Photocatalytic Degradation Of Levofloxacin Research Articles

In situ sonochemical synthesis of flower-like N-graphyne/BiOCl0.5Br0.5 microspheres for efficient removal of levofloxacin.

In this work, N-graphyne is in situ coupled with BiOCl0.5Br0.5via a facile one-step sonochemical method. To our knowledge, both the synthesis strategy for BiOCl0.5Br0.5 and the N-graphyne/BiOCl0.5Br0.5 photocatalytic system are new developments. A collection of characterization methods is adopted to detect the morphologies, structures, and electronic and optical properties. The results demonstrate that wrinkle-like N-graphyne nanosheets successfully enwind around or on flower-like BiOCl0.5Br0.5 microspheres, which are regularly assembled by BiOCl0.5Br0.5 nanosheets. Compared with pristine BiOCl0.5Br0.5, N-graphyne/BiOCl0.5Br0.5 composites exhibit superior adsorption capacity and visible-light-driven photocatalytic degradation of levofloxacin. In particular, the optimal N-graphyne amount for ameliorating the photocatalytic performance of BiOCl0.5Br0.5 is ascertained. In addition, the good stable performance for photocatalysis is confirmed by four cycling experiments. The dominant active species is confirmed to be O2˙- during photodegradation. The improved photocatalytic activity is attributed to the enhanced visible light response and the accelerated transfer/separation of photogenerated carriers by N-graphyne, which are verified using UV-vis absorption spectra, photocurrents, photopotentials, Nyquist plots, and Mott-Schottky curves. This study develops a new perspective for the synthesis and modification of BiOX solid solution, which can be used as an efficient photocatalyst.

Energy band reconstruction mechanism of Cl-doped Cu2O and photocatalytic degradation pathway for levofloxacin

Cl-doped Cu 2 O microparticles were prepared by hydrothermal synthesis . XRD, BET, SEM, TEM, UV–Vis and RSM were used to reveal the microstructure, optical properties and degradation regularity of the Cl-doped Cu 2 O microparticles. The band gap structures and state densities of Cl-doped Cu 2 O microparticles were computed based on density functional theory . The major intermediate degradation products and potential photocatalytic degradation pathways of levofloxacin were identified by HPLC–MS/MS. The photocatalytic active sites of levofloxacin and its intermediate products were calculated based on the frontier electron densities. The results showed that the prepared Cl-doped Cu 2 O microparticles increased the specific surface area and absorption efficiency of visible light compared with undoped pure Cu 2 O. The doping of Cl introduced hybrid orbitals and oxygen vacancy defects in the Cu 2 O crystal cell and decreased the forbidden bandwidth of Cu 2 O crystal microparticles, leading to a redshift of the absorption edge . Cl doping could form a shallow donor impurity energy level composed of Cl 3 p orbital in the energy gap of Cu 2 O and make the energy band denser and move to a lower energy, which could promote the electron leap to the conduction band through the impurity level . The doping of Cl can make the density of states curve of the Cu 2 O crystal shift to low-energy and the Cl-doped Cu 2 O rendered to half-metallic behavior and characteristic behavior of an n type semiconductor. The photocatalytic degradation of levofloxacin was attributed to attack of photogenerated holes and hydroxyl radicals , and the ring opening of the piperazine ring by oxidation and decarboxylation reactions from the quinolone ring might be two photocatalytic degradation pathways. This study revealed the mechanism of oxygen vacancy formation and the change rules of the band structure by doping of the nonmetal chlorine into Cu 2 O crystallites . • Migration laws of band structure and state density of Cl-doped Cu 2 O were revealed. • Doping of Cl introduced hybrid orbitals and oxygen vacancies in the Cu 2 O crystal. • Doping of Cl decreased band gap of Cu 2 O and led to red shift of absorption edge. • Holes and hydroxyl radicals are the main photocatalytic active species. • Degradation paths of levofloxacin were piperazine ring opening and decarboxylation.

Surface Lewis Acid Sites and Oxygen Vacancies of Bi2wo6 Synergistically Promoted Photocatalytic Degradation of Levofloxacin

Surface Lewis Acid Sites and Oxygen Vacancies of Bi2wo6 Synergistically Promoted Photocatalytic Degradation of Levofloxacin

Structural phase-transition in CeVO4 nanobelts by P-doping enables better levofloxacin photocatalysis

The visible-light-induced photocatalytic degradation of levofloxacin was investigated based on belt-like CeVO4 homojunctions via P-doping-induced partial phase transition from tetragonal zircon (t-CeVO4) to monoclinic monazite (m-CeVO4). Such a homojunction allowed for the complete interface optimization of t-CeVO4/m-CeVO4, to boost visible-light harvesting and enhance electron-hole transferring and separating, making a contribution to an effective visible-light-induced photocatalysis. P-doped CeVO4 homostructured nanobelts achieved outstanding photocatalytic activity, high long-term stability, and superior reusability in consecutive levofloxacin photocatalysis experiments. The striking photocatalytic performance of t-CeVO4/m-CeVO4 homojunction can be attributed to a favorable band structure, interface electronic properties, surface oxygen vacancy, and unique cumulative intrinsic properties of belt-like t-CeVO4 and m-CeVO4, synergistically created by this doping-induced structural phase transition strategy. A reaction mechanism for levofloxacin degradation is proposed in terms of band-gap discussion, and trapping experiments. This work might provide a deep insight into designing novel homojunction photocatalysts to facilitate the wastewater decontamination, and environmental remediation using photocatalytic technology.

Photocatalytic degradation of levofloxacin by a novel Sm6WO12/g-C3N4 heterojunction: Performance, mechanism and degradation pathways

Recent year pharmaceutical pollutants have highly detected in environment, because they do not completely mineralized and remain toxic. Semiconductor photocatalyst materials have well recognized as promising technology for environmental pollutants removal in the presence of visible light. In this work, a novel binary Sm6WO12 modified g-C3N4 nanosheets heterojunction was fabricated via simple facile method. The morphology of the newly prepared g-C3N4 and Sm6WO12 was confirmed as nanosheets and nanorods by using microscopy techniques. The sequence of characterization results verified that the Sm6WO12/g-C3N4 synergistically integrate the excellent properties and successful construction of hetero-structure between the Sm6WO12 and g-C3N4. The Sm6WO12/g-C3N4 nanocomposite heterojunction catalyst shows higher photocatalytic efficiency towards degrading pharmaceutical pollutant levofloxacin compared to individual g-C3N4 and Sm6WO12 photocatalyst. The results indicate that about 90.8% of levofloxacin was degraded after 70 min in the presence of Sm6WO12/g-C3N4 nanocomposite. Through radical trapping experiments, O2•− and •OH were proved to be the leading reactive oxidative species contributing to degradation of levofloxacin. Possible photodegradation pathways were proposed based on the detected intermediate products and transformation products. Furthermore, the synthesized Sm6WO12/g-C3N4 heterojunction demonstrated excellent reusability and stability without of loss of photocatalytic activity. Favorably, this study might provide a deep insight into mechanism and possible degradation pathways of levofloxacin by Sm6WO12 modified g-C3N4 heterojunction photocatalyst.

Enhanced Activation of Persulfate by Co-Doped Bismuth Ferrite Nanocomposites for Degradation of Levofloxacin Under Visible Light Irradiation.

In this study, magnetic visible light driven photocatalysts (bismuth ferrite, Bi2Fe4O9, BFO and Co-doped bismuth ferrite, Co-BFO) were successfully prepared by the facile hydrothermal method. The catalyst was used in the application of heterogeneous persulfate (PS) system under visible LED light irradiation for the degradation of levofloxacin (LFX), proving to be an excellent photocatalyst when evaluated by various characterization methods. The effect of Co-doping in the BFO structure was investigated that the decrease of band gap width and the generated photoelectrons and holes would effectively reduce the recombination of photogenerated electron-hole pairs, leading to the enhancement photocatalytic activity. The results demonstrated that Co-BFO catalyst had a high photodegradation efficiency over a wide pH range of 3.0–9.0 and the Co-BFO-2 composite displayed the optimal catalytic performance. It was found that the degradation rate of LFX by Co-BFO-2 catalyst was 3.52 times higher than that of pure BFO catalyst under visible light condition. The free radical trapping experiments and EPR tests demonstrated that superoxide, photogenerated holes and sulfate radicals were the main active species in the photocatalytic degradation of LFX. And a possible photocatalytic degradation mechanism of LFX was proposed in the Vis/Co-BFO/PS process. These findings provided new insight of the mechanism of heterogeneous activation of persulfate by Co-BFO under visible light irradiation.

Fabrication of highly active Z-scheme Ag/g-C3N4-Ag-Ag3PO4 (1 1 0) photocatalyst photocatalyst for visible light photocatalytic degradation of levofloxacin with simultaneous hydrogen production

The capacity of redox and the separation efficiency of electron-hole pairs are important indexes for evaluating the performance of photocatalyst. Herein, a novel Z-scheme Ag/g-C3N4-Ag-Ag3PO4 (1 1 0) photocatalyst is prepared by photo-assisted isoelectric point way. The prepared samples are characterized by XRD, SEM, TEM, EDS mappings, XPS, UV–vis, PL, TPR and EIS. The Z-scheme Ag/g-C3N4-Ag-Ag3PO4 (1 1 0) photocatalytic system exposes the Ag3PO4 (1 1 0) crystal plane with strong oxidizing ability and provides a large producing hydrogen reduction surface of g-C3N4 at the same time. Therefore, the photocatalytic degradation of levofloxacin (LEV) with simultaneous hydrogen production can be effectively achieved under visible light irradiation. Besides, the influence factors such as visible light irradiation time, sacrificial agents, Z-scheme Ag/g-C3N4-Ag-Ag3PO4 (1 1 0) photocatalyst dosage, initial pH and used times are studied systemically. Based on trapping tests and ESR analyzes, the mainly active species are confirmed in the photocatalytic degradation of LEV. Finally, the photocatalytic reaction mechanism on degradation of organic pollutants with simultaneous production hydrogen caused by Z-scheme Ag/g-C3N4-Ag-Ag3PO4 (1 1 0) photocatalyst is proposed.

Reduced graphene oxide-CdS heterostructure: An efficient fluorescent probe for the sensing of Ag(I) and sunset yellow and a visible-light responsive photocatalyst for the degradation of levofloxacin drug in aqueous phase

Herein, we report the synthesis and characterization of rGO-CdS heterostructure and their utilization as an efficient material for sensing and visible-light driven photocatalytic degradation applications. The heterostructure was synthesized by facile hydrothermal process and characterized by several techniques which exhibited intriguing compositional, morphological, structural, thermal, textural and photo-physical properties. The high resolution transmission electron microscopy (HRTEM) images of the prepared rGO-CdS heterostructure showed the successful deposition of CdS nanoparticles (CdS NPs) on the surface of reduced graphene oxide (rGO) sheets. The synthesized rGO-CdS heterostructure was employed as an outstanding fluorescent sensor for the selective and sensitive detection of heavy transition metal ion; Ag(I) and a synthetic food colorant; sunset yellow (SY). The detection limit of 12.35 μM and 7.89 μM was found to be for Ag(I) and SY, respectively. The prepared rGO/CdS heterostructure was also successfully applied for the photocatalytic degradation of fluoroquinoline antibiotic, levofloxacin (LVX), and food colorant SY under visible-light irradiation. The removal efficiency of 82.7% was obtained for LVX (10 mg/L) using rGO-CdS heterostructure in 60 min under visible-light irradiation. The synthesized heterostructure displayed enhanced photocatalytic decomposition (82.7%) than pure CdS NPs (67.5%) under optimized reaction conditions (0.50 g/L photocatalyst amount, 10 mg/L LVX initial concentration and pH 9.0). Approximate 66% of SY was degraded in 270 min under visible-light using the prepared heterostructure. The scavenger study confirmed the pivotal role of e, O2, OHs and OH in the photocatalytic decomposition process. The amended photocatalytic behaviour of the rGO-CdS heterostructure could be accredited to the enhanced visible light harvesting capability, effective charge separation and transportation of photogenerated charge carriers across the heterojunctional interface. To the best of our knowledge, this is the first report till date on the utilization of rGO-CdS heterostructure for the fluorescence sensing of Ag(I) and SY as well as photocatalytic degradation of LVX and SY.

In situ fabrication of BiVO4-CeVO4 heterojunction for excellent visible light photocatalytic degradation of levofloxacin

BiVO4-CeVO4 heterojunction was in situ prepared with hydrothermal method employing bismuth nitrate, cerium nitrate and ammonium vanadate as precursors. The microstructural and crystalline structure of the as-prepared materials were comparatively characterized by XRD, SEM, TEM, EDS, XPS, DRS, PL spectroscopy and photoelectrochemical measurement. Compared with bare photocatalysts, the BiVO4-CeVO4 heterojunction showed more efficient visible light photocatalytic activity of levofloxacin degradation, resulting from the enhancement of separation and transfer efficiency of photogenerated electron-hole pairs. The trapping experiments and ESR tests identified that the contribution of active species was in descending order of OH > h+ > O2− in photocatalytic degradation of levofloxacin, and a possible degradation mechanism was also proposed.

Photocatalytic degradation of levofloxacin by ternary Ag2CO3/CeO2/AgBr photocatalyst under visible-light irradiation: Degradation pathways, mineralization ability, and an accelerated interfacial charge transfer process study

Construction of highly efficient ternary photocatalytic systems is strongly attracting the attention of researchers. In this study, a novel ternary Ag2CO3/CeO2/AgBr photocatalyst with a double Z-scheme configuration was fabricated by in situ loading of Ag2CO3 onto CeO2 spindles and subsequently via an acid corrosion process. The ternary Ag2CO3/CeO2/AgBr composites exhibited enhanced photocatalytic activity for the photodegradation of levofloxacin (LVF) under visible light irradiation. Three-dimensional excitation–emission matrix fluorescence spectra revealed that the structure of LVF could be destroyed from the fluorescence point of view; liquid chromatograph–mass spectrometer tests indicated that LVF can be degraded via different pathways; a total organic carbon study showed that LVF could be effectively mineralized. Transient photocurrent response, photoluminescence, and electrochemical impedance spectroscopy indicated that ternary Ag2CO3/CeO2/AgBr composites had fast photoinduced charge separation efficiency. Active-species-trapping experiments and an electron spin resonance technique confirmed that h+, O2−, and OH all participated in a photodegradation process. On the basic of various performance characterization and experimental results, a double Z-scheme photocatalytic mechanism was proposed. It is expected that the ternary Ag2CO3/CeO2/AgBr composites can be used as a promising photocatalyst for energy conversion and environmental remediation. This work could provide a new approach to constructing ternary hybrid photocatalysts and a comprehensive understanding of the degradation pathways for LVF.

Photocatalytic degradation of levofloxacin in aqueous phase using Ag/AgBr/BiOBr microplates under visible light

Ag/AgBr/BiOBr microplates have been synthesized by precipitation method. The phase, structure, morphology and optical properties were explored by the XRD, XPS, FT-IR, FESEM, DRS and PL techniques. The band gap for Ag/AgBr/BiOBr microplates has been found to be 2.33eV which is significant in enhancing the visible light induced photocatalysis. The synthesized catalyst was consisted of tetragonal phase of BiOBr with diffraction peaks of Ag/AgBr. About 74% of levofloxacin (10mg/L, pH 8) was degraded with Ag/AgBr/BiOBr (1g/L) under 90min of irradiation. The photocatalytic degradation of levofloxacin was found to be fit with pseudo first order kinetics. The results revealed that modification of BiOBr with Ag/AgBr leads to an increase in the photocatalytic activity under visible light which may be ascribed to less e−-h+ recombination.

Au-Pd nanoparticles-decorated TiO2 nanobelts for photocatalytic degradation of antibiotic levofloxacin in aqueous solution

Novel TiO2 nanobelts decorated by bimetallic Au-Pd nanoparticles (Au-Pd/TiO2 NBs) were synthesized and used in photocatalytic (PC) degradation of antibiotic levofloxacin (LEV) in aqueous solution. The TiO2 NBs were prepared by potentiostatic anodization and the Au-Pd nanoparticles were assembled by electrodeposition. The structure and properties of Au-Pd/TiO2 NBs were well characterized by SEM, TEM, XRD, XPS, UV–vis DRS and photoelectrochemistry (PECH). The results of SEM and TEM revealed that perfect belt-like structure with 50–100nm in width and several micrometres in length were formed. Au-Pd bimetallic nanoparticles with diameter from 5 to 10nm were immobilized on the surface of TiO2 NBs. The results of UV–vis DRS and PECH showed that the Au-Pd/TiO2 NBs photocatalyst showed enhanced visible light absorption and lower recombination rate of electron-hole pairs compared with naked TiO2 NBs. The PC activity of Au-Pd/TiO2 NBs was evaluated by monitoring the decomposition of RhB in aqueous solution under simulated solar light, and results indicated that the Au-Pd/TiO2 NBs exhibited higher PC activity. The PC degradation efficiency of LEV can reach nearly 95% after 60min of simulated solar light irradiation, and about 93% after 100min of visible light irradiation. The decrease of PC degradation efficiency was found to be approximately 8% after 5 catalytic runs, indicating that Au-Pd/TiO2 NBs have super reusability. The scavenger study showed that OH, O2− and H2O2 were the main active species involved in the PC degradation of LEV.