Decomposition Of Tetracycline Research Articles

CaCO3-activited N-doped diatom biochar for the degradation of tetracycline

In this study, a N-doped diatom biochar (DBC) was prepared by one-step pyrolysis, where CaCO3 formed by marine diatom-mediated calcification was employed as an activator. Due to the activation effect of CaCO3, the specific surface area of the obtained DBC increased by more than 10 times, and the nitrogen presented as pyrrolic nitrogen (58.9%), pyridinic nitrogen (29.7%), and graphitic nitrogen (11.4%) in the DBC. In addition, the effects of important parameters and co-existing ions on the catalytic decomposition of tetracycline (TC) by DBC were investigated by using TC as a typical pollutant and PDS as an oxidant. The DBC/PDS system exhibited high activity over a broad pH range. Through radical scavenging experiments, electron spin resonance, and electrochemical results analysis, it was found that the degradation of TC in the system included both radical and nonradical pathways, and the most dominant reactive species was 1O2. Furthermore, the surficial reactive complexes formed by PDS on the catalysts also played an important role in attacking the adsorbed TC molecules. This study proposes an eco-friendly and economical technique to construct a clean advanced oxidation process capable of treating TC wastewater by utilizing the native biomass of diatom as a metal-free and efficient biochar catalyst while simultaneously reducing the use of chemical reagents.

Synthesis of a novel NiCo-LDH/Bi2WO6 Z-scheme heterojunction composite for photocatalytic degradation of tetracycline

This article aims at preparing of Z-scheme heterojunction NiCo-LDH/Bi2WO6 (LDH: layered double hydroxides) via a solvothermal technique, addressing the rapid recombination of electron-hole pairs caused by the narrow bandgap of Bi2WO6. Successful loading of NiCo-LDH onto Bi2WO6 was confirmed through various characterization techniques, assessing the composite's crystal structure, morphological traits, and performance. Notably, the NiCo-LDH/Bi2WO6 composite exhibited excellent photocatalytic performance in the degradation of tetracycline (TC), achieving an optimal reaction rate of 0.03 min−1, which is 4.8 times faster than that of Bi2WO6 alone. The findings demonstrate that the formation of the heterojunction structure facilitated the separation of photogenerated electron-hole pairs by reducing recombination in monomers. Free radical trapping experiments showcased that the decomposition of TC is primarily driven by h+ and ∙O2−. Additionally, liquid chromatography-mass spectrometry analysis identified the degradation products of TC and suggested two potential degradation pathways. The present research provides a novel approach for preparing LDH photocatalytic materials using NiCo-LDH/Bi2WO6.

G-C3N4 tubes decorated with MnMoO4·H2O: Outstanding S-scheme photocatalyst for detoxification of water pollutants upon visible light

Recently, the utilization of heterogeneous photocatalysts has been proposed as an effective solution for environmental purification, as one of the solar energy conversion processes, under mild conditions. In this research, MnMoO4·H2O nanoparticles were anchored on tubular g-C3N4 (abbreviated as TGCN) by a one-pot hydrothermal route. The phase structure, electronic environment, spectroscopic characteristics, composition, morphology, surface area, and electrochemical properties of the resultant materials were explored using XRD, XPS, EDX, FESEM, HRTEM, FTIR, PL, photocurrent, EIS, and BET analyses. The photocatalytic activity of TGCN/MnMoO4·H2O (20 %) nanocomposite was 4.25, 5.36, 9.07, 12.4, and 8.84 times better than modified GCN, and 3.91, 2.77, 6.24, 10.9, and 6.82 times higher than MnMoO4·H2O in removals of tetracycline, rhodamine B, methylene blue, methyl orange, and fuchsine pollutants, respectively. The improved visible-light absorption and rapid charge migration/separation between TGCN and MnMoO4·H2O counterparts through S-scheme heterojunction route were the key reasons for the boosted photocatalytic performance. The biocompatibility of solution after decomposition of tetracycline via the growth of wheat seeds was verified. Finally, the stability of the binary TGCN/MnMoO4·H2O (20 %) heterostructure was measured by the stability test after four reuses.

A water stable cobalt-bipyridine based hydrogen bonding double layered network for catalytic degradation of tetracycline

Reaction of Co(NO3)2∙6H2O, 2, 2′-bipyridine (bipy) and 1, 4-benzene dicarboxylic acid (H2BDC) by a two-step hydrothermal process, a stable inorganic-organic hybrid compound, [Co(bipy)(H2O)4]BDC (1), was obtained, which structure was characterized by X-ray single crystal diffraction analysis. Acted as catalyst, its photocatalysis-peroxymonosulfate (PMS) activation for tetracycline (TC) degradation was explored under solar light. The critical experimental factors in tetracycline decomposition were investigated, including the pH, [Co(bipy)(H2O)4]BDC dosage, tetracycline concentration, PMS dose, and temperature. [Co(bipy)(H2O)4]BDC has fast degradation performance, sufficient stability and reusability, that degradation rate were 97.5 % and 88.8 % after five cycles within 60 min. Furthermore, the sulfate radical (SO4•−, superoxide (O2•−), hydroxyl (•OH) free radicals and singlet oxygen (1O2) were confirmed as the key oxidation factors in the 1/PMS/SL system for tetracycline degradation.

Z-scheme heterojunction of TiO2/NH2-MIL-125(Ti) growing on carbon fibers cloth: Photocatalytic degradation of tetracycline and toxicity analysis

Photocatalysis stands out as a promising and eco-friendly method for antibiotics removal, yet traditional photocatalysts, mainly in powder form, are often prone to detachment and loss, making them difficult to recycle and reuse. In this work, we address this challenge by using carbon fiber (CF) cloth with a large area as a carrier for catalysts. To improve the photocatalytic efficiency, we synthesized TiO2 nanorods on the surfaces of CF cloth and incorporate NH2-MIL-125 (Ti) on them, thus the Z-scheme heterojunctions CF/TiO2/NH2-MIL-125(Ti) was obtained. In order to fully understand the structural properties and performance advantages of CF/TiO2/NH₂-MIL-125 (Ti) composites, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray photoelectron spectroscopy (XPS), UV–visible diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), Brunauer-Emmett-Teller (BET), Mott-Schottky (M-S) and valence band X-ray photoelectron spectroscopy (VB-XPS). Due to the special electronic transmission path of the Z-scheme heterojunctions, the CF/TiO2/NH2-MIL-125(Ti) composite achieve 95.30 % degradation of tetracycline (TC) within 210 min. The composite also shows exceptional reusability, with a degradation rate of 93.55 % maintained even after four cycles. Finally, we proposed a pathway and catalytic process for the decomposition of TC by CF/TiO2/NH2-MIL-125(Ti) and performed toxicity assessments of TC and its precursors using T.E.S.T. software. This novel photocatalyst composite offers a green and efficient approach for treating antibiotic wastewater, presenting a significant advancement in environmental remediation strategies.

Decomposition of tetracycline with peroxymonosulfate activated by an ordered hierarchical pores Fe-N/C catalyst rich in FeNx sites: Insights into singlet oxygen mechanism

FeNx sites show significant superiority in the degradation of antibiotic contaminants, but there are difficulties in successfully constructing highly dispersed FeNx sites. In this work, Fe-N/C catalysts doped with hierarchical ordered pores structure and FeNx active sites were prepared by metal node exchange strategy. Among them, Fe-N/C-2 had more excite species for peroxymonosulfate (PMS) owing to the synergy between Fe and N coordination, which achieved 89.36 % tetracycline (TC) removal rate within 20 min, and its reaction kinetic (k = 0.245 min−1) is 7.66 times more than original PMS system. Moreover, the material exhibited excellent activation performance in a variety of complex water environments, such as the coexistence of multiple anions, strong acids and alkalis (pH = 2.90 ∼ 10.73), and natural organic matter interference. Chemical bond detection confirmed the successful formation of FeNx sites, free radical trapping experiments showed that FeNx was the main catalytic site, and 1O2 was the main active component. Furthermore, the reaction principle of the FeNx site catalyzing the production of 1O2 from PMS was revealed in detail through mechanism exploration. Next, the probable pathways of TC decomposition were elaborated in terms of the intermediates identified by Liquid Chromatograph Mass Spectrometer (LC-MS). This study emphasized the significant potential of synthesizing Fe-N/C catalysts with activated FeNx sites, elucidated mechanism of FeNx in PMS activation, and confirmed its feasibility in TC degradation.

Resource utilization of medical waste incineration fly ash to activate peroxydisulfate for tetracycline degradation: Synergy between adsorption and PDS activation

Medical waste incineration fly ash (MWI FA) is classified as a hazardous solid waste. Therefore, the development of recycling technologies to convert MWI FA into useful products is necessary and challenging. In this study, we developed a sustainable approach for preparing a catalyst through the pyrolysis of water-washed MWI FA (WW FA-x, where x corresponds to the pyrolysis temperature). Subsequently, it was applied as a potent peroxydisulfate (PDS) activator to remove tetracycline (TC) from water. The results showed that the WW FA-800 exhibited remarkable adsorption performance as well as highly efficient catalytic activation of PDS, with a 115 mg/g maximum TC adsorption capacity and 93.5% (reaction kinetic rate = 315 μmol/g/h) TC removal within 60 min. A synergistic effect was achieved by adsorption and PDS activation. TC degradation was primarily driven by non-radical (1O2 and electron transfer) processes. WW FA-800 possesses multiple active sites, including defects, π–π*, O–CO groups, Fe0, and Cu(I). Three possible pathways for TC decomposition have been proposed, with the majority of intermediates exhibiting less toxicity than TC. Furthermore, the WW FA/PDS system exhibited an excellent anti-interference ability, and universality in the degradation of various organic contaminants. Notably, energy consumption was minimal, approximately 2.80 kWh/(g·TC), and the leachability of heavy metals in the WW FA-800 was within acceptable limits. This study provides a MWI FA recycling route for the development of highly active catalysts.

Efficiency and mechanistic insights of photocatalytic decomposition of tetracycline and rhodamine B utilizing Z-scheme g-C3N4/SnWO4 heterostructures under visible light irradiation

The hydrothermal approach was used in the design and construction of the SnWO4 (SW) nanoplates anchored g-C3N4 (gCN) nanosheet heterostructures. Morphology, optical characteristics, and phase identification were investigated. The heterostructure architect construction and successful interface interaction were validated by the physicochemical characteristics. The test materials were used as a photocatalyst in the presence of visible light to break down the antibiotic tetracycline (TC) and the organic Rhodamine B (RhB). The best photocatalytic degradation efficiency of TC (97%) and RhB (98%) pollutants was demonstrated by the optimized 15 mg of gCNSW-7.5 in 72 and 48 min, respectively, at higher rate constants of 0.0409 and 0.0772 min−1. The interface contact between gCN and SW, which successfully enhanced charge transfer and restricted recombination rate in the photocatalyst, is responsible for the enhanced performance of the gCNSW heterostructure photocatalyst. In addition, the gCNSW heterostructure photocatalyst demonstrated exceptional stability and reusability over the course of four successive testing cycles, highlighting its durable and dependable function. Superoxide radicals and holes were shown to be key players in the degradation of contaminants through scavenger studies. The charge transfer mechanism in the heterostructure is identified as Z-scheme mode with the help of UV–vis DRS analysis. Attributed to its unique structural features, and effective separation of charge carriers, the Z-scheme gCNSW-7.5 heterostructure photocatalyst exhibits significant promise as an exceptionally efficient catalyst for the degradation of pollutants. This positions it as a prospective material with considerable potential across various environmental applications.

Complete photodegradation of tetracycline induced by surface microenvironment of graphitic carbon nitride/silver phosphate

Silver phosphate (Ag3PO4) is a promising photocatalyst, but the photo-corrosion issue limits an effective and comprehensive photocatalysis degradation of tetracycline (TC). In this work, a unique graphitic carbon nitride-Ag3PO4 (KCN-AP(40 %)) core-shell structure was prepared via a simple chemical sedimentation method. The unique graphitic carbon nitride sheet encloses Ag3PO4 to trap excited electrons from the conduction band position of Ag3PO4, suppressing the reduction of Ag+ and Ag metal deposition on the surface of Ag3PO4. Under visible light irradiation, the optimized KCN-AP(40 %) can photodegrade nearby 100 % of TC within 20 min with a first-order kinetic constant of 0.127 min−1, which is 3.34 and 3.97-folds higher than those of Ag3PO4 and graphitic carbon nitride, respectively. A series of factors that may affect photoactivity of KCN-AP (40 %) including pH, inorganic ions, and organic matter are investigated. In final, the photodegradation mechanisms and intermediates were proposed based on ex-situ HPLC-MS. This work explains the deep decomposition of TC and presents a facile approach for designing and manufacturing Ag3PO4 based nanohybrids.

Construction of Bi2WO6/g-C3N4 Z-Scheme Heterojunction and Its Enhanced Photocatalytic Degradation of Tetracycline with Persulfate under Solar Light.

Z-scheme heterojunction Bi2WO6/g-C3N4 was obtained by a novel hydrothermal process; its photocatalysis-persulfate (PDS) activation for tetracycline (TC) removal was explored under solar light (SL). The structure and photoelectrochemistry behavior of fabricated samples were well characterized by FT-IR, XRD, XPS, SEM-EDS, UV-vis DRS, Mott-Schottky, PL, photocurrent response, EIS and BET. The critical experimental factors in TC decomposition were investigated, including the Bi2WO6 doping ratio, catalyst dosage, TC concentration, PDS dose, pH, co-existing ion and humic acid (HA). The optimum test conditions were as follows: 0.4 g/L Bi2WO6/g-C3N4 (BC-3), 20 mg/L TC, 20 mg/L PDS and pH = 6.49, and the maximum removal efficiency of TC was 98.0% in 60 min. The decomposition rate in BC-3/SL/PDS system (0.0446 min-1) was 3.05 times higher than that of the g-C3N4/SL/PDS system (0.0146 min-1), which might be caused by the high-efficiency electron transfer inside the Z-scheme Bi2WO6/g-C3N4 heterojunction. Furthermore, the photogenerated hole (h+), superoxide (O2•-), sulfate radical (SO4•-) and singlet oxygen (1O2) were confirmed as the key oxidation factors in the BC-3/SL/PDS system for TC degradation by a free radical quenching experiment. Particularly, BC-3 possessed a wide application potential in actual antibiotic wastewater treatment for its superior catalytic performance that emerged in the experiment of co-existing components.

Linker gadolinium as charge channel and singlet oxygen activation site in graphitic carbon nitride for enhancing photocatalytic decomposition of tetracycline

Reactive oxygen species are essential in photocatalytic water treatment. In this paper, Gd doped carbon nitride (CN) photocatalysts were prepared by simple thermal polymerization for the photocatalytic degradation of tetracycline under visible light irradiation. The photodegradation rate of 1.0GdCN is as high as 95% in 18 min, and the photocatalytic performance is much higher than that of CN. The improvement of photocatalytic performance is mainly attributed to the fact that Gd ion implantation directly provides active sites for oxygen activation and induces the formation of N vacancies. The results of characterizations show that the introduction of Gd in CN can improve the conversion ability of activated oxygen, carrier separation and energy band structure adjustment. Therefore, 1.0GdCN photocatalyst can be employed for efficient photocatalytic synthesis of tetracycline. Furthermore, three ways of photocatalytic degradation of tetracycline were revealed by high performance liquid chromatography-mass spectrometry. This work provides insights into the doping strategy of CN to improve the production of reactive oxygen species for environmental remediation.

Tetracycline removal using NaIO4 activated by MnSO4: Design and optimization via response surface methodology.

The appearance of recalcitrant organic pollutants such as antibiotics in water bodies has gained a lot of attention owing to their adverse effects on organisms and humans. The current study aims to develop a novel approach to eliminate antibiotic tetracycline (TC) from a synthetic aqueous solution based on the advanced oxidation process triggered by MnSO4-catalyzed NaIO4. A single-factor experiment was performed to observe the impact of pH, NaIO4 concentration, and MnSO4 dosage on TC decomposition, and a three-factor, three-level response surface experiment with TC removal rate as the dependent variable was designed based on the range of factors determined from the single-factor experiment. The single-factor experiment revealed that the ranges of pH, NaIO4 concentration, and MnSO4 dosage need to be further optimized. ANOVA (analysis of variance) results showed that the data from the response surface experiment were consistent with the quadratic model with high R2 (0.9909), and the predicted values were very close to the actual values. After optimization by response surface methodology, the optimal condition obtained was pH = 6.7, [NaIO4] = 0.39 mM, and [MnSO4] = 0.12 mM, corresponding to a TC removal of 96.56%. This optimization condition was fully considered to save the dosage of the high-priced chemical NaIO4.

Activation of Z-scheme heterojunction of peroxymonosulfate for augmented visible-light-induced photocatalytic decomposition of tetracycline and enhanced antimicrobial efficacy with O-doped g-C3N4@Co3O4

The widespread use of graphitic carbon nitride (CN) for environmental pollutant removal has been hampered by intrinsic limitations, notably facile electron-hole recombination and a limited surface area. This work successfully synthesized OCN/Co3O4 composite materials. Furthermore, the implementation of a peroxymonosulfate (PMS) reaction system remarkably enhanced the material’s capability to degrade Escherichia coli (E. coli) and tetracycline hydrochloride (TC). Compared with CN, the composite material possessed a notably larger specific surface area, affording it a profusion of reactive sites. Additionally, the replacement of carbon atoms with oxygen atoms in the original CN structure profoundly altered its electronic configuration. The characterization through UV–Vis diffuse reflectance spectra, photoluminescence, transient photocurrent responses, and electrochemical impedance spectroscopy also confirmed the excellent optical and electrochemical attributes of OCN/Co3O4. Experimental results illustrated OCN/Co3O4/Vis/PMS completely degraded E. coli at an initial concentration of 1 × 107 CFU mL−1 within 1 h and reduced TC with the adding concentration of 10 mg/L by 99.2% in only 20 min. An analysis was conducted on reactive oxygen species (ROS) using electron paramagnetic resonance spectroscopy and radical quenching experiments. The test results demonstrated the generation of ROS including •O2−, •OH, h+, and SO4•− within the reaction system. This work explored the degradation mechanism in the OCN/Co3O4/Vis/PMS system, providing innovative insights for the design of eco-friendly, efficient catalysts as well as the enhancement of TC and E. coli degradation through the synergistic activation of photocatalytic PMS.

Efficient synthesis and characterization of novel BiVO4/ZnO/graphene composites to study enhanced photocatalytic activity for organic pollutant degradation

This study reports the efficient synthesis and thorough characterization of novel graphene doped BiVO4/ZnO nanocomposites. Among these doping percentages, 3% BVZO/G is optimized composite as it shows the highest photocatalytic performance i–e 98% and 95% among all the doping percentages. Under the visible light exposure λ⩾420nm , the decomposition of tetracycline (TC) and methylene blue has been studied to evaluate the photocatalytic activity of the prepared composites. The characterization techniques such as photoluminescence spectroscopy, UV visible (UV-Vis) spectroscopy, x-ray diffraction, scanning electron microscopy, and Fourier transform infrared have been used to investigate the optical, structural, morphological, and vibrational properties respectively. The findings of the research indicate that the doping of graphene resulted in enhanced absorption of visible light and efficient mitigation of charge carrier recombination. To check the stability of optimized photocatalyst, reusability test has been performed. Additionally, role of active species has been examined using different scavengers in trapping experiment. By understanding the composite material for the enhanced photocatalysis, the results of this research help to design a sustainable and efficient photocatalyst.

The utilization of microwaves in revitalizing peroxymonosulfate for tetracycline decomposition: optimization via response surface methodology

Abstract Antibiotic contamination in water has received significant attention in recent years for the reason that the residuals of antibiotics can promote the progression of antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes (ARGs). It is difficult to treat antibiotics using conventional biological treatment methods. In order to investigate an efficient new method of treating antibiotics in water, in this study, microwave (MW) was employed in revitalizing peroxymonosulfate (PMS) to treat typical antibiotic tetracycline (TC). The Box–Behnken design (BBD) was applied to organize the experimental schemes. The response surface methodology (RSM) optimization was run to derive the best experimental conditions and validated using actual data. Moreover, the main mechanisms of PMS activation via MW were resolved. The results demonstrated that the relationship between TC removal rate and influencing factors was consistent with a quadratic model, where the P-value was less than 0.05, and the model was considered significant. The optimal condition resulting from the model optimization were power = 800 W, [PMS] = 0.4 mM, and pH = 6.0. Under such conditions, the actual removal of TC was 99.3%, very close to the predicted value of 99%. The quenching experiment confirmed that SO4•− and •OH were jointly responsible for TC removal.

Interfacial engineering of Bi12O17Br2/g-C3N4-x S-scheme junction boosting charge transfer for cooperative tetracycline decomposition and CO2 reduction

To realize the double winning goal of environment and energy, a novel dual-functional photocatalytic reaction system is designed by using CO2 conversion and pollutant oxidation in one cooperative system. S-scheme heterojunctions exhibit huge potential for accomplishing such synergetic coupling reaction system due to their strong redox ability and speedy charge separation rate. Howbeit, how to effectively adjust the charge transfer rate at nanometric heterointerface remains pivotal and challenging. Herein, interfacial Bi-N bond and N vacancy co-modulate Bi12O17Br2/g-C3N4-x S-scheme junction is constructed, which not only presents superior separation and migration efficiency of charges, but also possesses high redox capacity. A series of theoretical and experimental results manifest that the synergistic effect of interfacial Bi-N bond and N vacancy availably expedite carrier transfer dynamics, achieving excellent photo-redox activity for cooperative CO2 reduction and tetracycline oxidization. Furthermore, compared to two half-reactions, such elaborate cooperative reaction system displays an obviously elevated photo-redox activity. This work provides a deep insight into regulating interfacial charge migration of heterojunction by chemical bonds and defects.

Surface plasmon resonance Bismuth-modified NH2-UiO-66 with enhanced photocatalytic tetracycline degradation performance

For nearly a century, the misuse of antibiotics has gradually polluted water and threatened human health. Photocatalysis is considered an efficient way to remove antibiotics from water. Zirconium-based metal–organic frameworks have attracted much attention as promising photocatalysts for the degradation of antibiotics. However, single Zirconium-based metal–organic frameworks can still not achieve a more satisfactory photocatalytic efficiency, due to poor light absorption and charge separation efficiency. In this study, a novel metal-loaded metal–organic frameworks material was explored. As a potential photocatalytic material, the performance of NH2-UiO-66 in the photocatalytic degradation of tetracycline was greatly improved just by the loading of a single metal. Bismuth/NH2-UiO-66 photocatalysts of various compositions were physicochemically (TEM, SEM, XRD, XPS, BET, FTIR, UV–VIS, PL), and electrochemically (electrochemical impedance spectroscopy, photocurrent response) characterized. We evaluated the photocatalytic performance of Bismuth/NH2-UiO-66 composites by measuring their ability towards tetracycline decomposition in simulated sunlight irradiation conditions. The experimental results indicated that the introduction of metal Bismuth significantly boosts the photocatalytic activity of the composite catalysts. The final degradation rate of Bismuth/NH2-UiO-66 for tetracycline was found to be 95.8%, namely 2.7 times higher than pure NH2-UiO-66. This behavior is due to the surface plasmon resonance effect of Bismuth, which ameliorates the photocatalyst's electron-hole separation and strengthens the charge transfer. Apart from that, the presence of Bismuth magnifies the visible-light absorption range of Bismuth/NH2-UiO-66. In this study, an innovative approach for designing efficient and cost-effective metal-modified metal–organic frameworks photocatalysts is proposed.

Ytterbium induced surface polarization of graphitic carbon nitride with N vacancies towards enhanced photocatalytic decomposition of tetracycline

The recombination of photogenerated charges is always a hinder for the improvement of photocatalytic efficiency. Herein, as a case of study, graphitic carbon nitride (g-C3N4) modified with N vacancies and Yb doping (YbCN) was synthesized by the thermal polymerization of ytterbium nitrate and melamine. The optimized sample showed a photocatalytic efficiency of 99.9% within 30 min for degrading tetracycline (TC) under visible light irradiation (λ > 420 nm), which was 24 times than pure g-C3N4. The experimental results and density functional theory (DFT) calculations support that the enhanced performance for photocatalytic decomposition of TC was attributed to the doped Yb3+ and the formation of N vacancies. The doped Yb3+ and induced polarization can expand the light responsive range and inhibit the recombination of photogenerated carriers. Moreover, the introduction of Yb3+ in g-C3N4 can accelerate the adsorption and activation of O2 to generate 1O2, O2− and OH. Furthermore, the photocatalytic degradation pathway of TC was revealed by HPLC-MS and DFT calculations. Finally, the optimized sample catalyst was also employed for photocatalytic decomposition of TC in practical conditions including tap, river, and lake water. It was found that inorganic ions in real water can influence the photocatalytic degradation of TC. This work disclosed a strategy for the rational design of efficient g-C3N4-based materials for practical environmental remediation.

Ultrasonic degradation of tetracycline combining peroxymonosulfate and BiVO4 microspheres

Tetracycline (TC) has received widespread attention due to the negative impacts of the drug abuse on ecological system and human health. Sonodegradation coupled with catalyst has proven to be an efficient method to treating TC. In this paper, BiVO4 microspheres synthesized by hydrothermal method and peroxymonosulfate (PMS) were used as sonocatalysts. Comparison of the degradation experiments revealed that combination of BiVO4/PMS with ultrasound (US) resulted in the highest degradation rate of TC, and the synergistic factor was calculated to be 6.17, which indicates a very significant synergistic effect. Effects of many factors, such as US power, BiVO4 concentration, dosage of PMS, initial TC concentration and matrix ion, on tetracycline degradation were investigated, and the operating parameters were optimized by response surface methodology, which predicted that TC degradation rate could reach 91.4 % after 60 min by setting initial TC concentration of 20 mg/L, BiVO4 concentration of 1.156 g/L, PMS dosage of 2.331 mM, and US power of 419 W. Active species analysis verified that radicals, such as OH, SO˙4−, h+ and O˙2−, were the primary contributors to TC removal, and ultrasonic cavitation plays a key role in sonocatalysis. The TC degradation rate only decreased by 1.6 % after four reuses of BiVO4. Moreover, the intermediate of TC degradation was detected using a liquid chromatograph-mass spectrometer (LC-MS), and the degradation pathway revealed that deamination, decarbonization and ring-opening reaction eventually result in the decomposition of TC. This work proposes a method for an efficient degradation of TC in waste water.

Unleashing the power of solar light: WO3 nanorods decorated onto BiVO4 dendrites for tetracycline detoxification and water splitting.

The coupling of different oxide materials in a nanohybrid enables the customization of their optical and charge transport properties, leading to improved interfacial charge segregation and migration. In this study, BiVO4/WO3 (BVW), a sunlight-driven photocatalyst with distinct mole ratios was synthesized via a facile hydrothermal approach. The resultant catalyst exhibits a nanorods shape morphology decorated onto dendrite-like matrix and is studied for photocatalytic elimination of tetracycline (TC) and photoelectrocatalytic (PEC) H2 production. The effect of illumination time, solution pH, photocatalyst concentration, and mole ratios of BiVO4 to WO3 on the photocatalytic abatement of TC were tested sequentially as effective operating factors. Under optimal condition, 3:1 BiVO4:WO3 (31BVW) nanohybrid demonstrated a maximum degradation efficacy of 96.2% (rate constant ~0.0241 min-1), which is much better than its individual components and commercial TiO2-P25 (50.9%). The resultant by-products of TC decomposition were analyzed using GC-MS to explain the degradation mechanism. Moreover, as a photoanode, 31BVW showed a high photocurrent density of 0.64 mA/cm2 at 1.23 V vs RHE and a steady photocurrent for ~6 h under chronoamperometry study at1.23 V vs RHE. However, bare BiVO4 and WO3 exhibited the photocurrent density of 0.001 mA/cm2, and 0.015 mA/cm2, respectively at 1.23 V vs RHE. The Mott-Schottky analysis of 31BVW confirms their n-type behavior, with a calculated flat band potential of -0.067 V. The hydrogen production rate was theoretically calculated as 4.56 mmolcm-2 s-1 from chronoamperometric measurements. The photocatalyst's efficacy in TC degradation was further established via its reusability upto 7 cycles. Post degradation characterization of catalyst confirms its stability in lieu of practical usage. Comparative studies with existing literature revealed the superiority of reported photocatalysts in both applications. Overall, the binary BVW photocatalyst shows great potential for removing detrimental contaminants as well as H2 production via PEC water splitting due to efficient charge separation, reduced recombination, high surface area, and widen absorption window of the nanohybrid.