demand (COD) = 2684.7 mg-O₂ L ^-1) in a continuous-flow reactor (using, for first time, this kind of system with higher electrodes area of 35 cm²) using boron-doped diamond anode (Nb/BDD) and a carbon felt cathode (FC) electrodes. The effects of current density j (30, 60 and 90 mA cm^-2) and UV radiation wavelength (UVA and UVC) were studied to evaluate the treatment efficiency as well as the energy consumption. Results clearly showed that, the best efficiencies removing organic matter, in terms of COD, were about 66%, 68% and 89% with an energy consumption of only 19.41, 17.61 and 17.59 kWh kg COD^-1 for EF, PEF-UVA and PEF-UVC respectively, at 90 mA cm^-2 after 4 h of operation. The treatment of this kind of effluent produced organic and inorganic by-products, the acetic and formic acids as well as NO₂^-, NO₃^-, and NH₄⁺, being assessed their concentrations.

Electrocatalytic oxidation of low concentration cefotaxime sodium wastewater using Ti/SnO2-RuO2 electrode: Feasibility analysis and degradation mechanism

In this research, Ti/SnO₂-RuO₂ stable anode was successfully prepared by thermal decomposition method, and low concentration cefotaxime sodium (CFX) was degraded by green and sustainable electrocatalytic oxidation technology. The electrocatalytic activity and stability of the Ti/SnO₂-RuO₂ coating electrode were studied according to the polarization curve of oxygen and chlorine evolution. The effects of current density, initial concentration, pH, electrolyte concentration, and other technological parameters on the degradation efficiency were discussed. Orthogonal experiment results indicated that when the current density was 25 mA cm^-2, concentration of electrolyte was 5 mM and the pH value was 7, the best CFX removal rate of 86.33% could be obtained. The degradation efficiency of electrocatalytic oxidation was discussed through electrochemical analysis. Fourier transform infrared spectroscopy was used to analyze the different inlet and outlet stages before and after the degradation of CFX, and the possible degradation process was discussed. Therefore, the electrocatalytic oxidation of Ti/SnO₂-RuO₂ electrode was a clean and efficient technology, which could be widely used in the treatment of CFX wastewater.

Achieving Electrochemical-Sustainable-Based Solutions for Monitoring and Treating Hydroxychloroquine in Real Water Matrix

Hydroxychloroquine (HCQ) has been extensively consumed due to the Coronavirus (COVID-19) pandemic. Therefore, it is increasingly found in different water matrices. For this reason, the concentration of HCQ in water should be monitored and the treatment of contaminated water matrices with HCQ is a key issue to overcome immediately. Thus, in this study, the development of technologies and smart water solutions to reach the Sustainable Development Goal 6 (SDG6) is the main objective. To do that, the integration of electrochemical technologies for their environmental application on HCQ detection, quantification and degradation was performed. Firstly, an electrochemical cork-graphite sensor was prepared to identify/quantify HCQ in river water matrices by differential pulse voltammetric (DPV) method. Subsequently, an HCQ-polluted river water sample was electrochemically treated with BDD electrode by applying 15, 30 and 45 mA cm−2. The HCQ decay and organic matter removal was monitored by DPV with composite sensor and chemical oxygen demand (COD) measurements, respectively. Results clearly confirmed that, on the one hand, the cork-graphite sensor exhibited good current response to quantify of HCQ in the river water matrix, with limit of detection and quantification of 1.46 mg L−1 (≈3.36 µM) and 4.42 mg L−1 (≈10.19 µM), respectively. On the other hand, the electrochemical oxidation (EO) efficiently removed HCQ from real river water sample using BDD electrodes. Complete HCQ removal was achieved at all applied current densities; whereas in terms of COD, significant removals (68%, 71% and 84% at 15, 30 and 45 mA cm−2, respectively) were achieved. Based on the achieved results, the offline integration of electrochemical SDG6 technologies in order to monitor and remove HCQ is an efficient and effective strategy.