Tetracycline Hydrochloride Concentration Research Articles

Iron–Cobalt Bimetallic Metal–Organic Framework-Derived Carbon Materials Activate PMS to Degrade Tetracycline Hydrochloride in Water

Organic pollutants entering water bodies lead to severe water pollution, posing a threat to human health. The activation of persulfate advanced oxidation processes using carbon materials derived from MOFs as substrates can efficiently treat wastewater contaminated with organic pollutants. This research uses NH2-MIL-101(Fe) as a substrate, doped with Fe2+ and Co2+, to prepare Fe/Co-CNs through a one-step carbonization method. The surface morphology, pore structure, and chemical composition of Fe/Co-CNs were investigated using characterization techniques such as XRD, SEM, TEM, XPS, FT-IR, BET, and Raman. A comparative study was conducted on the performance of catalysts with different Fe/Co ratios in activating PMS for the degradation of organic pollutants, as well as the effects of various influencing factors (the dosage of Fe/Co-CNs, the amount of peroxymonosulfate (PMS), the initial pH of the solution, the TC concentration, and inorganic anions) on the catalyst’s activation of persulfate for TC degradation. Through radical quenching experiments and post-degradation XPS analysis, the active radicals in the FeCo-CNs/PMS system were investigated to explain the possible mechanism of TC degradation in the Fe/Co-CNs/PMS system. The results indicate that Fe/Co-CNs-2 (with a Co2+ doping amount of 20%) achieves a degradation rate of 93.34% for TC (tetracycline hydrochloride) within 30 min when activating PMS, outperforming other Co2+ doping amounts. In addition, singlet oxygen (1O2) is the main reactive species in the reaction system.

Degradation of tetracycline hydrochloride through g-C3N4/TiO2 nanotube arrays for photoelectrocatalytic activation of PMS system: Performance and mechanistic analysis

To enhance the pollutant degradation ability of TiO2 nanotube arrays (TNAs) in a photoelectrocatalytic system (PEC), g-C3N4/TNAs photoanode was synthesized using anodic oxidation-slow evaporation method. Then, peroxymonosulfate (PMS) was incorporated and the resulting PEC-PMS system was applied to degrade tetracycline hydrochloride (TCH). The results from SEM, XRD and UV–vis DRS analyses indicated that g-C3N4 was successfully loaded onto the surface of TNAs, reducing the forbidden bandwidth from 3.10 eV to 2.89 eV. I-t and EIS curves demonstrated that the loading of g-C3N4 increased the electron transfer rate of TNAs. The photoanode prepared with a g-C3N4 solution (concentration of 100 mg L−1) exhibited the best degradation performance for TCH. The degradation rate of TCH by the PEC-PMS system reached 95.69 % at a TCH concentration of 10 mg L−1, pH of 9, PMS dosage of 2 mM, and voltage of 2 V, significantly higher than that of the PEC system without PMS (35.14 %). The contribution of active radicals to the system was in the order of SO4·- > h+ > ·O2- > ·OH. Three possible pathways for TCH degradation were proposed based on the experimental results. In conclusion, this work provides a theoretical basis for the preparation of photoelectrodes responsive to visible light and their application in the degradation of pollutants by the PEC-PMS system.

High Efficiency Removal Performance of Tetracycline by Magnetic CoFe2O4/NaBiO3 Photocatalytic Synergistic Persulfate Technology.

The widespread environmental contamination resulting from the misuse of tetracycline antibiotics (TCs) has garnered significant attention and study by scholars. Photocatalytic technology is one of the environmentally friendly advanced oxidation processes (AOPs) that can effectively solve the problem of residue of TCs in the water environment. This study involved the synthesis of the heterogeneous magnetic photocatalytic material of CoFe2O4/NaBiO3 via the solvothermal method, and it was characterized using different characterization techniques. Then, the photocatalytic system under visible light (Vis) was coupled with peroxymonosulfate (PMS) to explore the performance and mechanism of degradation of tetracycline hydrochloride (TCH) in the wastewater. The characterization results revealed that CoFe2O4/NaBiO3 effectively alleviated the agglomeration phenomenon of CoFe2O4 particles, increased the specific surface area, effectively narrowed the band gap, expanded the visible light absorption spectrum, and inhibited recombination of photogenerated electron-hole pairs. In the Vis+CoFe2O4/NaBiO3+PMS system, CoFe2O4/NaBiO3 effectively activated PMS to produce hydroxyl radicals (·OH) and sulfate radicals (SO4-). Under the conditions of a TCH concentration of 10 mg/L-1, a catalyst concentration of 1 g/L-1 and a PMS concentration of 100 mg/L-1, the degradation efficiency of TCH reached 94% after 100 min illumination. The degradation of TCH was enhanced with the increase in the CoFe2O4/NaBiO3 and PMS dosage. The solution pH and organic matter had a significant impact on TCH degradation. Notably, the TCH degradation efficiency decreased inversely with increasing values of these parameters. The quenching experiments indicated that the free radicals contributing to the Vis+CoFe2O4/NaBiO3+PMS system were ·OH followed by SO4-, hole (h+), and the superoxide radical (O2-). The main mechanism of PMS was based on the cycle of Co3+ and Co2+, as well as Fe3+ and Fe2+. The cyclic tests and characterization by XRD and FT-IR revealed that CoFe2O4/NaBiO3 had good degradation stability. The experimental findings can serve as a reference for the complete removal of antibiotics from wastewater.

Seed-assisted two-step ZIF-67 growth on CS/PVA nanofibers for high-efficiency cadmium and tetracycline adsorption

Herein, novel ZIF-67/CS/PVA (CNF-2) nanofiber composites using a two-step seed-assisted in situ electrospinning method, with cobalt-based zeolitic imidazolate framework (ZIF-67) as the precursor was prepared. SEM, EDX, AFM, FTIR, and XRD analyses revealed the optimal formation of ZIF-67 nanoparticles both inside and on the surface of CS/PVA nanofibers without compromising the structure of these electrospun nanofibers. The unique porous structure and heterointerfaces of the ZIF-67/CS/PVA (CNF-2) nanofiber composites demonstrated remarkable adsorption capacities for cadmium (Cd) and tetracycline hydrochloride (TCH), achieving 1137.94 and 1029.5 mg/g, respectively. The adsorption effectiveness for Cd and TCH was 94.83 % and 85.79 %, respectively, under optimal adsorption conditions: pH 8, adsorbent dosage of 0.01 g, initial Cd and TCH concentration of 80 mg/L, and a contact time of 120 min. The study of coexisting Cd and TCH adsorption on CNF-2 under varying pH conditions (4–8) reveals a significant enhancement in Cd adsorption efficiency, increasing from 41.91 % to 97.49 %. Conversely, TCH exhibits a more modest improvement, with its adsorption efficiency rising from 72.53 % to 85.96 %. Kinetic and equilibrium studies revealed that the adsorption followed pseudo-second-order kinetics and the Langmuir isotherm. The prepared nanofiber adsorbed 60 % of Malachite green dye. The engineered adsorbent demonstrated impressive regeneration potential, maintaining its efficiency over three successive adsorption–desorption cycles.

Preparation of defect-enriched Cu-doped FeOCl/g-C3N4Z-scheme composites for efficient photo-Fenton-like performance

In this study, a Z-scheme heterojunction with abundant oxygen vacancies (OVs) formed by Cu-doped FeOCl (Cu-FeOCl) and graphitic carbon nitride nanosheets (CNNS) was successfully synthesized for the removal of tetracycline hydrochloride (TC). The prepared Cu-FeOCl/CNNS had excellent catalytic properties under hydrogen peroxide and light illumination, and the maximum reaction rate was nearly 156 and 48 times higher than that of FeOCl and CNNS, respectively. The enhancement of catalytic performance was due to the synergistic effect of Cu species, Fe species and Ovs, which effectively promoted the adsorption and activation of H2O2, and inhibited the recombination of photogenerated carriers. We further studied the effects of different reaction conditions (catalyst dosage, H2O2 dosage, initial pH, TC concentration, and coexisting substances) on the degradation reaction. 1O2, h+, •O2−, and •OH were active species participating in the reaction, and a possible TC degradation mechanism was studied. This work provided insights into the synergetic action of interface engineering, ion doping, and oxygen defects in the photo-Fenton-like system.

Interface engineering of Ti3C2 MXene assisted anatase/rutile TiO2 with hetero-phase junction for enhancing the photocatalytic activity of tetracycline hydrochloride removal and H2 production

The conventional heterojunction formed by combining two different semiconductors is associated with issues of low compatibility, restricted intimate contact, and limited charge anti-recombination process. To address these issues, a simple strategy was adopted to fabricate a hetero-phase junction flanked with two dissimilar crystal phases of a single semiconducting material. This study employed TiB2 as the initial material to fabricate an anatase/rutile TiO2 hetero-phase junction material (AR-TiO2), followed by its combination with highly conductive monolayer Ti3C2 nanosheets to develop an AR-TiO2/Ti3C2 composite photocatalyst. The photocatalyst displayed a wide range of light absorption and a remarkable capability for separating photogenerated carriers. The closely interconnected hetero-phase junction surface, formed by the rutile and anatase phases of AR-TiO2, combined with the incorporation of highly conductive Ti3C2 nanosheets, synergistically increased the availability of multi-dimensional active sites and increased the efficacy of separating photogenerated electron pairs. The optimized AR-TiO2/Ti3C2 achieved a degradation efficiency of 91.49 % for tetracycline hydrochloride (TCH) within 2 h and produced 1005.81 μmol of hydrogen in 6 h. The impacts of initial pH, co-existing anions, initial TCH concentration, initial temperature, and various pollutant species on the catalytic efficiency were also investigated. pH was shown to have the greatest impact on the photocatalytic performance of AR-TiO2/Ti3C2 for TCH degradation. •O2−, and h+ were identified as the primary reactive species that enabled the photocatalytic performance of AR-TiO2/Ti3C2 through trapping experiments. This study presents a novel method to synthesize hetero-phase junction photocatalysts and suggests that Ti3C2 has potential prospects for use in photocatalysis.

Round-the-Clock Adsorption-Degradation of Tetracycline Hydrochloride by Ag/Ni-TiO2.

The synergy of adsorption and photocatalysis is a good method to remove organic pollutants in wastewater. In recent decades, persistent photocatalysis has gained considerable interest for its ability to sustain the catalytic degradation of organic pollutants in the dark. Herein, we report three different TiO2 nanomaterials to remove tetracycline hydrochloride (TCH) in solution. We found that the removal ability of TiO2, Ni-TiO2, and Ag/Ni-TiO2 is 8.8 mg/g, 13.9 mg/g and 23.4 mg/g, respectively, when the initial concentration of TCH is 50 mg/L. Chemical adsorption could be the rate-determining step in the TCH adsorption process. Moreover, Ag nanoparticles dispersed on Ni doped TiO2 surface act as traps to capture photo-generated electrons upon illumination with indoor light. The holes in Ag/Ni-TiO2 serve as critical oxidative species in TCH degradation under dark conditions. This work provides new insights into the design of persistent photocatalysts that can be activated by weak illumination and degrade organic pollutants in wastewater after sunset.

Novel n–n Type CoCr2O4/NiFe2O4 Heterojunction Photocatalyst: Internal Magnetic Field Control of Photocatalytic Activity, Mechanism Insight and Pathway for Tetracycline Hydrochloride Degradation

AbstractHerein, a series of CoCr2O4/wt%NiFe2O4(CCO/wt%NFO) composites are successfully synthesized by a simple solution combustion method combined with mechanical grinding techniques. The preparation of CCO/wt%NFO composites result in an estimation of its photocatalysis performance by removing tetracycline hydrochloride (TC) as a model of antibiotic pollutants. The results show that the percentage of NFO by mass have a great influence on the morphology and the photocatalysis performance of CCO/wt%NFO composites. Superior photocatalysis performance is observed in CCO/25%NFO composites prepared at percentage of NFO is 25%. The photocatalyst used with CCO/25%NFO composites result in a removal ratio of 81% for TC. The generation of hydroxyl radical (•OH), superoxide anion radical (•O2−) and holes (h+) is largely responsible for degrading TC through photocatalysis in the presence of CCO/wt%NFO composites. The optimal operating conditions involve the initial concentration of TC and pH of TC being 50 mg L−1 and pH = 13, respectively. Furthermore, CCO/wt%NFO is highly reusable and stable during the photocatalytic removal process. The degradation pathway, toxicity, and photocatalytic mechanism of CCO/25%NFO composites for the degradation of TC are extensively examined through mass spectrometry, toxicity analysis, and energy band theory.

Effective degradation of tetracycline under visible light by microwave-assisted reflux synthesis of ZnO/MoS2/rGO ternary nanocomposites

ZnO@MoS2 and conducting rGO based ternary nanocomposites were synthesized by a bottom-up microwave-assisted reflux method and effectively investigated for the photocatalytic degradation of tetracycline hydrochloride (TCH) antibiotic. The XRD, EDAX and XPS results corroborates the formation of nanostructure composite with high phase purity. The ZnO nanorods are well grafted on the curled configuration of layered MoS2 and thin surfaced rGO sheets as visualised from HR-TEM analysis. Upon addition of rGO, there is a significant decrease in the bandgap and improved visible light response in the ternary nanocomposites is elucidated by UV–visible Diffuse Reflectance Spectroscopy (UV-DRS) analysis. The suppression in photo-induced electron/hole pair recombination and allowing easy charge transport of ZnMG-50 were evidenced from photoluminescence (PL) and photo-electrochemical impedance (photo-EIS) spectroscopy. From BET and BJH analysis, the enhancement in surface area and pore volume by loading of rGO (SBET = 264.794 m2/g and 0.548 cm3/g). The optimized ZnMG-50 nano-photocatalyst possess a superior photocatalytic performance with higher removal efficiency of 92.18 % was achieved at pH level 10, catalyst dosage 40 mg and TCH concentration 20 ppm within 180 min under illumination. The degradation process compiles a pseudo-first order reaction with a kinetic rate constant of 0.01365 min−1. The nonstop generation of hydroxyl (˙OH) and superoxide (O2˙-) reactive species were beneficial for free electrons in the active participation, which remains as a core factor in the degradation process. The detailed study on ZnMG-50 nanocomposite substantiated to be an efficient noble metal-free synthetic catalyst for enhanced photocatalytic degradation of antibiotics.

BiVO4 photoanode modified with FeOOH cocatalyst for visible-light-driven photoelectrocatalytic degradation of organic pollutants

Photoelectrocatalytic (PEC) could effectively and gently treat wastewater. Nonetheless, catalysts face the pronounced tendency of sluggish photogenerated carrier transfer and carrier recombination. In this paper, we herein fabricate FeOOH/BiVO4 photoanode through the incorporation of a cocatalyst FeOOH onto the BiVO4 surface. This modified photoanode demonstrated improved performance when coupled with peroxomonosulfate (PMS) for the purpose of oxidizing tetracycline hydrochloride (TCH) within the PEC system. In the presence of 0.3 mM PMS, the degradation efficiency of TCH increased from 65 % to 88 % within 60 min. The effects of PMS concentration, applied voltage and TCH concentration on the decomposition were studied in detail. Through free radical scavenging experiments, it was found that SO4•-, h+ and ·OH played an important role in TCH degradation. In addition, the FeOOH/BiVO4 with PMS activation in the PEC system also could be capable of dealing with some more organic pollutants (antibiotics and dyes) and achieving good degradation effect. More importantly, TCH degradation rate by FeOOH/BiVO4 photoanode is still over 80 % after five cycles of reuse. This work provides a promising approach for the synthesis of novel photoanodes in the PEC systems with excellent PEC properties in removing environmental pollutants.

Novel high entropy alloy/NiAl2O4 photocatalysts for the degradation of tetracycline hydrochloride: Heterojunction construction, performance evaluation and mechanistic insights

Novel NiAl2O4 (NAO)/high entropy alloy (HEA) (Ti), NAO/HEA (Mn) and NAO/HEA (Mo) heterojunction photocatalysts with high photocatalytic activity for the degradation of tetracycline hydrochloride (TC) under simulated sunlight irradiation were synthesized by the polyacrylamide gel method combined with a low temperature sintering technique. The effects of environmental parameters, including drug concentration, catalyst content and pH value, on the photocatalytic activity of NAO/HEA photocatalysts were investigated in detail on the basis of the response surface methodology (RSM) and experimental results. The optimal initial TC concentration, catalyst content, and pH were 100 mg/L, 1 g/L, and 5, respectively. The photocatalytic activity of NAO/HEA photocatalyst (84.6 %) was significantly improved compared to the degradation percentage of HEA (Ti) photocatalyst (36.5 %). The roles of active free radicals including h+, •O2−, •OH and oxygen vacancy in photocatalysis were verified using multiple characterization methods. In-depth analysis was conducted on the degradation pathway of TC, the safety of degradation intermediates, and the photocatalytic mechanism of NAO/HEA (Ti) photocatalyst. The Z - scheme heterojunction can significantly improve the transport efficiency of photogenerated carriers and inhibit the recombination rate of electron hole pairs in the system, which provides a new idea for exploring the application of new HEA - based heterojunction photocatalysts in the field of photocatalysis.

Mg–Fe Layered Double Hydroxides/Polyacrylonitrile Nanofibers for Solar-Light Induced Peroxymonosulfate Elimination of Tetracycline Hydrochloride

The photo-induced peroxymonosulfate (photo-PMS) reaction is a promising route to eliminate antibiotics from waste water. To achieve excellent photo-PMS activity in Mg–Fe layered double hydroxides (LDHs) for tetracycline hydrochloride (TCH) degradation under simulative solar-light irradiation, Mg–Fe LDHs-loaded polyacrylonitrile (Mg–Fe/PAN) nanofibers were in-situ prepared via the hydrothermal route. For comparison to the photocatalysis and photo-PMS process, the Mg–Fe/PAN-assisted photo-PMS process exhibited a better elimination activity for TCH elimination. In addition, the photo-PMS activities of Mg–Fe/PAN composites were greatly affected by Mg–Fe LDHs content, TCH concentration, pH, and inorganic salts. Among these Mg–Fe/PAN composites, the optimal MgFe2/PAN with a Mg/Fe molar ratio of 1:2 and a nominal Mg–Fe LDHs content of 2.0 wt. % removed 81.31% TCH solution of 80 mg L−1 TCH within 120 min. This enhanced photo-PMS capacity of MgFe2/PAN was ascribed to the abundant active sites formed by functional groups and oxygen defects for efficient TCH species adsorption and photon capturing, and the tight interface between Mg–Fe LDHs nanoparticles and PAN nanofibers for the rapid separation and transfer of photoinduced e−/h+ pairs. SO4•− and •O2− radicals were vital for the MgFe2/PAN-assisted photo-PMS reaction.

Zero valent iron modified carriers can promote anammox resistance to tetracycline hydrochloride stress

The toxic effects of antibiotics on anammox bacteria (AnAOB) draw much attention. Zero valent iron (ZVI) can improve anammox performance, but whether ZVI promotes resistance to antibiotics stress is unknown. In this study, the effect of tetracycline hydrochloride (TCH) on anammox in the 10 wt% ZVI modified carrier filled system (R1) was investigated. Results showed that semi-inhibitory concentration (IC50) of TCH in R1 was 30.93 mg/L. In comparison, IC50 of TCH in R0 filled with conventional carriers was only 18.87 mg/L. Long-term effects showed that the inhibition of anammox biofilm by low concentration of TCH (≤ 50 μg/L) was not significant, whereas R1 exhibited better anammox performance than R0 when TCH was 100–200 μg/L. More extracellular polymeric substances (EPS) on the modified carriers was beneficial to trap TCH to mitigate toxicity. In addition, the heme-c contents and the enzymatic activities of NIR, HZS, HDH of R1 were higher than those of R0 regardless of the TCH dosing. The synergistic TCH degradation bacterium Ignavibacterium was enriched in R1, which might further mitigate the toxic effect of TCH. qPCR results of antibiotic resistance genes (ARGs) showed tetX, tetA and tetG were up-regulated on ZVI modified carrier, implying more enzymes were produced to inactivate and pump out TCH to resist the stress.

A novel synchronous fluorescence spectrometry combined with fluorescence sensitization for the highly sensitive and simultaneous detection of enoxacin, ofloxacin and tetracycline hydrochloride residues in wastewater

The synergistic effect of sodium dodecyl sulfate (SDS) and Mg2+ could significantly enhance the fluorescence intensity of enoxacin (ENO) at λex/λem = 269.2 nm/385.6 nm, ofloxacin (OFL) at λex/λem = 290.8 nm/466.2 nm and tetracycline hydrochloride (TCH) at λex/λem = 372.6 nm/514.8 nm. Moreover, when the wavelength difference (Δλ) was chosen 135 nm, the synchronous fluorescence spectra of the three antibiotic complexes could be well separated and the interference of the samples matrix were eliminated primely. Therefore, only one synchronous fluorescence scan was needed to simultaneously determine the three antibiotics. Based on these facts, a synchronous fluorescence spectrometry combining fluorescence sensitization for highly sensitive and selective determination of ENO, OFL and TCH residues in wastewater was developed for the first time. The experimental results showed that the concentrations of ENO, OFL and TCH in the range of 0.5–550 ng mL−1, 1–1500 ng mL−1 and 10–5500 ng mL−1 showed a good linear relationship with fluorescence intensity. The limits of detection were 0.0599 ng mL−1, 0.115 ng mL−1 and 0.151 ng mL−1, respectively. The recoveries of the actual sample were 87.50%–99.99 %, 93.00%–98.50 % and 85.70%–98.42 %, respectively. Overall, the novel synchronous fluorescence spectrometry established in the experiment has the advantages of high sensitivity, good selectivity, fast detection speed and high accuracy. It has been successfully applied to the detection of residual amounts of ENO, OFL and TCH in wastewater with satisfactory results.

Enhanced Photocatalytic Activity of O‐deficient Modified CuAl2O4/MoS2 Composite Photocatalysts in Wastewater Treatment Applications

AbstractThe O‐deficient modified CuAl2O4/MoS2 composite photocatalysts (ODMCAOMSCP) are fabricated by a wet chemical route and low‐temperature treatment for the degradation of tetracycline hydrochloride (TC). The fine particles dotted on the large sheet are revealed to be comprised of large sheets with rich oxygen defects and nanoparticles, which endows it with a high optical absorption coefficient, available reactive species, excellent charge carrier separation, and high photocatalytic activity. The finely designed ODMCAOMSCP achieve a TC degradation first‐order rate constant of 0.01436 min−1, which is 3.99 and 2.70 times higher than that of MoS2 and CuAl2O4, respectively. Response surface analysis reveals that multiple environmental factors including initial TC concentration, catalyst content, and initial pH affect the photocatalytic activity of the catalyst on the basis of backpropagation (BP) neural network optimized by genetic algorithm and Box‐Behnken design. The degradation intermediates and degradation pathways are determined by a liquid chromatograph‐mass spectrometer (LC‐MS). The toxicity of TC over ‐ ODMCAOMSCP is studied by the toxicity analysis software and the cultivation of mung bean. Mechanism investigation demonstrates that the major active species of ODMCAOMSCP for the degradation TC are attributed to oxygen vacancy, hydroxyl radical (∙OH), and superoxide radical (∙O2−).

Bimetal doped Cu-Fe-ZIF-8/g-C3N4 nanocomposites for the adsorption of tetracycline hydrochloride from water.

Bimetal doped Cu-Fe-zeolitic imidazole framework-8 (ZIF-8)/graphitic carbon nitride (GCN) (Cu-Fe-ZIF-8/GCN) nanocomposites were prepared via one-pot and ion-exchange methods. The main influencing factors, such as adsorbent concentration, TC concentration, initial pH, and coexisting ions, were evaluated in detail. Due to the suitable pore structures and the presence of multiple interactions on the surface, the nanocomposite showed a high adsorption capacity up to 932 mg g-1 for tetracycline hydrochloride (TC), outperforming ZIF-8 by 4.8 times. The adsorption kinetics and adsorption isotherm were depicted in good detail using pseudo-second-order kinetic and Langmuir models, respectively. Thermodynamic calculation revealed that the adsorption of the nanocomposite under experimental conditions was a spontaneous heat absorption process, and was primarily driven by chemisorption. After four cycles of use, the nanocomposite retained 87.2% of its initial adsorption capacity, confirming its high reusability and broad application prospects in removing tetracycline-type pollutants from wastewater.

A new perspective for surface modifying TiO2 to effectively enhance its visible light photocatalytic activity

In this study, a new perspective was proposed to regulate the photocatalytic properties of TiO2 and a novel TiO2-based composite (BA@TiO2) with nitrogen-containing surface layer was obtained by surface modifying TiO2 with an organic molecular (3,3′-Diaminobenzidine, BA). The composite (BA@TiO2) exhibited high responsiveness to visible light and great photocatalytic activity, which could remove 92% of tetracycline hydrochloride (TC), and also maintained a high ability to photodegrade low concentrations of TC. The free radical trapping experiments showed that h+ and •O2- were the most dominant active species in the degradation process. The possible degradation pathways of TC were deduced with the help of HPLC-MS and fuikui index. QSAR was used to perform toxicity analysis of the degradation intermediates. In addition, the composites demonstrated good recyclable stability and removal efficiency of TC in real water samples, indicating BA@TiO2 is a purifying agent with great efficiency and sustainability for practical treatment of organic pollutants in aqueous media.

Functionalized magnetic chitosan-based adsorbent for efficient tetracycline removal: Deep investigation of adsorption behaviors and mechanisms

As removal performance of tetracyclines in traditional wastewater treatment plants cannot satisfy the increasingly strict discharge requirements, developing an efficient approach to overcome this problem is quite urgent. Herein, a novel functionalized magnetic chitosan-based adsorbent (Fe3O4@CAA) with core-shell structure and unique magnetic responsiveness was facilely prepared by ultrasound-initiated radical grafting copolymerization and cross-link reaction. The as-prepared Fe3O4@CAA was fully characterized with TEM, SEM, BET, FTIR, TGA, XRD, VSM, and served as an efficient adsorbent for tetracycline hydrochloride (TCH) removal. Adsorption behaviors of TCH by Fe3O4@CAA were deeply evaluated at different adsorption time, initial TCH concentration, reaction temperature, solution pH, and background pollutant concentration. Results showed that Fe3O4@CAA presented a more competitive adsorption capacity of 325.04 mg g−1 compared with Fe3O4@CS and other reported adsorbent, due to the introduction of more active adsorption sites by abundant functional groups, including amino groups, hydroxyl groups, and sulfonic acid groups. After saturated adsorption, TCH loaded Fe3O4@CAA was easily collected by magnetic separation, and recycled after acid pickling. Fe3O4@CAA was successfully reused in five adsorption-desorption cycles, without obvious adsorption capacity loss. In binary pollutant systems, inorganic cations and Pb(II) restrained TCH adsorption by competitive effect, while proper amount of Cu(II) promoted TCH adsorption by bridge effect. FTIR and XPS analyses revealed that the adsorption mechanism of TCH by Fe3O4@CAA mainly included electrostatic interaction and hydrogen bonding, and Cu(II) could play a “mediator” role to form a strong Cu(II)-TCH complex to enhance TCH removal performance. This study provides an effective strategy for the design of magnetic chitosan-based adsorbents and valuable guidance for the removal of tetracyclines from wastewater.

Designing of Z‐Scheme MgFe2O4/Fe2O3 Coupled CoCr2O4 Heterojunction with High Photocatalytic Activity for the Removal of Tetracycline Hydrochloride in Wastewater

AbstractA simple solution combustion method is used to synthesize spinel type MgFe2O4 (MFO) and CoCr2O4 (CCO) oxides, which are combined with the mechanical mixing method to construct a Z‐scheme MFO/wt%CCO heterojunction, which effectively degraded tetracycline hydrochloride (TC) under simulated sunlight irradiation. Various characterization techniques are used to confirm the phase structure, composition, near‐spherical morphology, ferromagnetic behavior, optical properties, and photocatalytic activity of Z‐scheme MFO/wt%CCO heterojunction. A variety of environmental experimental parameters confirmed that when the optimal initial TC concentration is 50 mg L−1, the catalyst content is 1 g L−1, and pH 13, the degradation percentage of TC by the MFO/75%CCO composites reached 89%. Active species verification experiments showed that the hole (h+), hydroxyl radical (•OH), and superoxide radical (•O2 −) are the main active species in photocatalytic reactions. Based on mass spectrometry, toxicity analysis, and energy band theory, the degradation pathway, toxicity, and photocatalytic mechanism of MFO/75%CCO composites for the degradation of TC are discussed in detail.

Methodological aspects of the use of Chlorella vulgaris green algae in biotesting the environment of industrial facilities

Excessive and uncontrolled use of tetracycline antibiotics in animal husbandry and poultry farming is the cause of their toxic effects on the body of employees of the enterprise. The fact of indirect exposure confirms the presence of background concentrations of antibiotics in the urine of workers of livestock and poultry complexes. To assess the toxic effect of background concentrations of antibiotics during inhalation and oral exposure, there is a need to improve the methodological tools of biotesting.
 The study aims to evaluate the methodological possibilities for biotesting water and air samples containing tetracycline hydrochloride (THC) in different concentrations using the green algae Chlorella vulgaris as a test object.
 The authors considered the main methodological aspects of assessing the toxic effect of tetracycline group antibiotic — tetracycline hydrochloride by bioassay using green algae Chlorella vulgaris as a test object. The criterion for assessing toxicity was the change in the optical density of the algae culture during the day. We have based the criteria for the use of chlorella vulgaris in the biotesting method for assessing the toxic effect of tetracycline hydrochloride concentrations contained in water and air.
 Toxicological studies have shown a very high correlation (R=0.99; R2=0.98; A=0.23, p=0.045) between the indicator of the optical density of the algae culture and the concentration of tetracycline hydrochloride in water in the range from 0.006 to 0.1 mg/ml. We have the methodological capabilities of biotesting tetracycline hydrochloride in air at the maximum permissible concentration (MPC) (0.1 mg/m3) and above.
 The study showed that the growth reaction of the Chlorella vulgaris green algae culture to the effects of tetracycline hydrochloride makes it possible to develop a methodological apparatus for assessing the toxicity of the antibiotic in concentrations created in working areas at livestock and poultry facilities.
 Ethics. The research did not require the conclusion of the Ethics Committee.