Norfloxacin Degradation Rate Research Articles

Research on a Metal–Organic Framework (MOF)-Derived Carbon-Coated Metal Cathode for Strengthening Bioelectrochemical Salt Resistance and Norfloxacin Degradation

Microbial fuel cells (MFCs) can realize the conversion of chemical energy to electrical energy in high-salt wastewater, but the easily deactivated cathode seriously affects the performance of MFCs. To enhance the stability and sustainability of MFC in such circumstances, a bimetallic organic framework ZIF-8/ZIF-67 was utilized for the synthesis of a carbon cage-encapsulated metal catalysts in this study. Catalysts with different Co and Ce ratio (Co@C (without the Ce element), CoCe0.25@C, CoCe0.5@C, and CoCe1@C) were employed to modify the activated carbon cathodes of MFCs. The tests demonstrated that the MFCs with the CoCe0.5@C cathode catalyst obtained the highest maximum power density (188.93 mW/m2) and the smaller polarization curve slope, which boosted the electrochemical activity of microorganisms attached to the anode. The appropriate addition of the Ce element was conductive to the stability of the catalyst’s active center, which is beneficial for the stability of catalytic performance. Under the function of the CoCe0.5@C catalyst, the MFCs exhibited superior and stable norfloxacin (NOR) degradation efficiency. Even after three cycles, the NOR degradation rate remained at 68%, a negligible 5.6% lower than the initial stage. Furthermore, based on the analysis of microbial diversity, the abundance of electrogenic microorganisms on a bioanode is relatively high with CoCe0.5@C as the cathode catalyst. This may be because the better cathode oxygen reduction reaction (ORR) performance can strengthen the metabolic activity of anode microorganisms. The electrochemical performance and NOR degradation ability of MFC were enhanced in a high-salt environment. This paper provides an approach to address the challenge of the poor salt tolerance of cathode catalysts in MFC treatment, and presents a new perspective on resource utilization, low carbon emissions, and the sustainable treatment of high-salt wastewater.

Iron-based metal organic framework (Fe-MOF)-doped sesame stalk biochar enhances antibiotic degradation: Important role of free radicals and comparison of multiple degradation processes

A novel iron-based metal organic framework-doped sesame stalk biochar (Fe-MOF@SBC) composite was successfully synthesized using sonication and used for the degradation of sulfamethoxazole (SMX), norfloxacin (NOR), erythromycin (ERY) and tetracycline (TC) in aqueous solution. The characterization results indicated that Fe oxide was successfully loaded on the biochar. The Fe-MOF@SBC composite presented a porous structure enriched in micropores and mesopores. Adsorption mechanisms, including pore filling, π–π electron donor–acceptor (EDA) interactions, hydrophobic interactions, hydrogen bonding and electrostatic interactions, and the catalytic effect of the Fe-MOF@SBC composite facilitated antibiotic degradation. Specifically, single-layer and multilayer adsorption occurred, and abundant oxygen-containing functional groups were involved in the degradation of NOR, which might be one reason for the high degradation rate of NOR by the Fe-MOF@SBC composite. Scavenging experiments combined with electron paramagnetic resonance (EPR) analysis indicated that free radicals such as •OH, O2−• and 1O2 played vital roles in the degradation of SMX, NOR, ERY and TC. Furthermore, the proposed degradation pathways and possible intermediates of SMX, NOR, ERY and TC were identified, which indicated that the adsorption properties and free radical (•OH, O2−• and 1O2) activity of the Fe-MOF@SBC composite strongly promoted the removal of SMX, NOR, ERY and TC.

MoS2@MWCNTs with Rich Vacancy Defects for Effective Piezocatalytic Degradation of Norfloxacin via Innergenerated-H2O2: Enhanced Nonradical Pathway and Synergistic Mechanism with Radical Pathway.

Molybdenum disulfide (MoS2)-based materials for piezocatalysis are unsatisfactory due to their low actual piezoelectric coefficient and poor electrical conductivity. Herein, 1T/3R phase MoS2 grown in situ on multiwalled carbon nanotubes (MWCNTs) was proposed. MoS2@MWCNTs exhibited the interwoven morphology of thin nanoflowers and tubes, and the piezoelectric response of MoS2@MWCNTs was 4.07 times higher than that of MoS2 via piezoresponse force microscopy (PFM) characterization. MoS2@MWCNTs exhibited superior activity with a 91% degradation rate of norfloxacin (NOR) after actually working 24 min (as for rhodamine B, reached 100% within 18 min) by pulse-mode ultrasonic vibration-triggered piezocatalysis. It was found that piezocatalysis for removing pollutants was attributed to the synergistic effect of free radicals (•OH and O2•-) and nonfree radical (1O2, key role) pathways, together with the innergenerated-H2O2 promoting the degradation rate. 1O2 can be generated by electron transfer and energy transfer pathways. The presence of oxygen vacancies (OVs) induced the transformation of O2 to 1O2 by triplet energy transfer. The fast charge transfer in MoS2@MWCNTs heterostructure and the coexistence of sulfur vacancies and OVs enhanced charge carrier separation resulting in a prominent piezoelectric effect. This work opens up new avenues for the development of efficient piezocatalysts that can be utilized for environmental purification.

Hydrothermal Synthesis, Formation Mechanism and Photocatalytic Activity of SnO2/BiOBr

AbstractSnO2/BiOBr photocatalytic materials were successfully synthesized by hydrothermal method with BiOBr as the precursor. X‐ray diffraction studies confirmed that BiOBr and SnO2 were successfully combined. After characterization, we proposed a possible formation mechanism for SnO2/BiOBr. The degradation experiment showed that the degradation rate of norfloxacin using SnO2/BiOB‐4 reached 85.9 %, which was approximately 50 and 65 percentage points higher than that of pure BiOBr and SnO2, respectively. The reaction rate was 4.3 times that of BiOBr. Based on the analysis of the degradation mechanism, the improved photocatalytic performance may be attributed to the optimized energy band structure resulting from the combination of the two monomers. This promotes the effective separation of photogenerated electrons and holes, leading to the generation of more active substances such as ⋅O2− and h+. As a result, the oxidation capacity is enhanced.

Development of efficient and economic Bi2O3/BN/Co3O4 composite photocatalyst: Degradation mechanism, pathway and toxicity study of norfloxacin

The production of cheap, efficient, and stable photocatalysts for degrading antibiotic contaminants remains challenging. Herein, Bi2O3/boron nitride (BN)/Co3O4 ternary composites were synthesized using the impregnation method. The morphological characteristics, structural features, and photochemical properties of the prepared photocatalysts were investigated via X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, and ultraviolet–visible (Vis) diffuse reflectance spectrum techniques. BN was used as a charge transfer bridge in the ternary composites, which afforded a heterojunction between the two semiconductors. The formation of the heterojunction substantially enhanced the charge separation and improved the photocatalyst performance. The degradation activity of the Bi2O3/BN/Co3O4 ternary composites against norfloxacin (NOR) under Vis light irradiation was investigated. The degradation rate of NOR using 5-wt% Bi2O3/BN/Co3O4 reached 98% in 180 min, indicating excellent photocatalytic performance. The ternary composites also exhibited high photostability with a degradation efficiency of 88.4% after five cycles. Hydroxyl radicals (•OH), superoxide radicals (•O2−), and holes (h+) played a synergistic role in the photocatalytic reaction, where h+ and •O2− were more important than •OH. Consequently, seven intermediates and major photocatalytic degradation pathways were identified. Toxicity experiments showed that the toxicity of the degradation solution to Chlorella pyrenoidosa decreased. Finally, the ecotoxicity of NOR and its intermediates were analyzed using the Toxicity Estimation Software Tool, with most intermediates exhibiting low toxicity.

Enhancement of norfloxacin degradation by citrate in S-nZVI@Ps system: Chelation and FeS layer

The degradation of organic pollution by sulfur-modified nano zero-valent iron(S-nZVI) combined with advanced oxidation systems has been extensively studied. However, the low utilization of nZVI and low reactive oxygen species (ROS) yield in the system have limited its wide application. Herein, a natural organic acid commonly found in citrus fruits, citric acid (CA), was combined with the conventional S-nZVI@Ps system to enhance the degradation of norfloxacin (NOR). The addition of CA increased the NOR removal by about 31% compared with the conventional S-nZVI@Ps system under the same experimental conditions. Among them, the enhanced effect of CA is mainly reflected in its ability to promote the release of Fe2+ and accelerate the cycling of Fe2+ and Fe3+ to further improve the utilization of nZVI and the generation of ROS; it also promotes the dissolution of the active substance (FeS) on the surface of S-nZVI to further improve the degradation rate of NOR. More importantly, the chelate of CA and Fe2+ (CA-Fe2+) had higher reactivity than alone Fe2+. Free radical quenching and electron spin resonance (ESR) experiments indicated that the main ROS for the degradation of NOR in the CA/S-nZVI@Ps system were SO4•- and OH•. CA-bound sulfur-modifying effects on NOR degradation was systematically investigated, and the degradation mechanism of NOR in CA/S-nZVI@Ps system was explored by various techniques. Additionally, the effect of common anions in water matrix on the degradation of NOR in CA/S-nZVI@Ps system and its degradation of various pollutants were also studied. This study provides a new perspective to enhance the degradation of pollutants by S-nZVI combined with advanced oxidation system, which can help to solve the application boundary problem of S-nZVI.

Facile synthesis of oxygen-deficient BiOBrxCl1−x solid solutions for efficient photocatalytic degradation of organic pollutants

In this study, a series of oxygen-deficient BiOBrxCl1−x (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1) solid solution photocatalysts by the microwave hydrothermal method. By changing the Br/Cl molar ratio, the light absorption edge of BiOBrxCl1−x was effectively red-shifted from 345 to 430 nm. The performance of BiOBr0.3Cl0.7 solid solution catalyst showed the best photocatalytic duty for the degradation of norfloxacin (NOR) and methyl orange (MO). The degradation rate of NOR reached 90.2% within 50 min (catalyst dosage: 20 mg), whereas that of MO reached 82.7% within 30 min (catalyst dosage: 5 mg). Environmental factors affecting the degradation of NOR by BiOBr0.3Cl0.7 (such as pH, type of inorganic anions, amount of catalyst, and concentration of NOR) were discussed in detail. The presence of oxygen vacancies (OVs) was confirmed by electron spin resonance (ESR) experiments. Furthermore, free radical capture and ESR experiments identified the main active free radicals involved in the degradation of NOR over BiOBr0.3Cl0.7. Finally, a possible photocatalytic degradation mechanism was proposed.

Self-assembly of 3D hierarchical halloysite-nanotube/CoAl-LDH-nanosheet hybrid microspheres for high-performance degradation of norfloxacin

In this paper, 3D hierarchical CoAl-LDH microsphere hybrid catalysts were fabricated via a facile two-step procedure. The results demonstrated that halloysite (Hal)-nanotube and CoAl-LDH-nanosheet were reconstructed into 3D hierarchical hybrid microspheres. In addition to providing Al element, the Hal also maintained a high specific surface area of the microspheres and exhibited excellent adsorption properties. The novel catalysts could activate peroxymonosulfate (PMS) to generate HO• and SO4•– free radicals, resulting in a 97% degradation rate of norfloxacin (NOR) at a concentration of 20 mg/L. This study provides insights into using nano-clay precursors for constructing CoAl-LDH hybrid catalysts to purify antibiotic contaminants from aqueous environments.

Red mud-based heterogeneous catalyst for hydrothermal resource-based degradation of norfloxacin in pharmaceutical wastewater by hydrogen peroxide

Red mud (RM) was used as a catalyst for the hydrothermal degradation of antibiotics in simulated pharmaceutical wastewater by H2O2 to produce formic acid. Formic acid could be adopted as hydrogen storage, conforming to carbon neutral strategy. When 10 mL norfloxacin (NOR) solution was used at 40 mg/L, the optimal reaction conditions were 0.02 g RM activated at 100 °C, 0.2 mL added H2O2, as well as the reaction time and temperature of 0.5 h and 90 °C, leading to NOR degradation rate of 69.26 % and a formic acid yield of 58.36 % (selectivity: 87.56 %). The RM catalyst presented good activity and stability in reuse. In this study, phase composition and structure of RM catalyst before and after the reaction were comprehensively characterized, and kinetic model was established. Moreover, the key intermediate pathway of NOR degradation was identified by LC-MS. Under the concept of “treating waste with waste”, these results suggested that wastewater-treatment technology of solid waste (Red Mud) was “Fenton-like” catalyst for resource-based degrading high-ecotoxicity antibiotic pollutants in pharmaceutical wastewater. This process could support environmental protection and green development of the pharmaceutical industry, together with hazardous waste-recycling treatment. In short, this research provides a theoretical basis for the subsequent engineering resource treatment of pharmaceutical wastewater.

Novel preparation of MOF derived Co(OH)2/ZnFe2O4 magnetic micro-nanoreactor with boost peroxymonosulfate activation for enhanced antibiotic contaminant oxidation

Development of highly efficient and recyclable catalysts based on peroxymonosate (PMS) activation for the degradation of dangerous antibiotic contaminants was still a challenging topic. In this study, a highly efficient and recyclable heterogeneous Co(OH)2/ZnFe2O4 (Co-ZF) catalysts derived from metal-organic frameworks (MOFs) were prepared by a facile alkaline solution hydrothermal method, a high specific surface area (100.4 m2 g−1) and soft magnetic properties (Ms=25.3 emu g−1) composite material was obtained, and used for degrading norfloxacin (NOF) via PMS activation. The effects of temperature, alkali concentration, pH, initial NOF concentration, PMS and catalyst dosage on NOF degradation were discussed in detail. The results illustrated that the degradation rate of norfloxacin by the 3Co-ZF160 catalyst synthesized under 3 M NaOH and 160 ℃ hydrothermal conditions was 97.2%, after four consecutive cycles of degradation, the degradation rate of NOF by 3Co-ZF160 remained over 91% within 60 min. In contrast, the degradation rate of the Co3O4/ZnFe2O4 (CZF-600) catalyst calcined at 600 ℃ was only 74% available. Furthermore, The results of radical quenching suggested that OH•, SO4•−, SO5•− and 1O2 functioned in the presence of the Co(OH)2/ZnFe2O4-PMS system. Eventually, NOF degradation pathways were tentatively proposed on the basis presented via LC-MS. The above results highlight that the practical application of Co(OH)2/ZnFe2O4 heterogeneous catalyst in aqueous solution was of great significance.

Eco-friendly fabrication of multifunctional magnetic plasmonic photocatalyst for adsorption, SERS monitoring and photodegradation of residual fluoroquinolone antibiotics in water

In this work, a kind of multifunctional magnetic plasmonic photocatalyst was prepared by a green and efficient process. Magnetic mesoporous anatase titanium dioxide (Fe3O4@mTiO2) was synthesized by microwave-assisted hydrothermal, and Ag NPs were simultaneously in-situ grown on Fe3O4@mTiO2 (Fe3O4@mTiO2@Ag), graphene oxide (GO) was then wrapped on Fe3O4@mTiO2@Ag (Fe3O4@mTiO2@Ag@GO) to increase its adsorption capacity for fluoroquinolone antibiotics (FQs). Owing to the localized surface plasmon resonance (LSPR) effect of Ag, as well as the photocatalytic capacity of TiO2, a multifunctional platform based on Fe3O4@mTiO2@Ag@GO was constructed for adsorption, surface-enhanced Raman spectroscopy (SERS) monitoring and photodegradation of FQs in water. The quantitative SERS detection of norfloxacin (NOR), ciprofloxacin (CIP), and enrofloxacin (ENR) was demonstrated with LOD of 0.1 μg mL−1, and the qualitative analysis was confirmed by density functional theory (DFT) calculation. The photocatalytic degradation rate of NOR over Fe3O4@mTiO2@Ag@GO was about 4.6 and 1.4 times faster than that of Fe3O4@mTiO2 and Fe3O4@mTiO2@Ag, indicating the synergetic effects of Ag NPs and GO, the used Fe3O4@mTiO2@Ag@GO can be easily recovered and recycled for at least 5 times. Thus, the eco-friendly magnetic plasmonic photocatalyst provided a potential solution for the removal and monitoring of residual FQs in environmental water.

Synergy of dielectric barrier discharge plasma and magnetically separable MOF-derived Co@C composite for the improved degradation of norfloxacin antibiotic in water

Norfloxacin (NOR) is a highly toxic fluoroquinolone antibiotic, which is continuously discharged into aquatic environment. Due to its poor biodegradability, NOR is difficult to be removed and has exerted a serious impact on environmental risk. In this paper, a coaxial double dielectric barrier discharge (DBD) device was designed and built, then was synergic with cobalt-carbon (Co@C) composites for the improved degradation of NOR in wastewater with high degradation efficiency. The Co@C composite, a porous carbon material, was synthesized by calcination of Co-metal organic frameworks (Co-MOFs), and was further characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Brunauer-Emmett-Teller surface analyzer, Fourier transform infrared spectrometry and vibrating sample magnetometer. The combination of DBD with Co@C system has an obvious synergistic effect for the removal of NOR. The degradation rate could reach to 84.7% and the treatment time was in 15 min, which were 14.1% higher and 10 min shorter than those of solo DBD system. The synergistic factor was estimated to be 1.12, and the energy yield of process could reach to the maximum of 7.6 mg/kWh. The effects of discharge voltage, pH, NOR initial concentration and Co@C dosage on the degradation rate of NOR have been explored in detail. The experimental results indicated that the system of DBD coupled with Co@C for NOR degradation was appropriate in a wide initial pH from 3.0 to 11.0. Moreover, Co@C could be reused several times and convenient to be magnetically recycled. Furthermore, it was proved that O3, •OH and H2O2 were the main reactive oxygen species during the catalytic decomposition reactions of NOR, and the generated O3 in DBD system could be converted into •OH under the synergic catalysis of Co@C, further promoting degradation efficiencies for NOR. Finally, main intermediate products of NOR degradation were analyzed by liquid chromatography-mass spectrometry, and possible degradation mechanism and pathways were speculated.

Near-infrared responsive Z-scheme heterojunction with strong stability and ultra-high quantum efficiency constructed by lanthanide-doped glass

Lanthanide-doped near-infrared (NIR) photocatalyst still obstructed by the less impressive photocatalytic efficiency and stability. In this work, we report a novel strategy by introducing the lanthanide-doped ferroelectric perovskites of SiTiO3 and Sr2Bi4Ti4O15 into the glass-ceramic (GC), then an efficient and stable NIR photocatalyst was fabricated through the method of facile in-situ HCl etching GC. The results show that Sr2Bi4Ti4O15, SrTiO3, and BiOCl were exposed to the superficial coating of the core-shell structured photocatalyst and constructed Z-scheme heterojunction, the heterojunction with built-in electric field could significantly facilitate the charge carriers separation and harvest NIR light for photocatalytic reaction simultaneously. The evident increase of Lewis basic sites over defect-rich photocatalyst is found, the •O2- and •OH radicals are generated. During the degradation of norfloxacin (NOR) under NIR light irradiation for 90 min, the NOR degradation rate is 86% (TOC removal rate is 30.7%), the high apparent quantum yield of 2.3% is achieved.

Preparation and characterization of highly efficient Z-scheme oxygen vacancy-BiOBr/CoFe2O4 heterojunction photocatalyst driven by visible light for antibiotic degradation

In this work, magnetic oxygen vacancy-BiOBr/CoFe2O4 (OV-BiOBr/CoFe2O4) composite with Z-scheme heterojunction was prepared by simple solvothermal method. The physicochemical properties of the prepared samples were characterized. The degradation rate of norfloxacin (NOR) by OV-BiOBr/CoFe2O4 under visible light irradiation can reach 94.61%. In addition, OV-BiOBr/CoFe2O4 composite also exhibits excellent photocatalytic performance for other antibiotics, it can be recovered by external magnetic field and still shows good photocatalytic activity after four consecutive times uses. Characterization and experimental results show that the improved photocatalytic performance of OV-BiOBr/CoFe2O4 can be attributed to the improvement of visible light response range, the increase of active sites and the effective separation of electron hole pairs. The results of free radical capture experiment and electron paramagnetic resonance spectra show that •O2− and h+ are the main active substance in photocatalytic degradation of NOR system. Then, combined with the band structure, a Z-scheme heterojunction electron transfer mechanism is proposed. This work enhances the photocatalytic performance of BiOBr and provides a new idea for antibiotic wastewater treatment.

Self-assembly synthesis of S-scheme g-C3N4/Bi8(CrO4)O11 for photocatalytic degradation of norfloxacin and bisphenol A

To realize the high-efficiency photodegradation of antibiotics, a novel S-scheme heterojunction photocatalyst g-C3N4/Bi8(CrO4)O11 was proposed and successfully prepared in this work. The 10% g-C3N4/Bi8(CrO4)O11 heterojunction exhibits the highest degradation rate of norfloxacin (NOR) and bisphenol A (BPA). The degradation rate of NOR on 10% g-C3N4/Bi8(CrO4)O11 is about 1.38 and 2.33 times higher than that of pure Bi8(CrO4)O11 and g-C3N4, respectively. Further, the degradation rate of BPA over 10% g-C3N4/Bi8(CrO4)O11 heterojunction is bout 1.35 and 9.11 times higher than that of pure Bi8(CrO4)O11 and g-C3N4, respectively. The formation of S-scheme heterojunction facilitates the separation of photogenerated electron-hole pairs and reduces the recombination of charge carriers, which was confirmed by photocurrent, electrochemical impedance spectroscopy, steady-state and time-resolved transient photoluminescence spectrum, etc. The in-situ X-ray photoelectron spectroscopy, radical trapping experiments and electron paramagnetic resonance results demonstrate that the charge transfer is in accord with S-scheme mechanism.

Preparation, performance and mechanism of p-Ag3PO4/n-ZnO/C heterojunction with IRMOF-3 as precursor for efficient photodegradation of norfloxacin

Ag3PO4/ZnO/C photocatalyst with p-n heterojunction has been prepared by ultrasound assisted precipitation based on ZnO/C obtained by pyrolysis using isoreticular metal-organic frameworks (IRMOF) as precursor. The results show that Ag3PO4 uniformly dispersed on the pores and surface of the porous ZnO/C, and the whole catalyst is floss cake-like. ZnO/C and Ag3PO4 are successfully composited and possess good photocatalytic activity and stability. The degradation rate of norfloxacin by Ag3PO4/ZnO/C can reach 89.48% under the best reaction conditions, which is 2.97 times than that of pure Ag3PO4, and Ag3PO4/ZnO/C also shows better photocatalytic performance and reusing stability than Ag3PO4. The results of the active species capture experiment confirms that ⋅O2− and holes (h+) play major roles in the process of degrading norfloxacin by Ag3PO4/ZnO/C under visible light irradiation. The main reason for the enhanced photocatalytic activity and stability of Ag3PO4/ZnO/C is that the introduction of ZnO/C has widened the light adsorption range and reduced the solubility of Ag3PO4 in Ag3PO4/ZnO/C. At the same time, the excellent electron transfer capability of graphite in ZnO/C and the p-n heterojunction formed between Ag3PO4 and ZnO can promote the electrons migrating from Ag3PO4 to ZnO/C, effectively inhibiting the photocorrosion of Ag3PO4.

Green and efficient photodegradation of norfloxacin with CsPbBr3-rGO/Bi2WO6 S-scheme heterojunction photocatalyst

Modern chemistry aims to identify excellent photocatalyst for pollution challenge associated with the antibiotics-containing wastewater. In this contribution, a novel CsPbBr3-rGO/Bi2WO6 S-scheme heterojunction with superior stability and excellent photocatalytic activity was achieved via trimercaptopropionic acid (MPA) modification for norfloxacin photodegradation. Here, MPA acted not only as an organic ligand to stable the composite by formation of strong -SH-Pb- bond and -COO-Bi-O- bond, but also worked as an electronic bridge to transfer and separate photogenerated carriers. The CsPbBr3-rGO/Bi2WO6 composite displayed the excellent photocatalytic activity compare with pure Bi2WO6 and rGO/Bi2WO6, and the norfloxacin degradation rate was about 66.79% with 120 min under visible light irradiation. The results of the UV-Vis diffuse reflectance spectra, PL spectra, transient photocurrent response, and reactive-species-trapping experiments indicated that the expanding light-harvesting scope, efficient charge separation ability, and large amounts of active species, are the major reasons for the enhancement photocatalytic activity of CsPbBr3-rGO/Bi2WO6 composite. According to the cycle experiment, the photodegradation rate of norfloxacin is no significant decrease, the XRD pattern and FTIR spectra before and after norfloxacin degradation displayed almost no change, indicating the superior stability of the CsPbBr3-rGO/Bi2WO6 composite. This work not only provides a new opportunity to strengthen the stability and charger-transfer efficiency of CsPbBr3 nanocrystals (NCs), but also opens up a new insight for photocatalytic application of CsPbBr3 NCs.

Optimization of photocatalytic degradation conditions and toxicity assessment of norfloxacin under visible light by new lamellar structure magnetic ZnO/g-C3N4

Degradation of norfloxacin (NFX) by zinc oxide (ZnO)/g-C3N4, a magnetic sheet ZnO with g-C3N4 on its surface was studied. Through a new preparation system method, hydrothermal reaction provides a solid-layered magnetic ZnO material basis, and the simple thermal condensation method was used to transform the urea into g-C3N4 on the magnetic sheet ZnO in a uniform and orderly manner to increase the stability and photocatalytic performance of the material. Compared with previous studies, the pore volume and photocatalytic performance of the material are improved, and became more stable. By studying the degradation effect of basic and photocatalytic materials prepared in different proportions, the kinetic constant of ZGF is 0.01446 (min−1). The response surface methodology (RSM) was used to study the optimization and effect of solution pH (4−12), photocatalyst concentration (0.2–1.8 g/L), and NFX concentration (3–15 mg/L) on the degradation rate of NFX during photocatalytic degradation. The R2 value of the RSM model was 0.9656. The NFX removal rate is higher than 90% when the amount of catalyst is 1.43 g/L, the solution pH is 7.12, and the NFX concentration is less than 8.61 mg/L. After 5 cycles, the degradation rate of magnetic materials decreased to 92.8% of the first time. The capture experiment showed that the photocatalytic machine Toxicities was mainly hole action. The TOC removal rate within 2 h was 30%, a special intermediate toxicity analysis method was adopted according to the characteristics of NFX's inhibitory effect on Escherichia coli community. The toxicity of degraded NFX solution disappeared, and the possibility of non-toxic harm of by-products was verified. LC-Q-TOF method was used to detect and analyze various intermediate products converted from NFX after photocatalytic degradation, and the photocatalytic degradation pathway of NFX was proposed.

Construction of Ag3PO4/TiO2/C with p-n heterojunction using Shiff base-Ti complex as precursor: Preparation, performance and mechanism

Ag3PO4/TiO2/C composite photocatalyst with p-n heterojunction was prepared by ultrasonic assisted in-situ precipitation on the basis of TiO2/C material prepared by pyrolyzing Schiff base-Ti complex (SHI-Ti). The results show that TiO2/C is mainly dispersed around Ag3PO4 particles, which significantly improves the photocatalytic performance and stability of Ag3PO4. The degradation rate of norfloxacin (NOR) and the reaction rate constant are 2.78 and 7.71 times than pure Ag3PO4 under the best conditions. The improvement of the photocatalytic performance and reuse stability of Ag3PO4/TiO2/C benefits from the enhancement of electron transfer capability and the improvement of spectral absorption range by the introduction of TiO2/C as well as the immobilization of Ag3PO4, thereby reducing its dissolution. Moreover, the formation of p-n heterojunction between Ag3PO4 and TiO2/C promotes the migration of photo-generated electrons from Ag3PO4 to TiO2/C that could weaken the photocorrosion of Ag3PO4 and improve the stability.

Promoted photocatalytic degradation and detoxication performance for norfloxacin on Z-scheme phosphate-doped BiVO4/graphene quantum dots/P-doped g-C3N4

• A ternary Z-scheme heterojunction BiVO 4 /GQDs/PCN is fabricated. • BiVO 4 /GQDs/PCN exhibits excellent visible light photodegradation activity for norfloxacin. • GQDs act as electron mediator to promote interfacial charge transfer. • Enhanced mineralization ability and detoxication performance can be achieved. • Degradation pathway, toxicity of intermediates and reaction mechanism are discussed. A novel kind of Z-scheme ternary heterojunctions phosphate-doped BiVO 4 /graphene quantum dots/P-doped g-C 3 N 4 (BVP/GQDs/PCN) were fabricated for the visible light degradation of norfloxacin (NOR), a typical antibiotic. Compared with binary type-II heterojunction phosphate-doped BiVO 4 /PCN (BVP/PCN), Z-scheme BVP/GQDs/PCN exhibited promoted interfacial charge transfer efficiency and broadened visible light response range, endowing them with excellent photodegradation activity and mineralization ability in NOR degradation. A high NOR degradation rate of 86.3% with a removal rate of total organic carbon (TOC) of 55.8% can be achieved over BVP/GQDs/PCN for 120 min visible light irradiation, which is an excellent performance compared with ever reported similar photocatalysts. In particular, because of the enhanced redox ability of photogenerated charges and the generation of multiple active species (eg. OH and O 2 − ) over Z-scheme photocatalytic system, the accumulation of highly toxic degradation intermediates was greatly inhibited, and a better detoxication performance was obtained compared to PCN and BVP/PCN. This work may shed light on the inhibition of highly toxic degradation intermediates of antibiotics by regulating the charge transfer mechanism, photocatalytic active species, and the degradation pathway of antibiotics.