Photodegradation Of Antibiotics Research Articles

Rational design of Z-scheme configured polymeric carbon nitride-decorated ZnWO4 nanofibers for enhanced visible-light-driven photodegradation of antibiotics

In this study, a Z-scheme heterostructure was meticulously engineered between zinc tungstate (ZnWO4) nanofibers and polymeric carbon nitride (PCN) nanosheets to augment the photocatalytic degradation of tetracycline (TC) under visible light irradiation. A cohesively integrated PCN/ZnWO4 photocatalyst structure was synthesized through an in-situ gas-solid reaction. The quantity and spatial distribution of PCN nanosheets were modulated by fine-tuning the gas precursor and reaction parameters. Relative to pristine ZnWO4 nanofibers and PCN photocatalysts, the distinct three-dimensional PCN/ZnWO4 heterostructure manifests a notable enhancement in photocatalytic performance, attributed to its plethora of active sites and a Z-scheme configuration that bolsters charge separation efficiency, achieving a tetracycline degradation rate of 95.4% upon exposure to simulated sunlight for 160 minutes. The employment of gas-solid reaction as a design paradigm pioneers a fresh paradigm in the strategic assembly of Z-scheme heterostructured photocatalysts, thereby illuminating a promising pathway for advancements in environmental remediation technologies.

Potential of solar photodegradation of antibiotics in shallow ditches: Kinetics, the role of dissolved organic matter and prediction models

Shallow ditches, which generally receive livestock or domestic sewage, are widely distributed in rural and suburban areas, making them important sites for antibiotic exposure. Because of the easy penetration of solar irradiation, the photochemical reactions of antibiotics tend to be active in shallow ditches. This study investigated the photodegradation potential of 21 commonly used antibiotics belonging to five categories in a typical shallow ditch by conducting simulated solar irradiation experiments. The influence of dissolved organic matter (DOM) in ditch water on the photodegradation of antibiotics was analyzed, and a model based on DOM changes was established to predict the degradation behavior of antibiotics. The results indicated that the degradation rates of different varieties of antibiotics in ultrapure water and ditch water followed the trend of fluoroquinolones > tetracyclines > sulfonamides > macrolides > lincosamides. In ditch water, direct photodegradation and photooxidation mediated by 3DOM∗ played predominant roles in the antibiotic photodegradation, whereas the contributions of singlet oxygen (1O2) and hydroxyl radicals (·OH) varied significantly depending on the reactivity of the antibiotics. A simple and effective model was proposed for predicting the photodegradation process of antibiotics in ditch water based on the degree of DOM photobleaching determined by excitation-emission matrix fluorescence spectroscopy coupled with parallel factor analysis. The prediction model was simplified by considering the similarity in photochemical properties within the same category of antibiotics and was validated by field tests. This study fills a critical research gap by evaluating the photodegradation of antibiotics in shallow ditches, thereby providing valuable insights into their fate and transport in shallow ditch water.

2D porous hexaniobate-bismuth vanadate hybrid photocatalyst for photodegradation of aquatic refractory pollutants

Metal oxide semiconductors are highly promising due to their excellent photocatalytic performance in the photodegradation of industrial waste containing refractory chemical compounds. A hybrid structure with other semiconductors provides improved photocatalytic performance. In this work, porous and two-dimensional (2D) hexaniobate-bismuth vanadate (Nb6-BiVO4) Z-scheme hybrid photocatalysts are synthesized by chemical solution growth (CSG) of BiVO4 over electrophoretically deposited Nb6 thin films. The structural and morphological analysis of Nb6-BiVO4 hybrid thin films evidenced the well-crystalline uniform growth of monoclinic scheelite BiVO4 over lamellar Nb6 nanosheets. The Nb6-BiVO4 hybrid thin films exhibit a highly porous randomly aggregated nanosheet network, creating the house-of-cards type morphology. The Nb6-BiVO4 hybrid thin films display a strong visible light absorption with band gap energy of 2.29 eV and highly quenched photoluminescence signal, indicating their visible light harvesting nature and intimate electronic coupling between hybridized species beneficial for photocatalytic applications. The visible-light-driven photodegradation performance of methylene blue (MB), rhodamine-B (Rh-B) dyes, and tetracycline hydrochloride (TC) antibiotic over Nb6-BiVO4 hybrid are studied. The best optimized Nb6-BiVO4 thin film shows superior photocatalytic activity for photodegradation of MB, Rh-B dyes, and TC antibiotic with photodegradation rates of 87.3, 92.8, and 64.7 %, respectively, exceptionally higher than that of pristine BiVO4. Furthermore, the mineralization study of Nb6-BiVO4 thin film is conducted using chemical oxygen demand (COD) analysis. The optimized Nb6-BiVO4 thin film shows superior percentage COD removal of 83.33, 85.42, and 61.36 % for MB, Rh-B dyes and TC antibiotic, respectively. The present results highlight the expediency of hybridization in enhancing the photocatalytic activity of pristine BiVO4 by minimizing its charge recombination rate and improving chemical stability.

Optical characteristic of dissolved organic matter polar fractions by spectrum technologies and the relationship with indirect photodegradation of ofloxacin

Ofloxacin (OFL) is a commonly used antibiotic and is widely present in various water bodies. Indirect photodegradation is crucial for the transformation and fate of antibiotics in surface water, which largely depends on the structure and composition of dissolved organic matter (DOM). Nevertheless, knowledge about the optical characteristics of diverse DOM polar fractions as well as the relationship with indirect photodegradation of antibiotics is still scarce. In this study, XAD-8 in combination with anion and cation exchange resins was used to separate DOM into six polar fractions: hydrophilic acid (HIA), hydrophilic basic (HIB), hydrophilic neutral (HIN), hydrophobic acid (HOA), hydrophobic basic (HOB) and hydrophobic neutral (HON). UV–vis and fluorescence spectroscopy were applied to analyze DOM polar fractions and explore their impact on OFL indirect photodegradation. The results showed that indirect photodegradation was the primary photodegradation route of OFL when the irradiation wavelength was greater than 320 nm, triple-state excited DOM (3DOM*) was the main reactive intermediates (RIs) that affected the indirect photodegradation of OFL. Excitation-emission matrix spectroscopy combined with parallel factor analysis (EEMs-PARAFAC) and correlation analysis demonstrated that terrestrial humic-like substances could yield generous RIs to facilitate OFL indirect photodegradation. The HIB and HOA fractions of SRNOM contained large aromaticity and humification degree and more terrestrial humic-like substances, thus exhibiting greater OFL indirect photodegradation rates. The HOA and HOB fractions of FA had abundant terrestrial humic-like substances and contributed more to OFL indirect photodegradation. This study helped us understand the effect of DOM structural characteristics on the OFL indirect photodegradation.

Synthesis of novel Fe-BiOCl based nanosheets assembled rod (FBC-NSR)-based photoactive materials: an effective photodegradation of antibiotics

Fe-incorporated BiOCl-nanosheet assembled rods (FBC-NSR) based photoactive materials were synthesized using a simple sol–gel process to degrade tetracycline (TC) pharmaceuticals compound (PCs) under solar irradiation. The as-prepared FBC-NSR-based photoactive materials were characterized using various characterization techniques including scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), photoluminescent (PL) spectroscopic analysis, and Fourier transform infrared spectroscopy (FT-IR). The structural changes were observed upon doping of Fe metals within the FBC-NSR-based photoactive materials. Intriguingly, the band gap value decreased from ~ 1.81 eV to ~ 1.29 eV with increasing the amount of Fe metals (0.5 g, and 1.0 g) within the FBC-NSR named as FBC-NSR-2 and FBC-NSR-3-based photoactive materials, respectively. The lower band gap value favors the photodegradation of environmental pollution. The synthesized FBC-NSR-3 shows the highest degradation ~ 97% and ~ 72.1% at 1 mg/L and 10 mg/L TC antibiotic, respectively. The photodegradation was higher at pH 10, indicating •OH radicals play a major role in the photodegradation of TC molecules. PL spectra confirm the higher oxygen vacancy, improved transfer of electrons, and separation efficiency of photo-induced electron hole-pairs, thereby high photodegradation efficiency. Therefore, the preparation of FBC-NSR-based photoactive materials is simple, cost-effective, and promising semiconductor materials for the removal of environmental pollution.

Machine Learning Assisted Imprinted Ag@PANI/CoFe2O4/C Heterojunction with Simultaneous Improvement of Selectivity and Activity for Antibiotic Photodegradation

Machine Learning Assisted Imprinted Ag@PANI/CoFe2O4/C Heterojunction with Simultaneous Improvement of Selectivity and Activity for Antibiotic Photodegradation

New 1,4-bis(1-imidazolyl)-2,5-dimethylbenzene ligand based Cd(II) MOF displaying pcu topology: Insights into antibiotics sensing and photocatalytic properties

In this work synthesis, spectroscopic and crystallographic characterization of a new Cd(II)-based metal-organic framework comprising 1,4-bis(1-imidazolyl)-2,5-dimethylbenzene (bdb) ligand having formula {[Cd(bdb)3]·2ClO4-}n (1) have been reported. The single crystal X-ray analysis reveals that MOF 1 shows octahedral coordination geometry and a two-fold interpenetrated pcu topology. MOF 1 have been employed as fluorescent sensor for the sensitive and selective detection of antibiotics and study suggests that 1 can be employed as an apt sensor for the detection of nitrofurazone (NFZ) antibiotic with KSV value of 2.94 × 104 M-1. Also, MOF 1 has been employed as light driven catalyst for the photodegradation of NFZ antibiotic and it photo-decomposes up to 91.79 % of NFZ in 20 min. The plausible sensing as well as photocatalytic mechanism employing which MOF 1 detects and photodecomposes NFZ, respectively have been explained with the aid of integrated experimental and theoretical calculations.

Visible light driven photocatalyst NiFe2O4/Ag2WO4 nanocomposite for the degradation of tetracycline (TC-HCl) antibiotics

The use of tetracycline (TC-HCl) antibiotics is harmful to ecosystems worldwide. Herein, NiFe2O4/Ag2WO4nanocomposite (NC) was synthesized via the hydrothermal method for the degradation of tetracycline. The photodegradation efficiency of TC-HCl reached 92.3% after being exposed to visible light for 90 min. Additionally, the stability of the NiFe2O4/Ag2WO4nanocomposite is maintained during the photodegradation of tetracycline, as verified by the recyclability test. Degradation efficiency up to 83% was still present after six cycles. The presence of DMPO-∙O2- and DMPO-•OH is confirmed by the ESR study, when the visible exposure period expanded to 15 min. High photocatalytic performance, strong recyclability, and stability make NiFe2O4/Ag2WO4a potential antibiotic photodegradation candidate.

Construction of PANI@V2O5-ZnIn2S4 Z-scheme heterojunction photocatalysts for highly effective degradation of industrial dyes and antibiotics

From an environmental protection, the highly effective photodegradation of organic dyes and antibiotics in wastewater needs to be solved expeditiously. Fortunately, the construction of Z-scheme heterojunction for photocatalytic degradation is considered to be an effective method. In this paper, after the fabrication of V2O5 by calcination and loading of PANI on its surface by aniline polymerization, a novel PANI@V2O5-ZnIn2S4 composite photocatalysts prepared by one-pot synthesis method and used for the degradation of industrial dyes (crystalline violet, Congo red) and antibiotics (tetracycline-TC). Under the optimal photodegradation conditions, the 30 wt% PANI@V2O5-ZnIn2S4 heterojunction photocatalysts resulted in more than 95 % degradation of CR, CV and TC solutions after 32 min of irradiation. The optimal photodegradation conditions of the simulated pollutants in real aqueous environments catalyzed by the as-synthesized photocatalysts were explored via response surface methodology (RSM). Multiple material characterization techniques, such as FESEM, HRTEM, XPS valence band spectrum, photoelectrochemistry, radical trapping experiments and EPR tests verified the existence of Z-scheme heterojunction. Especially, the coating of conductive PANI on the V2O5 surface can further improve the separation and transfer efficiency of photogenerated charge carriers, thereby enhancing the photocatalytic activity of the semiconductor photocatalyst. This study will provide a robust option for the design and construction of Z-scheme heterojunctions photocatalysts for environmental pollution remediation.

Donor polarization engineering of conjugated microporous polymers to boost exciton dissociation for photocatalytic degradation of tetracycline

The misuse and inevitable release of antibiotics can cause significant harm to both human health and the environment, and the use of polymeric semiconductors for photodegradation of antibiotics in aqueous environments is one of the most effective strategies to alleviate the current dilemma. Nevertheless, the inherently high exciton binding energy (Eb) and low photogenerated carrier transfer efficiency for most photocatalysts results in unsatisfactory photodegradation performance. Hence, this work proposes a donor polarization strategy to regulate the exciton dissociation of conjugated microporous polymers (CMPs) by minimizing their Eb. Results exhibited that the introduction of the strong donor unit 3,4-ethylenedioxythiophene (EDOT) not only reduces the Eb and effectively promotes exciton dissociation, but also broadens the visible light absorption of CMP. Among them, EdtTz-CMP with the lowest Eb (99 meV) delivered an efficiency of 94.6% in photocatalytic degradation of tetracycline (TC) with in 90 min, significantly higher than those of its analogues. This work provides a viable approach to design CMPs by tuning the intrinsic dipole of the donor for efficient environmental purification.

Interaction and band structure-determined inhibition of negative Cr (VI) and positive Fe (III) for antibiotic photodegradation by nitrogen-doped dissolved black carbon

The influences of the positive Fe3+ and the negative Cr2O72− on the tetracycline (TC) photodegradation by N-doped dissolved black carbon (NDBC) have been investigated in this work. A series of samples (NDBC300, NDBC400 and NDBC500) have been extracted from the corresponding biochar. NDBC400 has the best photodegradation performance (79%) for TC under visible light irradiation. Adding Cr2O72− and Fe3+ can reduces TC photodegradation efficiency into 37% and 53%, respectively. This maybe from that Cr2O72− has stronger interaction with NDBC400 than Fe3+ since it can quench more fluorescence intensity of NDBC400 than Fe3+. Furthermore, Cr2O72− can reduce the steady-state concentration of 3NDBC400*, 1O2 and •OH, whereas Fe3+can just reduce the steady-state concentration of 3NDBC400* and increase the concentration of •OH. This may explain why Cr2O72− has stronger inhibit performance of TC photodegradation by NDBC400 than Fe3+. The band structures of NDBC400, NDBC400-Fe3+ and NDBC400-Cr2O72− are constructed. And the VB of NDBC400-Fe3+ has a stronger ability to produce •OH than NDBC400. In summary, coupling interaction and band structure characterization of NDBC400, NDBC400-Fe3+ and NDBC400-Cr2O72− can explain well why Cr2O72 has stronger inhibition effect than Fe3+ and Fe3+ can increase the concentration of •OH. This work provides a deep insight for the photochemical behavior of dissolved black carbon and the transformation behavior of the co-existed metal ions and antibiotics.

Construction of g-C3N4@Bi-MOF@BiOCl double Z-type heterojunctions for photodegradation of antibiotics under visible light irradiation: Mechanism, pathway, and toxicity assessment

In this study, flower-like microspheres dispersed double Z-type heterojunction g-C3N4@Bi-MOF@BiOCl photocatalysts were prepared using Bi-MOF as the structural template. The photocatalyst showed good degradation ability for both tetracycline antibiotics under simulated sunlight irradiation, as well as stable recyclability and total organic carbon mineralization (TOC). This excellent photocatalytic activity was mainly attributed to the formation of double Z-type heterojunctions that accelerated charge separation and transfer and drove stronger redox capacity. In addition, the effects of conditions such as catalyst dosage, initial concentration of tetracycline hydrochloride (TC) and initial pH (3–11) value of the solution on the photocatalytic reaction were investigated. The results of free radical trapping experiments and ESR analyses indicated that O2−, h+ and OH were the active free radicals that could not be neglected for the degradation of tetracycline hydrochloride (TC), and a possible degradation mechanism was further proposed. Finally, the possible pathways for degradation of the intermediates were rationally deduced by gas chromatography (GC–MS) and evaluated by ecotoxicity analysis based on the utilization rate (T.E.S.T.) of the intermediates produced. This study provides an effective idea for the rational design and synthesis of highly efficient dual Z-type photocatalysts for antibiotic contamination in water-polluted environments.

A new Zn(II)-based 3D MOF with PCU-like topology: Potent photocatalyst for nitrofurazone antibiotic degradation

Metal-organic frameworks (MOFs), a sub-class of coordination polymers, are versatile multidimensional materials that have the potential to serve as photocatalysts for the degradation of antibiotics found in wastewater. Herein, a new three dimensional (3D) Zn(II)-based MOF [Zn(TA)(bpyp)·3H2O] (1) (bypy = 2,5-bis(pyrid-4-yl)pyridine; H2TA = terephthalic acid) has been synthesized and characterized. The MOF 1 shows a 3D PCU-like topology and exhibits semiconducting properties with band gap of 3.34 eV and hence used as a photocatalyst for photodegradation of antibiotics viz. sulfasalazine (SLA), nitrofurazone (NFZ) and furazolidone (FZD) under simulated UV light irradiation. The photocatalytic results suggest that MOF 1 exhibits best photocatalytic activity for the photodegradation of nitrofurazone (NFZ) in 60 min time-span. The effects of initial concentration of NFZ, and photocatalyst dosage have been monitored for the photocatalytic performance of 1. The radical trapping experiments suggest that (holes) h+ and superoxide radical (O2·−) collectively catalyzes the photodecomposition of antibiotics. The possible mechanism for the antibiotic degradation by photocatalyst 1 have been proposed by integrating experiment with density of states (DOS) calculations and Hirshfeld surface analysis.

Synthesis of waste derived bimetallic (Fe/Ca) Oxy-iodide (WD-BMOX) encapsulated with PVDF based nanosphere (WD-BMOX-P) as solar active agent: An efficient photodegradation of antibiotic

Tetracycline (TC) pharmaceutical compound is the third most used antibiotic after penicillin and quinolones, which developed bacterial resistance against them and environmental toxicity due to partially metabolized within humans and animals. At the same time, waste products (WPs) including food, agriculture, and plastic waste significantly increased day-by-day with the growing population. Therefore, there is a pleading requirement to develop a solar active agent that effectively degrades environmental pollution as well as reduces the burden of WPs. In this context, the present works focus on the development of waste-derived bimetallic (Fe/Ca) Oxy-iodide (WD-BMOX) encapsulated with PVDF-based nanosphere (WD-BMOX-P) as a solar active agent for the degradation of TC antibiotics. The band gap values of the synthesized WD-BMOX-P-based nanosphere are easily altered by changing the ratio of Fe/Ca. The lowest band gap values were observed to be ∼1.95 eV of the WD-BMOX-P-1:2, whereas upon increasing the Ca within the nanosphere band gap value significantly increases. The incorporation of PVDF polymer within the WD-BMOX-P aided advantages to formed nanosphere and improved oxygen vacancy, thereby high degradation efficiency. The highest degradation of TC antibiotics ∼96.8% and ∼ 69% was observed using WD-BMOX-P-1:2 nanosphere at 1 mg/L and 10 mg/L, of TC antibiotics within 60 min of solar irradiation, respectively. Moreover, ∼88% and 100% photodegradation of TC antibiotics was observed at pH 10 and the presence of H2O2 at 10 mg/L, respectively. The data indicate that the synthesized WD-BMOX-P-based nanosphere might be promising solar active agents, which effectively degrade TC antibiotics from water.

Design of High-Performance Molecular Imprinted Magnetic Nanoparticles-Loaded Hydrogels for Adsorption and Photodegradation of Antibiotics from Wastewater.

A hydrogel formulation of 2-hydroxy ethyl methacrylate (HEMA) containing covalently linked magnetite nanoparticles was developed to actively facilitate the selective removal and photocatalytic degradation of antibiotics. To this purpose, the hybrid materials were molecularly imprinted with Lomefloxacin (Lome) or Ciprofloxacin (Cipro), achieving a selectivity of 60% and 45%, respectively, starting from a solution of XX concentration. After the adsorption, the embedded magnetite was used with the double function of (i) magnetically removing the material from water and (ii) triggering photo-Fenton (PF) reactions assisted by UVA light and H2O2 to oxidize the captured antibiotic. The success of the material design was confirmed by a comprehensive characterization of the system from chemical-physical and morphological perspectives. Adsorption and degradation tests demonstrated the material's ability to efficiently degrade Lome until its complete disappearance from the electrospray ionization (ESI) mass spectra. Regeneration tests showed the possibility of reusing the material for up to three cycles. Ecotoxicological tests using algae Rapidocelis subcapitata, crustaceans Daphnia magna, and bacteria Vibrio fischeri were performed to evaluate the ecosafety of our synthesized materials.

Facile photo-induced oxygen vacancy Bi2O2[BO2(OH)] hierarchical nanosheets and its enhanced visible light photodegradation of fluoroquinolones antibiotics

Defect engineering, particularly oxygen vacancy introduction, enhances photocatalytic material performance by regulating light response and charge carrier utilization, while providing active sites. This project investigates oxygen vacancies in Bi2O2[BO2(OH)] for Rhodamine B and levofloxacin degradation. Findings show that 10 min of UV irradiation optimizes photocatalytic efficiency through oxygen vacancy activation, improving light absorption and charge carrier efficiency, leading to effective degradation of levofloxacin. This study establishes a link between photo-induced oxygen vacancies and photocatalytic performance, offering insights for developing efficient photocatalysts and managing antibiotic pollution.

Collaborative adsorption and photocatalytic degradation of high concentration pharmaceutical pollutants in water using a novel dendritic fibrous nano-silica modified with chitosan and UiO-66

This study presents a novel hybrid mesoporous material for degrading drug pollutants in water. The hybrid materials, derived from UiO-66 metal-organic framework and chitosan, coated on nano-silica, showed excellent drug adsorption through hydrogen-bonding interactions and efficient photodegradation of antibiotics. The hybrid material's enhanced conductivity and reduced band gap significantly improved pollution reduction by minimising electron-hole recombination. This allows for more efficient charge transport and better light absorption, boosting the material's ability to break down pollutants. Structural and morphological analyses were conducted using various techniques, including scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, Brunauer-Emmett-Teller analysis, X-ray photoelectron spectroscopy, and thermogravimetric analysis. Optimising the adsorption-photodegradation process involved investigating pH, catalyst dose, and radiation time. Non-linear optimisation revealed an efficiency exceeding 85 % for 400 mg/L tetracycline and doxycycline, the model antibiotics. The optimal parameters for maximal elimination were determined as pH = 4.3, hybrid mesosphere dose = 4.0 mg/mL, and radiation time = 10 min. Kinetic studies favored pseudo-second-order diffusion models over pseudo-first-order models. The hybrid mesosphere showed sustained efficiency after three cycles and performed well in real aqueous samples, removing over 80 % of each antibiotic. This study demonstrates the potential of the hybrid mesoporous material for removing pharmaceutical pollutants in water systems.

A new 3D Zn(II)‐based coordination polymer with kgd topology as potent photocatalyst for antibiotic degradation

A new coordination polymer (CP) with composition [Zn3(bpyp)2(TCB)2(H2O)2]n (1) has been engendered by performing reaction of Zn(II) with 1,3,5‐tris‐(4‐carboxyphenyl)benzene (H3TCB) and 2,5‐bis(pyrid‐4‐yl)pyridine (bpyp) under solvothermal condition. The single crystal X‐ray diffraction analysis for 1 suggests kgd topological behavior having resemblance with a tessellation composed of diamond shapes arranged in a star pattern and represented by the Schläfli symbol {41}2{42·62·81}. This newly designed CP exhibits optical band gap of 2.92 eV and employed as photocatalyst for photodegradation of antibiotics, namely, nitrofurazone (NFZ), chloramphenicol (CAP), sulfasalazine (SLA), oxytetracycline (OXY), and furazolidone (FZD). Among these antibiotics, 1 displays best photocatalytic activity against the photodegradation of NFZ and under optimized conditions viz. photocatalyst dosage of 15 mg, and initial NFZ concentration of 40 ppm, the CP 1 displays best catalytic performance and photo‐decomposed 93.04% NFZ with pseudo first order rate constant k of 0.04502 min−1 in 1 h. The likely photocatalytic mechanism has been evaluated using theoretical calculations.

A novel LaFeO3/g-C3N4/Ag3PO4 dual Z-scheme heterojunction with enhanced light absorption, charge carrier separation and transfer capacity for photodegradation of antibiotics

The effective separation of photogenerated carriers is still a key problem to be overcome in the preparation of efficient green photocatalysts. In this work, A novel ternary composite LaFeO3/g-C3N4/Ag3PO4 (LgA) with dual Z-scheme heterojunction structure photocatalyst was constructed by combining LaFeO3 with excellent photoelectric conversion rate and Ag3PO4 with high-quantum yield on the surface of g-C3N4 by electrostatic attraction and in-situ co-precipitation. The serial characterization confirmed that there were close heterojunction interfaces and well-matched band structures among them, which was conducive to improving the separation efficiency of photogenerated electron-hole pairs. The photocatalytic results showed that the photocatalytic degradation performance of LgA-4 composites for ciprofloxacin hydrochloride (HCIP) was significantly superior to that of g-C3N4, LaFeO3, Ag3PO4 or their binary composites, and the degradation efficiency could reach 90.2 %, which could be mainly attributed to the construction of dual Z-scheme heterojunction with large valence bands oxidation surface, improved the light absorption capacity and promoted the separation of photogenerated electron-hole pairs (e−-h+). LgA-4 also had good stability and efficient universality. Furthermore, the photocatalytic mechanism of HCIP photocatalytic degradation by LgA-4 heterojunction was particularly discussed according to the results of characterization, free radical quenching and ESR experiments. The potential degradation pathways for HCIP by LgA-4 were proposed as well based on the degradation intermediates detected by Ultra-high Performance Liquid Chromatography-Mass Spectroscopy (UPLC-MS), HCIP degradation was confirmed a process of reduced ecotoxicity. These results provided a facile pathway for the preparation and application of high efficiency photocatalysts in water pollution control.

Fabrication and characterisation of B-ZnO nanoparticles for photodegradation of ciprofloxacin antibiotic and textile dyes

ABSTRACT The study is centred on the synthesis of B-ZnO photocatalysts via a straightforward mechanochemical combustion method using various weight percentages of B. The synthesised photocatalysts were characterised by XRD, FTIR, FESEM, TEM, XPS, UV-DRS, and BET. Biopersistent ciprofloxacin (CIP) degradation efficiency was investigated with the synthesised B-ZnO. Among the compositions, 4%B-ZnO exhibited the highest photocatalytic efficiency in degrading CIP under both natural sunlight and UV-C. The excellent catalytic activity was attributed to the increased surface area of 4% B-ZnO determined through BET analysis. Under optimised conditions (CIP: 10 mg/L, pH: 6.3, photocatalyst dose: 0.4 g/L), the highest CIP photodegradation efficiency was 92.05% over only 60 min of sunlight irradiation and 90.95% under 80 min of UV-C irradiation. The degradation products of CIP exhibited no antibacterial activity against random soil bacteria. The degradation of CIP followed pseudo-first-order kinetics, with a rate constant of 0.023 min−1. Scavenger tests implied •O2 − radicals’ involvement in photodegradation. CIP mineralisation by 48.53% over 3 h under sunlight was observed. After undergoing four cycles of sunlight exposure, the degradation efficiency reached 84.89%. Additionally, during 80 min of UV-C irradiation, the photodegradation efficiency of the dyes turquoise blue and Congo red was 77.91% and 98.92%, respectively.