Removal Of Chloramphenicol Research Articles

Research on the Chloramphenicol Removal Performance of Co-Doped Porous Carbon Materials Derived from Co-Zn Bimetallic ZIFs

Chloramphenicol antibiotics (CAPs) are broad-spectrum antibiotics, and excessive consumption has led to increasingly dangerous residues in the environment. The accumulation of these highly toxic and difficult-to-biodegrade CAPs and their long-term exposure in ecological environments can pose insidious and long-term hazards to human health and aquatic organisms. In this study, co-carbon composite nanocatalysts (CoxZn10−x-NC) with many carbon nanotubes on the surface were prepared via the one-step pyrolysis of bimetallic CoxZn10−x-ZIF with different Co/Zn ratios and used for the degradation of trace amounts of CAPs in a water column. The microstructure and chemical composition of the prepared catalysts were fully characterized using SEM, TEM, and XPS. The CAP degradation experiments demonstrated that Co6Zn4-NC in CoxZn10−x-NC possessed the highest catalytic activity level, removing 100% of the CAPs in 60 min. The CAPs had a corresponding reaction rate constant of 0.22 min−1, and Co6Zn4-NC was able to completely mineralize 44.57% of them. Doping moderate amounts of Zn can effectively improve the carbon nanotube structure on the catalyst surface and promote the generation of monoatomic Co, thus improving catalytic activity. The results of the free-radical burst experiments and electron paramagnetic resonance (EPR) showed that the free-radical pathway mainly dominated within the Co6Zn4-NC+PMS system, in which SO4•− was the main ROS for CAP degradation.

EFFICIENCY OF WASTEWATER TREATMENT FROM CHLORAMPHENICOL USING Lemna minor

The article studies the effectiveness of wastewater treatment contaminated with chloramphenicol, a broad-spectrum antibiotic often found in the wastewater of pharmaceutical enterprises and healthcare facilities. The aim of the study was to determine the efficiency of chloramphenicol removal from model solutions using the biological agent Lemna minor depending on the initial concentration of the antibiotic and the treatment time. Model solutions with initial chloramphenicol concentrations of 2, 5, 10, and 20 mg/L were used. The treatment time ranged from 1 to 72 hours. Methods. The chloramphenicol content in the model solutions was determined using high-performance liquid chromatography. Results. Lemna minor effectively reduces the concentration of chloramphenicol, with a maximum reduction of 33.0% achieved at an initial concentration of 10 mg/L and 29.5% for 20 mg/L after 72 hours of treatment. The duckweed biomass was 0.04 g/mL. At 2 and 5 mg/L concentrations, the cleaning efficiency gradually increased for the first 24 hours, reaching a maximum of 23.2% and 26.8%, respectively, to 72 hours. This indicates that Lemna minor can effectively reduce antibiotic content in water but a long contact time is required to achieve maximum efficiency. In the control experiments where Lemna minor was not used, the chloramphenicol concentration remained unchanged over 72 hours, confirming the absence of natural decomposition or change in antibiotic content without a biological agent. Conclusions. The studies confirm the effectiveness of Lemna minor as a biological agent for reducing chloramphenicol concentrations in wastewater by up to 33%. The use of duckweed helps reduce the environmental impact of the antibiotic and contributes to lowering the risk of antibiotic resistance development.

Efficient photocatalytic degradation of chloramphenicol from contaminated water over rGO@MoS2 nanocomposites

Antibiotics-based effluents pose a severe threat to the natural ecosystem by acting as reservoirs for the growth of drug-resistant bacteria if untreated. Herein, a facile and scalable approach was developed to engineer photocatalysts associating reduced graphene oxide (rGO) and molybdenum disulfide (rGO@MoS2) that were used for the degradation of chloramphenicol (CAP) from contaminated water under UV-light. The hydrothermally produced rGO@MoS2 catalysts contain CO, COH, and COC functional groups that contribute to the binding of CAP onto their surface. The rGO surface modification with MoS2 layers offers a high surface area for light absorption. Results show that the rGO@MoS2 catalyst (1:1 w/w) exhibits the highest degradation efficiency (DE) of 86 % within 180 min of light exposure at neutral pH. Further, the kinetic modelling studies for CAP degradation by rGO@MoS2 1:1 showed high linearity with pseudo-first order kinetics (R2 ∼ 0.9). The isotherm modelling studies correspond to Langmuir isotherm (R2 ∼ 0.99), suggesting monolayer-type interaction of CAP with the photocatalyst surface during photodegradation. Furthermore, the mechanism of degradation elucidated using scavenging experiments showed the involvement of both holes (h+) and electrons (e−) that contribute to the degradation of CAP by generating reactive oxygen species (ROS) like OH● and O2●− radicals. The applicability of the rGO@MoS2 photocatalyst towards the degradation of CAP was tested in Ganga water, wherein a similar ∼86 % CAP removal was observed. Furthermore, the photocatalyst was found to be stable and could be reused five times. Overall, these findings demonstrate the usefulness of the rGO@MoS2 1:1 composite as an efficient photocatalyst that can be used for the degradation of harmful organic pollutants from water bodies to provide a safer and cleaner environment.

Insights into the role of electrochemical stimulation on sulfur-driven biodegradation of antibiotics in wastewater treatment

The presence of antibiotics in wastewater poses significant threat to our ecosystems and health. Traditional biological wastewater treatment technologies have several limitations in treating antibiotic-contaminated wastewaters, such as low removal efficiency and poor process resilience. Here, a novel electrochemical-coupled sulfur-mediated biological system was developed for treating wastewater co-contaminated with several antibiotics (e.g., ciprofloxacin (CIP), sulfamethoxazole (SMX), chloramphenicol (CAP)). Superior removal of CIP, SMX, and CAP with efficiencies ranging from 40.6 ± 2.6 % to 98.4 ± 1.6 % was achieved at high concentrations of 1000 μg/L in the electrochemical-coupled sulfur-mediated biological system, whereas the efficiencies ranged from 30.4 ± 2.3 % to 98.2 ± 1.4 % in the control system (without electrochemical stimulation). The biodegradation rates of CIP, SMX, and CAP increased by 1.5∼1.9-folds under electrochemical stimulation compared to the control. The insights into the role of electrochemical stimulation for multiple antibiotics biodegradation enhancement was elucidated through a combination of metagenomic and electrochemical analyses. Results showed that sustained electrochemical stimulation significantly enriched the sulfate-reducing and electroactive bacteria (e.g., Desulfobulbus, Longilinea, and Lentimicrobiumin on biocathode and Geobactor on bioanode), and boosted the secretion of electron transport mediators (e.g., cytochrome c and extracellular polymeric substances), which facilitated the microbial extracellular electron transfer processes and subsequent antibiotics removal in the sulfur-mediated biological system. Furthermore, under electrochemical stimulation, functional genes associated with sulfur and carbon metabolism and electron transfer were more abundant, and the microbial metabolic processes were enhanced, contributing to antibiotics biodegradation. Our study for the first time demonstrated that the synergistic effects of electrochemical-coupled sulfur-mediated biological system was capable of overcoming the limitations of conventional biological treatment processes. This study shed light on the mechanism of enhanced antibiotics biodegradation via electrochemical stimulation, which could be employed in sulfur-mediated bioprocess for treating antibiotic-contaminated wastewaters.

Molecular imprinting electrochemical sensor based on hollow spherical PProDOT-2CH2OH and chitosan-derived carbon materials for highly sensitive detection of chloramphenicol

The misuse of chloramphenicol (CAP) has jeopardized environmental safety. It is critical to create an effective and sensitive CAP detection technique. In this paper, a composite of chitosan (CS)-derived carbon material modified hollow spherical hydroxylated poly(3,4-propylenedioxythiophene) (PProDOT-2CH2OH) was designed, which innovatively used o-phenylenediamine and p-aminobenzoic acid as bi-functional monomers to prepare molecular imprinting polymer (MIP) sensors for highly sensitive analysis and determination of CAP. It was found that the hollow spherical structure of PProDOT-2CH2OH significantly enhanced the rapid electron migration. When combined with the CS-derived carbon material, which has multi-functional sites, it improved the electrical activity and stability of the sensor. It also provided more active centers for the MIP layer to specifically recognize CAP. Therefore, this MIP sensor had a wide linear response (0.0001 ∼ 125 μM), a low limit of detection (LOD, 6.6 pM), excellent selectivity and stability. In addition, studies showed that the sensor has potential practical value. Environmental implicationChloramphenicol (CAP) is one of the most widely used antibiotics with the highest dosage due to its low price and broad-spectrum antimicrobial properties. Due to its incomplete metabolism in living organisms and its difficulty in degrading in the environment, contamination caused by it can pose a threat to public health. In this study, a novel molecularly imprinted sensor (MIP/PC2C1/GCE) was designed to provide a new idea for rapid and precise removal of CAP by adsorption. The detection of CAP in pharmaceutical, water quality, and food fields was realized.

Regulating the electronic structure by P-doping cobalt-based catalyst for atomic hydrogen mediated electrocatalytic dechlorination

Electrocatalytic dechlorination by atomic hydrogen (H*) is efficient, but limited by the low efficiency of H* production. Herein, a phosphorus-doped cobalt nitrogen carbon catalyst (Co-NP/C) was prepared, which had high catalytic activity in a wide pH range (3−11). The turnover frequency of Co-NP/C (3.54 min−1) was 1.21–59000 times superior to that of current Pd-based and non-noble metal catalysts (0.00006–2.92 min−1). Co-NP/C significantly enhanced H* generation, which was 1.52, 2.44, and 3.77 times stronger than that of Co-N/C, NP/C, and N/C, respectively, since the introduction of phosphorus was found enhanced the electron density of cobalt and regulated the electron transfer. Co-NP/C showed outstanding catalytic performance after ten cycles and could achieve nearly complete chloramphenicol removal. This regulation method was verified to be effective for other non-noble metal (Fe, Mn, Cu, Ni) phosphorus doped catalysts, proposing a general class for efficient electrochemical dechlorination, which would be of great significance for the elimination of chlorinated organic pollutants.

Harnessing microwave energy to transform Nephelium lappaceum L. peel into activated carbon for chloramphenicol eradication in aqueous solutions

Emerging contaminants (EC) like chloramphenicol in wastewater are highly related to human, livestock, and aquaculture therapeutic activities. High levels of chloramphenicol in water may cause toxic effects on an aquatic environment, humans, and animals. The removal of chloramphenicol in wastewater was the main objective of this study. This study explores the use of microwave irradiation in the production of Rambutan peel-based activated carbon (RPAC) at a heating power of 700 W for 15 min under carbon dioxide, CO2 gas flow. RPAC had a BET surface area of 583.44 m2/g, mesopores surface area of 469.87 m2/g, total pore volume of 0.27 cm3/g, and average pore diameter of 2.31 nm. The equilibrium study shows that the concentration of Cp adsorbed by RPAC increased as the initial concentration increased from 4.93 mg/g to 25.10 mg/g. Isotherm adsorption determined that Langmuir was the preferred model since it has the lowest RSME and highest R2 of 3.34 and 0.9994, respectively. It was observed from kinetic studies that the adsorption system relies on the pseudo-second order. According to thermodynamic studies, the enthalpy change, △H° and Gibbs free energy, △G° obtained indicating that the adsorption process occurs in an exothermic and spontaneous state.

Cerium-substituted hierarchical Bi2WO6 microspheres for the effective removal of chloramphenicol and rhodamine B dye through photocatalysis

Cerium-substituted hierarchical Bi2WO6 microspheres for the effective removal of chloramphenicol and rhodamine B dye through photocatalysis

Synergistic photocatalytic ozonation of eliminating chloramphenicol over a 2D MXene-derived heterojunction

Herein, we demonstrate the first example of applying 2D MXene hetero-interfaced nanocomposites for a photocatalytic ozonation of chloramphenicol (CAP). The hierarchical 2D/2D Bi2MoO6/Ti3C2Tx MXene (BMT) hybrid enables a high CAP removal ratio of 95 % within 60 min that outperforms bare Bi2MoO6. Evidences from theoretical calculations and experimental findings prove that the adsorption capability of O3/O2 onto BMT surfaces is elevated and the electron transfer process is accelerated by virtue of hybridization with Ti3C2Tx, thus facilitating the generation of reactive oxygen species (ROSs) including •OH, 1O2 and •O2−. Such elaborate design provides a novel type of robust and cost-effective material adapted for integrated advanced oxidation processes (AOPs) in highly efficient removal of refractory organic substances in water environments.

Impact of environmental factors on the removal of chloramphenicol by zero-valent iron and pyrite mixture

Chloramphenicol (CAP) is an effective bacteriostatic pharmaceutical that has been widely applied in clinical prescriptions, animal husbandry and aquaculture, but the residues excreted by human and animals have resulted in environmental pollution. Here, we investigated the mechanism of enhanced removal of CAP by zero-valent iron (ZVI) and pyrite mixture, the effect of environmental factors (i.e., initial pH, and co-solutes (anions, cations and organic matter)) as well as the potential applications and environmental safety of ZVI/pyrite mixture. Results show that the mixing of pyrite with ZVI enhanced the removal efficiency of CAP from 14.2% to 80–100% with a range of pyrite/ZVI mass ratios from 1.0 to 4.0. The environmental factors can change the surface reactivity and composition of pyrite/ZVI mixture, consequently altering the removal of CAP. Mechanism study revealed that pyrite could suppress the pH increase, mitigate the passivation of ZVI surface, and accelerate the production of reactive Fe(II). The X-ray diffraction (XRD) and transmission electron microscopy (TEM) characterization results of the solids after reacting at different pH conditions indicated formation of highly reactive secondary minerals (such as green rust and iron sulfide (FeS)). In addition, in different co-solutes systems, the secondary minerals are differed, leading to the change of ZVI surface reactivity. This study extends the knowledge of the effect of environmental condition on ZVI technology in practical engineering systems.

Chloramphenicol Removal from Aqueous Solution Using Sodium Bicarbonate-Impregnated Coconut Husk-Derived Activated Carbon: Optimization and Insight Mechanism Study

Chloramphenicol Removal from Aqueous Solution Using Sodium Bicarbonate-Impregnated Coconut Husk-Derived Activated Carbon: Optimization and Insight Mechanism Study

Removal of chloramphenicol and resistance gene changes in electric-integrated vertical flow constructed wetlands

The performance of an electric-integrated vertical flow constructed wetland (E-VFCW) for chloramphenicol (CAP) removal, changes in microbial community structure, and the fate of antibiotic resistance genes (ARGs) were evaluated. CAP removal in the E-VFCW system was 92.73% ± 0.78% (planted) and 90.80% ± 0.61% (unplanted), both were higher than the control system which was 68.17% ± 1.27%. The contribution of anaerobic cathodic chambers in CAP removal was higher than the aerobic anodic chambers. Plant physiochemical indicators in the reactor revealed electrical stimulation increased oxidase activity. Electrical stimulation enhanced the enrichment of ARGs in the electrode layer of the E-VFCW system (except floR). Plant ARGs and intI1 levels were higher in the E-VFCW than in the control system, suggesting electrical stimulation induces plants to absorb ARGs, reducing ARGs in the wetland. The distribution of intI1 and sul1 genes in plants suggests that horizontal transfer may be the main mechanism dispersing ARGs in plants. High throughput sequencing analysis revealed electrical stimulation selectively enriched CAP degrading functional bacteria (Geobacter and Trichlorobacter). Quantitative correlation analysis between bacterial communities and ARGs confirmed the abundance of ARGs relates to the distribution of potential hosts and mobile genetic elements (intI1). E-VFCW is effective in treating antibiotic wastewater, however ARGs potentially accumulate.

Removal of antibiotics with different charges in water by graphene oxide membranes

Abstract Antibiotics are a large group of emerging organic pollutants with low concentration levels in the water. The presence of antibiotics will affect the ecological environment and human health. The removal of trace organic compounds by graphene oxide (GO) membranes has attracted extensive attention. This study investigated the removal of three differently charged antibiotics by GO membranes and the influence of water quality on the removal of antibiotics. It showed that a crosslinked ethylenediamine-GO (EDA-GO) membrane had better stability and higher antibiotic removal performance than a non-crosslinked GO membrane. Among the three antibiotics, penicillin (PNC) was negatively charged and had the highest removal efficiency due to steric effect and electrostatic repulsion. A low concentration (10 mmol L−1) of Na+ in water could increase the membrane flux but had no significant effect on the removal of antibiotics. Ca2+ could reduce the membrane flux and improve the removal of chloramphenicol (CAP) and PNC. The removal efficiencies of low-concentration antibiotics (500 μg L−1) were higher than those of high-concentration antibiotics (10 mg L−1). Furthermore, the removal of antibiotics under the condition of actual wastewater quality was higher than those in solutions prepared with ultrapure water. The EDA-GO membrane has great potential in the removal of antibiotics in wastewater.

Effectively facilitating the degradation of chloramphenicol by the synergism of Shewanella oneidensis MR-1 and the metal-organic framework

Electroactive bacteria (EAB) and metal oxides are capable of synergistically removing chloramphenicol (CAP). However, the effects of redox-active metal-organic frameworks (MOFs) on CAP degradation with EAB are not yet known. This study investigated the synergism of iron-based MOFs (Fe-MIL-101) and Shewanella oneidensis MR-1 on CAP degradation. 0.5 g/L Fe-MIL-101 with more possible active sites led to a three-fold higher CAP removal rate in the synergistic system with MR-1 (initial bacterial concentration of 0.2 at OD600), and showed a superior catalytic effect than exogenously added Fe(III)/Fe(II) or magnetite. Mass spectrometry revealed that CAP was transformed into smaller molecular weight and less toxic metabolites in cultures. Transcriptomic analysis showed that Fe-MIL-101 enhanced the expression of genes related to nitro and chlorinated contaminants degradation. Additionally, genes encoding hydrogenases and c-type cytochromes associated with extracellular electron transfer were significantly upregulated, which may contribute to the simultaneous bioreduction of CAP both intracellularly and extracellularly. These results indicated that Fe-MIL-101 can be used as a catalyst to synergize with EAB to effectively facilitate CAP degradation, which might shed new light on the application in the in situ bioremediation of antibiotic-contaminated environments.

Unveiling the Neglected Roles of Chloride and Sulfate in the Removal of Nitro Compounds by Sulfidated Zero-Valent Iron/Ferrous Ion Systems

Ferrous ions (Fe2+) can effectively promote the removal of pollutants by sulfidated zero-valent iron (S-ZVI), but the role of anions coexisting with Fe2+ was often ignored. This study systematically compared the performances of S-ZVI/FeCl2 and S-ZVI/FeSO4 systems for chloramphenicol (CAP) and nitrobenzene (NB) removal. The results showed that FeCl2 and sulfidation had a synergistic promoting effect on the reaction, but FeSO4 could not promote the removal of nitro compounds by S-ZVI. Liquid chromatography/mass spectrometry (LC/MS) and UV–vis analysis showed that only the nitro group was reduced during the removal of CAP and NB. The results of batch experiments showed that both NaCl and Na2SO4 could effectively promote the reaction, but the promotion effect of Na2SO4 weakened with the decrease of pH. X-ray photoelectron spectroscopy (XPS) analysis showed that Fe2+ could promote the adsorption of SO42– on the surface of S-ZVI. A possible mechanism was proposed: Fe2+ could maintain a low pH level because of hydrolysis, which promoted the adsorption of Cl– and SO42– on the surface of S-ZVI. Cl– promoted the reaction because of its pitting corrosion, while SO42– competed with nitro groups for the adsorption sites. Our findings suggest that the coexisting anions are quite essential in the removal of nitro compounds by S-ZVI/Fe2+ systems.

Determination of the fate of antibiotic resistance genes and the response mechanism of plants during enhanced antibiotic degradation in a bioelectrochemical-constructed wetland system

Chloramphenicol (CAP) has a high concentration and detection frequency in aquatic environments due to its insufficient degradation in traditional biological wastewater treatment processes. In this study, bioelectrochemical assistant-constructed wetland systems (BES-CWs) were developed as advanced processes for efficient CAP removal, in which the degradation and transfer of CAP and the fate of antibiotic resistance genes (ARGs) were evaluated. The CAP removal efficiency could reach as high as 90.2%, while the removed CAP can be partially adsorbed and bioaccumulated in plants, significantly affecting plant growth. The vertical gene transfer and horizontal gene transfer increased the abundance of ARGs under high voltage and CAP concentrations. Microbial community analysis showed that CAP pressure and electrical stimulation selected the functional bacteria to increase CAP removal and antibiotic resistance. CAP degradation species carrying ARGs could increase their opposition to the biotoxicity of CAP and maintain system performance. In addition, ARGs are transferred into the plant and upward, which can potentially enter the food chain. This study provides an essential reference for enhancing antibiotic degradation and offers fundamental support for the underlying mechanism and ARG proliferation during antibiotic biodegradation.

In Vitro Photo-Catalytic Degradation of Chloramphenicol Using Pharmaceutical Wastewater

Abstract: In this work, the performance of composite membranes for the treatment of Chloramphenicol (CAP) pollutants was investigated from pharmaceutical industrial wastewater. The composite membrane was under operated with different concentrations of CAP with Titanium dioxide (TiO2) in 10mg/L, 20mg/L and 30 mg/L. The composite membranes were cross-linked with glutaraldehyde for the elimination of H2SO4. Characterizations of synthesized composite membranes were carried out to analyze functionality, morphology, and hydrophilic behaviours. In continuous operation, the different time intervals of TiO2 were removed in centrifuging. The performance of the composite membrane is the removal of pollutant CAP by UV analysis, and kinetics model at different concentrations. The degree of swelling and contact angle were measured in different concentrations of CAP at TiO2. Liquid Chromatography (LC) is used to CAP with Titanium dioxide mixtures. Mass Spectrometry (MS) can be used for structural identity with high specificity. The MS is also used to analyze CAP from pharmaceutical industrial wastewater. The membranes were subjected to filtration of pharmaceutical wastewater which gave a maximum rejection of 95% of Chloramphenicol.

In Vitro Photo-Catalytic Degradation of Chloramphenicol Using Pharmaceutical Wastewater

Abstract: In this work, the performance of composite membranes for the treatment of Chloramphenicol (CAP) pollutants was investigated from pharmaceutical industrial wastewater. The composite membrane was under operated with different concentrations of CAP with Titanium dioxide (TiO2) in 10mg/L, 20mg/L and 30 mg/L. The composite membranes were cross-linked with glutaraldehyde for the elimination of H2SO4. Characterizations of synthesized composite membranes were carried out to analyze functionality, morphology, and hydrophilic behaviours. In continuous operation, the different time intervals of TiO2 were removed in centrifuging. The performance of the composite membrane is the removal of pollutant CAP by UV analysis, and kinetics model at different concentrations. The degree of swelling and contact angle were measured in different concentrations of CAP at TiO2. Liquid Chromatography (LC) is used to CAP with Titanium dioxide mixtures. Mass Spectrometry (MS) can be used for structural identity with high specificity. The MS is also used to analyze CAP from pharmaceutical industrial wastewater. The membranes were subjected to filtration of pharmaceutical wastewater which gave a maximum rejection of 95% of Chloramphenicol.

Enhanced reductive degradation of chloramphenicol by sulfidated microscale zero-valent iron: Sulfur-induced mechanism, competitive kinetics, and new transformation pathway

Crystalline iron sulfide (FeSx, i.e., FeS or FeS2) minerals as sulfur sources were used to prepare the mechanochemically sulfidated microscale zero-valent iron ((FeSx+ZVI)bm). Metastable FeS and FeS2 precursors were generated via aqueous coprecipitation and applied to fabricate FeSx@ZVI samples. (FeSx+ZVI)bm and FeSx@ZVI exhibited better chloramphenicol (CAP) degradation than ZVI due to the increase in specific surface areas, the decrease of electrochemical impedance, the formation of galvanic cells, and sulfur-induced pitting and local acidity. (FeSx+ZVI)bm had better CAP removal capacity than FeSx@ZVI under different S/Fe molar ratios, initial pH, and oxygen conditions. At the same time, FeSx@ZVI showed better electron utilization under oxic conditions, related to their Fe0 and sulfur spatial distribution. Nitro reduction and dechlorination of CAP by (FeSx+ZVI)bm produced nitroso, azoxy, amine, and monodechlorination products, while dechlorination was not involved in the degradation process of CAP by FeSx@ZVI. A new transformation pathway of nitroso-CAP to amine-CAP mediated by azoxy products is proposed via coupling a chain decay multispecies model and DFT calculations. The larger competitive reaction rates among O2, CAP, and its degradation products was determined by their lower LUMO energy. The contribution of direct electron transfer to nitro reduction was greater than that of atomic hydrogen, but the opposite was true for dechlorination. FeSx@ZVI had a larger DET contribution than (FeSx+ZVI)bm, and FeS2 promoted the DET contribution better than FeS. Toxicity assessment indicated that the rapid transformation of nitroso and azoxy products was crucial for eliminating the biotoxicity of CAP.

In-situ fabrication of a three-dimensional nanopalladium network into a biocathode enhances chloramphenicol degradation

Bioelectrochemical systems (BESs) with biocathodes are a promising technology for antibiotic removal, but they are often limited by inefficient electron transfer from the cathode to bacteria due to the low conductivity of biofilms. In this study, a conductive cathodic biofilm was established through in-situ synthesis and immobilization of biogenic palladium nanoparticles (Pd-NPs) for chloramphenicol (CAP) removal. Compared to the control biocathode, the limiting current density of the Pd-fabricated biocathode (Pd-biocathode) was increased by 4.3 times, and the charge transfer resistance was decreased by 673 % due to enhanced extracellular electron transfer. The Pd-biocathode showed accelerated CAP removal, with the removal rate constant (k) increasing by 44 % compared to the control biocathode. In particular, the removal efficiency of the Pd-biocathode increased by 71 % within 4 h. These results might be explained by the decreased charge transfer resistance of the biocathode, the selective enrichment of functional bacteria and the up-expression of genes encoding organic substance metabolism and degrading enzyme activity. In addition, the increased applied voltage negligibly affected the enhancement of CAP removal in the Pd-biocathode BES, but it enhanced CAP removal in the control BES. Additionally, glucose addition markedly improved the CAP removal rates. This work demonstrates the potential of an effective and simple biocathode modification strategy through the in-situ synthesis of conductive NPs that could increase the antibiotic removal rates, but also provides new insight into how microbe-electrode interactions can be improved to enhance BES performance in wastewater treatment.