Tetracycline Concentration Research Articles

Tetracycline removal by a natural biosorbent: optimization by response surface methods employing DOE/FFD design of the experiment

ABSTRACT This study utilised activated carbon, synthesised with H3PO4 as an active agent (referred to as C-H3PO4), as an adsorbent for the removal of tetracycline (TC), a commonly used pharmaceutical compound. The activated carbon underwent characterisation through SEM-EDS, FTIR, and XRD analyses. The C-H3PO4 particles were found to range in size from 63 to 50 µm and possessed acidic functions within a surface area of 590 mmol/g. To assess the adsorptive performance of C-H3PO4 in relation to tetracycline, several operational parameters were investigated, including contact time, temperature, pH, concentration of the pharmaceutical compound, and C-H3PO4 dosage. Optimal conditions were determined as follows: a pH of 2.8, a TC concentration of 15 mg/L, a temperature of 308 K, and an adsorbent dosage of 90 mg, utilising the design of experiments (DOE/FFD) for parameter optimisation. In addition, the analysis of variance (ANOVA) and three-dimensional surface plots were created to evaluate the interaction between the factors and the ideal conditions for removing tetracycline. The maximum adsorption capacity of C-H3PO4 onto TC was found to be 7.41 mg/g. The experimental data were best fitted using the pseudo-second-order and Freundlich models, suggesting a multilayer physisorption phenomenon.

Synthesis of Cu Nanoparticles Incorporated Mesoporous C/SiO2 for Efficient Tetracycline Degradation.

In this study, a Cu NPs-incorporated carbon-containing mesoporous SiO2 (Cu/C-SiO2) was successfully synthesized through a grinding-assisted self-infiltration method followed by an in situ reduction process. The obtained Cu/C-SiO2 was then employed as a Fenton-like catalyst to remove tetracycline (TC) from aqueous solutions. TEM, EDS, XRD, N2 adsorption-desorption, FTIR, and XPS methods were used to characterize the crystal structure, morphology, porosity, chemical composition, and surface chemical properties of the catalyst. The effects of initial TC concentration, catalyst dosage, H2O2 dosage, solution pH, HA addition, and water media on the TC degradation over Cu/C-SiO2 were investigated. Scavenging and electrochemical experiments were then carried out to analyze the TC degradation mechanism. The results show that the Cu/C-SiO2 can remove 99.9% of the concentrated TC solution (C0 = 500 mg·L-1), and it can be used in a wide pH range (R.E. = 94-99%, pH = 3.0-11.0). Moreover, hydroxyl radicals (•OH) were detected to be the dominant reactive species in this catalytic system. This study provides a simple and promising method for the synthesis of heteroatom-containing mesoporous catalysts for the decomposition of antibiotics in wastewater.

Bioaccessibility of polypropylene microfiber-associated tetracycline and ciprofloxacin in simulated human gastrointestinal fluids

Microplastics residues in natural waters can adsorb organic contaminants owing to their rough surface morphology and high specific surface area, potentially harming human health when ingested. Although humans inevitably ingest microplastics, the bioaccessibility of microplastic-associated chemicals in the human gastric and intestinal fluids remains unresolved. This study investigated the mechanism and primary factor controlling the bioaccessibility of polypropylene (PP) microplastic fiber-associated tetracycline (TC) and ciprofloxacin (CIP) in simulated human gastrointestinal fluids. After mixing 0.1 g of PP microfiber with 10 mg/L of TC (or CIP) for 96 h and exposure to simulated human gastrointestinal fluids, the TC concentrations were 0.440, 0.678, and 1.840 mg/L and the CIP concentrations were 0.700, 1.367, and 3.281 mg/L CIP in the simulated human saliva, gastric, and intestinal fluids after incubation for 60 s, 4 h, and 8 h, respectively. This indicated that the antibiotics TC and CIP adsorbed onto microfiber surface are readily released into human gastrointestinal fluids upon ingestion. Gastric and intestinal fluids showed enhanced bioaccessibility to TC/CIP adhered to PP microfiber. The primary factors affecting the bioaccessibility to TC/CIP adhered to PP microfiber surfaces were found to be pepsin in human gastric fluid and trypsin in human intestinal fluid. Molecular docking and simulated molecular dynamic analyses results showed that pepsin and trypsin stablish connections with TC via hydrogen bonds (reaction sites: pepsin TC: T139, T136, S97, D94, D277 and Y251; trypsin TC: S257, H120, K235, G274, and G276) and CIP via hydrophobic interactions (reaction sites: pepsin CIP: Y137, T136, T139, F173, I362, V353, and I275; trypsin CIP: W273, I161, C253, and C277). Our findings highlight that microplastic ingestion increases the risk of microplastics and the co-contaminants adsorbed to human health; thus, these findings are helpful to assess the risk of microplastics and co-contaminants to human health.

Effect of Mn(II) on Tetracycline Degradation by a Selected Strain Burkholderia sp.

Abstract Removal of residual tetracycline (TC) in the environment is an important issue for pollution control. In this study, a TC-degrading strain named JX_1 was isolated from the soil around an industrial park, the strain was identified as Burkholderia sp. by 16s rDNA sequencing analysis. The effects of various factors on TC degradation by the strain were studied, results indicated that the inoculation amounts and liquid volume had little effect on TC degradation rate. However, the degradation rate of TC by strain increased with the increase of pH, and the residual concentration increased gradually with the initial TC concentration increased. The degradation rate of 125 mg/L TC by strain JX_1 was 75.76 % under the conditions of temperature 37 °C, 2 mL inoculation amount and 200 mL liquid volume. Under the same conditions, the degradation rate of TC was increased to 91.39 % with the addition of 0.75 g/L MnSO4, indicating that Mn(II) could improve the degradation rate of TC by strain JX_1 to a certain extent.

Usage of MnFe2O4-rGO Nanocomposite as efficient Fenton catalyst for Tetracycline removal by heterogeneous sono Fenton process: Characterizations, catalytic performance assessment, and mechanism

In this study, monodisperse MnFe2O4/rGO nanoparticles was prepared and used as Fenton catalyst for Tetracycline (TC) degradation combining with ultrasonic process. The physicochemical properties of the resulted NPs were detected transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy techniques. The effect of operational parameters containing amount of catalyst, H2O2 concentration, initial TC concentration, initial pH of solution, ultrasonic power, and process time on the TC removal efficiency during heterogeneous sono-Fenton process was studied. The best sonocatalytic efficiency of 92.85% was attained by using 0.3 g/L MnFe2O4/rGO nanocatalyst, 10 mg/L TC, 12 mM H2O2, 450 W ultrasonic power, and at pH = 3 after 120 min. By using organic and inorganic scavengers, the primary active species was determined for TC removal during heterogeneous sono-Fenton oxidation.The results showed that ROS species were effective in TC removal in the order h+ > •OH > O2•−. Moreover, MnFe2O4/rGO nanocomposite were reusable up to the five consecutive cycles without any notable loss in activity.

Dual-excitation carbon dots-based lateral flow visual sensing device for ratiometric determination and discrimination of tetracyclines in food

Excessive releasing of tetracyclines in the nature has constituted a major threat to ecosystem. Therefore, it is crucial to develop an accurate and convenient on-site analysis device for tetracyclines. Herein, we construct a neoteric dual-excitation carbon dots (DE-CDs) through microwave radiation and establish an excitation-based ratiometric approach for quantitative tetracyclines determination. The ratio of different excitation intensities under the same emission wavelength changes linearly in response to tetracyclines concentration. As a proof of feasibility, we choose doxycycline (DOX) as the analysis model. It shows a low detection limit (LOD) of 61 nM in a wide concentration range of 0.061–80 µM, suggesting that this sensor is conducive to application potential in tetracyclines determination of food products. Moreover, considering the differentiated overlap between tetracyclines absorbance and DE-CDs excitations, the discrimination of tetracyclines is realized in the form of mixtures. Significantly, combining with the DE-CDs, RGB (Red, Green and Blue) analysis and 3D printing technologies, we construct a miniaturized visual sensing device with low LOD and achieve the discrimination of TCs based on RGB variations, showing a great opportunity for industrial production of pollutant monitoring sensors in resource-constrained areas.

Continuous purification of drugs by ionic liquid-drawn organic solvent forward osmosis and solute recovery

Classical purification of pharmaceuticals is energy-intensive and employs toxic solvents that are discarded, calling for more sustainable methods. Here, we purified tetracycline by organic solvent forward osmosis using ionic liquids. Results show the osmotic enrichment of feed solutions containing different concentrations of tetracycline in methanol. The solvent flux during the filtration process is mainly influenced by solvent properties, such as molecular size, viscosity, polarity, and the solvent–membrane interaction. We evaporated the diluted draw solution to recover the draw solute for reuse. Overall ionic liquids appear as suitable draw solutes for organic solvent forward osmosis for pharmaceutical compound enrichment with draw solute recovery and reuse.

Adsorptive removal of tetracycline antibiotic onto magnetic graphene oxide nanocomposite modified with polyvinylpyrroilidone

Disposal of pharmaceutical compounds in wastewaters poses potential environmental risk, especially to aquatic life. Herein, magnetic CuFe2O4-graphene oxide (GO) modified with polyvinylpyrrolidone (PVP) ternary nanocomposite (PMGO) was prepared, by a simple ultrasonic method, and successfully applied to the removal of tetracycline (TC) as a model pharmaceutical species. The defect sites of graphene oxide layers served as nucleation centers that allowed the anchoring of both PVP and CuFe2O4 nanoparticles, resulting in reduced agglomeration chances of GO sheets and thus enhanced its TC removal efficiency. Furthermore, the synthesized PMGO was characterized using SEM-EDS, HRTEM, XRD, XPS, FTIR, BET, and VSM. The removal including was optimized by examining the effects of operating parameters, including, initial TC concentration, solution pH, contact time, and PMGO mass. Adsorption isotherms were examined using three-parameters (Hills and Sips) and two-parameters (Langmuir, Freundlich and Tekman) models. PMGO exhibited a maximum adsorption capacity of 193.8 mg/g according to Sips model that exhibited the best fit to experimental data. Moreover, TC removal fitted the PSO kinetics. The removal mechanism was inferred based on adsorption isotherms and kinetic investigations, as well as changes of medium pH and spectral analysis of PMGO composite after adsorption and revealed that electrostatic attraction, π-π interaction, and H-bonding were essential contributing forces, where a TC monolayer was adsorbed onto the PMGO surface and OH− and H+ exerted competitive effects. Importantly, the synthesized nanocomposite exhibited outstanding performance even in the presence of coexisting species (NaCl and SDS surfactant), as well as excellent reusability for practical applications.

Determination and monitoring of tetracycline and degradation products in livestock slaughterhouse wastewater treatment plant effluent

Aim of our study was the determination and monitoring of tetracycline (TC) and degradation products (DEP) in livestock slaughterhouse wastewater treatment plant (SWWTP) effluent. For this purpose, TC and DEP values in SWWTP were investigated. The concentrations of TC and DEP were monitored for 12 months. TC, 4-epitetracycline (ETC), 4-epianhydrotetracycline (EATC), anhydrotetracycline (ATC), and physicochemical parameters of pH, suspended solids (SS), BOD5, COD, and TP were calculated. The maximum TC concentration was determined as 1.68±0.08 µg/L in March and the minimum TC was 1.08±0.05 µg/L in January. The maximum ETC was 2.93±0.14 µg/L in March and April. The minimum ETC was 1.98±0.1 µg/L in January. EATC was 10.82±0.5 µg/L in September, and minimum EATC value was determined as 9.14±0.4 µg/L in March. The maximum ATC value was 8.62±0.4 µg/L in June and the lowest ATC value was 6.61±0.3 µg/L in September. Concentrations of TC and DEP detected in SWWTP effluent were listed in descending order as EATC> ATC> ETC> TC.

Construction of CoTiO3/TiO2/Ti composite catalytic membrane for degradation of tetracycline via peroxymonosulfate activation: Reactive oxygen species and electron transfer pathways

The advanced oxidation processes based on peroxymonosulfate (PMS) has shown great promise for the removal of emerging contaminants in water reuse applications. Constructing cobalt-based composite nanomaterials is an effective strategy to achieve electron transfer and reduce the leaching of cobalt ions. Here, a CoTiO3/TiO2/Ti (CTT) catalytic membrane was fabricated using TiO2 nanotubes as both template and reactant, and then was applied to activate PMS for tetracycline (TC) degradation in a continuous flow-through reactor. The CTT/PMS system showed a remarkable TC degradation efficiency of 96.99%, exhibiting anti-interference performance towards Cl−, HCO3– and humic acid in water (>90.00% degradation efficiency). It has been proved that OH, SO4−, and 1O2 existed in the CTT/PMS system, and the CTT membrane served as a medium for mediating the electron transfer from TC to PMS. Density functional theory calculations indicated that the construction of a composite structure of CoTiO3 and TiO2 successfully enhanced the activation of PMS by the electron transfer from Ti atoms of TiO2 to Co sites. We proposed three potential degradation pathways for TC, followed by toxicity analysis of the intermediate products. After being exposed to an initial TC concentration of 20 mg/L and a membrane flux of 600 LMH for 30 hours, the CTT catalytic membrane exhibited a TC degradation rate exceeding 92.23% and mineralization rate surpassing 64.43%. This work supplied a new approach for fabricating cobalt-based catalytic membrane for PMS activation, with potential applications in water reuse.

Characteristics of antimicrobial residues in manure composts from swine farms: Residual patterns, removal efficiencies, and relation to purchased quantities and composting methods in Japan

Present study provides first comprehensive results on the residual levels of 19 antimicrobial (AM) residues in 12 Japanese swine manure composting facilities that use open or enclosed types of treatment methods. Tilmicosin (14000 μg/kg d.w.) and tiamulin (15000 μg/kg d.w.) were present in the highest concentrations in manure composts. Morantel (MRT) had the highest detection frequency (100%) in compost, suggesting its ubiquitous usage and resistance to degradation during composting. Sulfamethoxazole had low detection frequencies and concentrations, likely due to limited partitioning to the solid phase. A positive correlation (p < 0.05) between purchasing quantities and residue levels in manure composts was detected for fluoroquinolones (FQs). The removal efficiencies of AMs in enclosed-type facilities were lower and more inconsistent than those in open-type facilities. Tetracyclines (TCs), lincomycin, and trimethoprim were easily removed from open-type facilities, whereas FQs and MRT persisted in both facilities. After discontinuing the usage of oxytetracycline (OTC), TCs concentrations reduced drastically in input materials, remained pseudo-persistent in composts for up to 4 months, suggesting a time lag for composting and were not detected (<10 µg/kg) after 4 months of OTC withdrawal. This study emphasizes on the effectiveness of manure composting methods in reducing AM residues in swine waste.

A novel Corchorus olitorius-derived biochar/Bi12O17Cl2 photocatalyst for decontamination of antibiotic wastewater containing tetracycline under natural visible light

Herein, a novel composite of Corchorus olitorius-derived biochar and Bi12O17Cl2 was fabricated and utilized for the degradation of tetracycline (TC) in a solar photo-oxidation reactor. The morphology, chemical composition, and interaction between the composite components were studied using various analyses. The biochar showed a TC removal of 52.7% and COD mineralization of 59.6% using 150 mg/L of the biochar at a pH of 4.7 ± 0.5, initial TC concentration of 163 mg/L, and initial COD of 1244 mg/L. The degradation efficiency of TC increased to 63% and the mineralization ratio to 64.7% using 150 mg/L of bare Bi12O17Cl2 at a pH of 4.7 ± 0.5, initial TC concentration of 178 mg/L, and COD of 1034 mg/L. In the case of biochar/Bi12O17Cl2 composite, the degradation efficiency of TC and COD mineralization ratio improved to 85.8% and 77.7% due to the potential of biochar to accept electrons which retarded the recombination of electrons and holes. The synthesized composite exhibited high stability over four succeeding cycles. According to the generated intermediates, TC could be degraded to caprylic acid and pentanedioic acid via the frequent attack by the reactive species. The prepared composite is a promising photocatalyst and can be applied in large-scale systems due to its high degradation and mineralization performance in a short time besides its low cost and stability.

Label-free colorimetric detection of tetracycline using gold nanoparticles with different surface charge

Visual detection assay based on aptamer unmodified gold nanoparticles shows great potential in biotechnology. Here, we reported a visible, salt-free and highly sensitive tetracycline (TC) assay based on a colloidally stable mixture of AuNPs that contains poly (diallyl dimethylammonium chloride) capped AuNPs ((+)AuNPs) and tetracycline-specific aptamer capped AuNPs (Apt-capped AuNPs). This reported TC assay was visible and salt-free that did not need any salt during TC detection. With naked eyes, nanomolar tetracycline concentrations could be identified within 20 min. A detection limit of tetracycline down to a concentration of 1.0 fM with a broad detection range of 8 order of magnitudes (5 × 10−14 M to 5 × 10−6 M) was reached. Furthermore, the reported TC assay also exhibited good selectivity for tetracycline over other antibiotics, metal cations, proteins and amino acids. These findings clearly demonstrated the high potential of the reported TC assay for TC detection and monitoring.

Evaluation of tetracycline removal by magnetic metal organic framework from aqueous solutions: Adsorption isotherm, kinetics, thermodynamics, and Box-Behnken design optimization

In our current research, an intriguing magnetic nano sorbent Fe3O4@Zr-MOF was synthesized in the lab. We used this adsorbent for successfully removing tetracycline (TC) from water. We performed a number of experiments and studies to further support this, including the following: vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller surface area (BET). Our studies have determined that the Fe3O4@Zr-MOF boasts a considerable surface area of 868 m2/g with the highest adsorption capacity (qmax) of 942.12 mg/g. Study the factors that effect on adsorption process such as pH, TC concentration, adsorbent dose, and temperature. The adsorption isotherm was fitted to the Langmuir equation, whereas the kinetic isotherm to the pseudo-second-order equation. The adsorption process was chemisorption as well as the adsorption energy was 20 kJ/mol. Adsorption thermodynamics indicated that the adsorption process was both endothermic and spontaneous. As temperatures increased, the amounts of materials absorbed also increased. The Fe3O4@Zr-MOF has magnetic properties as it easily to remove from the solution after adsorption process. The adsorbent was used for five cycles with high efficiency and without change in the chemical composition as well as the XRD was the same before and after reusability. The mechanism of the interaction between Fe3O4@Zr-MOF and TC was expected on: Electrostatic interaction, π-π interaction, hydrogen bonding, and pore filling. The adsorption results were optimized using Box Behnken-design (BBD).

MOF-derived La/ZnO–TiO2 composite with enhanced photocatalytic ability for degradation of tetracycline

Developing effective and stable photocatalysts for organic pollutants degradation are still a big challenge in practical water treatment now. In this work, La doped ZnO–TiO2 composite (La/ZnO–TiO2) were successfully fabricated by using PVP modified ZIF-8/TiO2 as template via the absorption and pyrolysis routes. All as-fabricated materials were analyzed by XRD, SEM, TEM, BET, XPS, UV–vis absorption spectra and ESR spectra. PVP modified ZIF-8/TiO2 was fully transferred into ZnO–TiO2 after being pyrolyzed at high temperature under air atmosphere. The doping of La can make ZnO–TiO2 exhibiting red-shifted, which is attributed to the capture of photo-generated electrons by La, leading to the effective separation between photo-generated electrons and holes. Furthermore, the photocatalytic performance of all as-fabricated materials were explored by degradation of tetracycline (TC) solution under UV light irradiation. La/ZnO–TiO2 exhibits excellent stability. And the photocatalytic degradation rate of La/ZnO–TiO2 is 99.2%, which is even higher than ZnO (87.4%), ZnO–TiO2 (87.4%), P25 (TiO2) (92.7%). More than that, the effect of catalyst's dose, effect of TC concentration and effect of pH for TC degradation have been well explored. The excellent photocatalytic performance of La/ZnO–TiO2 makes it possible to be applied for degradation of organic pollutants in practice.

Jasmine waste derived biochar as green sulfate catalysts dominate non-free radical paths efficiently degraded tetracycline

Because of the potential environmental harm caused by the extensive application of tetracycline (TC), this study used jasmine waste rich in organic matter as a precursor and one-step carbonization into metal-free carbon-based materials to efficiently activate peroxymonosulfate (PMS) toward degrading TC. The jasmine waste biochar (JWB) with a heating rate of 10 °C min−1 and a heating temperature of 700 °C was selected as the most suitable material based on its catalytic performance. The effects of catalyst dose, PMS dose, initial pH value, coexisting inorganic anions and TC concentration on the JWB/PMS/TC system were thoroughly optimized. The results showed that the degradation efficiency of TC by JWB/PMS system was 90%. Meanwhile, the combination of electron paramagnetic resonance, masking experiments and X-ray photoelectron spectrometry confirmed that JWB degraded TC mainly through the non-radical radical pathway of 1O2 oxidation and mediated the electron transfer to PMS. In addition, some degradation products were analyzed by LC-MS and possible degradation pathways of the system were proposed. Therefore, this paper proposes a novel method for recycling jasmine waste and providing a low-cost catalyst for the oxidation treatment of refractory organic matter.

Comparative Metagenomic and Metatranscriptomic Analyses Reveal the Response of Black Soldier Fly (Hermetia illucens) Larvae Intestinal Microbes and Reduction Mechanisms to High Concentrations of Tetracycline.

Black soldier fly (Hermetia illucens L) larvae (BSFL) possess remarkable antibiotic degradation abilities due to their robust intestinal microbiota. However, the response mechanism of BSFL intestinal microbes to the high concentration of antibiotic stress remains unclear. In this study, we investigated the shift in BSFL gut microbiome and the functional genes that respond to 1250 mg/kg of tetracycline via metagenomic and metatranscriptomic analysis, respectively. The bio-physiological phenotypes showed that the survival rate of BSFL was not affected by tetracycline, while the biomass and substrate consumption of BSFL was slightly reduced. Natural BSFL achieved a 20% higher tetracycline degradation rate than the germ-free BSFL after 8 days of rearing. Metagenomic and metatranscriptomic sequencing results revealed the differences between the entire and active microbiome. Metatranscriptomic analysis indicated that Enterococcus, Vagococcus, Providencia, and Paenalcaligenes were the active genera that responded to tetracycline. Furthermore, based on the active functional genes that responded to tetracycline pressure, the response mechanisms of BSFL intestinal microbes were speculated as follows: the Tet family that mediates the expression of efflux pumps expel tetracycline out of the microbes, while tetM and tetW release it from the ribosome. Eventually, tetracycline was degraded by deacetylases and novel enzymes. Overall, this study provides novel insights about the active intestinal microbes and their functional genes in insects responding to the high concentration of antibiotics.

Boosting Tetracycline Degradation with an S-Scheme Heterojunction of N-Doped Carbon Quantum Dots-Decorated TiO2.

N-doped carbon quantum dots (N-CQDs) derived from the Rumex crispus L. plant were incorporated into TiO2 via a facile hydrothermal method. As-prepared materials were characterized and used in the photocatalytic tetracycline (TC) degradation under UVA light irradiation by examining several operational parameters involving the N-CQDs amount, initial TC concentration, pH, and photocatalytic reaction time. XRD analysis revealed the conversion of the rutile phase to the anatase phase after the incorporation of N-CQDs into the TiO2 structure. The results revealed that the N-CQDs/TiO2 photocatalysts demonstrated the highest efficiency in TC degradation compared to other processes of adsorption, photolysis (UVA), and photocatalysis with TiO2 (TiO2/UVA). Under optimized conditions, 10 mg/L TC at pH 5.15 with 0.2 g/L N-CQDs/TiO2 catalyst showed 97.7% photocatalytic degradation for 120 min under UVA irradiation. The formation of an S-scheme heterojunction between N-CQDs and TiO2 provided enhanced charge separation and strong redox capability, causing significant improvement in the photocatalytic performance of N-CQDs/TiO2. Trapping experiments showed that O2•- and h+ are the predominant reactive species for the TC elimination in an aqueous solution.

Effective degradation of tetracycline via persulfate activation using silica-supported zero-valent iron: process optimization, mechanism, degradation pathways and water matrices.

Pure zero-valent iron (ZVI) was supported on silica and starch to enhance the activation of persulfate (PS) for tetracycline degradation. The synthesized catalysts were characterized by microscopic and spectroscopic methods to assess their physical and chemical properties. High tetracycline removal (67.55%) occurred using silica modified ZVI (ZVI-Si)/PS system due to the improved hydrophilicity and colloidal stability of ZVI-Si. Incorporating light into the ZVI-Si/PS system improved the degradation performance by 9.45%. Efficient degradation efficiencies were recorded at pH 3-7. The optimum operating parameters determined by the response surface methodology were PS concentration of 0.22mM, initial tetracycline concentration of 10mg/L, and ZVI-Si dose of 0.46g/L, respectively. The rate of tetracycline degradation declined with increasing tetracycline concentration. The degradation efficiencies of tetracycline were 77%, 76.4%, 75.7%, 74.5%, and 73.75% in five repetitive runs at pH 7, 20mg/L tetracycline concentration, 0.5g/L ZVI-Si dose, and 0.1mM PS concentration. The degradation mechanism was explained, and sulfate radicals were the principal reactive oxygen species. The degradation pathway was proposed based on liquid chromatography-mass spectroscopy. Tetracycline degradation was favorable in distilled and tap water. The ubiquitous presence of inorganic ions and dissolved organic matter in the lake, drain, and seawater matrices interfered with the tetracycline degradation. The high reactivity, degradation performance, stability, and reusability of ZVI-Si substantiate the potential practical application of this material for the degradation of real industrial effluents.

Highly Efficient Photo-Fenton Ag/Fe2O3/BiOI Z-Scheme Heterojunction for the Promoted Degradation of Tetracycline.

Novel Ag/Fe2O3/BiOI Z-scheme heterostructures are first fabricated through a facile hydrothermal method. The composition and properties of as-synthesized Ag/Fe2O3/BiOI nanocomposites are characterized by powder X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, UV-Vis diffuse reflectance spectra, etc. The Ag/Fe2O3/BiOI systems exhibit remarkable degradation performance for tetracycline (TC). In particular, the composite (Ag/Fe2O3/BiOI-2) shows the highest efficiency when the contents of Ag and α-Fe2O3 are 2 wt% and 15%, respectively. The effects of operating parameters, including the solution pH, H2O2 concentration, TC concentration, and catalyst concentration, on the degradation efficiency are investigated. The photo-Fenton mechanism is studied, and the results indicated that •O2- is the main active specie for TC degradation. The enhanced performance of Ag/Fe2O3/BiOI heterostructures may be ascribed to the synergic effect between photocatalysis and the Fenton reaction. The formation of Ag/Fe2O3/BiOI heterojunction is beneficial to the transfer and separation of charge carriers. The photo-generated electrons accelerate the Fe2+/Fe3+ cycle and create the reductive reaction of H2O2. This research reveals that the Ag/Fe2O3/BiOI composite possesses great potential in wastewater treatment.