Photocatalytic Degradation Ability Research Articles

High performance Zn–Al LDH modified forward osmosis membrane with antibacterial, anti-membrane fouling, and photocatalytic degradation ability

Forward osmosis membrane has shown great potential in the fields of seawater desalination and sewage treatment. However, the concentration polarization phenomenon and membrane fouling in the water treatment process greatly reduce the water treatment performance and restrict its application. To address these challenges, we employed a pre-buried seed-in-situ growth method to facilitate the Zn–Al layered double hydroxide (Zn–Al LDH) growth on the thin nanofiber membrane, and use it as the support layer for the preparation of a Zn–Al LDH modified forward osmosis membrane. Studies have shown that the introduction of Zn–Al LDH significantly improves the water treatment efficiency of the forward osmosis membrane (In Al-DS mode, the water flux increased by 87.5 %, up to 50.50 LMH, with a low specific salt flux of 0.13 g L−1). It also exhibits exceptional antibacterial, anti-membrane fouling, and photocatalytic degradation properties. This research presents a novel approach for the development of advanced high-efficiency forward osmosis membranes.

Superhydrophilic PANI/Ag/TA@PVDF Composite Membrane with Antifouling Property for Oil-Water Separation.

The current membrane materials used for oil-water separation suffer from low separation efficiency and poor durability, and membrane contamination is also a key issue that must be addressed urgently. In this paper, a superhydrophilic PANI/Ag/TA@PVDF composite membrane with PANI-Ag NPs heterojunction structure was prepared via chelation and reduction of Ag+ by tannic acid (TA) and in situ growth of hydrochloric acid-doped polyaniline (PANI). TA endows the prepared composite membrane with excellent superhydrophilicity and underwater oleophobicity, remarkable oil-water separation capacity (the separation efficiency of more than 97% for soybean oil), and extraordinary antifouling properties. Notably, the range of photodegradation is expanded from UV to visible light by the construction of a Schottky heterostructure between PANI and Ag NPs, the photocatalytic degradation ability of composite membrane for organic pollutants has been improved obviously, and the degradation efficiency for crystal violet (CV) is 97.9%. Considering these merits, the PANI/Ag/TA@PVDF composite membrane provides an effective strategy to overcome the shortcomings of existing membrane materials, presenting enormous potential in the treatment and purification of oily wastewater.

Construction of direct-Z-scheme heterojunction photocatalyst of g-C3N4/Ti3C2/TiO2 composite and its degradation behavior for dyes of Rhodamine B

Direct-Z-scheme g-C3N4/Ti3C2/TiO2 photocatalyst with giant internal electric field were prepared by one-step aqueous sonication self-assembly method using g-C3N4 and MXene of Ti3C2 as the source materials. The chemical composition and structure of the catalysts was characterized by FT-IR, XRD, SEM, TEM and XPS. The XPS characterization indicated that Ti3C2 was partially oxidized to TiO2 during the composite process. As a result, an efficient direct-Z-scheme heterojunction structure consisting of the g-C3N4 and TiO2 with Ti3C2 as an electron bridge was constructed. The photocatalytic performance of the prepared catalysts was evaluated by degrading the rhodamine B (RhB) wastewater. Compared with the single g-C3N4, the g-C3N4/Ti3C2/TiO2 composite photocatalyst exhibited efficient and stable photocatalytic degradation ability, with a degradation efficiency as high as 99.2% for RhB under optimal conditions (2% Ti3C2, pH=3). The high degradation performance of g-C3N4/Ti3C2/TiO2 for RhB was attributed to the combination of Ti3C2, TiO2, and g-C3N4 components, forming a direct-Z-scheme heterojunction with a high-speed electron transport channel structure. The role of Z-scheme heterojunctions in electron transport is verified by photoelectrochemical characterization, along with photoluminescence (PL). Our research provides a simple method to design photocatalysts by constructing direct-Z-scheme electron transport channels for highly efficient treatment of dye wastewater.

Study of the Structure and Photocatalytic Degradation Ability of a New Complex Manganese

Study of the Structure and Photocatalytic Degradation Ability of a New Complex Manganese

Green synthesis of gold nanoparticles using macroalgae Halimeda macroloba extract and their photocatalytic degradation of methylene blue and methyl orange

AbstractGreen synthesis of gold nanoparticles (AuNPs) is gaining attention of researchers because of their varieties of biomedical and environmental applications. This study reported the novel eco‐friendly synthesis of AuNPs using green macroalgae Halimeda macroloba (HM) extract and evaluate their photocatalytic potential. The green synthesized H. macroloba mediated gold nanoparticles (HM‐AuNPs) was characterized using UV–visible spectrophotometry, Fourier‐transform infrared (FT‐IR) spectroscopy, transmission electron microscope (TEM), scanning electron microscope‐energy dispersive spectroscopy, x‐ray photoelectron spectroscopy (XPS), and particle size distribution (PSD) anlaysis. The UV–visible spectrum shows a sharp intense plasmonic resonance peak at 543 nm. The bioactive compounds present in HM were primarily responsible for the biological reduction of gold ions validated by FT‐IR analysis. XRD analysis proved the crystalline face centered cubic structure of the HM‐AuNPs. The average particle size of 18.72 nm and morphological evidences were obtained from the images from TEM. The metallic form of biosynthesised HM‐AuNPs was confirmed by XPS results with a distinctive binding energy. The photocatalytic degradation ability of the green synthesized HM‐AuNPs was investigated against the methylene blue (MB) and methylene orange (MO) dyes under sunlight irradiation. The HM‐AuNPs exhibited 97.23% and 89.91% photocatalytic activity against MB and MO after 90 min of exposure to sunlight, respectively. The overall results of this research indicate that H. macroloba mediated HM‐AuNPs can be used as an effective option for the degradation of industrial dyes.

NOx degradation by cement mortar containing B-TiO2/MgAl-CLDH under visible light: Experimental and modeling

In this paper, an advanced photocatalyst, B-TiO2/MgAl-CLDH, was synthesized and applied in cement mortar. The photocatalytic NOx degradation ability of cement mortar containing B-TiO2/MgAl-CLDH under different initial NOx concentrations and flow rates was investigated. The results show that B-TiO2/MgAl-CLDH has stronger visible light absorption, lower recombination rate of electron-hole pairs and narrower optical band gap than commercial nano-TiO2 (P25), resulting in enhanced NOx removal efficiency. Specifically, the maximum NOx degradation ratio of B-TiO2/MgAl-CLDH is 23.4% within 30 min, which is about 5 times that of P25. For photocatalytic mortar, the initial NOx concentration (from 1.0 ppm to 2.0 ppm) and flow rate (from 1 L/min to 3 L/min) were positively correlated with NOx removal amount, while negatively correlated with NOx removal ratio. Based on the internal molecular diffusion properties of NOx, Langmuir-Hinshelwood and the power law kinetic models were used to predict the NOx degradation ability of photocatalytic mortar. The modeling of NOx degradation process presents a reliable prediction of the NOx removal ability of photocatalytic mortar, serving as a valuable tool for assessing the mortar’s NOx removal effectiveness for policymakers and engineers.

Biogenic synthesis, characterization and photocatalytic activity of cerium nanoparticles for treatment of dyes contaminated water

In this study, Murraya Koenigii leaf extract mediated cerium oxide nanoparticles (Ce-NPs) were synthesized using an eco-friendly approach. The surface morphology, elemental composition, surface functional groups, crystal structure and thermal stability of the synthesized Ce-NPs were examined using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-Ray diffraction (XRD) and thermogravimetric (TGA) analysis. The synthesized Ce-NPs were evaluated for their photocatalytic activity with respect to degradation of methylene blue dye (MBD) and acid orange-7 dye (AO7D) aqueous solution in the presence of sunlight. The dye degradation activity of the developed Ce-NPs was analyzed by the analysis of absorbance in treated and untreated aqueous dyes solution using UV–Vis spectrophotometer. The result of the study inferred that Ce-NPs have promising photocatalytic degradation ability (>98 %) for both AO7D and MBD (concentration = 10 mg L−1 of each dye) within 100 min exposure to sunlight.

Comprehensive investigations into the synergy of S-scheme heterojunction between nitrogen-doped ZnO nano-rods and g-C3N4 nanosheets for improved photocatalytic degradation

In this work, N-ZnO nanorods decorated with 2D g-C3N4 prepared by hydrothermal synthesis are studied for their synergistic effect in regard to enhanced photocatalytic activity. The synthesized material is characterized with XRD, FESEM, EDX, TEM and HR-TEM to perform the structural, morphological and elemental analysis along with XPS and FTIR for tracking sample purity and to study the elemental composition on the surface of the material; UV–Visible spectroscopy and PL spectroscopy for investigating the optical properties, bandgap calculation and to inquire about the defects in the structure. N-ZnO/g-C3N4 shows remarkable photocatalytic MB degradation ability upon solar irradiation which is 2.8 and 1.2 times exceeds than pristine ZnO and g-C3N4, attributed to the s-scheme mechanism for charge migration. The construction of s-scheme heterojunction among N-ZnO and g-C3N4 generates an internal electric field that saliently promotes charge separation at the interface. Furthermore, post-stability test for 8 cycles with XRD and FTIR analysis to verify the material integrity is presented. The scavenger experiments revealed the involved active species. This research does seem to pique interest in the creation of cutting-edge photocatalysts that utilize the solar spectrum to remove harmful organic dyes from water.

A magnetically recyclable Fe3O4/ZnIn2S4 type-II heterojunction to boost photocatalytic degradation of gemifloxacin

In this study, a magnetic recyclable Fe3O4/ZnIn2S4 flower-like heterojunction photocatalyst was successfully constructed by means of a hydrothermal method. It not only exhibited an enlarged the specific surface area, but also improved the absorption of visible light, which greatly enhanced the photocatalytic degradation ability. The results of the photocatalytic activity tests showed that the maximum rate (0.01903 min−1) of degradation of gemifloxacin (GMF) by Fe3O4/ZnIn2S4 was significantly increased by 1.67 and 23.79 times compared with those of pure ZnIn2S4 and Fe3O4, respectively. Based on the difference in Fermi energy levels between ZnIn2S4 and Fe3O4 and the electron gain/loss of the elements of the Fe3O4/ZnIn2S4 heterojunction, a type-II electron transfer mechanism was proposed to illustrate that the Fe3O4/ZnIn2S4 heterojunction improved the photocatalytic activity by promoting the separation and transfer ability of the photogenerated carriers. By combining liquid chromatography mass spectrometry -ion trap-time of flight technology and a condensed Fukui function, a possible degradation mechanism of GMF was proposed.

Oxygen Functionalized Graphitic Carbon Nitride for Photocatalytic Degradation of Dye

Photocatalyst such as graphitic carbon nitride (g-C3N4) is being studied intensively due to its ability in photocatalysis. g-C3N4 is a metal-free semiconductor photocatalyst with a bandgap of approximately 2.7 eV which contributes to its good visible light harvesting ability. In this work, bulk g-C3N4 was produced via pyrolysis of melamine in a muffle furnace. Functionalized g-C3N4 with improved properties was synthesized via modified Hummers method. The powdered form of functionalized g-C3N4 were characterized using SEM and EDX to identify its physiological properties. The result showed that the introduction of oxygen into g-C3N4 is proven by the increased content of oxygen in the functionalized g-C3N4 upon oxidation using Hummers method. Besides, exfoliation of g-C3N4 to smaller particle size observed from the SEM images. Then, the phototcatalytic performances of the bulk g-C3N4 and functionalized g-C3N4 were evaluated by degrading of Methylene Blue (MB) dyes under LED light irradiation. The result revealed that the bulk g-C3N4 has a higher efficiency in removal of dyes (56.40 % in 150 minutes) than the functionalized g-C3N4 (22.60 % in 150 minutes) which indicates that it has a better photocatalytic degradation ability, which possibly due to the destruction of compound structure under strong acid treatment.

A synergistically enhanced photocatalytic 2D MXene nanofibrous composite membrane for wastewater treatment

Despite notable advancements in membrane technology, the efficacious separation of intricate oily wastewater via membrane filtration continues to pose formidable barriers for the industry. Recent methods, encompassing the integration of two-dimensional (2D) nanosheets to improve membrane properties, have demonstrated a propensity for encountering challenges like swelling, fouling, and operational instability during the filtration process. Herein, we meticulously designed a polyvinylidene fluoride (PVDF) nanofibrous membrane (NFM) tailored with a 2D nanostructured composite of MXene nanosheets and TiO2 nanofrost for the pioneering treatment of intricate oily wastewater. The resultant membrane exhibited remarkable separation performance concerning surfactant-stabilized emulsions while maintaining excellent water permeability. Additionally, the membrane demonstrated outstanding antifouling and self-cleaning capabilities while also showing high efficiency in removing metal cations from oily wastewater, which may be related to the intercalation of TiO2 nanofrost. Furthermore, in response to the synergistic impact of MXene nanosheets and TiO2 nanofrost, the TiO2@MX-PVDF NFM presented exceptional photocatalytic degradation ability for the breakdown of organic pollutants under visible irradiation. Consequently, present work unveils an advanced, reliable and remarkably efficient approach for developing a 2D multifunctional MXene composite membrane designed specifically for treating complex oily wastewater.

2D vermiculite nanofiltration membrane with TiO2 nanoparticles as versatile intercalator for enhanced water purification

Two-dimensional (2D) materials membranes have gained widespread attention for their unique structure and outstanding separation performance. Herein, we developed a 2D vermiculite nanofiltration (TiO2@VMT) membrane using TiO2 nanoparticles as versatile intercalator. The interlayer spacing of vermiculite nanosheets was tuned from 1.352 ± 0.002 nm to 1.424 ± 0.004 nm. As a result, the optimized TiO2@VMT membrane exhibited high water flux of 261 L m−2 h−1, which was 14 times higher than that of vermiculite membrane, simultaneously showed excellent rejections (>98 %) for various organic dyes (molecular weight >374 g mol−1). Due to the photocatalytic degradation ability of TiO2 nanoparticles towards organic foulants, the TiO2@VMT membrane possessed excellent anti-fouling performance, with a flux recovery rate exceeding 90 % under UV radiation after three cycles of filtration experiment using oil-in-water emulsion and BSA solution as model foulants. Accordingly, our work may offer a possible route for the development of 2D nanofiltration membrane for efficient water purification.

Rational Design of Environmentally Friendly Carbon Nanotube Embedded Artificial Vesicle‐Structured Photocatalysts for Organic Pollutants Degradation

AbstractPhotocatalytic degradation is one of the most promising methods for addressing environmental issues without introducing pollution sources. Nonetheless, the majority of works are devoted to explore high‐efficiency semiconductor photocatalysts, but the potential environmental risks in their application are usually neglected. In this work, an environmentally friendly vesicle‐structured photocatalyst is rationally designed by employing magnetic layered double oxide‐hollow spheres@antimony tin oxide as a core, phospholipid as membrane, and carbon nanotubes (CNTs) as channels, yielding a multi‐structural material with robust organic pollutants photocatalytic degradation and mineralization ability. Materials characterization, computational modeling, and cytotoxicity tests suggest that under visible light irradiation, photogenerated charges can be rapidly generated and transfer in the core composite, and H2O2 can be effectively activated to generate hydroxyl radical for organic pollutants rapid degradation. The construction of phospholipid membranes and embedded CNTs not only maintains the photodegradation performance of the material, but also restrains its environmental risk. Such a synthetic approach advances the development of bionic photocatalytic materials.

Acetylene black doped zinc oxide (AB-ZnO) nanorods activated peroxydisulfate for degradation of dyeing wastewater

Zinc oxide (ZnO) nanorods and acetylene black (AB) doped ZnO (AB-ZnO) nanorods were fabricated by the hydrothermal method, and characterized by various methods (XRD, EDS, SEM, BET, FT-IR, Zeta potential). The photo-catalytic degradation ability of AB-ZnO/PDS/vis system on simulated dyeing wastewater was studied with methyl orange (MO) as the target pollutant. The effects of AB doping ratio, AB-ZnO dosage, PDS concentration, initial pH, and temperature on MO degradation were comprehensively investigated. The AB-ZnO/PDS/vis system has a wide range of pH applications from 3 to 11. The prepared material of AB-ZnO had excellent stability that the degradation efficiency on MO remained above 90 % after 4 cycles. The theoretical optimal removal rate of MO was 98.59 % when AB-ZnO dosage was 1.0 g/L, PDS concentration was 2.0 mmol/L, initial pH was 5, and temperature was 50 °C. Furthermore, degradation kinetic model, the orthogonal experiment and the degradation mechanisms were elaborated. By using methanol and tert-butanol as free radical inhibitors, it was confirmed that SO4·- and ·OH were the main active free radicals in AB-ZnO/PDS/vis system.

The Study on the Novel Complex Structure and Photocatalytic Degradation Ability of Manganese

The vigorous development of the dye industry has led to increasingly serious harm to the water environment. Currently, dye wastewater has become one of the most difficult industrial wastewater to degrade. Therefore, how to treat dye wastewater in a green and economical manner is receiving increasing attention. Photocatalytic technology has attracted much attention in the treatment of dye wastewater due to its advantages such as fast speed, no selectivity, and complete degradation. However, the current application of traditional photocatalytic materials is greatly limited due to the high recombination rate of photo generated charge carriers and the difficulty in separating and recovering powder catalysts. Therefore, it is of great significance to study the preparation and application of visible light response catalysts with high catalytic activity. The structure of the complex was characterized by X-ray single crystal diffractometer, and the manganese complex was determined by UV and IR spectroscopy, which was then used for the photocatalytic degradation of methyl orange solution.

Effective approach to improve photocatalytic dye degradation ability of ZnO based nanopowder: simultaneous cationic and anionic doping, and enzyme coupling

Effective approach to improve photocatalytic dye degradation ability of ZnO based nanopowder: simultaneous cationic and anionic doping, and enzyme coupling

Bifunctional S-scheme CdSSe/Bi2WO6 heterojunction catalysts exhibit generalized boosting performance in photocatalytic degradation of tetracycline hydrochloride, photoelectrochemical and electrocatalytic hydrogen production

In this work, by a simple method of hydrothermal synthesis, the CdSSe/Bi2WO6 S-scheme heterojunction catalyst is successfully obtained and the results are verified by XPS, EPR, band structure, etc. The S-scheme heterojunction can maintain the strong redox potential energy position of both catalysts, and adjust the electron transfer path to improve the electron-hole separation efficiency, and thus improve the charge transfer efficiency. CdSSe has a high conduction band (−1.13 eV) and a narrow bandgap width (1.59 eV), exhibiting good light absorption characteristics and reduction ability; the valence band position of Bi2WO6 is much low (2.58 eV), indicating good oxidation activity. This heterojunction has excellent oxidation and reduction capabilities and exhibits multifunctional catalysts. Its photocatalytic degradation ability of tetracycline hydrochloride is 2.2 times that of the original CdSSe, while its photoelectrochemical activity is 11 times that of CdSSe, reaching a photocurrent density of − 2.081 mA/cm2 at 0 V (vs. RHE). The electrocatalytic activity of its hydrogen evolution has also been enhanced. This study developed a design strategy for a novel bifunctional S-scheme heterojunction catalyst.

Fabrication of multifunctional g-C3N4-modified Au/Ag NRs arrays for ultrasensitive and recyclable SERS detection of bisphenol A residues.

Monolayer g-C3N4-modified Au/Ag nanorods (g-C3N4/Au/Ag NRs) array is fabricated as a dual-function platform with high surface-enhanced Raman scattering (SERS) response and excellent photocatalytic degradation ability for bisphenol A (BPA) residues. FDTD simulation results of Au/Ag NRs proves that the electromagnetic field intensity is significantly enhanced at the gap of Ag NRs and Au NPs and the protrusion of Au NPs, which endows the arrays with excellent SERS activity. The arrays exhibit high sensitivity for rhodamine 6G (R6G) (LOD = 1.1 × 10-11 mol/L) and high SERS enhancement (EF = 9.2 × 107). In addition, the g-C3N4/Au/Ag NRs could degrade ˃90% of BPA adsorbed on the substrate surface within 140 min under visible light irradiation, and maintains its SERS activity after repeated use for 4 times. The dual-function platform with high SERS response and excellent recycling capability is proved to be reliable and is very promising for monitoring of BPA residues in food.

Simultaneous preparation of ZnO/rGO composites through Zn(OH)2 decomposition and graphite oxide reduction and their photocatalytic properties.

ZnO/reduced graphite oxide (rGO) composites were simultaneously prepared by the thermal reduction of graphite oxide (GO) and the decomposition of Zn(OH)2. The samples were characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, photoluminescence, and DRS. Results indicate that Zn(OH)2 was heated and decomposed into ZnO at a low temperature (200 ℃), while GO was reduced to graphene. The synthesized ZnO particles were small and loaded on graphene layers. The ZnO/rGO photocatalysts exhibited excellent photocatalytic activity against methylene blue (MB) under simulated sunlight irradiation. The ZnO/50% rGO photocatalyst showed the best MB photodegradation rate of up to 99.7% within 3min. Synchronous reaction provided an efficient, simple, and fast preparation method for ZnO/rGO composites, with an excellent solar photocatalytic degradation ability.

PVDF Nanofiber Modified with ZnO Nanowires/Polydopamine for the Treatment of Sewage Containing Heavy Metals, Organic Dyes, and Bacteria.

In various countries worldwide, the issue of wastewater contamination poses a significant threat due to its intricate composition of heavy metals, organic dyes, and microorganisms, thereby complicating the purification process. Consequently, researchers have expressed considerable interest in materials capable of eliminating organic, heavy metal, and microbial pollutants. This study focuses on the fabrication of a water purification membrane (PDA/ZnO-NWs/PVDF) with a hierarchical structure and the ability to remove multiple pollutants. The membrane was created by modifying poly(vinylidene fluoride) (PVDF) nanofiber with zinc oxide nanowires (ZnO-NWs) and reinforcing it with polydopamine (PDA). The experimental results demonstrate that the PDA/ZnO-NWs/PVDF membrane exhibits a range of functionalities, including long-lasting superhydrophilicity, Cu(II) adsorption, photocatalytic degradation, and antibacterial ability. The manipulation of the DA synthesis procedure allows for the adjustment of the wettability, adsorption, and photocatalytic and antibacterial activities of the PDA/ZnO-NWs/PVDF composite. According to the Langmuir isotherm, the maximum Cu(II) adsorption capacity of the PDA/ZnO-NWs/PVDF membrane is determined to be 65.75 mg/g, which is significantly higher (27.26 mg/g) than that of the ZnO-NWs/PVDF membrane (38.49 mg/g). The PDA/ZnO-NWs/PVDF composite exhibited a notable degradation capacity toward rhodamine B under natural sunlight, reaching a maximum of 5.97 mg/g. Additionally, the degradation rate achieved during daylight hours was as high as 90.42%. Furthermore, the antibacterial efficacy of the PDA/ZnO-NWs/PVDF composite against both Gram-positive and Gram-negative bacteria approached 100%. This work presents a promising approach for the treatment of wastewater containing various coexisting contaminants.