Tetracycline Photocatalytic Degradation Research Articles

Synthesis of S scheme 2D/2D g-C3N5/g-C3N4 heterojunction for photocatalytic degradation tetracycline

2D/2D g-C3N5/g-C3N4 heterojunction (CNH) is successfully synthetized for photocatalytic degradation of tetracycline (TC) from wastewater. CNH exhibits excellent photocatalytic activity for TC photocatalytic degradation with removal of 99.8 % at N5/N4 mass ratio of 1.5, which has fast separation rate of the photogenerated carriers. The TOC mineralization rate of CNH (83.9 %) is larger than that of the pure g-C3N4 and g-C3N5. The active group capture experiment analysis indicates that ·O2−plays a crucial role in TC degradation process. TC degradation mechanism analysis result indicates that CNH with π-π* electron delocalization superposition following S scheme charge transfer mechanism is constructed. Density functional theory calculation is also applied to further investigate TC degradation mechanism. TC photocatalytic degradation path is systemically analyzed by MS-UPLC technology. The TC removal is significantly inhibited by the CO32− and HCO3−compared to SO42− and the NO3−, which is also investigated in the river water and tap water. Besides, the CNH has good stability with removal of 93.8 % after 5 cycles.

Synthesis of NiFe2O4 Photocatalyst to Apply for Treatment of Residual Tetracycline in Aqueous Environment with Addition of H2O2

In the study, NiFe2O4 was successfully synthesized by hydrothermal method for treatment of residual tetracycline (TC) in aqueous environment. The study also investigated effects of H2O2 as electron an acceptor to enhance TC photocatalytic degradation of the synthesized NiFe2O4. The properties of synthesized materials were determined by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-Vis absoprtion spectroscopy (UV-VIS) and vibrating sample magnetometer (VSM) systems. The obtained results indicated that the synthesized NiFe2O4 were nano-particles with average size of approximately 50 nm. The synthesized NiFe2O4 also exhibited high visible light absorption and magnetic ability. The TC removal results indicated that the NiFe2O4 adsorbed certain amount of tetracycline under dark condition. Under visible light, the NiFe2O4 further degraded significant tetracycline amount. Finally, the study investigated that H2O2 effectively acted as electron acceptor for hydroxyl radical production to degrade tetracycline.

Fabrication of Ag-decorated La0.9Ag0.1FeO3 for efficient photocatalytic degradation of tetracycline under visible light with the assistance of water oxidation

The photocatalytic conversion of molecular O2 into reactive oxygen species, such as superoxide radicals (·O2-), has become the focus in the oxidative removal of organic pollutants. Nevertheless, the inefficient light absorption, limited adsorption of O2, and the fast recombination rate of photo-induced electron-hole pairs considerably impede the conversion efficiency of the photocatalysts. Herein, we report the synthesis of Ag@LAFO photocatalyst, which contains Ag nanoparticles (NPs)-decorated LAFO (Ag-substituted LaFeO3), to enhance the photodegradation efficiency of tetracycline (TC) with the assistance of water oxidation. Structural and spectroscopic analyses confirmed the successful decoration of Ag NPs on LAFO, which was prepared by substituting 10 % La with Ag. The efficiency of TC photocatalytic degradation rate of Ag@LAFO is 76.25 %, which is 6.1-fold higher than that of pure LFO (12.41 %). The trapping experiment of active radicals verified that ·O2- was crucial in the decomposition of TC molecules and was continuously supplied by the reduction of O2 molecules supported by photocatalytic water oxidation. Moreover, the Ag NPs in Ag@LAFO were found to be crucial for boosting the capture of photo-induced electrons and the activation of adsorbed O2. This study offers a new perspective on the conversion of O2 to ·O2- with the assistance of photocatalytic water oxidation for photocatalytic degradation of organic pollutants.

Construction of a floating photothermal-assisted photocatalytic system with a three-dimensional hollow porous network structure

Solar energy is the inevitable choice to achieve the low-carbon, green, and circular development of society, and photocatalysis technology is one of the shining pearls. To make full use of the solar spectrum and solve the shortcomings of the recovery difficulty of powdery materials and the loss of activity due to the influence of the external environment, it is possible to construct floating materials using melamine sponges to recover photocatalytic materials quickly. At the same time, floating materials can absorb oxygen in the air for the generation of active groups, effectively solving the problem of less O2 in the water. The carbon-based materials have excellent light absorption properties, high thermal conductivity, and excellent photothermal conversion efficiency and are ideal for constructing floating photothermal photocatalytic systems. As an example, we combined a cheap melamine sponge with urea, prepared a hollow porous network structure g-C3N4 (HPNCN) with a high specific surface area by direct thermal shrinkage method, and then attached the CoO to its surface by hydrothermal method to form a heterojunction with a suitable band gap. Various characterization tests verified the photothermal-photocatalytic properties. Among them, 30% CoO/HPNCN has the best photocatalytic degradation effect on tetracycline (TC), and the removal rate is 88.1%. After five cycles, the removal rate is only 5% lower than the initial, indicating that it has good stability and recyclability. We conducted an active ingredient capture experiment, ESR, and LC-MS analysis to clarify the intermediates and reaction mechanism of TC photocatalytic degradation. On this basis, the ECOSAR program and QSAR method were used to analyze the environmental toxicity of TC and its intermediate products. These results provide a broad prospect for the potential application of the floating photothermal-photocatalysis system in antibiotic pollution control and its application in other fields.

Cl-doped CuO for electrochemical hydrogen evolution reaction and tetracycline photocatalytic degradation

Photocatalysts play a vital role in energy conversion technologies and wastewater treatment. Catalyst's electronic structure can be tuned by a simple anion doping strategy to enhance the catalytic properties. In this work, different atomic percentages of Cl‾ doped into CuO lattices were synthesized using deep eutectic solvent (DES) by increasing the molar ratio of choline chloride to urea. Here, DES act as a green solvent and, Cl‾ source in preparing catalysts. Further, catalysts' crystallinity and surface properties were analyzed through X-ray diffractometer and transmission electron microscopy. X-ray photoelectron spectroscopy confirms the presence of Cl‾ dopant in CuO lattices. Synthesized catalysts were studied for electrochemical hydrogen evolution reaction (HER) and tetracycline photocatalytic degradation. Among the synthesized electrocatalysts, 2.48 at% of Cl-doped CuO catalyst displays optimum HER activity in 1 M H2SO4 electrolyte with an overpotential of 400 mV at the current density of 10 mA cm−2 and a Tafel value of 89 mV dec−1. Moreover, the same catalyst shows 83.5% degradation of tetracycline in 240 min under the illumination of a 35 W Xe arc lamp. This work provides a simple strategy to develop a catalyst with Cl‾ doping into CuO crystal structure by DESs and enhance its HER and wastewater treatment activity.

Morphological and elemental tuning of BiOCl/BiVO4 heterostructure for uric acid electrochemical sensor and antibiotic photocatalytic degradation

Deep eutectic solvents (DES) consisting of EG-(ChCl: C2H6O2) and TU-(ChCl: CH4N2S) assisted synthesized BiOCl/BiVO4 heterostructured catalyst studied for electrochemical uric acid (UA) sensor and tetracycline photocatalytic degradation. The chemical composition of the BiOCl/BiVO4 catalyst was analyzed by X-ray photoelectron spectroscopy (XPS). UV–vis spectroscopy reveals increased absorption of visible light till the near-infrared region, which results in a narrowing of band gap energy from 2.3 eV to 2.2 eV for BiOCl/BiVO4-TU. Morphology of catalyst analyzed using field-emission scanning electron microscope (FE-SEM) and Transmission electron microscope (TEM) technique. Time-Resolved photoluminescence (TRPL) confirms an increased lifetime of e−/h+ pair after heterostructure formation. The catalyst-modified glassy carbon electrode shows selectivity toward the detection of uric acid (UA). The limit of detection (LOD) is estimated to be 0.04688 μM for UA; also, interference and stability of catalyst were studied. Photocatalytic activity of the synthesized catalyst was investigated by degrading tetracycline (TC) antibiotic pollutants, and their intermediate product was analyzed by ion trap mass spectrometry (MS).

An insight into tetracycline photocatalytic degradation by MOFs using the artificial intelligence technique

Tetracyclines (TCs) have been extensively used for humans and animal diseases treatment and livestock growth promotion. The consumption of such antibiotics has been ever-growing nowadays due to various bacterial infections and other pathologic conditions, resulting in more discharge into the aquatic environments. This brings threats to ecosystems and human bodies. Up to now, several attempts have been made to reduce TC amounts in the wastewater, among which photocatalysis, an advanced oxidation process, is known as an eco-friendly and efficient technology. In this regard, metal organic frameworks (MOFs) have been known as the promising materials as photocatalysts. Thus, studying TC photocatalytic degradation by MOFs would help scientists and engineers optimize the process in terms of effective parameters. Nevertheless, the costly and time-consuming experimental methods, having instrumental errors, encouraged the authors to use the computational method for a more comprehensive assessment. In doing so, a wide-ranging databank including 374 experimental data points was gathered from the literature. A powerful machine learning method of Gaussian process regression (GPR) model with four kernel functions was proposed to estimate the TC degradation in terms of MOFs features (surface area and pore volume) and operational parameters (illumination time, catalyst dosage, TC concentration, pH). The GPR models performed quite well, among which GPR-Matern model shows the most accurate performance with R2, MRE, MSE, RMSE, and STD of 0.981, 12.29, 18.03, 4.25, and 3.33, respectively. In addition, an analysis of sensitivity was carried out to assess the effect of the inputs on the TC photodegradation by MOFs. It revealed that the illumination time and the surface area play a significant role in the decomposition activity.

Employing manufactured Mn3O4–ZnO nanocomposite for ameliorated photocatalytic performance under visible light

Pluronic P-65 was appropriated as a structure-directing agent in this study to create mesoporous Mn3O4–ZnO nanostructured materials with 1, 2, 3, and 4 wt% Mn3O4 NPs. ZnO NPs (nanoparticles) were extremely disseminated and they were completely consistent in size or shape, with mean particle diameter close to 20 nm. The resulting mesoporous structure revealed by the produced Mn3O4–ZnO nanostructured materials had a large surface area as well as a large pore volume. Upon visible illumination, photocatalytic effectiveness of the manufactured Mn3O4–ZnO nanostructured materials was examined for tetracycline (TC) degradation and was furtherly correlated with those of pure ZnO NPs and commercial P-25. After 120 min of illumination by visible light, Mn3O4–ZnO heterojunction with 3.0 wt% Mn3O4 NPs was capable of accomplishing almost complete decomposition of TC however, only 3.7 and 8.9% of TC were decomposed by the application of ZnO NPs and commercial P-25 (commercial titanium dioxide), correspondingly. In other words, the removal effectiveness of such heterojunctions was 27 and 11-fold stronger than those of pure ZnO NPs and P-25, accordingly. In addition, the decomposition performance of 3 wt% Mn3O4–ZnO nanostructured material is eminent in comparison to other manufactured nanostructured heterojunctions. To investigate the mechanism of TC photocatalytic degradation, transient photocurrent intensity as well as photoluminescence characteristics were addressed. It is envisioned that this research may give some ideas for comprehending more heterojunctions with distinguished behaviorism.

Carbon nitride coupled with Ti3C2-Mxene derived amorphous Ti-peroxo heterojunction for photocatalytic degradation of rhodamine B and tetracycline

Exploring the solar-driven photocatalyst for antibiotic and dye degradation has been confronted with a great challenge. In this study, a novel and original photocatalyst derived from the g-C3N4/amorphous Ti-peroxo complexes (CATC) heterojunction was successfully synthesized towards Rhodamine B (RhB) and tetracycline (TC) degradation under visible light irradiation (λ>420 nm). Based on the special photocatalytic activity, Ti3C2-Mxene acted as the starting precursor of amorphous Ti-peroxo complexes via one-step H2O2 oxidation route. Multiple characterization techniques were applied to explore the crystal structure, element composition, and photoelectrochemical property of photocatalyst. As expected, the modified photocatalyst possessed a favorable photocatalytic performance towards the preferable reaction rate for RhB (0.0483 min−1) and TC (0.0208 min−1) degradations, which were 16.65 times and 69.3 times higher than that of pure g-C3N4 (CN) material, profiting from the generated direct Z-scheme heterojunction with favorable redox capacity. Here, h+,∙O2- and ∙OH were verified as typical active radicals for RhB and TC degradation through free radical quenching experiments and electron spin resonance characterization. Degradation intermediate products were also confirmed by high performance liquid chromatography–mass spectrometer (HPLC-MS). The effects of initial pH and ionic strength on RhB and TC photocatalytic degradation performances were discussed. In addition, a preferable reusability and stability performance ensured the modification photocatalyst had a great application potential in wastewater treatment. This study provided a unique avenue through one-step method for the construction of g-C3N4 and Mxene based photocatalyst towards the degradation of antibiotics and dyes from wastewater.

Construction of Pdisa/Biobr Type-I Scheme Heterojunction for Efficient Tetracycline Photocatalytic Degradation

Construction of Pdisa/Biobr Type-I Scheme Heterojunction for Efficient Tetracycline Photocatalytic Degradation

Ag-doped Bi2WO6/BiOI heterojunction used as photocatalyst for the enhanced degradation of tetracycline under visible-light and biodegradability improvement

A new Bi2WO6/BiOI/Ag heterojunction composite was fabricated by the deposition of Ag nanoparticles on Bi2WO6/BiOI via two-step hydrothermal process and characterized by X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and high resolution transmission electron microscope (HRTEM) analyses. The photoelectric properties of the as-prepared composites were investigated by UV–vis diffuse reflectance spectrum (DRS), transient photocurrent response, electrochemical impedance spectroscopy (EIS) and photoluminescence spectrum (PLS). It was found that the amount of Ag in Bi2WO6/BiOI/Ag exhibited an evident influence on photoelectric properties and photocatalytic activity. Compared with the other as-prepared photocatalysts, Bi2WO6/BiOI/Ag-8 presented the highest photocatalytic activity for tetracycline degradation ascribed to the heterojunction structure and the surface plasmon resonance (SPR) action, which evidently enhanced the visible-light absorbance, and promoted the separation/transfer of photo-generated electron/hole (e–/h+) pairs. The organic intermediates formed during tetracycline photocatalytic degradation were identified and the degradation pathway was proposed. For the recommended photocatalyst, the hydroxyl radical (∙OH) and superoxide anion radical (∙O2–) produced by the Z-scheme photocatalytic mechanism with Ag as co-catalyst were responsible for the degradation. In addition, the photocatalytic degradation of tetracycline evidently reduced the solution toxicity and enhanced the biodegradability.

Insight into the activity of TiO2@nitrogen-doped hollow carbon spheres supported on g-C3N4 for robust photocatalytic performance

Designing an advance nanostructure semiconductor is an efficient strategy to promote the charge separation and thus improve the photocatalytic activity. Herein, a relatively high recombination rate of electron-hole pairs and low specific surface area of g-C3N4 (GCN) were subjected to the surface deposition of the core shell nanoparticles composed of nitrogen doped hollow carbon spheres (N-HCSs) as the supporting scaffold and TiO2 nanoparticles as the photoactive layer. The ternary composites with different TiO2@N-HCS content were prepared through a simplified nanocasting method followed by the two consecutive hydrothermal process. The effects of nitrogen doping in carbon framework, and nanoparticles amount were evaluated on the photocatalytic ability through the photodegradation of tetracycline (TC) molecules under the visible light irradiation. At the optimum content of core shell nanoparticles (7 wt%), the solar-driven TC photocatalytic degradation for ternary composite was approximately 85%, which was much better (about three times) than that of the pure GCN. More interestingly, the experimental results revealed that doping of nitrogen atoms has a positive role on the charge separation and the resulting photocatalytic efficiency. The employed hollow carbon spheres here play three important roles: (1) providing a substrate to uniformly dispersion of TiO2 nanoparticles without any aggregation; (2) reducing the combination of charge carriers and improving the separation of photoinduced carriers; (3) formation of larger surface area and more active sites on the photocatalyst surface. Furthermore, the underlying photocatalytic degradation mechanism was introduced by the controlled experiments using photoluminescent and radical scavenger tests.

Photocatalytic Degradation of Tetracycline and Copper Complex by Bi2MoO6/Bi2S3 Heterojunction

Bi2MoO6/Bi2S3 heterojunctions were synthesized by the solvothermal method. The morphology, chemical composition, and photoelectric properties of the heterojunction materials were characterized by XRD, TEM, UV-Vis, XPS, and I-T. Tetracycline (TC) and tetracycline-copper (TC-Cu) composites were degraded by the as-prepared heterojunctions under visible light. The effects of pH, initial concentration of TC, and molar ratio of TC to Cu2+ on the degradation deficiency of TC were investigated. Additionally, the main active radicals, intermediates, and mechanisms were ascertained by in situ capture experiments and the identification of intermediates. The toxicities of TC and TC-Cu before and after degradation were evaluated by chlorella growth inhibition experiments. The results showed that the prepared Bi2MoO6/Bi2S3 heterojunction was a uniform nanosheet and its band gap was 1.76 eV. Bi2MoO6 and Bi2S3 with a mass ratio of 3:1 (MS-0.3) exhibited a composite ratio of TC and Cu2+ was 2:1 and had the best photocatalytic performance. When the concentration of TC was 10 mg·L-1 with neutral solutions, after reacting for 60 min, the degradation rate of TC and mineralization rate of the solution for TC-Cu were 85.63% and 52.94%, respectively. The results of active group capture experiments showed that the main active group of the heterojunction was the·O2- radical in visible light. In addition, the results of growth inhibition experiments showed that the presence of Cu2+ reduces the toxicity of TC photocatalytic degradation products in the TC-Cu complex, and the antibiotics can be effectively removed in the TC-Cu complex by photocatalytic oxidation.

Tetracycline Photocatalytic Degradation under CdS Treatment

Industrialization and the growing consumption of medicines leads to global aquatic contamination. One of the antibiotics widely used against bacterial infections in both human and veterinary medicine is tetracycline. Despite its positive antibiotic action, tetracycline is resistant against degradation, and therefore it accumulates in the environment, including the aquatic environment, creating great health hazards, possibly stimulating antibiotic resistance of pathogenic organisms. In this research, aqueous suspensions of semiconductor nanoparticles CdS were used for photocatalytic activity studies in the presence of methylene blue as a model compound, and finally, in the presence of tetracycline, a broad-spectrum antibiotic widely used against bacterial infections, as well as a live-stock food additive. The mechanism and kinetic rate constants of photocatalytic degradation processes of methylene blue and tetracycline were described in correlation with the energy diagram of CdS nanoparticles.

Constructing CeO2/nitrogen-doped carbon quantum dot/g-C3N4 heterojunction photocatalysts for highly efficient visible light photocatalysis.

Ternary CeO2/nitrogen-doped carbon quantum dot (NCQD)/graphitic carbon nitride (g-C3N4) heterojunction nanocomposites were prepared by a high-temperature calcination and hydrothermal method and tested for degrading tetracycline (TC) and generating H2. Compared with CeO2 and g-C3N4, the Z-scheme CeO2/NCQDs/g-C3N4 (CSNx, where x represents the amount of CeO2 in wt%) nanoparticles showed a higher TC photodegradation capacity and H2 evolution ability owing to enhanced efficient charge separation and photocatalytic stability. CSN5 showed the best photodegradation activity for TC degradation (100 mL, 20 mg L-1; 100% degradation in 60 min; λ≥ 420 nm) and the highest H2 evolution rate of 1275.42 μmol h-1 g-1 was approximately 3.73- and 32.25-times higher than those of pristine g-C3N4 (341.85 μmol h-1 g-1) and pure CeO2 (39.55 μmol h-1 g-1), respectively. Superoxide (˙O2-) and hydroxyl (˙OH) radicals were also confirmed to be formed on the sample surface for TC photocatalytic degradation. As an electronic medium, NCQDs transferred electrons between the g-C3N4 and CeO2 interface to promote the electron-hole separation. This work affords a helpful perspective for synthesizing efficient charge separation and environmentally friendly photocatalysts by controlling the surface heterostructure.

Effects of divalent copper on tetracycline degradation and the proposed transformation pathway.

To reveal the characteristics of tetracycline (TC) photocatalytic degradation under Cu(II) coexistence, effects of Cu(II) on TC photocatalytic degradation by ZnO nanoparticles (ZnO NPs) as a function of pH, humic acid (HA), and initial Cu(II) concentration were investigated. Interaction of TC with Cu(II) in the treatment process was analyzed by circular dichroism (CD) spectroscopy, while TC degradation pathway was investigated by high-performance liquid chromatography-mass spectrometry. Sixty-five percent and ninety-one percent TC degradation within 60min in the absence and presence of Cu(II), respectively, was reported. Both adsorption and photocatalytic degradation of TC under Cu(II) coexistence increased with increasing pH from 3 to 6, while decreased with further increase in pH. HA inhibited the degradation of TC by ZnO NPs both in the presence as well absence of Cu(II), while TC degradation decreased from 91 to 73% and from 73 to 37% in the presence and absence of Cu(II), respectively. TC degradation by ZnO NPs first increased then decreased with increasing Cu(II). Maximum TC degradation (about 94%) was obtained in the optimum concentration range of Cu(II) (0.05-0.15mmol/L). In addition, there was a lag effect between TC adsorption and degradation on ZnO NPs. TC degradation was improved via Cu(II)-TC surface complexation and followed N-demethylation and hydroxylation routes. This study could be of potential importance in extrapolating the transformation of TC or other antibiotics under the coexistence of heavy metals in water.

La2Zr2O7/rGO synthesized by one-step sol-gel method for photocatalytic degradation of tetracycline under visible-light

In this study, La2Zr2O7/rGO (LZO/rGO) composite photocatalyst was prepared by a one-step sol-gel method, which achieved synthesis of LZO and reduction of GO simultaneously. LZO/rGO-3 (dosage of GO: 0.5 g) was well-crystallized and had the specific surface area of 16.5 m2/g which was higher than that of LZO (9.4 m2/g). Moreover, the introduction of rGO improved the surface microstructure and slightly reduced the band gap (LZO/rGO-3: 2.42 eV), expanding the light absorption range. Tetracycline (TC) was chosen as the target contaminant to assess photocatalytic activity in visible-light. The removal rate and constant of reaction rate (kapp) of LZO/rGO-3 was 82.1% and 0.3097 min−1 after 40 min, which was significant higher than that of LZO (57.8% and 0.1741 min−1). In addition, the TC degradation follows pseudo-first-order kinetic and shows thestability after five cycling experiments. The enhanced photocatalytic activity was mainly due to two aspects. Firstly, the improved surface appearance provided more adsorption and reaction sites. Secondly, the rGO as co-catalyst (electron trap) reduced the recombination of electron-hole pairs, and further promoted production of active substances. The photocatalytic mechanism was proposed coupled with analysis of energy structure, active substances and degradation pathways, indicating that h+, 1O2, O2− and H2O2 were the main active substances in TC photocatalytic degradation, and the generation of 1O2 was of vital importance.

Synthesis and Modification of Zn-doped TiO2 Nanoparticles for the Photocatalytic Degradation of Tetracycline.

The synthesis of Zn-doped TiO2 nanoparticles by solgel method was investigated in this study, as well as its modification by H2 O2 . The catalyst was characterized by transmission electron microscopy, X-ray diffraction, Brunauer-Emmett-Teller, UV-visible reflectance spectra and X-ray photoelectron spectroscopy (XPS). The results indicated that doping Zn into TiO2 nanoparticles could inhibit the transformation from anatase phase to rutile phase. Zn existed as the second valence oxidation state in the Zn-doped TiO2 . Zn-doped TiO2 that was synthesized by 5% Zn doping at 450°C exhibited the best photocatalytic activity. Then, the H2 O2 modification further enhanced the photocatalytic activity. Zn doping and H2 O2 modifying narrowed the band gap and efficiently increased the optical absorption in visible region. The optimal degradation rate of tetracycline by Zn-doped TiO2 and H2 O2 modified Zn-doped TiO2 was 85.27% and 88.14%. Peroxide groups were detected in XPS analysis of H2 O2 modified Zn-doped TiO2 , favoring the adsorption of visible light. Furthermore, Zn-doped TiO2 modified by H2 O2 had relatively good reusability, exhibiting a potential practical application for tetracycline's photocatalytic degradation.