Effect Of Photodegradation Research Articles

Study of Natural Herbal Dyes Photodegradation Effect to Optical Properties for Dye-Sensitized Solar Cells

The stability of natural dyes for use in dye-sensitive solar cells is known from their photodegradation characteristics. Photodegradation effects using artificial light radiation on natural herbal dyes were investigated. Three natural herbal dyes, namely Fagraea acuminatissima, sappanwood, and kulit setong were used in this study. The stability of the natural herbal dyes under artificial light radiation was studied. The optical properties of the natural herbal dyes as indicators of their stability were characterized using FTIR and UV-VIS absorption. Stability testing of natural herbal dyes was conducted in a room with artificial lighting for 5 weeks. Observations of changes in their optical properties were performed weekly. It can be seen that all three natural herbal dyes contained anthocyanin. In addition to anthocyanin, Fagraea acuminatissima and sappanwood also contain chlorophyll. In contrast, the kulit setong contains beta-carotene in addition to anthocyanin. The degradation percentage showed that sappanwood degrade to all of its pigments. While an increase occurred in the chlorophyll peak of Fagraea acuminatissima and the beta-carotene peak of kulit setong. This clearly shows that Fagraea acuminatissima has the highest stability, and potentially increases the efficiency of solar cells.

A highly efficient bifunctional Z-scheme photocatalyst with spatially-separated and synergistically-enhanced adsorption and photodegradation

Adsorption-enhanced photodegradation and its unique kinetics are studied in a bifunctional Z-scheme photocatalyst. MoS2 nanoflakes are selectively deposited on the edges of TiO2 nanosheets to form an edge-connected MoS2/Au/TiO2 Z-scheme heterostructured photocatalyst, with rapid pollutant adsorption on MoS2 surfaces and subsequent degradation on TiO2 surfaces. The spatial separation of two components promotes the formation of Z-scheme charge transfer and maintains the effective bifunctions. As a result, the optimal system (10 %MoS2/Au/TiO2) could remove up to 90 % of pollutant within 30 mins and subsequently eliminates the residue to a level below ppm. Detailed study on the synergistic effects of adsorption and photodegradation indicates that the system exhibits an adsorption-enhanced photodegradation due to the pre-concentration effect by MoS2 and a surface-diffusion mechanism of pollutant molecules migrating from MoS2 to TiO2. This work provides a novel strategy in designing the bifunctional photocatalyst for effective water treatment.

Facile preparation of three-dimensional copper foam incorporated with Au/CuO nanorods as a durable, reusable and efficient SERS substrate

An exceptionally durable and recyclable three-dimensional copper foam (CF) modified CuO nanorods with Au nanostructures on its surface is noticeable for the application in surface-enhanced Raman scattering (SERS). The utilization of CF as a 3D frame substrate allowed for the advancement of its beneficial characteristics, such as an increased surface-active area resulting from its high porosity and superior chemical/physical stability. By thermally oxidizing CF at a temperature of 500 °C, CuO nanorods were fabricated directly onto CF to exploit its advantageous properties, such as its high surface-active area and photodegradation effect. Following that, Au nanostructures were deposited onto the surfaces of CuO nanorods via photoreduction. The purpose of incorporating Au nanostructures was to optimize the SERS phenomenon, since Au exhibits high SERS efficiency and excellent surface stability. The Au/CuO@CF SERS substrate demonstrated the capability to measure MB at a concentration of 0.1 nM. Meanwhile, the recyclability of the Au/CuO@CF was evaluated by subjecting it to UV irradiation three times while utilizing MB samples. Subsequently, the Au/CuO@CF substrate's physical durability was evaluated via sandpaper abrasion test. In addition to confirming the long-term usability, the Au/CuO@CF demonstrated its resilience by maintaining good measurement performance even after being subjected to ambient air for up to 25 days.

Highly efficient defluorination of perfluorooctanoic acid by a BiOCl-ND photocatalyst: Enhanced charge transfer and synergistic mechanism

Considerable attention has been given to the control of perfluorooctanoic acid (PFOA) environmental pollution due to its degradation resistance and potential risks. In this study, Bismuth oxychloride based nanodiamond (BiOCl-ND) composite materials were successfully synthesized by using hydrothermal method. The complete decomposition of PFOA and a high defluorination ratio of 74.6% by BiOCl-ND 10:1 was obtained under UV light irradiation within 60 min, and the composite's degradation rate constant was nearly 3.8 times than that of pure BiOCl. It was demonstrated that critical roles played in PFOA degradation were photogenerated holes (h+) and superoxide radicals (·O2−). A synergistic effect between BiOCl and ND and the heterostructure was revealed, the differences of the energy band structure between BiOCl and ND reduced the recombination of photogenerated e−-h+ and enhanced the charge transfer. In this process, a large number of h+ with oxidizing properties and·O2− generated from both BiOCl and ND played a critical role, and oxygen vacancies (OVs) also participated in the reaction as active species and contributed to electron transfer. Additionally, the photocatalytic decomposition intermediates of PFOA and the release of fluorine ions were analyzed to verify the effective defluorination of PFOA, and the results confirmed a gradual decrease in the toxicity of the reaction matrix during PFOA degradation. Hence, these results might provide insights for the development of photocatalysts to improve the photodegradation effect of PFOA in water.

Self-Assembly of Nanovesicles for Enhanced Adsorption and Efficient Photodegradation of 2,4,6-Trichlorophenol.

The compound 2,4,6-trichlorophenol poses significant risks to both the aquatic environment and human health. Its inherent persistence and stability present challenges in achieving complete purification, thus warranting its inclusion as a priority pollutant. The present study reports the development of an amphiphilic small-molecule compound that self-assembles into nanovesicles exhibiting remarkable adsorption and photodegradation capabilities. Through the synergistic effects of hydrogen bonding, van der Waals forces, π-π interactions, and electrostatic interactions, these vesicles efficiently adsorb 2,4,6-trichlorophenol from aqueous solutions within 1 min while demonstrating exceptional environmental stability and broad applicability. Upon self-assembly into vesicles, not only are more adsorption sites exposed, but charge separation and migration within the vesicles are also facilitated. Through the synergistic effects of adsorption and photodegradation, complete removal of 2,4,6-trichlorophenol in aqueous solution can be achieved within 8 h while exhibiting excellent recycling capability. This approach offers a viable strategy for designing and synthesizing pure organic photodegradable materials.

Recent Advances in Magnetic Feˣ⁺/TiO₂ Microfibers for Wastewater Treatment as Climate Change Mitigation

Chemical dyeing and finishing processes used in the clothing and textile industries are among the main contributors that can increase the impact of climate change. Photocatalysis using nanosized titanium dioxide (TiO2) has been continuously developed as a promising technology for purifying dye wastewater into simpler and environmentally friendly components. In addition, the decoration of iron cations (Fe2+) and (Fe3+) increases the reusability of the photocatalyst due to their magnetic properties, which are easy to collect for the recycling process. Magnetic Fex+/TiO2 microfibers have been successfully prepared using a hydrothermal method using titanium dioxide in an alkaline solution. Cations were added into the solution with the different molar ratios of Ti/Fex+ to produce Fe2+/TNW and Fe3+/TNW, respectively. Photocatalysis activity test using magnetic Fex+/TNW was carried out using methylene blue in a reactor equipped with an incandescent bulb lamp representing solar light. The results showed that adding the cations resulted in a new shape of palm tree leaves, like titanate microfibers. Controlling the cation’s molar ratio produces the magnetic Fex+/TNW with a 50-150 µm length. SEM images of each material presented the uniformly elongated shape and aggregated on one side morphology. In addition, paramagnetic properties indicate that magnetic Fex+/TNW can be easily separated from the dispersion in less than 1 minute using an external magnet. A photocatalysis activity test of magnetic Fex+/TNW was performed by calculating the percent degradation of methylene blue with variations in irradiation time in visible light conditions. The result showed the effectiveness of photodegradation of methylene blue was significantly increased in materials with 3.3 molar ratios of both Ti/Fe2+ and Ti/Fe3+ with a percent degradation reaching 79% and 70%, respectively, in 5 hours. In conclusion, magnetic Fex+/TNW is introduced as an alternative dye wastewater treatment technology that has reusable properties and works well on sustainable energy sources of solar light.

Effects of photodegradation on the composition characteristics and metal binding behavior of sediment-derived dissolved organic matter (SDOM) in nansi lake, China

Sediment-derived dissolved organic matter (SDOM) is instrumental in the cycling of nutrients and heavy metals within lakes, influencing ecological balance and contaminant distribution. Given the influence of photodegradation on the alteration and breakdown of SDOM, further understanding of this process is essential. In this research, the properties of the SDOM photodegradation process and its metal-binding reactions in Nansi Lake were analyzed using the EEM-PARAFAC and 2D-SF/FTIR-COS techniques. Our study identified three sorts of humic-like components and one protein-like component in SDOM, with the humic-like material accounting for 71.3 ± 5.19% of the fluorescence intensity (Fmax). Photodegradation altered the abundance and structure of SDOM, with a 41.6 ± 5.82% decrease in a280 and a 29.1 ± 9.31% reduction in Fmax after 7 days, notably reducing the protein-like component C4 by 54.0 ± 5.17% and the humic-like component C2 by 48.5 ± 2.54%, which led to SDOM being formed with lower molecular weight and aromaticity. After photodegradation, the LogKCu values for humic-like and protein-like substances decreased (humic-like C2: LogKCu: 1.35 ± 0.10–1.11 ± 0.15, protein-like C4: 1.49 ± 0.14–1.29 ± 0.34), yet the preferential binding sequence of protein-like materials and specific functional groups with Cu2+ such as aliphatic C-OH, amide (I) C=O and polysaccharide C-O groups remained unaltered. Our results enhance the knowledge of light-induced SDOM alterations and offer insights into SDOM-metal interactions in aquatic ecosystems.

Achieve efficient photocatalytic degradation of multiple pollutants by constructing WO3-x/BiOBr heterojunctions with hierarchical structure on carbon fibre cloths

Photocatalytic technology has shown excellent application potential in water pollution treatment, but the design and preparation of reusable photocatalysts that can degrade multiple pollutants with high efficiency is a major difficulty limiting the development of this field. Herein, the CF/WO3-x/BiOBr heterojunctions with hierarchical structures were synthesized via a two-step hydrothermal method, in which sheet BiOBr with high-efficiency {001} exposed crystal plane self-assembled into flower-like structure. Due to the unique microstructure control and suitable energy band structure matching, the CF/WO3-x/BiOBr-2.5 M has shown excellent photodegradation effect on a variety of pollutants at the same time (91.2 % for RhB dye, 71.5 % for TCH antibiotic and 88.2 % for Cr(VI) heavy metal pollutant). The synthesis of WO3-x/BiOBr heterojunctions enabled an efficient redox reaction, which facilitated the effective separation and transport of electron-hole pairs. Overall, the results provide a novel approach to designing cloth-based photocatalytic systems with unique structures capable of degrading multiple pollutants.

Microplastics and Antibiotics in Aquatic Environments: A Review of Their Interactions and Ecotoxicological Implications

Microplastics and antibiotics are two significant emerging pollutants found together in water bodies, raising concerns about their mutual effects. This review delves into how microplastics and antibiotics interact in aqueous environments and the ecotoxicological implications of such interactions, particularly the bioavailability of antibiotics and the prevalence of antibiotic-resistance genes. It outlines that antibiotics attach to microplastics primarily through hydrophobic, hydrogen-bonding, and electrostatic interactions. Other bonds, comprising halogen bonding, cation−π interaction, and negative charge-assisted hydrogen bonds, may also be involved to better explain antibiotic adsorption patterns. The adsorption of antibiotics to microplastics often follows the pseudo-second-order kinetic model and in some instances, the pseudo-first-order kinetic model. The common adsorption isotherms governing this interaction are the linear and Freundlich models. Microplastics may increase the biodegradation of adsorbed antibiotics due to the presence of antibiotic-degrading bacteria in the biofilms. They could also hamper direct photodegradation but facilitate indirect photodegradation of adsorbed antibiotics. However, their photodegradative effect remains inconclusive. Microplastics and antibiotics exhibit significant toxicity to algae, while their effects on fish and daphnia are less noticeable, suggesting that their combination does not pose an immediate threat to the well-being and proliferation of larger aquatic organisms. In some instances, microplastics reduce the deleterious effects of antibiotics on aquatic life. Microplastics serve as catalysts for gene transfer, enhancing the propagation of antibiotic-resistance genes in these ecosystems. This review underscores the importance of understanding the regulatory mechanisms of microplastics on antibiotic-resistance gene diversity, particularly at the gene expression level.

Green synthesis and studies on citrus medica leaf extract-mediated Au–ZnO nanocomposites: A sustainable approach for efficient photocatalytic degradation of rhodamine B dye in aqueous media

Abstract Incorporating narrow band gap oxide semiconductors and metals into zinc oxide (ZnO) nanostructures broadens the range of light sensitivity to include visible wavelengths. In this study, the photocatalytic degradation of rhodamine B (RhB) dye was studied as a model for environmental pollution in aqueous media. This study describes the use of photodegradation catalysts, including gold (Au), ZnO, and Au–ZnO nanocomposites (prepared in ratios of 90:10 and 95:5) using the extract of Citrus medica leaves. X-ray diffraction (XRD) findings have shown that ZnO nanoparticles (NPs) have a hexagonal wurtzite structure. Field emission-scanning electron microscopy findings have depicted that ZnO NPs have diverse shapes, including spherical, quasi-spherical, hexagonal, and anisotropic, with some clumping. Au exhibits consistent spherical shapes and sizes with even distribution. Au–ZnO (90:10) shows quasi-spherical NPs with interconnected spherical Au, forming a porous and uneven surface. Au–ZnO (95:5) has spherical gold nanoparticles (Au NPs) dispersed on a textured ZnO surface, with some clustering and size variation as evident from the transmission electron microscopy, atomic force microscopy, and diffuse reflectance UV-visible spectroscopy analysis. The characterization results have demonstrated the uniform distribution of Au across the ZnO lattice. Additionally, the XRD patterns confirmed the hexagonal wurtzite structure of ZnO. Furthermore, energy-dispersive analysis of X-ray (EDX)-mapping verified the inclusion of zinc, oxygen, and Au in the hybrid Au–ZnO nanocomposites and their effective distribution. The topological analysis revealed a rough surface for the generated nanostructures. By comparing the results of various techniques, EDX analysis using atomic and weight ratios confirmed the presence of oxygen and Au in the nanocomposite. Additionally, the surface area analysis (BET) test has reported that the adsorption and desorption of nitrogen follow a Type III isotherm. The presence of an H3-type hysteresis loop further confirms the mesoporous nature of the composites, which reports the presence of wedge-shaped pores. The Au–ZnO (90:10) nanocomposite exhibits a higher surface roughness compared to other composites. In addition, this UV-visible diffuse reflectance spectroscopy has enumerated the band gaps of various nanomaterials using UV-visible spectroscopy. Moreover, the analysis has unveiled that combining ZnO with Au NPs (doping) improved the photocatalytic performance of ZnO. This improvement is attributed to the formation of additional energy levels within the ZnO band gap due to the presence of Au ions. Experimental investigation of the breakdown of RhB dye under visible light irradiation revealed superior photocatalytic activity for the Au–ZnO (90:10) nanocomposite compared to both Au–ZnO (95:5) and pure ZnO and Au counterparts. Multiple experiments confirmed the effective photodegradation and removal of RhB dye from the aqueous medium using the nanocatalyst under visible light irradiation. Under optimal conditions (1.0 g·L−1 photocatalyst, 10 ppm RhB, and pH 10), 99% photodegradation efficiency was reached within 50 min of irradiation. Investigation of reactive species revealed that the increased effectiveness of photodegradation in Au–ZnO (90:10) stems from the presence of photogenerated holes and hydroxyl radicals. The study also analyzed the reaction kinetics and order, and the reusability of the best photocatalyst Au–ZnO (90:10)) was confirmed through five consecutive cycles, demonstrating its sustained effectiveness in photodegradation. These findings highlight the potential of Au–ZnO (90:10) nanocomposite as a promising material for photocatalytic degradation of organic dyes.

Allochthonous dissolved organic matter sources: effect of photodegradation on leaf leachates of invasive and native species from an Andean Patagonia catchment

Allochthonous dissolved organic matter sources: effect of photodegradation on leaf leachates of invasive and native species from an Andean Patagonia catchment

MXene/ZnS/chitosan-cellulose composite with Schottky heterostructure for efficient removal of anionic dyes by synergistic effect of adsorption and photocatalytic degradation

Nowadays, dye water pollution is becoming increasingly severe. Composite of MXene, ZnS, and chitosan-cellulose material (MX/ZnS/CC) was developed to remove anionic dyes through the synergistic effect of adsorption and photocatalytic degradation. MXene was introduced as the cocatalyst to form Schottky heterostructure with ZnS for improving the separation efficiency of photocarriers and photocatalytic performance. Chitosan-cellulose material mainly served as the dye adsorbent, while also could improve material stability and assist in generation of free radicals for dye degradation. The physics and chemistry properties of MX/ZnS/CC composite were systematically inspected through various characterizations. MX/ZnS/CC composite exhibited good adsorption ability to anionic dyes with adsorption capacity up to 1.29 g/g, and excellent synergistic effects of adsorption and photodegradation with synergistic removal capacity up to 5.63 g/g. MX/ZnS/CC composite performed higher synergistic removal ability and better optical and electrical properties than pure MXene, ZnS, chitosan-cellulose material, and MXene/ZnS. After compounding, the synergistic removal percentage of dyes increased by a maximum of 309 %. MX/ZnS/CC composite mainly adsorbs anionic dyes through electrostatic interactions and catalyzes the generation of •O2−, h+, and •OH to degrade dyes, which has been successfully used to remove anionic dyes from environmental water, achieving a 100 % removal of 50 mg/L dye.

Climate, litter quality and radiation duration jointly regulate the net effect of UV radiation on litter decomposition

Photodegradation via ultraviolet (UV) radiation is an important factor driving plant litter decomposition. Despite increasing attention to the role of UV photodegradation in litter decomposition, the specific impact of UV radiation on the plant litter decomposition stage within biogeochemical cycles remains unclear at regional and global scales. To clarify the variation rules of magnitude of UV effect on plant litter decomposition and their regulatory factors, we conducted a meta-analysis based on 54 published papers. Our results indicated that UV significantly promoted the mass loss of litter by facilitating decay of carbonaceous fractions and release of nitrogen and phosphorus. The promotion effect varied linearly or non-linearly with the time that litter exposed to UV, and with climatic factors. The UV effect on litter decomposition decreased first than increased on precipitation and temperature gradients, reaching its minimum in the area with a precipitation of 400–600 mm, and a temperature of 15–20 °C. This trend might be attributed to a potential equilibrium between the photofacilitation and photo-inhibition effects of UV under this condition. This variation in UV effect on precipitation gradient was in agreement with the fact that UV photodegradation effect was weakest in grassland ecosystems compared to that in forest and desert ecosystems. In addition, initial litter quality significantly influenced the magnitude of UV effect, but had no influence on the correlation between UV effect and climate gradient. Litter with lower initial nitrogen and lignin content shown a greater photodegradation effect, whereas those with higher hemicellulose and cellulose content had a greater photodegradation effect. Our study provides a comprehensive understanding of photodegradation effect on plant litter decomposition, indicates potentially substantial impacts of global enhancements of litter decomposition by UV, and highlights the necessity to quantify the contribution of photochemical minerallization pathway and microbial degradation pathway in litter decomposition.

Evaluating the single-shot photodegradation of optically-transparent bulk polymers under two-photon Raman-resonant laser irradiation in nanosecond regime (multiplex CARS test)

Laser-induced photodegradation of bulk optically-transparent polymers was probed under laser irradiation at two-photon Raman resonance. The photodegradation effect was inspected for organic polymers poly-(methyl methacrylate) and polystyrene by means of single-shot multiplex coherent anti-Stokes Raman scattering (CARS) spectroscopy performed with nanosecond-pulsed laser sources. Under such conditions of photoirradiation in the visible spectral range, the laser pulse intensity threshold for photodegradation of these polymers was determined.

New versus naturally aged greenhouse cover films: Degradation and micro-nanoplastics characterization under sunlight exposure

The understanding of microplastic degradation and its effects remains limited due to the absence of accurate analytical techniques for detecting and quantifying micro- and nanoplastics. In this study, we investigated the release of nanoplastics and small microplastics in water from low-density polyethylene (LDPE) greenhouse cover films under simulated sunlight exposure for six months. Our analysis included both new and naturally aged (used) cover films, enabling us to evaluate the impact of natural aging. Additionally, photooxidation effects were assessed by comparing irradiated and non-irradiated conditions. Scanning electron microscopy (SEM) and nanoparticle tracking analysis (NTA) confirmed the presence of particles below 1 μm in both irradiated and non-irradiated cover films. NTA revealed a clear effect of natural aging, with used films releasing more particles than new films but no impact of photooxidation, as irradiated and non-irradiated cover films released similar amounts of particles at each time point. Raman spectroscopy demonstrated the lower crystallinity of the released PE nanoplastics compared to the new films. Flow cytometry and total organic carbon data provided evidence of the release of additional material besides PE, and a clear effect of both simulated and natural aging, with photodegradation effects observed only for the new cover films. Finally, our results underscore the importance of studying the aging processes in both new and used plastic products using complementary techniques to assess the environmental fate and safety risks posed by plastics used in agriculture.

Photodegradation and Thermal Effects in Violet Phosphorus

AbstractViolet phosphorus (VP) is garnering attention for its appealing physical properties and potential applications in optoelectronics. A comprehensive investigation of the photodegradation and thermal effects of exfoliated VP on SiO2/Si substrates is presented. The degradation rate of VP is strongly influenced by the wavelength and exposure duration of light. Light illumination of VP above the bandgap leads to faster degradation, attributed to interactions with reactive oxygen species. Power‐dependent photoluminescence (PL) measurements at low temperature (T = 4 K) show neutral exciton (X0) and trion (T) intensities linearly increase with excitation power, while the energy difference between peak energies decreases. The T/X0 spectral weight ratio increases from 0.28 at 300 K to 0.69 at 4 K, suggesting enhanced T formation due to reduced phonon scattering. Temperature‐dependent Raman is used to investigate the phonon properties of VP. Tracking peak positions of 9 Raman modes with temperature, the linear first‐order temperature coefficient is obtained and found to be linear for all modes. The results provide a deeper understanding of VP's degradation behavior and implications for optoelectronic applications.

3D‐printed green and low‐cost porous g‐C3N4/geopolymer components for the removal of methylene blue from wastewater

AbstractIn this study, we report that geopolymer materials containing different amounts of graphitic carbon nitride (g‐C3N4) (C3N4/GP) can remove methylene blue (MB) using the synergistic effects of adsorption and photodegradation. A geopolymer containing 3 wt% g‐C3N4 (3 wt%C3N4/GP) had the best MB removal efficiency of 94.62% within 60 min, under visible light. The results showed that geopolymers can act as carriers for g‐C3N4, and the relative amount of adsorbent and photocatalyst influences the removal of MB. 3 wt%C3N4/GP was also used for additive manufacturing by using direct ink writing technology. In order to improve the efficiency of MB removal, a pore‐forming agent (K12) was added in the synthesis process to prepare three‐dimensional‐printed porous C3N4/GP. The results showed that the porous C3N4/GP was effective in removing MB. This work provides a simple strategy for preparing efficient and green materials for removing organic pollutants.

Photocatalytical and corrosion behavior of sputtered zirconium oxynitride thin films doped with titanium

ZrTiON coatings were deposited by reactive magnetron sputtering process of a single Zr target, while Ti was added by placing Ti ribbons on the erosion track of the Zr sputtering target. The variation of parameters such as the number of Ti ribbons, the applied sputtering current, and the reactive gas flow led to obtaining different sample configurations. The coatings were analyzed in terms of chemistry (chemical composition and chemical states) by X-ray Photoelectron Spectroscopy, morphology by Atomic Force Microscopy, surface energy, photodegradation tests, electrochemical studies, and accelerated corrosion tests. It was found that the coatings show features of oxides, nitrides, and oxynitrides, depending on the deposition conditions applied. The photodegradation efficiency regarding methylene blue solutions under visible light varies between 58% and 96%, depending on the type of illuminant and the sample characteristics, while the lowest corrosion rate was exhibited by the reference samples deposited without the addition of Ti. The samples doped with Ti and deposited with 1.5 A sputtering current exhibited a more efficient photodegradation effect, compared to the reference ZrON sample. The accelerated corrosion tests showed that the coatings deposited with an applied current of 2 A behaved significantly better than the ones deposited with 1.5 A sputtering current after 8 h of exposure to the water vapor and sulfur dioxide gas atmosphere.

Biosynthesis of silver nanoparticles using tea leaf extract (camellia sinensis) for photocatalyst and antibacterial effect

Silver nanoparticles (C. AgNPs) are synthesized by the biological reduction method using extracts from green tea leaves (Camellia Sinensis) collected from tea hills at an altitude of 100 m above the ground. The chemicals present in the tea leaf extract act as reducing agents used to reduce Ag+ ions to silver atoms to form C. AgNPs in the solution. In this work, we optimized the C. AgNPs synthesis process by investigating the influence of reaction parameters such as concentration of tea leaf extract (1 ppm–50 ppm), reaction temperature (30 °C-60 °C), reaction time (5 min–100 min), and reaction rate (400 rpm–800 rpm) through absorption UV–Vis spectroscopy, TEM transmission electron microscopy, and spectroscopy X-ray. Organic compounds in tea leaf extract are detected by NMR measurement. The functional groups on the C. AgNPs are shown on the Fourier transform infrared (FTIR) spectrum. The C. AgNPs are used to degrade MB dye at 10 ppm concentration based on the photocatalytic effect using a 6500 K white light source. The C. AgNPs have also been studied for their antibacterial activity on two bacteria, Pseudomonas aeruginosa (P.A) and Staphylococcus aureus (S.A), while a positive control is Ampicillin 50 mg/ml and a negative control is H2O. The results reveal that the C. AgNPs with diameters in the range of 25 nm–55 nm degrade 10 ppm MB dye after 1 h with photodegradation efficiency up to 96 %. The antibacterial ability of C. AgNPs against both bacteria is good, even superior to that of Ampicillin. Furthermore, the particle synthesis efficiency and therefore the antibacterial activity as well as the photodegradation effect of C. AgNPs are higher than previously reported. At the same time, using green tea leaf extract to synthesize C. AgNPs creates environmentally friendly products. These useful behaviors are the potential to increase the scope and applicability of C. AgNPs, especially for biomedical applications in the near future.

Developing a versatile and resilient PVDF/CeO2@GO-COOH photocatalytic membrane for efficient treatment of antibiotic-contaminated wastewater

This study focuses on enhancing the performance of PVDF membranes by incorporating CeO2 photocatalyst in combination with carboxyl-functionalized graphene oxide (GO-COOH). The carboxyl groups of GO-COOH serve a dual purpose: providing anchoring sites for CeO2 and enhancing the interfacial interaction with the polymer. The PVDF/CeO2@GO-COOH membranes were fabricated using sequence of physical blending and phase inversion processes, resulting in significantly improved internal structure with an average pore size diameter of 1.20–1.35 nm. Moreover, the CeO2@GO-COOH photocatalyst exhibited superior compatibility with PVDF. The as-prepared PVDF/CeO2@GO-COOH photocatalytic membranes (PMs) demonstrated remarkable photocatalytic activity, outperforming PVDF/CeO2, achieving degradation efficiencies of 85.55 % for ciprofloxacin and 84.82 % for sulfanilamide (both at 20 mg/L) under UV irradiation for 150 min. Photo-filtration experiments confirmed the synergistic effect of molecular separation and photodegradation, resulting in the removal of 99.5 % of ciprofloxacin and 79.5 % of sulfanilamide, coupled with a relatively high pure water flux of 115.44 L.m−2.h−1. The PM also exhibited excellent stability, self-cleaning properties, and reusability, with a flux recovery rate (FRR) of 97.5 % after five cycles of use. Finally, the PVDF/CeO2@GO-COOH membrane holds great promise for the treatment of pharmaceutical industry wastewater, offering a comprehensive solution that combines efficient pollutant degradation, high permeate flux, stability, and reusability.