Degradation Of Chloramphenicol Research Articles

Antibiotic Chloramphenicol degradation using submerged thermal plasma synergized with LaMnO3 catalyst

The present study focused on the degradation of antibiotic Chloramphenicol (CAP), an emerging contaminant, using submerged thermal plasma (STP) technology. Almost 99 % degradation and 82 % mineralization were achieved within 20 min of treatment by Ar/CO2 plasma, generated at 6.2 kW discharge power using a customized thermal plasma torch inside the aqueous solution. Kinetic analysis revealed first-order reaction for CAP degradation with a rate constant of 0.257 min−1. Long-lived species, such as H2O2, O3, NO2–, NO3–, and Cl- formed during plasma treatment were quantified. LaMnO3 perovskite (LMO) nanopowder prepared through a novel thermal plasma route, was introduced as catalyst into the treatment system which enhanced the degradation and mineralization efficiency by 34 % and 17 %, respectively, showing a strong synergetic effect between STP and catalyst. The energy yield was elevated from 102 mg/kWh to 144 mg/kWh with the addition of catalyst into the STP treatment system. Liquid chromatography-mass spectroscopy was used to identify the various degradation intermediates produced during thermal plasma treatment and correspondingly possible degradation pathways were proposed. The antibacterial activity assessment results revealed a significant reduction in the antimicrobial activity of all treated solutions against Gram-positive Bacillus cereus and Gram-negative Pseudomonas aeruginosa bacteria. Additionally, seed germination and growth assessment revealed a reduction in phytotoxicity of the treated solutions. STP, combined with the LMO, proved highly effective in treating pharmaceutical contamination in aqueous medium.

Effective photocatalytic degradation of antibiotic chloramphenicol and anionic direct violet 51 dye using g-C3N4 embedded NiO nanocomposite

Effective photocatalytic degradation of antibiotic chloramphenicol and anionic direct violet 51 dye using g-C3N4 embedded NiO nanocomposite

Synergistic effect on simultaneous treatment of Cr(VI) and chloramphenicol using a non-thermal plasma technology

Toxic organic and heavy metal contaminants commonly exist in industrial waste stream and the treatment is of great challenge. In this study, a dielectric barrier discharge (DBD) non-thermal plasma was employed for the simultaneous treatment of two important contaminants, chloramphenicol (CAP) and Cr(VI) in an aqueous solution through redox transformations. More than 70% of CAP and 20% of TOC were degraded in 60 min, while Cr(VI) was completely removed in 10 min. The hydroxyl radicals could be the main active species for the degradation. Meanwhile, the consumption of hydroxyl radicals was beneficial to the reduction of Cr(VI). The synergistic effect was investigated between CAP degradation and Cr(VI) reduction. The reduction of Cr(VI) would be enhanced in the presence of CAP with a low concentration and could be inhibited under a high concentration of CAP, because part of hydroxyl radicals could be consumed by a low concentration of CAP and the obtained intermediates with a higher kinetic rate. However, CAP with a high concentration could also react with some reductive species, such as eaq- and •H, which could compete with Cr(VI) and inhibit the reduction of Cr(VI). In addition, the presence of Cr(VI) could enhance the degradation and mineralization of CAP, and the identification of obtained intermediates indicated that the presence of Cr(VI) could change the degradation path of CAP as Cr(VI) would react with reductive species and enhance the generation of hydroxyl radicals, leading to more hydroxylation reactions. Moreover, the mechanism for the simultaneous redox transformations of CAP and Cr(VI) was illustrated. This study indicates that the DBD non-thermal plasma technology could be one of better solutions for simultaneous elimination of heavy metal and organic contaminants in aquatic environment.

Expression of Concern: Effective degradation of chloramphenicol in wastewater by activated peroxymonosulfate with Fe-rich porous biochar derived from petrochemical sludge

Expression of Concern: Effective degradation of chloramphenicol in wastewater by activated peroxymonosulfate with Fe-rich porous biochar derived from petrochemical sludge

Unexpectedly enhanced degradation of acetaminophen by sulfoxides probe in Fe(II)-activated persulfate oxidation: The mechanism and the selectivity

Sulfoxides are widely recognized as probes for identifying and evaluating the generation and contribution of high-valent metals in advanced oxidation processes. However, this paper was surprising to find that the presence of sulfoxides selectively enhanced the degradation of specific pollutants in the Fe(II)/PS system. Represented by methyl phenyl sulfoxide (PMSO), scavenging experiments for active species showed that the presence of PMSO transformed the mechanism from radical dominated (55.60 %) to nonradical dominated (60.91 %), greatly improving the anti-interference ability of the system. Determining the concentration of Fe(Ⅱ) and total iron (Fetot) in solution revealed that the presence of PMSO improved the utilization efficiency of Fe(II) and PS by enhancing the redox reaction between Fe(II) and PS, and resulted in the generation of Fe(IV) more favorably than the generation of SO4·− and ·OH. Additionally, comparing the proven high-valent iron dominated Fe(II)/PI system with the free radical dominated Fe(II)/PS system of this paper, it was revealed that the selectively enhanced oxidation of PMSO specifically targets the free radical dominated system. Experiments have shown that the degradation of acetaminophen, ibuprofen, phenol, and p-chlorophenol was enhanced by PMSO, while the degradation of norfloxacin, primidone, chloramphenicol, sulfamethoxazole, p-nitrophenol, benzoic acid, and nitrobenzene was inhibited. Based on density functional theory (DFT) calculations, PMSO has a selectively enhanced degradation effect for organic pollutants with ionization potential (IP) below 8.66 eV, and vice versa, it has an inhibitory effect. The present study provides new insights into the contribution of sulfoxide to the assessment of high-valent metals and sheds new light on the mechanism of active species.

Revealing the biological significance of multiple metabolic pathways of chloramphenicol by Sphingobium sp. WTD-1

Chloramphenicol (CAP) is an antibiotic that commonly pollutes the environment, and microorganisms primarily drive its degradation and transformation. Although several pathways for CAP degradation have been documented in different bacteria, multiple metabolic pathways in the same strain and their potential biological significance have not been revealed. In this study, Sphingobium WTD-1, which was isolated from activated sludge, can completely degrade 100 mg/L CAP within 60 h as the sole energy source. UPLC-HRMS and HPLC analyses showed that three different pathways, including acetylation, hydroxyl oxidation, and oxidation (C1-C2 bond cleavage), are responsible for the metabolism of CAP. Importantly, acetylation and C3 hydroxyl oxidation reduced the cytotoxicity of the substrate to strain WTD-1, and the C1-C2 bond fracture of CAP generated the metabolite p-nitrobenzoic acid (PNBA) to provide energy for its growth. This indicated that the synergistic action of three metabolic pathways caused WTD-1 to be adaptable and able to degrade high concentrations of CAP in the environment. This study deepens our understanding of the microbial degradation pathway of CAP and highlights the biological significance of the synergistic metabolism of antibiotic pollutants by multiple pathways in the same strain.

Ce/Fe bimetallic MOF derivatives in situ modified bulk carbon aerogel composite cathode for efficient heterogeneous electro-fenton degradation of chloramphenicol

In this study, we utilized a Ce-modified iron-based metal-organic framework derivative to in situ modify bulk CA (Ce/Fe@C-CA) as a bifunctional composite cathode to degrade chloramphenicol (CAP) in the heterogeneous electro-Fenton (EF) process. The composite cathode exhibited satisfactory CAP degradation efficiency, wide pH adaptability (2–9) and low metal leaching. Under the appropriate conditions (pH = 5, current density = 6 mA/cm2), 94.89% of CAP degradation efficiency was obtained within 60 min. The introduction of Ce increased the oxygen vacancy content, enhanced the cathodic electrochemical activity, promoted the production of a variety of reactive oxygen species and participates in the degradation of CAP, of which ·OH and 1O2 were dominant. Meanwhile, the electron transfer and synergistic catalysis between Ce and Fe promoted the regeneration of the metal active site, which was beneficial to improve the reuse stability of the Ce/Fe@C-CA cathode. The degradation pathway of CAP was obtained by DFT calculations and UPLC-MS/MS detection. This study not only proposed a novel bifunctional electro-Fenton cathode, but also provided a effective strategy for the treatment of actual pharmaceutical wastewater.

Laser flash photolysis and quantum chemical studies of UV degradation of pharmaceutical drug chloramphenicol: Short-lived intermediates, quantum yields and mechanism of photolysis

Using methods of time-resolved and stationary photolysis, HPLC-MS and quantum-chemical calculations by the DFT method, the mechanism of direct UV photolysis of the antibiotic chloramphenicol (CAP) was established. For the first time, short-lived intermediates formed during photolysis were detected. The primary photoprocess is the cleavage of the β-C-C bond relative to the aromatic system with the formation of 4-nitrobenzylalcohol radical and residual aliphatic radical. The first radical in deoxygenated solutions predominantly transforms into para-nitrobenzaldehyde and its secondary photolysis products. In the presence of oxygen, the aromatic radical and para-nitrobenzaldehyde are transformed into para-nitrosobenzoic and para-nitrobenzoic acids as a result of reaction with reactive oxygen species (ROS). Formation of ROS is provoked by reactions of aliphatic radical with dissolved oxygen, so this radical is very important for CAP degradation. The quantum yield of direct photolysis of CAP is ∼3% and does not depend on the presence of dissolved oxygen and on the change of the excitation wavelength in the range of 254–308 nm. Obtained data are important for further understanding of the transformation pathways of CAP and similar PPCP in natural and wastewaters under the action of sunlight and artificial UV radiation.

Cathodic membrane with confined interlayer spacing for efficient electrocatalytic dehalogenation of antibiotics

Conventional catalytic membranes often exhibit inadequate catalytic efficiency due to limited retention time for pollutants during filtration. In this study, a single-atom catalyst (Ni-NG) was prepared by dispersing single nickel atoms onto nitrogen-doped graphene oxide sheets. Subsequently, under controlled conditions, the assembly of Ni-NG with reduced graphene oxide (rGO) sheets led to the fabrication of efficient electrocatalytic cathodic membranes (ECMs). The ECMs were designed to concentrate and dehalogenate antibiotics simultaneously by utilizing the confined single nickel atoms within the multilayered ECMs through electrocatalytic reduction. Remarkably, complete degradation of chloramphenicol (CAP, 20 mg L−1) in the solution was achieved within a remarkably short time of 3.0 ms by ECM8 which had an area of 7.1 cm2 and comprised Ni-NG (16.9 μg) and rGO (16.9 μg), with an interlayer spacing of 0.37 nm, during filtration (40 L m−2 h−1). The reaction rate constant (k) for CAP degradation by ECM8 was approximately 3 × 108 min−1, surpassing the highest value in the literature. Furthermore, the ECM demonstrated both high energy efficiency and stability, highlighting the great potential for practical applications. The electrocatalytic cathodic membrane, designed to primarily concentrate pollutants in confined interlayer spaces through the sieving effect, shed lights on the highly efficient dehalogenation of organic compounds in pharmaceutical salt-laden wastewater.

DBDP collaboration Cu@PAF-45-COOH experimental study on catalytic degradation of chloramphenicol in water

DBDP collaboration Cu@PAF-45-COOH experimental study on catalytic degradation of chloramphenicol in water

Efficient visible-light photocatalysis of chloramphenicol using novel engineered biochar-based Ti-doped Bi2WO6 composite: Mechanisms, degradation pathways, and applications

A novel engineered biochar (ACB)-based Ti-doped Bi2WO6 composite (Ti-Bi2WO6@ACB) was synthesized via a one-step hydrothermal reaction for the efficient degradation of chloramphenicol (CAP) and extensive environmental applications. Multiple characterization techniques, CAP degradation effects, total organic carbon (TOC) removal, effects of environmental factors, recycling tests, actual wastewater treatment, enhancement strategies, and disinfection effects were systematically evaluated. It was found that Ti-Bi2WO6@ACB is a Ti3+ self-doped TiO2/Bi2WO6/ACB ternary heterogeneous photocatalyst. The introduction of ACB and Ti doping enhanced the elemental composition, oxygen-containing functional groups, defect structure (oxygen vacancies), visible-light absorption, and active sites. Moreover, Ti-Bi2WO6@ACB effectively inhibited the recombination of photogenerated carriers. The removal efficiency of Ti-Bi2WO6@ACB for 50 mg⋅L−1 CAP was 92.44 % at 120 min of irradiation, and the TOC removal rate was 67.72 %, which was significantly higher than that of the control treatment. Ti-Bi2WO6@ACB is reusable and photostable, with approximately 99 % sterilization of Staphylococcus aureus and Escherichia coli within 10 min of light irradiation and 48 h of cultivation. The addition of H2O2, ultrasonication, heating, and blowing air in the system improved the photocatalytic efficiency. The ultrasound enhancement mechanisms are related to the effects of cavitation, microjets, and photocatalysis coupled with sonocatalysis. CAP degradation was dominated by OH, O2−, and h+. The doping of Ti3+/TiO2 generated more defects and O2−, and the ACB acted as a carrier to prevent the agglomeration of TiO2 and Bi2WO6. Further, the degradation process of CAP was documented and the degradation pathways may include hydroxylation addition, methanol denaturation, substitution, C–N bond breaking, oxidation, hydrolysis, and decarboxylation reactions. The research presents fresh insights into the development of high-performance engineered biochar-based composite for environmental detoxification.

Enhanced degradation of chloramphenicol via heterogeneous activation of peroxymonosulfate by Fe3O4 and gallic acid

In this study, we demonstrated the effective degradation of wide-spectrum antibiotic chloramphenicol (CAP) by Fe3O4/peroxymonosulfate (PMS) system modified by gallic acid (GA). GA/Fe3O4/PMS showed a substantially higher degradation rate (77.6%) than Fe3O4/PMS (8.3%). The active components were detected by electron spin-resonance spectroscopy (ESR) and the quenching experiments. The results showed that the hydroxyl radical (HO•) was the main reason for the degradation of CAP. In the GA/Fe3O4/PMS system, the trace amount of dissolved iron ion were not the main species that activated PMS. Surface characterization and theoretical simulations showed that Fe atoms on Fe3O4 were responsible for PMS activation rather than a homogenous reaction. Five probable CAP degradation pathways were identified by density functional theory (DFT) calculations and liquid-phase mass spectrometry. Finally, the reusability of Fe3O4 was measured, and the GA/Fe3O4/PMS system maintained high efficiency after 5 times applications. The total organic carbon (TOC) removal rate reached 46.5% after reacting for 12 h. The gallic acid effectively promotes the circulation of Fe(II)/Fe(III) on solid surfaces and enhanced the degradation capacity of the original system. The research proposed a new way of directly employing plant polyphenols to boost the degradation ability of contaminants in heterogeneous systems.

Carbon nano-onions acting as artificial pili enhance chloramphenicol degradation in an anaerobic membrane bioreactor

Carbon-based materials are commonly used to promote methane production and organic degradation by enhancing direct interspecies electron transfer (DIET). Carbon nano-onions (CNOs) were first applied in an anaerobic membrane bioreactor to treat chloramphenicol (CAP) wastewater in this study. Results demonstrate that CAP was almost undetectable in the effluent after 188 days of operation. In Phases 1–3 (days 1 to 152), CAP increase in the influent led to maximum concentrations of 291.1 mg/L for acetic acid and 86.3 mg/L for propionic acid. In Phase 4 (days 153 to 188), the concentrations of acetic acid and propionic acid increased to a maximum of 211.5 mg/L and 342.3 mg/L. During Phase 3, the maximum methane productivity was 0.72 L/d, and the methanogenic lag time was 4.97 days. However, with the addition of CNOs and a higher CAP load, the maximum methane productivity reached 0.71 L/d, accompanied by a reduced methanogenic lag time of 1.22 days. Moreover, it significantly enhanced the abundances of Geobacteraceae, norank o norank c Thermodesulfovibrionia, Syntrophobacteraceae, Methanosaetaceae and Methanobacteriaceae which exhibited much higher specific growth rates in the family level. CNOs with high electrical conductivity acted as artificial pili to enhance DIET between Geobacteraceae and Methanosaetaceae, as well as between Syntrophobacteraceae and Methanobacteriaceae or Methanosaetaceae. Furthermore, CNOs dosing during Phase 4 mitigated membrane contamination, and the maximum filtration resistance was 11% lower than that of Phase 3. These results suggest that CNOs can be used effectively in AnMBR for treating CAP wastewater, particularly for enhancing methanogens.

Efficient activation of peroxydisulfate by 3D flower spherical-like Fe–NC for organic contaminant removal: Fe(IV)=O as a dominant species

The high-valent iron-oxo species (Fe(IV)O) exhibit great prospects for the removal of organic contaminants in iron-mediated persulfate activation. Nevertheless, an adequate research of the mechanisms involved in Fe(IV)-based activation processes and organic degradation remains elusive. Here, an Fe encapsulated in N-doped carbons catalyst (2Fe–NC) with three-dimensional flower shape and mesoporous structure was developed, which can 100 % remove various organic pollutants such as chloramphenicol (CAP), sulfamethoxazole, amoxicillin, benzoic acid, and bisphenol A within 30 min by peroxydisulfate (PDS) activation. In the oxidation system, 2Fe–NC as an electron transfer medium was critical to mediate electron transfer from organic compound to PDS, accompanied by the redox cycle of Fe(IV)/Fe(II) and Fe(IV)/Fe(III). Multiple experiments reveal that the oxidation mechanism of 2Fe–NC@PDS system is similar to the dioxygen activation mechanism of binuclear active sites, which activates PDS to form surface-active Fe(IV)O species without producing radicals. The two pathways of CAP degradation simulated by density functional theory calculations release 6.92 and 4.23 eV, respectively, which is thermodynamically favorable. Overall, the new insights gained in this work offer a significant route to design more effective advanced oxidation processes for refractory contaminant treatment.

Nitrogen-doped bimetallic MOFs derivatives for efficient ionizing radiation catalytic degradation of chloramphenicol

Electron beam (EB) irradiation has received increased attention in sewage disposal due to the high efficiency, no additional chemicals and wastes produced. However, it’s still limited by relatively high processing costs. In this work, we report a novel nitrogen-doped Fe/Ni bimetallic metal organic frameworks (MOFs) derivative for efficient ionizing radiation catalytic degradation of chloramphenicol (CAP). Compared with the single EB irradiation, the radiation-catalytic process allows a 2.8-fold increment in degradation rate constant and a 21.2-fold enhancement in the TOC removal rate. The EPR experimental results confirmed that the optimized composite catalyst significantly enhances the generation of hydroxyl radicals. Intriguingly, the synergistic effect of Fe/Ni element in the valence state were observed in the radiation-catalytic process, in which the generation of Fe2+ promoted the production of hydroxyl radical. The adsorption experiments reveal that most of the high removal effect origins from complete degradation rather than the adsorption effect. These key indicators of irradiation degradation are all the highest compared to the reported literature. In addition, the catalyst also has excellent cycle stability under irradiation. The high-performance ionizing radiation catalytic degradation in synergy with bimetallic MOFs derivatives provides a facile and general strategy for efficient EB irradiation treatment of organic wastewater.

Influence of humate on the degradation of chloramphenicol by sulfidated ferrihydrite under dynamic anoxic/oxic environments: A combined DFT calculation and experimental study

Sulfidation of ferrihydrite is known to affect the degradation of contaminants, but little was known about the role of natural organic matter (NOM) in antibiotics degradation by sufidated ferrihydrite under redox-dynamic conditions. Here, a typical antibiotic (i.e., chloramphenicol (CAP)) was chosen to investigate how it redistributed when ferrihydrite reacted with reductive dissolved sulfide (S(-II)dis) in the presence of humate (HA) under dynamic anoxic/oxic environments. In anoxic environments, HA enhanced CAP reduction via dichlorination or decarboxylation by sufidated ferrihydrite in the low concentration of S(-II), while HA inhibited CAP reduction in the high concentration of S(-II) by the contribution of S(-II) and surface-bound Fe(II) (Fe(II)adsorbed). When the conditions transited from anoxic to oxic, remaining CAP molecules in solutions continued undergoing oxidative degradation to form the succinic acid, hexanedioic acid, CO2, and H2O by the attack of ·OH. Meantime, HA was adsorbed to ferrihydrite to block autocatalytic Fe(II) oxidation, which inhibited the generation of ·OH under oxic conditions. Additionally, from the density function theory (DFT) calculation and intermediate products analysis obtained from HPLC-MS/MS, two oxidative degradation pathways of CAP during the oxidation of sulfidated ferrihydrite have been proposed. Collectively, the framework elucidated different roles of HA in CAP elimination and environmental behavior of ferrihydrite when exposed to the S(-II) under the dynamic redox conditions.

Implementation of visible light-driven photocatalytic degradation of antibiotic chloramphenicol using Bi2S3/ZrO2 and Bi2WO6/ZrO2 heteronanostructures

Zirconium dioxide-incorporated bismuth sulfide (Bi2S3/ZrO2) and bismuth tungstate (Bi2WO6/ZrO2) heteronanostructures (HNSs) were fabricated to serve as photocatalysts for the visible light-driven degradation of antibiotic chloramphenicol (CAP). A two-step hydrothermal process was applied to synthesize HNSs, and their structural and optical properties were validated by several analytical techniques. Interestingly, a multi-structural feature was ascertained in which nanoflower-structured ZrO2 was attached to the surface of nanorod- and nanosheet-structured Bi2S3 and Bi2WO6, respectively, resulting in the formation of Bi2S3/ZrO2 and Bi2WO6/ZrO2 HNSs. For the photocatalytic degradation of CAP, both HNSs showed magnificent catalytic activity during a visible light-based photocatalytic degradation. Furthermore, when peroxymonosulfate (PMS) was used as an activator for an oxidative catalytic reaction, the photocatalytic degradation rate was drastically enhanced to nearly 5 times. Bi2S3/ZrO2 and Bi2WO6/ZrO2 showed ∼96 % CAP degradation in 15 min, with rate constants of 0.2511 and 0.2163 min−1, respectively. The synergistic effects of the substantial generation and separation of photoinduced charge carriers are responsible for the highly improved catalytic activity. Scavenger analysis demonstrated that hydroxyl radical species predominated in the effective degradation process. These kinds of inorganic-based HNSs are expected to rule the field of contaminated water remediation, which will also expand a platform for the fabrication of photocatalyst materials.

F-enhanced anti-bonding activation effect of FeO on catalytic degradation of chloramphenicol by dielectric barrier discharge plasma

In this study, dielectric barrier discharge (DBD) plasma and F/FeO catalyst were utilized to degrade chloramphenicol (CAP) in water. The operation conditions, catalyst properties and catalytic mechanisms were systematically studied, and the anti-bonding activation effect was highlighted as the key for the catalytic effect. The results show that CAP was 100% degraded by DBD and F/FeO after 8 min treatment under optimal operating conditions, and F/FeO catalyst increased the degradation efficiency of CAP by 34.1%. FeO transferred electrons into the π* anti-bonding orbital of O3 and the σ* anti-bonding orbitals of H2O2 and O2, leading to an anti-bonding activation effect and weakening their bonding. Additionally, F facilitated the electron transfer of FeO and changed the stable adsorption of O3 and H2O2 on FeO to dissociated adsorption on F/FeO. The –OH groups generated by the H2O2 dissociation could induce a non-Fenton catalytic pathway. The intensive electron transfer of F/FeO converted O2 into ·O2−. The ant-bonding activation of O3, H2O2 and O2 on F/FeO facilitated the production of ·OH. A degradation pathway for CAP was proposed based on the findings of experiments and simulation. The developmental toxicity of CAP was weakened after F/FeO/DBD treatment. This study proposes an efficient plasma catalyst for purifying antibiotic wastewater, and provides a new insight into the mechanism of the plasma/catalysis process.

Efficient Electrochemical Oxidation of Chloramphenicol by Novel Reduced TiO2 Nanotube Array Anodes: Kinetics, Reaction Parameters, Degradation Pathway and Biotoxicity Forecast.

The key component of electrochemical advanced oxidation technology are high-efficiency anodes, and highly efficient and simple-to-prepare materials have generated a lot of interest. In this study, novel self-supported Ti3+-doped titanium dioxide nanotube arrays (R-TNTs) anodes were successfully prepared by a two-step anodic oxidation and straightforward electrochemical reduction technique. The electrochemical reduction self-doping treatment produced more Ti3+ sites with stronger absorption in the UV-vis region, a band gap reduction from 2.86 to 2.48 ev, and a significant increase in electron transport rate. The electrochemical degradation effect of R-TNTs electrode on chloramphenicol (CAP) simulated wastewater was investigated. At pH = 5, current density of 8 mA cm-2, electrolyte concentration of 0.1 M sodium sulfate (Na2SO4), initial CAP concentration of 10 mg L-1, CAP degradation efficiency exceeded 95% after 40 min. In addition, molecular probe experiments and electron paramagnetic resonance (EPR) tests revealed that the active species were mainly •OH and SO4-, among which •OH played a major role. The CAP degradation intermediates were discovered using high-performance liquid chromatography-mass spectrometry (HPLC-MS), and three possible degradation mechanisms were postulated. In cycling experiments, the R-TNTs anode demonstrated good stability. The R-TNTs prepared in this paper were an anode electrocatalytic material with high catalytic activity and stability, which could provide a new approach for the preparation of electrochemical anode materials for difficult-to-degrade organic compounds.

Elimination of chloramphenicol through electro-fenton-like reaction: Reaction mechanism and electron transfer pathway

An electro-Fenton-like reaction process relying on peroxymonosulfate activation can stably degrade chloramphenicol (CAP) within 16 min, where the kinetic rate constant can be as high as 0.089 min−1 and the energy consumption value can be as low as 25.1 kWh•m^−3. Evidence indicated that the use of a Na2SO4 solution as the electrolyte can enhance CAP degradation due to rapid electron transfer properties. The generated electrons and active free radicals are responsible for CAP degradation, and the electrons can be transferred from the highest occupied molecular orbital of CAP to the lowest unoccupied molecular orbital of peroxymonosulfate via the PbO2 electrode. Density functional theory calculations based on Fukui index analysis elucidated the key attack sites in CAP; moreover, reaction-free energy calculations shed light on potential CAP degradation pathways. Not only does this study afford an insight into the activation of peroxymonosulfate for organic pollutant degradation but also provides an innovative technology with potential applications in wastewater purification.