Degradation Of Tetracycline Antibiotics Research Articles

Carbon-based heterostructure from multi-photo-active nanobuilding blocks SrTiO3@NiFe2O4@Fe0@Ni0@CNTs with derived nanoreaction metallic clusters for enhanced solar light-driven photodegradation of harmful antibiotics

We reported on the sequential development of a high-operative photocatalyst with penta-component inorganic bulk heterojunction for improved charge trapping characteristics at particle–particle interfaces for enhanced solar light-driven photocatalytic degradation of active tetracycline antibiotic. Structural, morphological, optical, and electronic properties of the synthesized samples were investigated using a series of complementary characterization techniques, such as XRD, FE-SEM, HR-TEM, XPS, as well as hard and soft XAS in both total electron yield (TEY) and fluorescence yield (TFY). For the case of the carbon composite material, SrTiO3@NiFe2O4@Fe0@Ni0@CNTs, a reduced crystallinity when compared to the starting support material was noticed, although this translated into a significant improvement of the morphology and the photocatalytic performance. The SrTiO3@NiFe2O4@Fe0@Ni0@CNTs fibrous photocatalyst can efficiently achieve a high-to-total degradation of tetracycline antibiotic under visible light irradiation in less than two hours, following a non-linear PFO kinetic model with an apparent reaction rate of about 0.0606 min−1 and an 98% photodegradation activity. The XPS and XAS analysis demonstrated unequivocally the appearance of nanoscale zero-valent iron (Fe0) and zero-valent nickel (Ni0) on the photocatalyst surface, which facilitates the separation of photogenerated e+ and h+ pairs, and the appearance of more active sites.

Electrodeposited manganese oxides as efficient photocatalyst for the degradation of tetracycline antibiotics pollutant

One of the important environmental challenges of the 21st century is the effective removal of pollutants from the aquatic environment. In this study, electrodeposited manganese oxides (MnyOx) films were applied as visible-light-driven photocatalyst for the removal and mineralization of Tetracycline (TC) antibiotics. The photocatalytic activity of as-deposited and annealed MnyOx was tested at different pH values using LED visible illumination, resulting in 92.4 % of TC mineralization efficiency after 180 min for the best performing manganese oxide. Quenching experiments showed that hydroxyl radicals (OH) are the main active species responsible for the TC degradation. The photocorrosion of MnyOx has been studied by quantifying the concentration of the dissolved manganese cations during the photocatalytic experiments. By comparing the catalyst mass loss with the % of TC mineralization, we revealed that the degradation of the oxide surface structure is the factor that, more than the photocorrosion, is limiting the photocatalytic activity of MnyOx films. Finally, the photocatalytic mechanism of TC mineralization is proposed based on the detection of the intermediates species of the mineralization process by High-Performance Liquid Chromatography Mass-Spectroscopy. The facile synthesis process and the superior mineralization rate can open up a new approach for the possible large-scale utilization of electrodeposited MnyOx films as an effective visible light photocatalyst.

Dense and uniform growth of TiO2 nanoparticles on the pomelo-peel-derived biochar surface for efficient photocatalytic antibiotic degradation

To clarify the impact of TiO2 growth and deposition on an activated biochar substrate and disclose the deciding mechanistic aspect in photocatalysis, we report TiO2 nanoparticle growth and deposition on the pomelo-peel-derived activated biochar surface by a combined process of liquid-phase deposition in the presence of KOH-activated biochar and then pyrolysis in the air. The TiO2 growth process is investigated by varying the liquid-phase deposition duration. Initially, TiO2 grows over the surface of activated biochar into small microcrystallites, leaving much bare surface of the activated biochar. Prolonging the growth time allows the growth to be saturated and gives rise to dense and uniform TiO2 nanoparticles (with an average size of about 28 nm) over the activated biochar surface, with strengthened interfacial contact. The overgrowth is not favorable for the uniform dispersion of TiO2 nanoparticles while forming large-size aggregates with weakened interfacial contact between TiO2 and activated biochar. Meanwhile, the graphitic domains of the underlying activated biochar substrate are significantly restored, with the Raman D-to-G band intensity estimated to be 0.05, contrasting to 0.95 for the activated biochar. Some surface functional groups of the activated biochar participate in anchoring TiO2 nanoparticles, especially C-OH. The optimal activated biochar-TiO2 composite is stable and exhibits efficient and robust photocatalytic degradation of tetracycline antibiotics, with the photocatalytic reaction rate constant estimated to be 0.021 min−1. More importantly, the determining factor that affects the photocatalytic performance is disclosed to be the photogenerated charge carrier separation capability.

Graphitic carbon nitride loaded on powdered mesoporous silica nanoparticles for photocatalytic tetracycline antibiotic degradation under UV-C light irradiation

Graphitic carbon nitride loaded on powdered mesoporous silica nanoparticles for photocatalytic tetracycline antibiotic degradation under UV-C light irradiation

Green synthesis of superparamagnetic maghemite nanoparticles using banana pseudo-stem: a reusable heterogeneous catalyst for Fenton-like degradation of tetracycline antibiotics

Ferric ions impregnated in banana pseudo stem biomass are converted to superparamagnetic maghemite nanoparticles (MNPs) which activated persulphate towards the degradation of tetracycline antibiotic.

Enhanced Photo-Assisted Fenton Degradation of Antibiotics over Iron-Doped Bi-Rich Bismuth Oxybromide Photocatalyst

Herein, combining photocatalysis and Fenton oxidation, a photo-assisted Fenton system was conducted using Fe-doped Bi4O5Br2 as a highly efficient photocatalyst to realize the complete degradation of Tetracycline antibiotics under visible light. It has been observed that the optimized photocatalyst 5%Fe-doped Bi4O5Br2 exhibits a degradation efficiency of 100% for Tetracycline with H2O2 after 3 h visible-light irradiation, while a degradation percentage of 59.8% over the same photocatalyst and 46.6% over pure Bi4O5Br2 were obtained without the addition of H2O2 (non-Fenton process). It is unambiguous that a boost photo-assisted Fenton system for the degradation of Tetracycline has been established. Based on structural analysis, it demonstrated that the Fe atoms in place of the Bi sites may result in the distortion of the local structure, which induced the occurrence of the spontaneous polarization and thus enhanced the built-in electric field. The charge separation efficiency is enhanced, and the recombination of electrons and holes is inhabited so that more charges are generated to reach the surface of the photocatalyst and therefore improve the photocatalytic degradation efficiency. Moreover, more Fe (II) sites formed on the 5%Fe-Bi4O5Br2 photocatalyst and facilitated the activation of H2O2 to form oxidative species, which greatly enhanced the degradation efficiency of Tetracycline.

Photocatalytic degradation of tetracycline antibiotic and organic dyes using biogenic synthesized CuO/Fe2O3 nanocomposite: pathways and mechanism insights.

Tetracycline (TC) is a frequently administered antibiotic in many countries, due to its low price and excellent potency. However, certain antibiotics can be hazardous to living creatures due to their accumulation by complexation with metal ions which can contribute to teratogenicity and carcinogenicity. In this investigation, copper oxide-ferric oxide nanocomposite (CuO/Fe2O3 nanocomposite) was synthesized employing Psidium guajava (P. guajava) leaf extract as a reductant as well as a capping agent in an environment friendly and economical green synthesis method. The as-synthesized CuO/Fe2O3 nanocomposite was comprehensively characterized using various sophisticated techniques and its efficiency as a photocatalyst for degradation of tetracycline (TC) antibiotic and toxic dyes, i.e., rhodamine B (RhB) and methylene blue (MB) were investigated. The CuO/Fe2O3 nanocomposite exhibited exceptional efficiency for degradation of TC antibiotic (88% removal in 80min), RhB (96% removal in 40min), and MB (93% elimination in 40min) with apparent rate constant of 0.048, 0.068, and 0.032min-1, respectively. In the degradation experiments, photocatalytic activity of CuO/Fe2O3 nanocomposite was studied by varying different factors such as time of contact, catalyst dose, and solution pH. The role of reactive species in antibiotics and dye degradation was validated by radical scavenging studies which indicated that.OH radical played a critical role in photocatalytic decomposition. Furthermore, liquid chromatography-mass spectrometry (LC-MS) investigations were employed to anticipate a plausible mechanism for TC degradation.

Photodegradation of tetracycline antibiotic by ternary recyclable Z-scheme g-C3N4/Fe3O4/Bi2WO6/Bi2S3 photocatalyst with improved charge separation efficiency: Characterization and mechanism studies

This article argues the design of the recyclable Z-scheme g-C3N4/Fe3O4/Bi2WO6/Bi2S3 (CNFBB) photocatalyst as an efficient concept to obtain photogenerated charge carriers with high redox potential. A cost-effective magnetic CNFBB nanocomposite was fabricated via a multistep method by decorating Fe3O4, Bi2WO6, and Bi2S3 on the surface of pure g-C3N4 nanosheets. The photocatalytic capability was demonstrated for the visible-light degradation of tetracycline antibiotic (TC) in an aqueous solution. Sophisticated analytical techniques such as XRD, FTIR, elemental mapping, EDS, SEM, AFM, TEM, VSM, DRS, PL, and BET were employed for the characterization of synthesized nanomaterials. The CNFBB catalyst showed improved TC degradation activity (98 % in 105 min) under LED illumination with a remarkable degradation rate of 0.0341 min−1, which is 2.27 times higher than that of ternary CNFB. The improved photocatalytic ability was ascribed to the synergistic impacts of g-C3N4, Fe3O4, Bi2WO6, and Bi2S3 by developing a quaternary CNFBB nanostructure with a high surface area, lower band gap energy, high stability, easily recycled, excellent redox potential, and an efficient charge separation mechanism. Interestingly, the CNFBB hybrid displayed good reusability and high stability after six cycles of experiments. The photodegradation mechanism was charge migration pathways, and band locations were systematically explained by the Z-scheme heterojunction system verified by radical quenching experiments, ESR results, and band structure calculation. This work can open new horizons in designing other Bi-based systems supported by g-C3N4 nanosheets for wastewater purification.

Efficient Degradation of Tetracycline Antibiotics by Engineered Myoglobin with High Peroxidase Activity

Tetracyclines are one class of widely used antibiotics. Meanwhile, due to abuse and improper disposal, they are often detected in wastewater, which causes a series of environmental problems and poses a threat to human health and safety. As an efficient and environmentally friendly method, enzymatic catalysis has attracted much attention. In previous studies, we have designed an efficient peroxidase (F43Y/P88W/F138W Mb, termed YWW Mb) based on the protein scaffold of myoglobin (Mb), an O2 carrier, by modifying the heme active center and introducing two Trp residues. In this study, we further applied it to degrade the tetracycline antibiotics. Both UV-Vis and HPLC studies showed that the triple mutant YWW Mb was able to catalyze the degradation of tetracycline, oxytetracycline, doxycycline, and chlortetracycline effectively, with a degradation rate of ~100%, ~98%, ~94%, and ~90%, respectively, within 5 min by using H2O2 as an oxidant. These activities are much higher than those of wild-type Mb and other heme enzymes such as manganese peroxidase. As further analyzed by UPLC-ESI-MS, we identified multiple degradation products and thus proposed possible degradation mechanisms. In addition, the toxicity of the products was analyzed by using in vitro antibacterial experiments of E. coli. Therefore, this study indicates that the engineered heme enzyme has potential applications for environmental remediation by degradation of tetracycline antibiotics.

Photocatalytic degradation of tetracycline antibiotics in swine wastewater using Fe3+-loaded NaBiO3 coupled with sodium persulfate

The Fe3+-loaded NaBiO3 was prepared for photocatalytic removal of tetracycline hydrochloride (TCH) from swine wastewater. Fe3+ greatly reduced the recombination efficiency of the photoinduced electron–hole pairs of NaBiO3. Moreover, the TCH photocatalytic degradation rate constant of Fe3+-loaded NaBiO3 was two-times higher than that of Vis+NaBiO3 after 100 min of reaction. Fe-NaBiO3 combined with PS (100 mg L−1) favored TCH (10 mg L−1) degradation rate (98.8%) at neutral pH. Moreover, the oxidation system was not inhibited by the fulvic acid, and showed a good photocatalytic stability. The superoxide radicals were the main active species involved in the catalytic degradation.

Ultrafast synthesis of laccase-copper phosphate hybrid nanoflowers for efficient degradation of tetracycline antibiotics

The presence of antibiotics in the environment causes increasing attention due to their potential risks to ecosystems and public health. Laccases are versatile oxidases capable of degrading various organic contaminants including pharmaceuticals. However, the performance of bacterial laccases on tetracycline antibiotics (TCs) degradation is seldom investigated. In this work, a bacterial laccase from Bacillus amyloliquefaciens was immobilized as laccase-inorganic hybrid nanoflowers (Lac-hNFs) by a facile and rapid method. The immobilized laccase was employed to remove different TCs including tigecycline, which is a third-generation TC that its degradation by laccase has not been reported. Lac-hNFs were synthesized by sonication-mediated self-assembly of laccase and copper ions in 5 min at room temperature. About 95% of laccase could be encapsulated in the nanoflowers, and the obtained Lac-hNFs exhibited great enhancement in stability under harsh conditions. The immobilized laccase showed a half-life of 11.7 h at 60 °C, which was about 1.4-fold higher than that of the free enzyme. Meanwhile, Lac-hNFs retained 81% of the initial activity after incubation at 25 °C for 10 days. The laccase in combination with acetosyringone could efficiently decompose tetracycline, doxycycline, and tigecycline. More than 79% of the three TCs were transformed in 1 h. Compared with the free enzyme, Lac-hNFs demonstrated higher capacity in the removal of TCs. Furthermore, Lac-hNFs remained their high degradation capacity after five cycles of reuse. Bacterial growth inhibition test revealed that most of the toxicity of TCs was eliminated after Lac-hNFs treatment. The main transformation products were identified by LC-MS, and the possible degradation pathways were proposed. The interaction mechanism between laccase and TCs was also analyzed using molecular docking. This work provides an efficient way to remove toxic organic pollutants.

Ternary novel TiO2/MgBi2O6/Bi2O3 nanocomposites with n-n-p heterojunctions: Impressive visible-light-triggered photocatalytic degradation of tetracycline

A series of novel ternary TiO2/MgBi2O6/Bi2O3 nanocomposites were synthesized by a facile hydrothermal method. The ternary nanocomposites were characterized by XRD, FESEM, HRTEM, EDX, PL, EIS, Photocurrent, UV–vis DRS, BET, XPS, Raman, and FT-IR analyses. The photocatalytic performance of TiO2 for the degradation of tetracycline antibiotic after combining with MgBi2O6/Bi2O3 was significantly improved, which is 46.1 and 18.5 times higher than pristine TiO2 and MgBi2O6/Bi2O3 photocatalysts, respectively. Furthermore, the ternary photocatalyst efficiently degraded MO, RhB, and MB dye pollutants, which is 22.5, 30.4, and 30.0 as high as TiO2 and 11.2, 14.4, and 17.8 folds larger than MgBi2O6/Bi2O3 photocatalysts, respectively. The photoluminescence and electrochemical analyses confirmed promoted separation and facile transfer of the charges thanks to construction of n-n-p heterojunctions among n-TiO2, n-MgBi2O6, and p-Bi2O3 components and more production of charge carriers due to integration of small band gap MgBi2O6 and Bi2O3 components with wide band gap TiO2.

Photocatalytic Degradation of Tetracycline under Visible Light Irradiation on BiVO4 Microballs Modified with Noble Metals

Monoclinic scheelite bismuth vanadate (BVO) microballs were prepared by a facile hydrothermal method and subsequently modified with 2 wt% of noble metals (NM = Au, Ag, Cu, Pt and Pd) by a photodeposition route. All materials were characterized by diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR). The photocatalytic performance was investigated by degradation of tetracycline antibiotic under visible light irradiation. Moreover, photocurrent generation under UV/vis was also examined. It was found that BVO modification with all tested NMs resulted in a significant improvement in photocatalytic performance. The highest activity was obtained for Cu/BVO with mainly oxidized forms of copper. Based on scavenger tests (∙O2− and ∙OH as the main responsible species for TC degradation) and redox properties, it was proposed that the Z-scheme mechanism between copper oxides and BVO was responsible for enhanced photocatalytic activity. However, the co-participation of zero-valent forms of NMs should also be considered, either as electron scavengers, plasmonic sensitizers or conductors. Presented data reveal that porous microballs, highly attractive for practical applications due to micro-sized diameter and efficient light harvesting inside the structure, could be efficiently used for environmental and energy purposes under solar radiation.

Building synergism through heterojunction of n-CaTiO3 with p-CaFe2O4 for upgraded photocatalytic degradation of pharmaceuticals

Herein, n-type CaTiO3 was constructed with p-type CaFe2O4 through in-situ growth method and the as-prepared heterostructure ([email protected]) was tested in photocatalytic degradation of persistent pharmaceutical under simulated sunlight. The heterojunction could harvest more visible light, suppress recombination owing to new oxygen vacancies and strong interfacial interaction. SEM and TEM images verified the attachment of tiny-rod CaFe2O4 around CaTiO3 nanoplates while the CaFe2O4 growth was observed by XRD and HRTEM analyses. Benefiting from p-n heterojunction, the optimal [email protected](0.50) catalyst displayed effective photocatalytic degradation of tetracycline antibiotic (80.81%) which was superior to that of pristine CaTiO3 (20.8%) and CaFe2O4 (45.1%) catalysts. Radical scavenging tests showed that the photo-induced holes were the main active species in the reaction and the underlying degradation mechanism was discussed. This study examines a novel p-n heterojunction between titanate and ferrite type materials that contribute a scientific basis for design of efficient and cost-effective photocatalysts.

Supramolecular Precursor Strategy to Construct g-C3N4/Silica Hybrid Nanosheets for Photocatalytic Degradation of Dye and Antibiotic Pollutants.

To construct a highly active g-C3N4 (CN)/silica hybrid nanosystem, the supramolecular precursor strategy of introducing melamine–cyanuric acid (MCA) by synergistically using micromolecular melamine (m) and urea (u) for CN nanostructure construction on the silica nanosheets (SiNSs) surface was researched. The results showed that the introduction of MCA supramolecular aggregates promoted the generation of ordered CN nanostructures attached to SiNSs, and the morphology of the CN nanostructure could be regulated through the m/u mass ratio. When the ratio is equal to 1/30, a typical g-C3N4/silica hybrid nanosheet (mu-CN/SiNSs-3) was successfully prepared, which showed the ultra-high photocatalytic activity for Rhodamine B dye degradation within 25 min with an apparent rate constant of 0.186 min−1, owing to the large surface area of highly dispersed and ordered CN nanosheets, a strong interaction between CN and SiNSs, high photogenerated carriers separation efficiency, and the more negative conduction band potential offering more active species of 1O2 and •O2−. Unexpectedly, the mu-CN/SiNSs-2 composite (m/u = 1/10) exhibited the highest activity for tetracycline antibiotic degradation, mainly due to the morphological advantage of a certain number of nanotubes generated on the CN/SiNSs hybrid nanosheets. It indicates that the supramolecular precursor strategy by synergistically using melamine and urea is highly efficient for the nanostructure construction of the CN/SiNSs hybrid system, enabling an appropriate nanostructure for the photodegradation of various pollutants.

Study on the synthesis and characterization of CoTiO3 catalysts and their catalytic properties in Oxone activation for the degradation of tetracycline antibiotic in water

The chemical degradation of sulfate by activated Oxyone has the advantages of high degradation capacity, wide pH range and convenient transportation and storage, making it one of the most attractive advanced oxidation processes (AOPs). Besides, Co is the metal most capable of activating Oxone to produce sulfate. Therefore, it is critical to develop Co-based catalyst, an effective and recyclable heterogeneous catalyst, for activating Oxone to degrade tetracycline. In this study, CoTiO3 was extensively investigated for the activation of Oxone to generate sulfate radicals and degrade tetracycline antibiotics. The results showed that more than 95% of tetracyclines could be degraded at the amount of CoTiO3 catalyst of 0.02 g, the Oxone reagent concentration of 0.4 mmol l−1, and the pH value of 7. The removal rate of tetracyclines could still reach more than 85% after the CoTiO3 composite was repeatedly used for four consecutive cycles. These results indicate that CoTiO3/Oxone can be explored as an effective system for degrading long-lived organic pollutants.

Revealing the charge transfer mechanism in magnetically recyclable ternary g-C3N4/BiOBr/Fe3O4 nanocomposite for efficient photocatalytic degradation of tetracycline antibiotics.

Pharmaceutical compounds in water bodies pose hazards to the ecosystem because of their biotoxicity potency. To eradicate such pharmaceutical compounds, a novel g-CN/BiOBr/Fe3O4 nanocomposites was prepared using a simplistic route and appraised for photodegradation of model tetracycline antibiotics. The g-CN/BiOBr/Fe3O4 nanocomposites exhibited complete tetracycline degradation in just 60min exposure of simulated light irradiation, which is 6 times higher than the g-CN. Under the analogous condition, the tetracycline mineralization ability of the g-CN/BiOBr/Fe3O4 nanocomposites was evaluated to be 78% of total organic carbon removal. The superior photocatalytic performance is ascribed to the extended visible light harvesting ability and enhanced charge carrier separation/transfer with impeded recombination rate in light of effective indirect Z-scheme heterojunction construction. Based on band-edge potential and radical trapping studies indicate that h+>•O2->•OH are the active species responsible for photodegradation. Furthermore, the ternary nanocomposites are magnetically retrievable and recyclable while retaining their stable photocatalytic performance. This work endows a new perspective on the rational design and construction of magnetically recoverable ternary nanocomposite for environmental remediation.

Improved degradation of tetracycline antibiotic in electrochemical advanced oxidation processes (EAOPs): bioassay using bacteria and identification of intermediate compounds

AbstractAmong the pharmaceutical compounds, tetracycline is the second most common group of antibiotics in terms of production and consumption worldwide, which their entrance in to hospital, domestic and industrial wastewaters pollute water sources and environment and finally leads to antibiotic resistance. The aim of this study was to determine the efficiency of electrochemical processes, Fenton, electro-Fenton (EF) and sono-electro-Fenton (SEF) separately and using Graphite (G)/β-PbO2anode to remove tetracycline from aqueous solutions. First, experiments for the electrochemical process by the response-surface methodology (RSM) using variables including pH (3–9), initial tetracycline concentration (20–100 mg/L), electrolysis time (4–45 min) and current density (0.5–4.5 mA/cm2) was designed and the optimal conditions of these variables were 3.5, 25.6 mg/L, 42.6 min, and 1.98 mA/cm2, respectively. Under the optimal conditions of the electrochemical process, the effect of FeSO4with values of 0.02-0.08 g/250 mL in the Fenton process and the effect of H2O2of 0.05–0.5 mg/L in the EF process were investigated, and the optimal values of 0.06 g/250 mL and 0.2 mg/L was obtained for FeSO4and H2O2, respectively. Under optimal conditions, the removal efficiencies of SEF, EF, sono-electrochemical (SEC), electrochemical, Fenton and ultrasonic processes were 98.8%, 93.6%, 87.9%, 81.3%, 71.6%, and 11.5%, respectively. G/β-PbO2anode had only 37.5% higher removal efficiency than graphite anode. Under the optimal conditions of SEF process, changes in toxicity reduction by bioassay with E. coli and Staphylococcus aureus bacteria were 86% and 58.4%, respectively, and the kinetic study showed that the removal of tetracycline by SEF process with R2=0.9975 followed the pseudo-first-order kinetics. Finally, intermediate compounds obtained from tetracycline analysis were identified using LC-MS analysis.

Antimicrobial photodynamic inactivation of wastewater microorganisms by halogenated indole derivative capped zinc oxide

Novel 5-bromoindole (5B)-capped zinc oxide (ZnO) nanoparticles (5BZN) were synthesized to improve the antibacterial, antibiofilm, and disinfection processes for the control of microorganisms in wastewater treatment. When exposed to 5BZN, the biofilm density and cell attachment were reduced dramatically, as measured by scanning electron microscopy (SEM). The 5BZN were also investigated for photodynamic treatment of multidrug-resistant (MDR) bacteria and toxicity. The combination of 5B and ZnO exhibited strong antibacterial and antibiofilm activities against MDR bacteria even at low doses (20 μg/mL). After 12.5 mW/cm2 blue LED irradiation, the composite 5BZN showed superior photodynamic inactivation of two wastewater MDR, Enterobacter tabaci E2 and Klebsiella quasipneumoniae SC3, with cell densities reduced by 3.9 log CFU/mL and 4.7 log CFU/mL, respectively, after 120 min. The mechanism of bacterial inactivation was studied using a scavenging investigation, and H2O2 was identified mainly as the reactive species for bacterial inactivation. The 5BZN exhibited higher photodynamic inactivation towards the total coliform bacteria in wastewater effluents under a blue LED light intensity of 12.5 mW/cm2 with almost complete inactivation of the coliform bacteria cells within 40 min. Furthermore, when 5BZN (100 mg/L) was added to the reactor, the level of tetracycline antibiotic degradation was increased by 63.6% after 120 min. The toxicity test, animal model nematode studies and seed germination assays, showed that 5BZN is harmless, highlighting its tremendous potential as a self-healing agent in large-scale photodynamic disinfection processes.

Metal organic framework-derived Zr/Cu bimetallic photocatalyst for the degradation of tetracycline and organic dyes

The exploitation of tetracycline antibiotics (TCs) has caused significant hazards to both the humans as well as the environment. As a result, developing efficient strategies to eliminate these contaminants is both important and practicable. Photocatalytic degradation appears to be one of the most potential techniques for extracting antibiotics. Semiconductors seem to be the most extensively used photocatalysts even though their performance is still hampered by light absorption limitations and poor charge separation. MOFs are worthy choices for the construction of hierarchical nanostructures with semiconductors to address the foregoing concerns because of their extraordinary features including better surface area and extensive active sites. Zr/Cu-MOF was synthesised by precipitation refluxing method and its efficacy as a photocatalyst for the degradation of TC antibiotics and poisonous dyes such as rhodamine B and methylene blue was examined in this study. The Zr/Cu-MOF displayed excellent efficacy for degradation of tetracycline (93 % in 80 min), Rhodamine B (96 % in 70 min) and methylene blue (96 % in 50 min) with rate constant of 0.0308, 0.052 and 0.068 min−1. The contribution of reactive species in antibiotics and dye degradation was confirmed by radical scavenging investigations which showed that.OH radical has a significant role in photocatalytic decomposition. In addition, tests using liquid chromatography-mass spectrometry (LC-MS) were carried out in order to predict a probable mechanism for TC degradation.