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Incorporation in Lipid Microparticles of Acid Red 87, a Colourant Used in Tattoo Inks: Effect on Photodegradation Under Simulated Sunlight and Laser Radiation
摘要： Tattoo colourants decompose under solar radiation and when exposed to laser light for their removal, leading to the accumulation in the dermis of toxic products. Aim of this study was to develop lipid microparticles (LMs) loaded with the colourant, Acid Red 87 (C.I. 45380) used in tattoo inks, and to investigate the effect of this system on the photostability of the colourant under simulated sunlight or laser irradiation. LMs loaded with C.I. 45380 were prepared by melt emulsification using tristearin and phosphatidylcholine as excipients. They were characterized by optical microscopy, laser diffraction, X-ray diffraction and release studies. Free C.I. 45380 and the colourant-loaded LMs were irradiated with a solar simulator or a Q-switched laser. Irradiation with a solar simulator demonstrated that photodecomposition of C.I. 45380 was markedly reduced by incorporation of the dye in the LMs, from 20.5 ± 4.6% to 1.3 ± 1.8%. Conversely, the laser-induced degradation of the colourant (30.1 ± 6.6%) was not significantly influenced by encapsulation in the LMs (the encapsulated C.I. 45380 loss was 27.4 ± 5.5%). Incorporation of C.I. 45380 in lipid microparticles enhances the photostability under sunlight of tattoo inks containing this colourant, without affecting its laser-induced degradation and hence laser removal efficiency.
关键词： photodegradation,Acid Red 87,tattoo colourants,laser radiation,lipid microparticles
更新于2025-09-19 17:13:59
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A Review on Quantum Dots Modified g-C3N4-Based Photocatalysts with Improved Photocatalytic Activity
摘要： In the 21st century, the development of sustainable energy and advanced technologies to cope with energy shortages and environmental pollution has become vital. Semiconductor photocatalysis is a promising technology that can directly convert solar energy to chemical energy and is extensively used for its environmentally-friendly properties. In the field of photocatalysis, graphitic carbon nitride (g-C3N4) has obtained increasing interest due to its unique physicochemical properties. Therefore, numerous researchers have attempted to integrate quantum dots (QDs) with g-C3N4 to optimize the photocatalytic activity. In this review, recent progress in combining g-C3N4 with QDs for synthesizing new photocatalysts was introduced. The methods of QDs/g-C3N4-based photocatalysts synthesis are summarized. Recent studies assessing the application of photocatalytic performance and mechanism of modification of g-C3N4 with carbon quantum dots (CQDs), graphene quantum dots (GQDs), and g-C3N4 QDs are herein discussed. Lastly, challenges and future perspectives of QDs modified g-C3N4-based photocatalysts in photocatalytic applications are discussed. We hope that this review will provide a valuable overview and insight for the promotion of applications of QDs modified g-C3N4 based-photocatalysts.
关键词： organic pollutant photodegradation,H2 production,graphitic carbon nitride (g-C3N4),photocatalysis,CO2 reduction,quantum dots (QDs)
更新于2025-09-19 17:13:59
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Dynamic growth of rhombic dodecahedral Cu <sub/>2</sub> O crystals controlled by reaction temperature and their size-dependent photocatalytic performance
摘要： Compared with low-index {100} or {111} planes of Cu2O crystals, rhombic dodecahedra (RD) Cu2O crystals exposing 12 {110} facets exhibit the most superior photodegradation of organic pollutants. Herein, a series of RD Cu2O crystals with different sizes were successfully synthesized by precisely adjusting the reaction temperature ranging from 40 °C to 100 °C. The results revealed that truncated rhombic dodecahedra (TRD) Cu2O crystals were fabricated when the temperatures was 40 °C. More importantly, on raising the temperature to above 40 °C, Cu2O architectures dynamically evolved from TRD to RD. Meanwhile, the sizes gradually decreased with elevation of the temperature, while the RD morphology of Cu2O crystals remained, demonstrating the importance of temperature for determining the morphology and size of Cu2O crystals. In addition, we also carefully investigated the visible-light photodegradation performance of Cu2O crystals for methyl orange (MO). RD Cu2O crystals exhibited superior photocatalytic activity compared with TRD, and showed size-dependent photocatalytic activity for MO. The photocatalytic activity of RD Cu2O crystals can be greatly improved by decreasing the size. In particular, RD-60 with the minimum size achieved the best photocatalytic properties compared to the other RD and TRD Cu2O crystals, and still displayed high photocatalytic efficiency even after three cycles. Such results advance the understanding that temperature modulation serves as an effective means to fabricate RD Cu2O crystals.
关键词： size-dependent photocatalytic performance,photodegradation,reaction temperature,Cu2O crystals,rhombic dodecahedra
更新于2025-09-16 10:30:52
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Micropatterning and defect engineering of colloidal photonic crystals <i>via</i> laser direct writing
摘要： Micropatterning and defect engineering of colloidal photonic crystals (CPCs) play a significant role in the functionality of photonic crystals as they are crucial for optical chip integration, microcavity lasing, chemical sensing, etc. However, obstacles have arisen in recent years especially due to the lack of a general, cost-effective and versatile strategy to make these functional structures in one step. Traditional micro-/nanofabrication techniques may work for one structure but fail for another and the fabrication process is mostly complicated, which potentially incurs reproducibility issues. Here, point defects, waveguides and micropatterns with variable feature sizes (4B500 nm) can be easily created in polystyrene (PS)/SiO2 CPC films via laser direct writing, which is based on selective photodegradation of PS beads. By applying different laser powers or irradiation times, different coloured micropatterns and images with high resolution can be generated, which has great implications for image displays and anti-counterfeiting.
关键词： photodegradation,Micropatterning,colloidal photonic crystals,anti-counterfeiting,defect engineering,laser direct writing,image displays
更新于2025-09-16 10:30:52
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Enhanced Visible Light Photodegradation of Microplastic Fragments with Plasmonic Platinum/Zinc Oxide Nanorod Photocatalysts
摘要： Microplastics are persistent anthropogenic pollutants which have become a global concern owing to their widespread existence and unfamiliar threats to the environment and living organisms. This study demonstrates the degradation of fragmented microplastics particularly low-density polyethylene (LDPE) film in water, through visible light-induced plasmonic photocatalysts comprising of platinum nanoparticles deposited on zinc oxide (ZnO) nanorods (ZnO-Pt). The ZnO-Pt nanocomposite photocatalysts were observed to have better degradation kinetics for a model organic dye (methylene blue) compared to bare ZnO nanorods, attributed to the plasmonic effects leading to better interfacial exciton separation and improved hydroxyl radical activity along with a 78% increase in visible light absorption. These demonstrations of the plasmonically enhanced photocatalyst enabled it to effectively degrade microplastic fragments as confirmed following the changes in carbonyl and vinyl indices in infrared absorption. In addition, visual proof of physical surface damage of the LDPE film establishes the efficacy of using plasmonically enhanced nanocomposite photocatalytic materials to tackle the microplastic menace using just sunlight for a clean and green approach towards mitigation of microplastics in the ecosystem.
关键词： microplastics,platinum nanoparticle,ZnO nanorod,LDPE film,visible light photodegradation,nanocomposite
更新于2025-09-16 10:30:52
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Synthesis of N-doped TiO <sub/>2</sub> /SiO <sub/>2</sub> /Fe <sub/>3</sub> O <sub/>4</sub> magnetic nanocomposites as a novel purple LED illumination-driven photocatalyst for photocatalytic and photoelectrocatalytic degradation of naproxen: optimization and different scavenger agents study
摘要： N-doped TiO2/SiO2/Fe3O4 as a new magnetic photocatalyst that is active in visible light has been prepared by simple sol–gel method. The prepared samples were characterized by XRD, FESEM, EDX, TEM, BET, BJH, VSM, XPS, FT-IR, and DRS–UV/Vis analysis. The photocatalytic effect of synthesized samples on naproxen degradation was studied. The operational parameters were optimized through central composite design to achieve maximum efficiency. The optimum values for maximum efficiency were obtained at pH of 4.29, catalyst mass of 0.06 g, naproxen concentration of 9.33 mg L(cid:1)1, and irradiation time of 217.06 min. At these optimum conditions, the maximum photocatalytic degradation percentages of naproxen were found to be 96.32% at desirability function value of 1.0. Coupling the electrical current with the photocatalytic process proved that the electrical current was considerably efficient in decreasing the degradation time of removing the naproxen from aqueous solutions. The photocatalytic activity of the nanoparticles was also studied under sunlight. Considering the results provided by UV–Vis spectrophotometry and total organic carbon, it was found that the prepared samples are extraordinarily efficient to degrade naproxen under both purple LED and solar lights. Furthermore, the effect of different scavenger agents on naproxen degradation has been studied.
关键词： pharmaceutical compound,experimental design,Photodegradation,core–shell nanocomposite,titanium dioxide
更新于2025-09-16 10:30:52
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Charge Injection from Excited Cs2AgBiBr6 Quantum Dots into Semiconductor Oxides
摘要： Lead-free double perovskites such as Cs2AgBiBr6 are gaining attention because of their environmental friendliness compared to the lead halide perovskites. In order to establish their photoactivity, we have probed the excited state behavior of Cs2AgBiBr6 nanocrystals and charge injection from their excited state into different metal oxides (TiO2, ZnO). The electron transfer rate constants determined from ultrafast transient absorption spectroscopy were in the range of 1.2–5.2 × 1010 s-1. Under steady state photolysis (ambient conditions) the electrons injected into TiO2 are scavenged by atmospheric oxygen, leaving behind holes which accumulate within the quantum dots (QDs). These accumulated holes further induce oxidation of QDs, resulting in the overall photodegradation of perovskite film. Annealed films of Cs2AgBiBr6 nanocrystals, when employed as an active layer in solar cell, delivered photocurrent under visible light excitation.
关键词： Metal oxides,Quantum dots,Photodegradation,Charge injection,Cs2AgBiBr6,Solar cells,Lead-free double perovskites
更新于2025-09-12 10:27:22
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Photo‐oxidation of poly(ethylene terephthalate) films intended for photovoltaic backsheet
摘要： The photodegradation of 36 μm thick poly(ethylene terephthalate) ?lm under arti?cial weathering conditions has been investigated. A weatherometer was used to expose samples to a broad wavelength range of light in an oxidative environment, replicating outdoor exposure. Irradiations were also performed using UV lamps of wavelengths 302 and 365 nm light, in an oxidative environment. After exposure, the extent of degradation was determined using attenuated total re?ectance Fourier transform infrared spectroscopy, diffuse re?ectance infrared Fourier transform spectroscopy, UV–visible spectroscopy, ?uorescence spectroscopy, differential scanning calorimetry, contact angle measurements, and scanning electron microscopy. Results show the production of a series of degradation products, including carboxylic acid end groups, anhydrides, aldehydes, quinones, and monohydroxy terephthalate groups.
关键词： poly(ethylene terephthalate),photodegradation,UV lamps,weatherometer,oxidative environment,degradation products
更新于2025-09-12 10:27:22
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Photocatalytic filtration reactors equipped with bi-plasmonic nanocomposite/poly acrylic acid-modified polyamide membranes for industrial wastewater treatment
摘要： In this study, two new composite membranes with antifouling and anti-biofouling properties were prepared through the modification of commercial polyamide (PA) discs using combination of in-situ polymerization of polyacrylic acid (PAA) and grafting of two synthesized bi-plasmonic Au-Ag and Ag-Au photocatalysts. The synthesis and characterization of the photocatalysts in batch mode were discussed in details as primary studies. Two intense 405-nm and 532-nm lasers for Ag-Au and Au-Ag photocatalysts, respectively and a solar-simulated xenon lamp for both photocatalysts were applied for photodegradation studies and the results were compared. In addition, the effect of other parameters such as type and amount of photocatalysts, and initial concentration of pollutants on the degradation efficiency of ofloxacin (OFX) and methylene blue (MB) as the model pollutant drug and dye were comprehensively investigated and the Langmuir-Hinshelwood adsorption model was used for evaluation of kinetics, degradation rate and half-life time of the reactions. After selection of xenon lamp as the optimum light source, the photodegradation of OFX and MB was evaluated in a dead-end membrane reactor (MR) and flux performance, antifouling property and pollutant removal of the membranes were evaluated using pharmaceutical and textile wastewater samples. In addition, the antibacterial activity of the prepared membranes was evaluated using Gram-negative E. coli bacteria as the model microorganism using thin film assay and Kirby-Bauer disk diffusion methods to examine the anti-biofouling potential of the constructed reactors. It was demonstrated that the prepared MR is able to produce cleaner water with more stable ?ux performance and good membrane fouling/biofouling properties in energy saving manner with respect to the unmodified ones.
关键词： Membrane ?ltration,Wastewater treatment,Permeate ?ux,Bi-plasmonic nanoparticles,Photodegradation,Antifouling/anti-biofouling properties
更新于2025-09-11 14:15:04
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Cu-S codoping TiO <sub/>2</sub> /SiO <sub/>2</sub> and TiO <sub/>2</sub> /SiO <sub/>2</sub> /Fe <sub/>3</sub> O <sub/>4</sub> core-shell nanocomposites as a novel purple LED illumination active photocatalyst for degradation of diclofenac: the effect of different scavenger agents and optimization
摘要： Cu-S co-doped TiO2/SiO2 as a novel photocatalyst which is active in visible light was synthesized by simple sol-gel method. Also, Fe3O4 nanoparticles were used as the core to create a magnetically separable photocatalyst. The prepared samples were characterized by XRD, BET, BJH, DRS-UV/Vis, PL, FESEM, EDX, TEM, XPS, and VSM analysis. The photocatalytic effect of synthesized samples was examined on diclofenac (as a model hazardous contaminant) degradation. The central composite design was employed to optimize the operational parameters including irradiation time, pH, photocatalyst mass, and diclofenac concentration, whose optimal values were 213.85 min, 4.31, 0.06 g, and 10.25 mg L?1 for irradiation time, pH, photocatalyst mass, and diclofenac concentration, respectively. Under the optimum conditions, the photocatalytic degradation percentages of diclofenac at desirability function value of 1.0 were found to be 99.56%. The photocatalytic activity of the nanoparticles was also studied under sunlight. Overall, the UV/Vis spectrophotometry and total organic carbon results indicated that the synthesized nanoparticles have an extraordinary photocatalytic activity for the degradation of diclofenac under both purple LED and solar lights. Furthermore, different scavenger agents were investigated.
关键词： Diclofenac,LED light,Photodegradation,Titanium dioxide,Codoping,Scavenger agents
更新于2025-09-11 14:15:04