Scavenging Test Research Articles

Design and fabrication of graphitic carbon nitride incorporated zinc silicate hybrid nanocomposite for effective degradation of eriochrome black T dye as water pollutant under sunlight irradiations

This paper presents an approach to prepare zinc silicate (Zn2SiO4) and its nanocomposites with graphitic carbon nitride (g-C3N4) for enhanced photocatalytic performance. Zn2SiO4 was synthesized using a simple and cost-effective sonochemical method, followed by the fabrication of Zn2SiO4/g-C3N4 through an ultrasonic-assisted co-precipitation method. The characterization of Zn2SiO4 and its nanocomposites was carried out using various techniques such as XRD, FTIR, EDS, SEM, TEM, BET, and DRS. The main focus of this study was to investigate the photocatalytic efficiency of g-C3N4, Zn2SiO4, and different Zn2SiO4 nanocomposites for the degradation of eriochrome black T (EBT) and erythrosine (ER). It is worth noting that this is the first time Zn2SiO4 has been combined with carbon nitride, which resulted in excellent photocatalytic performance. The experimental results revealed that several factors influenced the efficiency of the photocatalytic process, including the content of Zn2SiO4 in the nanocomposite, catalyst loading, and initial concentration of EBT. Among all the tested compositions, Zn2SiO4/g-C3N4 with 10 % Zn2SiO4 exhibited the best performance. Specifically, when 70 mg of 10 % Zn2SiO4/g-C3N4 was used as a catalyst, it achieved a remarkable degradation efficiency of 75.5 % for 10 ppm EBT. This finding highlights the potential application of Zn2SiO4/g-C3N4 nanocomposites as efficient photocatalysts for environmental remediation. The results of scavenger test indicated that superoxide radicals and positive holes played significant roles in driving the photodegradation reactions. Furthermore, a kinetics study was performed to determine the rate constant (k) associated with the photocatalytic process. It was observed that a higher rate constant (k = 0.011 min−1) corresponded to a higher efficiency of 75.5 %. This finding suggests that the Zn2SiO4/g-C3N4 nanocomposites possess excellent photocatalytic activity and can effectively degrade organic pollutants.

Exploring the physical properties of pristine γ-In2S3 and its influence on Ba doping for photocatalytic degradation of 2,4-D herbicide

In this work, pristine γ-In2S3 nanoribbons were synthesized using a facile solution process and uniquely doped with Ba for the first time. XRD and Raman spectroscopy confirmed the formation of pure-phase γ-In2S3 and successful Ba doping. XPS further validated the presence of Ba 3d core level with In 3d and S 2p after the inclusion of Ba. FESEM and HRTEM images showed the formation of nanoribbons, with the width increasing from 60 to 100 nm after doping. The anticipated stoichiometry of In and S, with approximately 2 atomic % of Ba, was confirmed by EDS. After Ba-doping, the bandgap was narrowed from 3.66 eV to 3.03 eV, and the charge carrier recombination was substantially reduced, as witnessed by PL and EIS. The potential of pristine γ-In2S3 and Ba-doped γ-In2S3 as new photocatalysts was highlighted in this study, exploring their applicability for the photodegradation of the stubborn herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The materials demonstrated impressive performances, achieving degradation efficiencies of 77.08 % and 94.15 % before and after doping, respectively, within 210 min. The scavenging tests revealed a significant contribution of O2•− and •OH for 2,4-D degradation using Ba-doped γ-In2S3 photocatalyst. Besides photocatalysts used in this study demonstrated excellent stability after four cycles. These findings suggest a promising approach for developing cost-effective semiconductors to remove persistent herbicides.

Peroxymonosulfate-activated photocatalytic degradation of norfloxacin via a dual Z-scheme g-C3N5/BiVO4/CoFe − LDH heterojunction: Operation and mechanistic insights

The design of novel dual Z-scheme heterojunction plays a significant path in eradicating organic contaminants via enriched charge carrier separation. Herein, a wet chemical method was used to synthesize ternary g-C3N5/BiVO4/CoFe–LDH (CBCF) nanocomposites, and their corresponding abilities were characterized as follows: crystal phases, optical properties, surface morphologies, and compositions. The g-C3N5/BiVO4/CoFe–LDH-30% (CBCF-3) sample optimized the removal efficiency of norfloxacin (NOR) by up to 95.3% through peroxymonosulfate (PMS) activation in a visible light medium. The combined effects from the Vis/PMS/CBCF-3 catalytic system led to 7-times higher degradation efficiency than visible light only system. This improved performance was attributed to the generation of reactive radical species because of higher PMS utilization and an effective Z-charge transfer process from well-oriented band structures. Moreover, scavenging tests and electron spin resonance analysis revealed the production of active radical and non-radical species, namely •OH, SO4•−, •O2−, and 1O2. Based on the appropriate experimental analysis, the expected NOR degradation mechanism and possible pathways were proposed. Then, the toxicity evaluation results revealed that the intermediate products may not have an adverse effect on the aquatic ecosystems. This research study provides a positive outcome for wastewater remediation using enriched dual Z-scheme mechanism.

Engineering S-scheme heterojunction MgO/WO3-integrated Graphene photocatalyst for robust detoxification of tetracycline: Mechanistic insight and actual matrix remediation

The widespread usage of pharmaceutical compounds for treating humans and animals has led to substantial environmental harm to living organisms globally. Herein, the engineering of step-scheme (S-scheme) heterojunction composite incorporating a co-adsorbent agent is garnering attention as a promising approach for environmental remediation, owing to its improved redox potential and expanded active surface area. This study is the first to employ a graphene-integrated MgO/WO3 S-scheme heterostructure (denoted as MWG) as a ternary photocatalyst for the disintegration of tetracycline (TCY) under UV light exposure. The results confirmed that the MWG nanocatalyst exhibited a significantly improved photocatalytic activity in the degradation of TCY when contrasted with pure MgO, WO3, and graphene (GRP) nanomaterials. Kinetic investigation elucidated that the detoxification of TCY under optimized circumstances was best described by a pseudo first-order kinetic model with regression coefficients higher than 0.97. The scavenging tests revealed that HO● species are the primary agents involved in the TCY degradation during the photocatalytic process. Trapping experiments, photoelectrochemical techniques, and band structure analysis were conducted to propose the plausible detoxification mechanism via the MWG/UV process. A notable enhancement in the biodegradability of actual wastewater was attained following treatment with the MWG/UV process, resulting in 79.6% and 64.8% COD and TOC elimination, respectively, over a 200 min of reaction time. To sum up, the employment of a graphene-integrated MgO/WO3 S-scheme heterojunction composite under UV light illumination can be considered a novel and effective approach for the remediation of real pharmaceutical effluents in real-world scenarios, attributable to its robust redox capacity, significant stability, economic viability, and heightened efficacy in degradation/mineralization processes.

Effect of inorganic anions on quinoline removal by catalytic ozonation: Performance and mechanism

Heterogeneous catalytic ozonation is widely used in advanced treatment for the removal of refractory organics from bio-treated coking wastewater. However, the effect of inorganic anions on quinoline removal by catalytic ozonation remains unclear. In this study, the effect of three inorganic anions including Cl-, Br-, SO42- on performance and mechanism for quinoline removal by TiO2 catalyst was investigated. Results indicated that all three anions have inhibitory effects on quinoline removal; meanwhile Br- exhibited the strongest inhibition. Furthermore, the effect of factors including initial solution pH, ozone concentration, catalyst dosage and coexistence of anions on Br- inhibition was explored. The Br- inhibition mechanism was further systematically analyzed by characterizing the physicochemical properties of catalysts and investigating free radicals and quinoline degradation pathways. The inhibition caused by Br- became stronger with the coexistence of SO42-. The presence of Br- reduced the amount of oxygen vacancies and active sites on catalysts. Also, the activity and stability of catalysts decreased because of the Ti ions leaching, which was obviously exacerbated as the coexistence of SO42-. Moreover, the Br- and SO42- both could react with •OH to form abundant RHS (BrOH•-, Br• and Br2•-) with low oxidative activity to further inhibit quinoline removal. The radical scavenging tests demonstrated that the main reactive oxygen species (ROS) was changed from •OH to O2•- and 1O2 in the catalytic ozonation system by the introduction of Br- and SO42-. Meanwhile, brominated byproducts were found to be generated during the degradation of quinoline by GC-MS analysis.

Synergistic effect of Sonophotocatalytic degradation of crystal violet and alizarin red S dyes using Ag-doped ZnSnO3 nanoparticles

This study proposes an environmentally conventional sonophotocatalytic method that uses silver (Ag)-doped ZnSnO3 nanoparticles (NPs) to effectively eliminate industrial dye-polluted wastewater. This study was conducted to investigate the effect of the Ag doping ratio of the synthesized ZnSnO3 NPs on the removal of dye molecules. We used crystal violet (CV) and alizarin red S (AR) dyes as test pollutants to examine the catalytic activity of the synthesized Ag-doped ZnSnO3 NPs in response to the ultrasound and visible light stimulation. The most effective photocatalytic performance was exhibited by 4 % Ag-ZnSnO3 NPs, which degraded 95 % of the CV and 52 % of the AR dye in 100 min. Surprisingly, using sonophotodegradation to combine ultrasound with visible-light irradiation has resulted in almost complete degradation of the CV dye in 100 min, demonstrating a strong beneficial synergy between the sonocatalytic and photocatalytic processes. Additionally, the sonophotocatalytic degradation of the CV and AR dyes was examined at various pH values. It shows to have high stability across several cycles of dye treatment, indicating that this method can be used for industrial effluents. Scavenger tests demonstrated that the primary active species in the dye degradation is O2•−. Ultimately, the prepared Ag-ZnSnO3 NPs and sonophotocatalytic processes may offer a promising path toward a variety of environmental uses, including the remediation of water and the removal of other organic contaminants.

Visible light photodegradation of methylene blue by ionic liquid based TiO2/Fe3O4 nanophotocatalysts

The environmental impact of dyes as significant water pollutants has prompted increased attention. Photocatalytic processes have emerged as a potential solution for eliminating organic pollutants from wastewater. However, widespread industrial application faces challenges such as the high production cost of photocatalysts, difficulties in enhancing their efficiency, and concerns related to reusability. This study focuses on synthesizing a TiO2/Fe3O4 nanocomposite using an ionic liquid to modify the TiO2 structure, reduce the energy band gap, and improve photocatalyst recoverability through a magnetic field. Incorporating various percentages of iron into the photocatalyst using ionic liquid as both a solvent and modifier, the study employed XRD, FT-IR, FE-SEM, EDX, BET, and DRS analyses. Results highlighted the significance of the anatase and crystalline phases and the use of iron oxide (II-III) in influencing photocatalytic performance. Operational parameters were investigated, including pollutant concentration, catalyst concentration, pH, water type, and light source. Active species generated during photocatalytic degradation, such as trap holes and free radicals, were identified through various scavenger tests. The findings underscore the significant potential of this nanocomposite for visible light photocatalytic degradation, achieving notable removal efficiencies under different operational conditions, including 85 % under tungsten halogen lamp light and 92 % under sunlight.

Simultaneous photocatalytic hydrogen peroxide production and pollutant degradation via bipyridine-based polyimide covalent organic framework

Covalent organic framework (COF) photocatalysts for hydrogen peroxide (H2O2) production are receiving significant attention because of the ever-increasing demand for H2O2. Despite the redox-active property and notable photophysical characteristics of polyimide (PI), the potential of PI-based COFs (PICs) for photocatalytic H2O2 production remains unexplored. Herein, we present a dual redox-active bipyridine-containing PIC (PIC-BPY) as an efficient photocatalyst for H2O2 production. PIC-BPY demonstrated exceptional performance by achieving an H2O2 production rate of 2772 μmol gcat.−1, which is three times higher than its biphenyl-based counterpart. We elucidated the reaction pathway through a series of scavenger tests and electron spin resonance analysis, thereby confirming the additional active role of BPY along with that of PIC framework. Furthermore, we harnessed hydroxyl radicals generated during photocatalysis to explore the potential of PIC-BPY for concurrent pollutant degradation and H2O2 production.

Electron-transfer dynamics and photocatalytic H2-production activity of PbS@Cu2S nanocomposites

BackgroundLead citrate is a precursor that can be prepared by recycling the spent lead paste of lead-acid batteries. Lead citrate is used to synthesize lead oxide, which can be repeatedly utilized for the lead-acid battery application. MethodsWe report a new application of lead citrate precursor to synthesize PbS@Cu2S nanomaterials for photocatalytic H2 production. PbS@Cu2S was prepared by microwave-assisted hydrothermal and ion-exchange processes. The electron-transfer dynamics and H2-production activity of PbS@Cu2S photocatalysts were studied. Significant findingsA S-scheme heterojunction is proposed based on the results of Tauc plots, ultraviolet photoelectron spectroscopy, the electron paramagnetic resonance scavenger test, and in situ near-edge X-ray absorption fine structure (NEXAFS) analysis. Results of in situ NEXAFS reveal the transfer of photoexcited electrons from PbS to Cu2S. By loading an optimized amount of Cu2S, the carrier separation and photocatalytic activity of PbS@Cu2S photocatalysts are improved. This technology can transform the lead citrate precursor to the PbS@Cu2S photocatalyst with excellent high H2 production activity (3824 μmol g−1 h−1).

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.

Resveratrol and lipoic acid: A promising combination for treating dry eye disease

The purpose of this study was to develop an ophthalmic preparation (LA/Res/HP-β-CD) containing alpha-lipoic acid (LA) and resveratrol (Res)/hydroxypropyl-β-cyclodextrin (HP-β-CD) inclusion complex and to investigate the effect of LA/Res/HP-β-CD on medicating the dry eye disease. The inclusion complex of Res/HP-β-CD was prepared by solvent evaporation method to solve the poor water-solubility of Res, and the optimal proportion of resveratrol and lipoic acid in formulation was screened by hydroxyl radical scavenging test in vitro. Comparing with Res/HP-β-CD, the preparations of LA/Res/HP-β-CD had longer t1/2 and larger AUC in tears, had more advantages in increasing Res concentration in cornea, conjunctiva and sclera, improving tear secretion and tear film stability, repairing the corneal epithelial and conjunctiva injury, improving mucin and inorganic salt components of tears, reducing pro-inflammatory factor IL-1β in the cornea, enhancing Vitamin D level of eyes. These results showed that LA improved the therapeutic effect of Res, and the combined preparations would exhibit a potential application prospect in treating dry eye disease.

Synthesis of surficial-modified green biochar catalyst generated by biogas residue biochar and potential application for catalytic ozonation degradation of ciprofloxacin

This study synthesized novel, green, and easily recoverable surface-modified economical catalysts via hydrothermal treatment (HT) successfully, utilizing biogas residue biochar (BRB), a food waste product from anaerobic fermentation, pyrolyzed at 500 °C for 50 min. Using autoclaves, a total of six solutions were prepared, each having 1 g fine-grinded BRB, surficial modified by adding glycerol (GL) (10 or 20 mL) and SDI water (70 or 60 mL), and heated in an oven at 240 °C, 180 °C, and 120 °C for 24 h. Afterward, the catalysts showed the potential for degradation of widely used emerging pollutants like ciprofloxacin. Taking advantage of catalytic surface modification, the catalytic ozonation degradation was more effective than that of a single ozonation. However, under similar conditions, catalyst amount 0.20 g, ozone dose 15 mg L−1, and ciprofloxacin 80 mg L−1, the performance of the 10 mL GL-180 °C catalyst was excellent. It showed a 92.45%–94.41% optimum removal rate in the 8–10 min interval. After five continuous cycles, the 10 mL GL-180 °C catalyst exhibited excellent stability and reusability. XPS, FT-IR, BET, XRD, and SEM before and after the reaction confirmed the successful synthesis and degradation mechanism. A possible degradation pathway was unrevealed based on a liquid chromatography-mass spectrometer (LC-MS) and scavenger test, proving the significant roles of superoxide radicals (O2•-), hydroxyl radicals (•OH), and singlet oxygen (1O2). Further, Electron paramagnetic resonance (EPR) analysis confirmed the presence of active oxygen species. Subsequently, 10 mL GL-180 °C showed promising degradation for the actual water environment, such as groundwater (73.55%) and river water (64.74%). This work provides a valuable economic strategy to convert biogas residue biochar into a low-cost catalyst for organic pollutant decomposition.

SnS thin films deposited at room temperature – Efficient and reusable dark catalyst for water remediation at ambient conditions

This study describes the dark catalytic degradation of cationic, anionic, and commercial dyes by SnS thin films under dark ambient conditions without the assistance of any external stimuli. The thin films were deposited by a modified SILAR (Successive Ionic Layer Adsorption and Reaction) method at room temperature and characterised using XRD, XPS, FESEM, TGA, and UV–visible spectrophotometers. The dark catalytic degradation of methylene blue (MB) dye was investigated using a spectrophotometer and validated by LCMS analysis and an adsorption desorption test. Within 15 min, 48 % of the MB dye (original concentration: 10 mg/l) had been degraded by the catalyst, and by 90 min, the degeneration was almost complete. The ROS (reactive oxygen species) scavenger test and indicator test confirmed the role of the hydroxyl radical in the degradation process. The influence of initial dye concentration, magnetic stirring, and the composition of the catalyst on the degradation efficiency was also studied. The same catalyst was used five times in succession to test its reusability, and it was then structurally and thermally characterised to test its stability. This study emphasises the possible use of SnS thin film as an effective, reliable, and reusable around-the-clock catalyst for the degradation of dye-contaminated waste water without the assistance of light or any chemical additives.

Engineered design of MnFe2O4/CoNiFe-LTH/g-C3N4 heterocatalyst for doxycycline degradation via Fenton oxidation process: Optimization and mechanism

The removal of organic contaminants from waterways is vital to the ecosystem. A novel MnFe2O4/CoNiFe-LTH/g-C3N4 catalyst was synthesized via self-assembly preparation, and linked with H2O2 for the Fenton degradation of doxycycline (DXY). The MnFe2O4/CoNiFe-LTH/g-C3N4 was characterized using FTIR, XRD, XPS, VSM, SEM, TOC, GC–MS, and ICP-OES. Interestingly, the magnetically separable and high-stability catalyst achieved 89.11 % DXY degradation, and 69.30 % TOC removal efficiency within 60 and 120 min, respectively (at pH = 7.5, catalyst dosage= 0.01 g, H2O2 = 400 ppm, T = 20 °C, and DXY concentration= 100 ppm). In addition, the synergistic effect of metal cations (Co, Ni, Fe, and Mn) triggered Fenton degradation through a continuous closed cycle of electrons. A pseudo-first-order kinetic model also fitted DXY degradation with MnFe2O4/CoNiFe-LTH/g-C3N4. Furthermore, the radical pathway mechanism was confirmed with XPS before and after degradation, and with radical scavenging tests. The DXY degradation pathway was speculated by GC–MS analysis. Quantitative structure-activity relationship (QSAR) was applied to assess intermediates for developmental toxicity. The MnFe2O4/CoNiFe-LTH/g-C3N4 catalytic activity on H2O2 decomposition was determined via titrimetric analysis. Recycling tests and ICP-OES measurements were further used to investigate the catalyst's resilience and reusability. Besides, MnFe2O4/CoNiFe-LTH/g-C3N4 demonstrated a performance of 70 % over eight catalytic degradation runs with minimal metal leaching. Eventually, MnFe2O4/CoNiFe-LTH/g-C3N4 is a viable catalyst for breaking down organic contaminants in wastewater.

Rational Bi[sbnd]Mo[sbnd]O nanospheres decorated g-C3N4 for photocatalytic performance of dye degradation

Developing a superior heterostructured composite, optimizing performance through synergies from complementary advantages in diverse materials, remains an ongoing challenge. The rise in organic contaminants in freshwater bodies possesses a major threat to human health. Various dyes such as Rhodamine B, Eosin Y and Methylene Blue are found in excess concentration due to industrial usage and their removal is important for environmental remediation and contaminant-free water. In this study, we report synthesis and fabrication of Bi2MoO6/g-C3N4 (BM/CN) composite photocatalyst and Rhodamine B photodegradation studies. The composite photocatalysts have been characterized using XRD, TGA, FT-IR, UV–Vis, TRPL, SEM, TEM, XPS, electrochemical, and BET studies over g-C3N4, Bi2MoO6, and Bi2MoO6 (10–40 wt%) supported on g-C3N4 photocatalysts. The photocatalytic studies are performed using various composite photocatalysts of BM/CN show 30%-Bi2MoO6 supported on g-C3N4 (30BM/CN) exhibits maximum visible light activation for dye degradation with 3.6 and 2.4-fold higher rate of degradation than bare g-C3N4 and Bi2MoO6, respectively. Higher surface area, broad light absorption, enhanced lifetime, lower charge transfer and higher transient photocurrents of the composite photocatalysts compared to g-C3N4 and Bi2MoO6. Moreover, study is aided with scavenger tests to support the proposed mechanism.The increased photoactivity of 30BM/CN is due to the synergistic interplay of improved charge generation and a reduction in the electron-hole (e−/h+) recombination rate.

Fabrication and characterization of C–doped TiO2 nanoparticles for the photodegradation of organic dyes

A low-cost sol-gel method is used to synthesize C-doped TiO2 (C–TiO2) nanoparticles. Nanoparticles of undoped TiO2 and varying C weight percentages (4%, 6%, and 8%) of C–TiO2 are generated. XRD, FTIR, FESEM-EDS, UV–Vis DRS, PL, BET, and XPS are used to analyze the characteristics of all the nanoparticles. The EDS data indicate that the TiO2 lattice has been successfully doped with carbon. The band-gap energy of 6% C–TiO2 is shifted to 2.94 eV, as confirmed by UV–Vis DRS, resulting in improved visible-light absorption and, hence, increased photocatalytic activity by lowering the electron-hole recombination rate. Under natural sunlight irradiation, 6% C–TiO2 achieves a 91% removal efficiency of Rhodamine B (RhB) dye in 90 min and 84% removal efficiency of Congo Red (CR) dye in 30 min. A probable photodegradation pathway was estimated using the scavenger test, and the •O2 − and •OH radicals are recognized as potentially active species for RhB degradation.

Preparation of MWCNT/CoMn2O4 nanocomposite for effectual degradation of picric acid via peroxymonosulfate activation

In recent years, using nanomaterials based on multi-wall carbon nanotubes (MWCNT) through the activation of peroxymonosulfate (PMS) has attracted more attention to the degradation of organic pollutants. This research presented a new route for the synthesis of MWCNT/CoMn2O4 nanocomposite for the degradation of picric acid using advanced oxidation processes (AOPs). Firstly, CoMn2O4 nanoparticles were prepared and then loaded on MWCNT using ultrasonic waves. The results of various analyzes confirmed the successful loading of nanoparticles on carbon nanotubes. As the degradation process proceeds through oxidation processes, the high electronic conductivity of MWCNT and the active sites of Mn and Co in the nanocomposite play an essential role in activating PMS to generate reactive oxygen species (ROS). An investigation of the reaction mechanism in different conditions showed that the highest speed of picric acid decomposition in the presence of nanocomposite (98%) was in 47 min. However, the scavenger test showed that HO· and SO4·− radicals are more important in the degradation process. Meanwhile, the results showed that removing picric acid using MWCNT/CoMn2O4 was more effective than CoMn2O4 alone and confirmed the interaction effect of MWCNT nanotubes with AB2O4 nanocatalyst.

Facile synthesis of Ni-doped ZnS nanostructures and their photocatalytic activity to RhB

In this paper, pure ZnS and Ni-doped ZnS nanostructures (Ni–ZnS) were prepared by facile template-free hydrothermal method. The as-prepared Ni–ZnS was characterized by XRD, SEM, EDS, XPS, and UV–Vis DRS. The effects of different Ni doping amounts and hydrothermal reaction temperatures were investigated. The photocatalytic ability was evaluated for the degradation of Rhodamine B (RhB) under visible light irradiation. The results indicated that the doping of Ni effectively enhanced the photocatalytic activity of pure ZnS. Ni–ZnS exhibited significantly enhanced photocatalytic properties, the reaction rate constant (0.01154 min−1) is higher than that of pure ZnS (0.00218 min−1). Carrier separation efficiency and charge transport efficiency were investigated by transient photocurrent response (TPS) and electrochemical impedance spectroscopy (EIS). Scavenger test was used to determine the role of active species, combining the analysis results of UV–Vis DRS, TPS, and EIS, accordingly the photocatalytic mechanism of Ni–ZnS was proposed.

Rapidly chemical preparation of Mn doped ZnO nanostructures for photocatalysis efficiency based on UV light system and mechanism insights

Through a facile chemical precipitation process, pure zinc oxide (ZnO) and various ratio of Mn-doped zinc oxide (Zn1-xMnxO) nanostructured materials were synthesized. The degradation of an azo dye acid orange 2 (AO-2) solution under UV light was investigated using the synthesized materials as photocatalysts. XRD, FTIR, DLS, FESEM, EDS, PL, BET, magnetic, TGA and UV–vis techniques were used to elucidate the structural, functional, particle, elemental, morphological, and optical aspects of the catalysts. The XRD and FESEM analysis showed the hexagonal ZnO structure and spherical shape of the ZnO nano-photocatalyst, respectively. The crystal sizes of Zn1-xMnxO are 27.40–38.31 nm. The optical band gap energy of Zn1-xMnxO are 2.53–3.10 eV. Under UV irradiation for 60 min, MZ-25 NPs demonstrated better degradation (100.0%) of AO-2 dye. The effect of various factors such as catalyst quantity, and pH of the dye solution on the rate removal was investigated. After 60 min of UV light irradiation, dye removal was obtained under ideal conditions (with catalyst loading of 3 mgL−1, and pH 4). The rate constant values of MZ-25 sample are determined to be 0.0219 min−1. The scavenging test reveals that ∙O2 − and ∙OH are responsible for the photo-degradation of AO-2 dye.

Fabricating of Pd and Ni bimetal modified halloysite nanotube composite and its application for photocatalytic degradation of tetracycline

Tetracycline (TC) is extensively employed as a broad-spectrum antibacterial agent, and its byproducts have been identified in a variety of water bodies, posing a significant risk to both aquatic ecosystems and human health. Among the prevalent techniques for treating water contaminants, photodegradation stands out. In this research, we synthesized a novel nanocomposite material, embedding bimetallic nanoparticles onto halloysite nanotubes (HNT) (Pd@Ni/N-HNT), aimed at photocatalytically degrading TC. The Pd@Ni/N-HNT demonstrated the capability to enhance the TC degradation efficiency to 100 % under visible light for a duration of 120 min, effectively doubling the performance of pure H2O2 degradation. The influence of pH levels in aquatic environments on the TC degradation efficiency was explored. Through electron spin resonance (EPR) studies and free radical scavenging tests, it was verified that •O2− and h+ are pivotal in the degradation process. Furthermore, Pd@Ni/N-HNT showcased effective degradation capabilities in both tap and river water, achieving degradation rates exceeding 70 % in 120 min and 95 % in 180 min, respectively. This investigation not only sheds light on the potential of utilizing Pd@Ni/N-HNT as a potent catalyst for the photocatalytic degradation of TC but also offers a comprehensive framework for the future development of nanomaterials aimed at the environmental remediation of organic pollutants. The findings herein provide a pivotal reference and guide for advancing the application of nanotechnology in the purification of water, thereby contributing to the safeguarding of aquatic ecosystems and public health.