Tetracycline Hydrochloride Concentration Research Articles

Ultrasound-activated peracetic acid to degrade tetracycline hydrochloride: Efficiency and mechanism

The removal of pollutants by peraceticacid (PAA) has attracted much attention. However, such removal is not achievable solely by PAA without activation. This paper investigated the efficiency and mechanism of ultrasound-activated peracetic acid (US/PAA) to remove tetracycline hydrochloride (TCH). The results indicated that US/PAA process could successfully remove organic contaminants from water, and the degradation efficiency of TCH could reach 99.4% within 30 min. Adding ultrasonic radiation into the PAA solution could effectively activate PAA, and the US/PAA process increased the degradation efficiency of TCH by 4.88 times compared to the PAA process. The electron paramagnetic resonance (EPR) experiment and the radical quenching experiment both demonstrated that singlet oxygen (1O2) and organic radicals (RO·) played an important role in the degradation of TCH during US/PAA process. The effects of the PAA dose, pH, ultrasound power, and initial TCH concentration on the removal of TCH in US/PAA process were investigated. The pH was the main factor, and the highest degradation efficiency was reached at a neutral pH (6.5–8.0). Additionally, the influence of water components (Cl−, HCO3−, SO42−, and humic acid) on the removal of TCH by US/PAA process was studied. The results showed that all water components inhibited the elimination of TCH, except 5 mmol/L HCO3−. Finally, the possible degradation products of TCH were identified by high performance liquid chromatography triple quadrupole mass spectrometer (HPLC-MS) analysis, and the potential degradation pathways mainly involved hydroxylation, demethylation, dehydration, and ring cleavage reaction.

Preparation of Novel Triangular Prism e -Zn(OH)2 by the Facile Precipitation Route for the Photocatalysis Under Visible Light

Objective: This study aims to decompose antibiotic of tetracycline hydrochloride (TCH) in aqueous medium by photocatalysis under the visible light irradiation. Method: Photocatalyst e -Zn(OH)2 was synthesized by facile precipitation method from an aqueous containing zinc nitrate, using trisodium citrate dihydrate. The characterization of as-prepared material was confirmed by XRD, SEM, FI-IR, and UV-Vis-DR. The catalytic performance of catalyst was evaluated by batch reaction. Finding: e -Zn(OH)2 has an orthorhombic structure with a length prism of 5-7 mm and triangle angles of 56.92, 69.46, and 66.71o e -Zn(OH)2 has been shown to efficiently degrade tetracycline hydrochloride. The degradation efficiency (DE) and reaction rate at the TCH concentration of 5 mg/L were the highest, exhibiting 89.51% and 0.120 min-1, respectively. The alkaline medium was an appropriate condition for degradation of TCH on catalyst. Application/Improvement: e -Zn(OH)2 was synthesized by the facile precipitation method, it has relatively strong photocatalytic ability for applying in treatment of medical wastewater. Novelty: Novel triangular prism e -Zn(OH)2 was prepared for photocatalysis. The relationship between structure and catalytic efficiency was investigated in detail. In addition, the photocatalytic mechanism of TCH on e -Zn(OH)2 has been proposed. Keywords: Photocatalyst; Zn(OH) 2; Tetracycline hydrochloride; Degradation; Kinetic

Highly Efficient Degradation of Tetracycline Hydrochloride in Water by Oxygenation of Carboxymethyl Cellulose-Stabilized FeS Nanofluids.

The transformation of organic pollutants by stabilized nano-FeS in oxic conditions is far less understood than in anoxic states. Herein, carboxymethyl cellulose-stabilized FeS (CMC-FeS) nanofluids are prepared at a CMC-to-FeS mass ratio of 1/2 and their performance of tetracycline hydrochloride (TC) degradation under oxic conditions was investigated. Here, we showed that TC could be efficiently removed by oxygenation of CMC-FeS nanofluids at neutral initial pH. We found that CMC-FeS dosages as low as 15 mg/L can achieve the TC removal efficiency as high as 99.1% at an initial TC concentration of 50 mg/L. Oxidative degradation plays a predominated role in TC removal (accounting for 58.0%), adsorption has the second importance (accounting for 37.0%), and reduction has minor impact (accounting for 4.1%) toward TC removal. Electron spin resonance assays, fluorescent detection using coumarin as a probe, and radical scavenging experiments confirm that hydroxy radicals (•OH), both in free and surface-bound forms, contribute to oxidation of TC. Humic acids brought detrimental effects on TC removal and therefore should be biologically degraded in advance. This work offers a facile and cost-effective solution to decontaminate TC in natural and engineered water bodies.

Photocatalytic degradation of tetracycline hydrochloride by a Fe3O4/g-C3N4/rGO magnetic nanocomposite mechanism: modeling and optimization.

The photocatalytic degradation of antibiotics requires a good separation efficiency of photogenerated electron-hole pairs and a wide visible light absorption range. Current studies have discussed the successful preparation of ferroferric oxide/graphite carbon nitride/reduced graphene oxide (Fe3O4/g-C3N4/rGO). The phase structure and morphology of the Fe3O4/g-C3N4/rGO composites were characterized by XRD, HR-TEM, SEM, and EDS. The obtained composites were used to degrade tetracycline hydrochloride (TCH) to evaluate its photocatalytic activity. The effects of four variables on the degradation of TCH were analyzed by the response surface method and artificial intelligence (gradient regression tree, random forest, artificial neural network, etc.). The results showed that the graphite carbon nitride in the catalyst maintained its original structure and that the photocatalytic activity was significantly improved. The degradation rate of TCH was 86.7% under the optimal conditions (the Fe3O4/g-C3N4/rGO dosage was 0.1g, pH = 7.0, the initial concentration of TCH was 20mg/L, and the visible light irradiation time was 60min). At the same time, the degradation rate of TCH changed little after the material was used five times, which indicates that the stability and recyclability of the Fe3O4/g-C3N4/rGO photocatalyst were excellent. Finally, a possible photocatalytic mechanism of the Fe3O4/g-C3N4/rGO photocatalyst is proposed in this paper.

Sulfate radicals induced from peroxymonosulfate on electrochemically synthesized TiO2-MoO3 heterostructure with Ti-O-Mo bond charge transfer pathway for potential organic pollutant removal under solar light irradiation.

Here, a novel method for synthesis of heterostructured TiO2-MoO3 (MT) nanosheets photocatalyst by utilizing a facile electrochemical method and examined it's photocatalytic activity by the degradation of tetracycline hydrochloride (TCH), a model of organic pollutants, in the presence of peroxymonosulfate (PMS) under solar light irradiation (SL) was reported for the first time. The influence of several factors on the degradation efficiency including the initial concentration of TCH, solution pH, catalyst dosage, PMS concentration, and the existence of inorganic anions was explored. The MT-15/PMS system displayed a promising photocatalytic performance and up to 97% of TCH was degraded in 90min the rate of the degradation reaction of MT-15/PMS was the highest (0.05299 min-1) compared to 0.00251, 0.00337, 0.00546, 0.00735, 0.01337min-1of TiO2-P25, TiO2-P25/PMS, MoO3, MoO3/PMS, and MT-15 respectively. The enhancement can be attributed to several reasons. First, the 2D morphology of the optimized heterostructure photocatalyst plays a significant role in providing much more active sites on its surface. Next, the boosted light absorption efficiency and higher photoproduced electron-hole pair separation ability, induced by the unique direct transformation of photogenerated electrons from the valance band of TiO2 to the conduction band of MoO3 via the Ti-O-Mo bond formed at the interface of MT heterostructure. Finally, the appropriate accessible reactive sites for the activation of PMS together with the synergistic effect between activation of PMS and photocatalytic processes eased the production of active species for the degradation of pollutants. Based on the scavenger experiments and EPR analysis, hydroxide and sulfate radicals were found to be the dominant free radical active species in the degradation process. Furthermore, the synergistic degradation reaction mechanism was proposed.

Degradation of Tetracycline Hydrochloride by a Novel CDs/g-C3N4/BiPO4 under Visible-Light Irradiation: Reactivity and Mechanism

In recent years, with the large-scale use of antibiotics, the pollution of antibiotics in the environment has become increasingly serious and has attracted widespread attention. In this study, a novel CDs/g-C3N4/BiPO4 (CDBPC) composite was successfully synthesized by a hydrothermal method for the removal of the antibiotic tetracycline hydrochloride (TC) in water. The experimental results showed that the synthesized photocatalyst was crystalline rods and cotton balls, accompanied by overlapping layered nanosheet structures, and the specific surface area was as high as 518.50 m2/g. This photocatalyst contains g-C3N4 and bismuth phosphate (BiPO4) phases, as well as abundant surface functional groups such as C=N, C-O, and P-O. When the optimal conditions were pH 4, CDBPC dosage of 1 g/L, and TC concentration of 10 mg/L, the degradation rate of TC reached 75.50%. Active species capture experiments showed that the main active species in this photocatalytic system were holes (h+), hydroxyl radicals, and superoxide anion radicals. The reaction mechanism for the removal of TC by CDBPC was also proposed. The removal of TC was mainly achieved by the synergy between the adsorption of CDBPC and the oxidation of both holes and hydroxyl radicals. In this system, TC was adsorbed on the surface of CDBPC, and then the adsorbed TC was degraded into small molecular products by an attack with holes and hydroxyl radicals and finally mineralized into carbon dioxide and water. This study indicated that this novel photocatalyst CDBPC has a huge potential for antibiotic removal, which provides a new strategy for antibiotic treatment of wastewater.

Facile synthesis of NiAl2O4/g-C3N4 composite for efficient photocatalytic degradation of tetracycline

Designing high-efficiency photocatalysts responsive to visible light is important for the degradation of antibiotics in water. Heterojunction engineering is undoubtedly an effective strategy to improve the photocatalytic performance. In this work, spinel-type metal oxides (NiAl2O4, NAO) are synthesized by a simple sol-gel and calcination process. After compounding graphitic carbon nitride (g-C3N4), NAO/g-C3N4 heterojunction is obtained, which then is used as the photocatalyst for tetracycline hydrochloride (TC). The effects of photocatalyst dosage, the initial concentration of TC, and solution pH on photodegradation performance are systematically studied. The removal rate of TC on NAO/g-C3N4 reach up to ∼90% after visible light irradiation for 2 hr and the degradation rate constant is ∼7 times, and ∼32 times higher than that of pure NAO and g-C3N4. The significantly improved photocatalytic activity can be attributed to the synergistic effect between well matched energy levels in NAO/g-C3N4 heterojunctions, improvement of interfacial charge transfer, and enhancement of visible light absorption. This study provides a way for the synthesis of efficient photocatalysts and an economic strategy for removing antibiotics contamination in water.

Efficient degradation of antibiotics by photo-Fenton reactive ceramic membrane with high flux by a facile spraying method under visible LED light

The traditional treatment of antibiotics confronts high energy consumption but low removal efficiency. In this study, a photo-Fenton ceramic membrane (PF-CM) was prepared by an innovative and facile approach of spray printing method with nano hematite (α-Fe2O3) for the removal of tetracycline hydrochloride (TC) as a model antibiotic. The SEM, TEM, XPS, and UV–Vis DRS were used to characterize the PF catalyst of α-Fe2O3. The as-prepared α-Fe2O3 was loaded to a flat ceramic membrane (CM) by a spray printing and low-temperature sintering method to form a photo-Fenton reactive membrane (α-Fe2O3-CM). A new α-Fe2O3-CM fixed bed water treatment system with visible LED light was fabricated for the removal of TC by comprehensive consideration of degradation rate and permeates flux. The reusability and stability of the α-Fe2O3-CM were also investigated. To reveal the reactive radicals involved in the PF-CM process for a deeper insight into the degradation mechanisms, quenching experiments and EPR analysis were performed. The SEM/EDS images indicated that the α-Fe2O3 was loaded tightly onto the α-Fe2O3-CM, and pure water permeates flux of the α-Fe2O3-CM could reach as high as 55.8 kg/(m2·h·kPa). The α-Fe2O3-CM fixed-bed treatment system is suited for TC treatment, and the removal efficiency could reach 82% even when the TC concentration is as low as 20 mg/L. Moreover, α-Fe2O3-CM could retain long-term stability and exhibit a self-cleaning function in antibiotic wastewater treatment for five cycles, which was further confirmed by SEM/EDS images and iron dissolution experiments. The quenching experiments and EPR analysis revealed that reactive radicals involved in the PF-CM process were h+, ·O2−, and, ·OH responsible for TC degradation. This research also provides a utilization proposal for scale-up α-Fe2O3-CM for water and wastewater treatment.

Step-scheme heterojunction g-C3N4/TiO2 for efficient photocatalytic degradation of tetracycline hydrochloride under UV light

Construction of heterojunction between semiconductors is considered an effective strategy for enhancing photocatalytic capability. Herein, this work prepared an abundant porous g-C3N4/TiO2 photocatalyst, with the two-dimensional (2D) nanosheet g-C3N4 and nanoparticle TiO2. The heterojunction both enhanced the ultraviolet (UV) light absorption ability, and inhibited the recombination of photogenerated electron-hole (h+) pairs. As expected, the optimal 4 % g-C3N4/TiO2 (g-C3N4:TiO2 = 1:25) exhibited a prominent degradation efficiency of 96.53 % in the photocatalytic performance of tetracycline hydrochloride (TCH) under UV irradiation. The recycling of the heterojunction photocatalyst g-C3N4/TiO2 remained stability and reusability. The main active species were·O2-, h+ and·OH, and the formation of internal electric field on the step-scheme (S-scheme) heterojunction interface accelerated the migration of photogenerated carriers. Moreover, several environmental factors on degradation such as dose, pH, and the initial concentration of TCH were investigated. This work could be spread to the conceive of other S-scheme heterojunction photocatalysts in application to different environmental demands.

Heterogeneous catalytic oxidation of tetracycline hydrochloride based on persulfate activated by Fe3O4/MC composite

In this study, a novel magnetic mesoporous carbon composite (Fe3O4/MC) was prepared by manganese carbonate (MnCO3) as the template to activate persulfate (PS) for tetracycline hydrochloride (TC) degradation. The characterization results showed that Fe3O4 nanoparticles were evenly distributed on the surface of MC, and Fe3O4/MC had the large surface area of 433.88 m2∙g−1. When the initial TC concentration was 50 mg·L−1, Fe3O4/MC dosage was 0.0336 g, PS dosage was 0.0476 g and the reaction temperature was 30 °C, Fe3O4/MC + PS system could degrade 92.9% of TC within 90 min. TC degradation efficiency increased with the increase of Fe3O4/MC dosage and temperature, but decreased with the increase of TC initial concentration and pH value. The increase of PS concentration first improved TC degradation efficiency, and then was not conducive to its degradation. The quenching experiments indicated that the sulfate radical (SO4•−), superoxide radical (•O2–) and singlet oxygen (1O2) in Fe3O4/MC + PS system contributed to TC degradation. Meanwhile, the toxicity evaluation of the degradation products confirmed that the toxicity of TC in Fe3O4/MC + PS system was greatly reduced. Totally, this study systematically investigated the performance of the Fe3O4/MC + PS system for TC removal, laying a theoretical and practical foundation for treatment of potential antibiotic wastewater (ppm range) in the future.

S-scheme Cs2AgBiBr6/Ag3PO4 heterojunction with efficient photocatalysis performance for H2 production and organic pollutant degradation under visible light

A dual-function S-scheme Cs2AgBiBr6/Ag3PO4 (CA) heterojunction photocatalyst with nano-flower structure was synthesized to achieve green energy hydrogen (H2) production and persistent organic pollutants degradation under visible light. The high crystalline quality and strong interface of CA enhanced the photocatalysis performance. Specifically, the photodegradation efficiency of tetracycline hydrochloride (TC) reached to 92.43 % in 60 min. And the yield of photocatalytic H2 evolution (PHE) accumulated about 4915.4 μmol/g within 6 h. The effects of initial pH, catalysts dosage, initial TC concentration and various sacrificial agents were investigated. It was found that the photocatalytic performance of CA for TC degradation and PHE was mainly affected by pH and various sacrificial agents. The TC degradation efficiency and PHE yield remained at 89.3 % and 3798.12 μmol/g in the fifth time photocatalytic cycle experiment, showing a high photostability of CA. Additionally, the photodegradation kinetics of TC was fitted well the pseudo-first-order mode and the rate constant k (0.0931 min−1) proved fast photodegradation rate. The analysis of the charge transfer mechanism and density functional theory calculation revealed that more photoinduced active species (holes, ·O2- and ·OH) were inspired and attacked nucleophilic and radical reaction sites on TC molecules. Furthermore, the emerging intermediates were detected by LC-MS, and the three possible degradation pathways of TC were proposed.

Oxygen vacancy-regulated TiO2 nanotube photoelectrochemical sensor for highly sensitive and selective detection of tetracycline hydrochloride

Investigation of the mechanism of oxygen vacancy-regulated photoelectrochemical sensors for highly sensitive and selective determination of biomolecules containing electron-donating groups is an innovative research field. In this study, oxygen vacancy-regulated TiO2 nanotube arrays (Ov-TNTs) with high photoelectrochemical activity were synthesized and applied to defect tetracycline hydrochloride (TC). The synergistic effect of oxygen vacancies and Ti3+ droves Ov-TNTs with a narrow energy band to generate more photogenerated carriers under irradiation. The photocurrent response of the oxygen vacancy-regulated photoelectrochemical sensor decreased with increasing TC concentration, which could be mainly attributed to adsorption of TC, which consumed part of the oxygen vacancies on the surface of Ov-TNTs. This system had excellent linearity in the range of 0.1–1000 nM with a detection limit of 0.33 nM (S/N = 3). In addition, the sensor was highly selective for TC determination due to the mutual electrostatic interaction between negatively charged TC-containing electron-donating groups (-NH2 and -OH) and positively charged Ov-TNTs. This study provided a foundation for developing an oxygen vacancy-regulated adsorptive photoelectrochemical sensor.

Preparation of TiO2 photocatalyst microspheres by geopolymer technology for the degradation of tetracycline

In this paper, TiO2-based geopolymer microspheres (TiO2@GMs) were prepared by dispersion-suspension-solidification technique using water glass activated metakaolin-based geopolymer slurry as a binder. The effects of different factors on the sphericity and particle size of TiO2@GMs were investigated, and the order of importance was found to be TiO2 dosage > water volume > water glass modulus > rotation speed. Secondly, in the Fenton system under UV light irradiation, TiO2@GMs exhibited excellent performance in the degradation of tetracycline hydrochloride (TC). At a TC concentration of 20 mg/L, liquid-to-solid ratio of 0.3 g/L, H2O2 (30 wt%) of 10 mM, and pH = 4.47, 98.6% TC was degraded by TiO2@GMs within 30 min TiO2@GMs can be easily separated from the reaction product and showed excellent recycling performance, with a degradation efficiency of 90.6% after five success reuses. Finally, a plausible photocatalytic degradation mechanism of TiO2@GMs for TC was discussed. This newly designed TiO2@GMs composite can be deemed as an alternative material for the degradation of TC and other similar antibiotic on large scale.

Removal of tetracycline onto KOH-activated biochar derived from rape straw: Affecting factors, mechanisms and reusability inspection

A porous biochar (BC) was prepared using the recycled agricultural waste rape straw as resources by combining high temperature carbonization with KOH activation procedure, and applied into tetracycline hydrochloride (TC) adsorption. The multiple characteristic techniques were adopted to investigate the structures and properties of as-prepared BC. The results demonstrated that the BC activated by KOH would possess the more graphite-like structures, more abundant oxygen-containing functional groups, and larger specific surface area (1531 m2/g) comparing with unactivated BC, which were favorable for the TC adsorption. The effects of initial TC concentration, solution pH value, salt ionic strength and adsorption temperature on the adsorption performances were explored in detail. The adsorption data could be well fitted by the pseudo-second-order kinetic model and Freundlich isothermal model. The maximum adsorption capacity of KOH activation BC could reach 325.07 mg/g at 30 °C. The endothermic and spontaneous properties of the adsorption system was implied by thermodynamic study. The adsorption TC mechanism of KOH activation BC was involved in the pore filling, π-π electron donor-acceptor interaction, hydrogen bonding and electrostatic action. Regeneration experiments showed that the TC removal efficiency could still attain 97.0% even after six cycling experiment, suggesting that the BC had the excellent reusability and stability. These results indicate the feasibility of a win-win strategy for the application of agricultural waste to water remediation.

Photo-Fenton reaction for the degradation of tetracycline hydrochloride using a FeWO4/BiOCl nanocomposite

Heterogeneous photo-Fenton technology combines photocatalytic and Fenton reactions to utilize solar energy and H2O2 efficiently, which is currently one of the most effective technologies for removing organic pollutants. In this work, FeWO4/BiOCl composite with different BiOCl contents was successfully produced by a two-step hydrothermal method. The photo-Fenton efficiency of the synthesized materials was assessed by the degradation of tetracycline hydrochloride (TCH) under simulated solar irradiation. The as-synthesized FeWO4/BiOCl composite exhibited significantly higher photocatalytic performances than individual semiconductors in the presence of H2O2 under simulated solar irradiation, and the apparent reaction rate constant reached as high as 0.0531 min−1, which was 4 times and 1.5 times higher than that of BiOCl and FeWO4, respectively. The effects of pH, TCH concentration, H2O2 concentration, and catalyst dosage on TCH degradation were investigated to identify the optimized reaction conditions. The excellent recyclability of FeWO4/BiOCl composite towards TCH photo-Fenton degradation was also shown. Photoelectrochemical analysis was performed to check the effective charge separation. The remarkably enhanced photo-Fenton catalytic performance of FeWO4/BiOCl composite was ascribed to effective charge separation and the production of more ·OH radicals. The FeWO4/BiOCl composite has proven to be a highly efficient and promising catalyst for Fenton-like processes to deal with practical environmental issues.

Electrospun poly(ω-pentadecalactone-co-ε-caprolactone)/gelatin/chitosan ternary nanofibers with antibacterial activity for treatment of skin infections

In recent years, there is an increasing attention on biocompatible electrospun nanofibers for drug delivery applications since they provide high surface area, controlled and sustained drug release, and they mimic the extracellular matrix. In the present study, tetracycline hydrochloride (TCH) antibiotic loaded poly(ω-pentadecalactone-co-ε-caprolactone)/gelatin/chitosan nanofibrous membranes were fabricated as a controlled drug delivery system. Poly(ω-pentadecalactone-co-ε-caprolactone) copolymer has been enzymatically synthesized in previous studies, thus it provides an originality to the membrane. Combination of a synthetic polymer, a protein, and a polysaccharide in order to obtain a synergetic effect is another novelty of this work and there exists limited examples for such electrospun membrane. Varied amounts of TCH was electrospun together with poly(ω-pentadecalactone-co-ε-caprolactone)/gelatin/chitosan (50/40/10 vol ratio) polymer blend (fiber diameters ranged between 85.7–225.2 nm) and several characterizations (morphological and molecular structure, wettability characteristics, and thermal behavior) were applied to examine the drug incorporation. Subsequently, in vitro drug release studies were conducted and mathematical modeling was applied for the detection of transport mechanism of drug. TCH release proceeded 14 days through an initial burst release in first hour and followed by a sustained release. 1% TCH-loaded sample was shown as optimal preparation with 96.5% total drug release and 11.8% initial burst release. TCH-loaded preparations demonstrated a good antibacterial activity against Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacteria and a limited effect (no inhibition zone observed below 3% TCH concentration) against Gram-negative (Escherichia coli) bacterium. Thus, TCH concentrations of ≥ 3% could be preferred to obtain a wide-spectrum effectiveness. The presented drug delivery system is suggested to be applied for treatment of skin infections as a wound dressing device.

Enhanced performance of microbial fuel cell with electron mediators from tetracycline hydrochloride degradation

Tetracycline hydrochloride (TCH) is a typical antibiotic pollutant with high toxicity and persistence. The degradation of TCH and the generation of the associated electron mediator in a dual chamber microbial fuel cells (MFCs) were studied. The results of liquid chromatography revealed that TCH could be effectively removed (>93%) in MFCs mode. The maximum COD removal was 88.14 ± 1.47% in MFCs while it was 69.57 ± 1.36% in open circuit MFCs. According to cyclic voltammetry, the presence of the relevant redox peaks clearly suggested that the intermediates from TCH degradation could act as endogenous electron mediator. The highest power density of 120.02 ± 2.76 mW/m2 and the lowest internal resistance of 18.68 Ω were achieved in MFC with 2 mg/L of TCH. Microbial community analysis illustrated that Bacteroides, Comamonas, Clostridium_sensu_stricto, Desulfovibrio and Geobacter were enriched and played a dominant role in TCH degradation and power generation. Electrochemical active bacteria had certain tolerance to TCH and the inhibiting threshold value of TCH was below 5 mg/L. This study provided a new thinking that low concentration of TCH could produce electron mediators to improve the performance of MFC system.

Calcination synthesis of tin niobate loaded porous carbon nitride S-scheme heterojunction for photocatalytic H2 production and tetracycline degradation

The fabrication of heterojunctions with large interfacial contact areas is an effective technique for the development of high-performance photocatalysts. Step-scheme (S-scheme) heterojunctions with enhanced charge separation and strong redox ability have been regarded as promising photocatalytic materials in recent years. Herein, an S-scheme heterojunction based on tin niobate nanosheets and porous carbon nitride was designed and constructed using a one-plot calcination method. The multifunctional photocatalyst showed greatly enhanced photocatalytic activity and outstanding chemical stability toward hydrogen evolution and tetracycline hydrochloride (TCH) degradation, with reaction rates 1.64 and 12.28 times higher for TCH degradation and H2 production, respectively, compared to those of pristine g-C3N4. Meanwhile, TCH degradation experiments at different pH, TCH concentrations, catalyst dosages, and anions were evaluated. The main reactive species, possible degradation intermediates, and pathways were determined. The heterojunction exhibited a high surface area and broad visible-light absorption, which are responsible for the improved photocatalytic performance and high apparent quantum yield (AQY). In addition, an S-scheme charge transfer mechanism under an internal electric field was proposed following the results of in-situ irradiation X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS), ESR, and Mott-Schottky measurements. This study offers a reasonable way to design another novel 2D/2D S-scheme heterojunction photocatalysts for energy and environmental applications.

S-defected In2S3/ZnS nanospheres for enhancing solar-light photocatalytic capacity

S-defected In 2 S 3 /ZnS nanospheres were synthesized via a microwave-assisted hydrothermal route for facilitating the solar-light induced photodegradation of tetracycline hydrochloride (TCH). The removal efficiency of TCH over In 2 S 3 /ZnS was higher in comparison to pure ZnS and In 2 S 3 . The adsorption-photocatalytic capacity of S-defected In 2 S 3 /ZnS was affected by In 2 S 3 content, TCH concentration, inorganic salts, pH, and quenchers. The removal efficiency of optimal 3-In 2 S 3 /ZnS for TCH solution of 50 mg L −1 was 100% within 90 min, and decreased to 93.26% after five cycle times. The main active species were •O 2 - and h + in solar-light driven photocatalytic system. The enhanced photocatalytic performance of S-defected In 2 S 3 /ZnS was due to the tight interface between In 2 S 3 and ZnS for the efficient transfer and utilization of photo-induced carriers. • In 2 S 3 /ZnS nanospheres were prepared by a microwave-assisted hydrothermal route. • Tight interface of In 2 S 3 and ZnS favored the transfer and utilization of charge carriers. • S-defected In 2 S 3 /ZnS exhibited the excellent photocatalytic activity and durability.

Efficient solar-light photocatalytic activity of FeS/S-doped MgO composites for tetracycline removal

To overcome the poor visible-light harvesting and the inferior charge transfer and separation of MgO, MgO nanosheets were co-modified by S and FeS (FeS/S-MgO) via a high-temperature sulfurized route. Compared with pure S-MgO, FeS/S-MgO exhibited higher photocatalytic capacity for tetracycline hydrochloride (TCH) under solar light irradiation. It’s attributed to the junction interface between FeS and O-defected S-MgO for promoting the transfer and separation of photo-induced carriers and enhancing the visible-light absorption capacity. The photocatalytic activity of FeS/S-MgO was greatly affected by FeS content, TCH concentration, pH, inorganic salts, and quenchers. The optical 3-FeS/S-MgO with a FeS content of 7.94 wt% degrade 97.10% TCH solution of 40 mg L −1 , and declined to 94.21% after five cycles under the same conditions. •OH and h + played the crucial role in 3-FeS/S-MgO assisted photocatalytic system. • FeS/S-MgO composites were prepared by high-temperature sulfurization. • FeS/S-MgO enhanced the visible-light harvesting and the charge transfer. • •OH and h + played the vital role in solar-light driven degradation of TCH.