Photodegradation Experiments Research Articles

Photoelectric activity evaluation of surface-loaded ferroferric oxide/titanium dioxide composite prepared from ilmenite

This work demonstrates a surface-loaded Fe3O4/TiO2 composite with the magnetic Fe3O4 deposited on the surface of anatase TiO2 nanocrystal which can be directly prepared from the ilmenite using the coprecipitation method. After the acidolysis treatment with the 95% dissolution rate, the ilmenite will be first transformed into H2TiO3 and FeCl2, and the photoactive anatase TiO2 nanocrystals are obtained from the calcined H2TiO3 at 500[Formula: see text]C. Then a surface-loaded Fe3O4/TiO2 composite TF is finally achieved by the coprecipitation method, which is carefully elaborated to balance the magnetism and photoactivity of Fe3O4/TiO2 composite by the optimal contents of Fe3O4 and TiO2. It is encouraging to note that Fe3O4/TiO2 composite TF shows a good comprehensive performance in serial photodegradation experiments of Rhodamine B. The degradation rate of Rhodamine B is more than 99% during 60 min under the irradiation of both xenon lamp and sunlight. During at least six cycles, the composite TF can show stable photocatalytic activity and good durability together with the recovery and recycling potentials by using an external magnet.

Photodegradation of ciprofloxacin and its interaction with Cu(II) in different water matrices: Insight into degradation pathways

Co-contamination of ciprofloxacin (CIP) and Cu(II) is common in marine aquaculture water. However, the transmission and transformation of these substances in natural water matrices are often overlooked. This study sought to assess the impact of Cu(II) on CIP degradation in distilled (DI) and simulated (SI) mariculture water, as well as to develop a relationship between Cu(II), CIP, and its degradation products. First, complexation assays and analog computations revealed that Cu (II) forms complexes by binding to the oxygen atoms of the carbonyl (C=O) and carboxyl (COOH) groups in the CIP molecule. Second, photodegradation experiments showed that Cu(II) significantly hindered the degradation effect of CIP in DI water, while Cu(II) did not significantly hinder the degradation of CIP in SI water. Furthermore, the effect of Cu(II) on the degradation mechanism of CIP was determined by combining quenching and EPR experiments, Materials Studio software calculations, and UPLC-MS results. It was demonstrated that Cu(II) enhanced the production of singlet oxygen (1O2), hydroxyl radicals (•OH), and superoxide radicals (•O2−) in DI water. In the presence of Cu(II), CIP undergoes hydroxylation and decarbonylation reactions, forming hydroxylated and nitroxylated products. Additionally, direct defluorination and cleavage of the piperazine ring occur, followed by complexation reactions with Cu(II). However, in SI water, the production of 1O2 depends on the indirect action of Cu(II) and the excited state transformation of organic matter. Experimental evidence has shown that CIP can create intermediate compounds that include O-O peroxide rings, with or without the presence of Cu(II). When Cu(II) is present, the cyclopropyl group of the CIP molecule is more prone to transformation and so degradation. Finally, the toxicity assessment results indicated that both Cu(II) and SI water increased the toxicity of the degradation products.

Extraction of bio-hydroxyapatite from devilfish (Loricariidae) for the fluoride and cadmium adsorption from water and its feasible photocatalytic properties

In this study, the adsorption capacity of bio-hydroxyapatite (Bio-HAp) from devilfish for the removal of F- and Cd(II) from aqueous solutions was investigated. This material was synthesized according to a 2FI factorial experimental design by varying the extraction conditions for Bio-HAp, including the type of pretreatment (alkaline and peroxide), the calcination temperature from 550 to 850 °C, and the sonication process. The maximum adsorption capacities were 8.48 and 83.56 mg g-1 for F- and Cd(II), respectively. Statistical analysis showed the importance of the type of pretreatment, temperature, and sonication for adsorption. The predicted optimal conditions were Bio-HAp extracted from bone with peroxide pretreatment, calcination at 550 °C and sonication. The surface of the Bio-HAp was found to be mesoporous and basic in character. TGA, FT-IR and SEM-EDS characterizations confirmed the presence of F- and Cd(II) on the Bio-HAp surface and confirmed the adsorption mechanisms by electrostatic forces, ion exchange, and chemisorption. The Praunitz-Rake model of adsorption isotherm showed better agreement with the equilibrium adsorption data of F- and Cd(II) at pH 7. Furthermore, photodegradation experiments showed 100% degradation methylene blue (MB) under natural sunlight. This study indicates an effective photodegradation process, suggesting high adsorption capacity of the samples. The use of devilfish as an adsorbent promises to be a viable and sustainable option for the removal of fluoride and cadmium from water, and for use in photodegradation experiments.

Photodegradation Processes and Weathering Products of Microfibers in Aquatic Environments.

Microplastics, particularly microfibers (MFs), pose a significant threat to the environment. Despite their widespread presence, the photochemical reactivity, weathering products, and environmental fate of MFs remain poorly understood. To address this knowledge gap, photodegradation experiments were conducted on three prevalent MFs: polyester (POL), nylon (NYL), and acrylic (ACR), to elucidate their degradation pathways, changes in surface morphology and polymer structure, and chemical and colloidal characterization of weathering products during photochemical degradation of MFs. The results showed that concentrations of dissolved organic carbon, chromophoric dissolved organic matter (DOM), and fluorescent components consistently increased during weathering, exhibiting a continuous release of DOM. Scanning electron microscopy and Raman spectroscopy revealed changes in the surface morphology and polymer spectra of the MFs. During the weathering experiments, DOM aromaticity (SUVA254) decreased, while spectral slope increased, indicating concurrent DOM release and degradation of aromatic components. The released DOM or nanoplastics were negatively charged with sizes between 128 and 374 nm. The production rate constants of DOM or the photochemical reactivity of MFs followed the order ACR > NYL ≥ POL, consistent with their differences in chemical structures. These findings provide an improved understanding of the photochemical reactivity, degradation pathways, weathering products, and environmental fate of microfibers in the environment.

Structural, optical, magnetic, and photocatalytic degradation characteristics of Co0.5Ni0.5Fe2O4 nanoparticles synthesized by plasma arc discharge process

Co0.5Ni0.5Fe2O4 nanoparticles were prepared by the plasma arc discharge method under arc currents of 200, 300, and 400 A in an air atmosphere. The XRD patterns reveal the formation of a single-phase cubic spinel. According to FESEM results, the average particle size in all powders is less than 100 nm. X-ray elemental mapping data confirms the homogeneous composition of the as-synthesized powders. The magnetic and optical data demonstrate a primarily soft ferromagnetic semiconductor behavior, characterized by a saturation magnetization ranging from 62 to 83 emu/g and a band gap energy between 1.86 and 2.15 eV. The photocatalytic activity of the powders synthesized using a 200 A arc, which possesses the lowest band gap energy of 1.86 eV, was assessed by conducting photodegradation experiments on the dyes congo red, methylene blue, and malachite green under UV irradiation in the presence and absence of H2O2. After 105 min of irradiation, the photocatalytic efficiencies of the powders without H2O2 were determined to be 29 %, 57 %, and 83 % for congo red, methylene blue, and malachite green dyes, respectively. However, in the presence of H2O2, the efficiencies significantly increase to 91 %, 95 %, and 96 % for the respective dyes.

Structural and Electronic Factors Controlling the Efficiency and Rate of Intersystem Crossing to the Triplet State in Thiophene Polycyclic Derivatives.

Thiophene polycyclic derivatives are widely used in organic light-emitting diodes, photovoltaics, and medicinal chemistry applications. Understanding the electronic and structural factors controlling their intersystem crossing rates is paramount for these applications to be successful. This study investigates the photophysical, electronic structure, and excited state dynamics of 1,2-benzodiphenylene sulfide, benzo[b]naphtho[1,2-d]thiophene, and benzo[b]naphtho[2,3-d]thiophene in polar aprotic and non-polar solvents. Steady-state absorption and emission spectroscopy, femtosecond transient absorption spectroscopy, and DFT and TD-DFT calculations are employed. Low fluorescence quantum yields of 1.2 to 2.7% are measured in acetonitrile and cyclohexene, evidencing that the primary relaxation pathways in these thiophene derivatives are nonradiative. Linear interpolation of internal coordinates calculations predict that an S-C bond elongation reaction coordinate facilitates the efficient intersystem crossing to the T1 state. Excitation of 1,2-benzodiphenylene sulfide and benzo[b]naphtho[1,2-d]thiophene at 350 nm or benzo[b]naphtho[2,3-d]thiophene at 365 nm, populates the lowest-energy 1ππ* state, which relaxes to the 1ππ* minimum in tens of picoseconds or intersystem crosses to the triplet manifold in ca. 500 ps to 1.1 ns depending on the position at which the benzene rings are added. Excitation at 266 nm does not affect the intersystem crossing rates. Laser photodegradation experiments demonstrate that the thiophene polycyclic derivatives are highly photostable.

Photocatalytic performance of Soot/TiO2 nanocomposite against toxic dye

Nowadays, composing semiconductors with carbon structures to enhance their optical properties shows huge interest as a nanophotocatalyst for trending applications (i.e., photodegrading pollutants). In this study, TiO2 and soot/TiO2 nanocomposites were prepared via a one-step sol-gel assisted hydrothermal method, using a temperature of 220 °C and a reaction time of 6 h. Characterization by X-ray diffraction and Raman spectroscopy confirmed that the resulting TiO2 and soot/TiO2 materials exhibited a pure anatase crystal phase, without the presence of other TiO2 polymorphs. Soot composition on TiO2 showed enhanced photocatalysis properties, such as a lower combination rate of electron-hole pairs than pure TiO2. Crystal violet (CV) was applied as a pollutant model to examine the photocatalytic degradation of synthesized TiO2 and soot/TiO2. The photodegradation experiments of CV dye in its aqueous media by UV light interaction showed 26.63 % and 89.09 % in the presence of TiO2 and soot/TiO2 nanocomposite, respectively. In the basic media (pH 11), maximum photodegradation (97.95 %) is attained when 0.004 g of Photocatalyst (soot/TiO2) is used. Using the recycled photocatalyst, the dye's photodegradation efficiency remained high throughout the reusability cycles, even after four consecutive cycles.

Dual-pathway charge transfer mechanism of anatase/rutile TiO2-Ag3PO4 hollow photocatalyst promotes efficient degradation of pesticides

Exploring high-performance photocatalysts still remains a big challenge due to poor charge separation efficiency. Herein, we prepare a novel anatase/rutile TiO2-Ag3PO4 hollow photocatalyst (A/R-TiO2-Ag3PO4) for addressing this challenge. Microstructural characterization and photoelectric measurements confirm that the synergy of hollow structure and dual-heterojunction can provide abundant active sites and boost efficient charge separation through dual-pathway charge transfer mechanism. The A/R-TiO2-Ag3PO4 photocatalyst exhibits the highest photocurrent density (15.25 µA cm−2), which is 8.4 and 5.2 times than that of A-TiO2-Ag3PO4 (1.82 µA cm−2) and P25-Ag3PO4 (2.93 µA cm−2), respectively. Photo-degradation experiment shows that A/R-TiO2-Ag3PO4 presents a high degradation percentage (98.7 %) of thiamethoxam (THX) within 30 min, which is 1.45 and 1.23 times than that of A-TiO2-Ag3PO4 (68.1 %) and P25-Ag3PO4 (80.7 %), respectively. Furthermore, the degradation percentage of THX by A/R-TiO2-Ag3PO4 is as high as 96.4 % after seven successive cycles, indicating excellent cycling stability. Therefore, this work provides a new insight into exploring other high-performance photocatalysts by combining hollow structure and dual-heterojunction.

HYDROTHERMALLY DEVELOPED TITANIUM DIOXIDE AND EUROPIUM-DOPED COMPOSITE MATERIALS FOR PHOTODEGRADATION APPLICATIONS

Metal oxide nanocomposites are a critical element in nanoscale technology. Because of their many uses, a great deal of study has involved photocatalytic materials. These photocatalytic degradation characteristics also included applications like solar-cell applications. Waste­water management was included in the photodegradation property. The following study explored the development of europium tungstate nanocomposites with titanium dioxide and how they can be used in photocatalytic applications. The synthesis was conducted using the hydrothermal method and is characterized by Fourier-transform infrared spectroscopy, X-ray diffraction spectroscopy, scanning electron microscopy, and energy-dispersive spectroscopy. Application experiments were conducted using four distinct dyes, namely methyl orange, methylene blue, congo red and methyl red. The photodegradation experiments were conducted using visible light emitted by a tungsten-filament lamp. Methylene blue and methyl orange degraded to 20 % and 35 % after 1 hour respectively. After 90 min, the degradation of methylene blue went down to 15 % and congo red degraded down to 9 %. With the experiment conducted, the sample showed that it had a relatively higher photodegradation property with the dyes used. The results show that the compound had better reaction with these dyes, with a degradation down to 10 %.

Hydrothermal synthesis and characterization of 0D/2D SrMoO4/g-C3N4 composite with direct Z-scheme heterojunction: Efficient photocatalytic Ciprofloxacin degradation

Ciprofloxacin (Cip) is a common pollutant that causes sewage problems, and its effective removal is a great contribution to the clean water environment. Direct Zener-scheme (Z-scheme) heterojunction photocatalyst is a promising design idea for the removal of residual antibiotics in water. The goal of this study is to construct a binary composite photocatalyst with Z-scheme heterojunction to effectively remove residual ciprofloxacin in wastewater. Herein, a direct Z-scheme 0D/2D SrMoO4/g-C3N4 (SMOCN) composite photocatalyst was synthesized by ultrasonic-assisted hydrothermal way and its interior information (chemical structure, micromorphology, and physic-optical property) was detected by various characterization instruments (XRD, FT-IR, EDX, XPS, UV–Vis DRS, and PL). Meanwhile, the photocatalytic activity of all-prepared catalysts were estimated by Cip photodegradation experiments under simulated sunlight (500 W Xenon lamp). Among them, 89.9 % of Cip was broken down by 30SMOCN composite within 180 min at pH 7.0, which respectively reached 2.56 times of bare SMO and 2.03 times of bare CN. Furthermore, 85.2 % of Cip targeted molecule is still removed by SMOCN (excellent stability and recyclability) after five cycle runs. Finally, the reasonableness of SMOCN conforming to the direct Z-scheme mechanism is verified by comparison of optical properties, quenching experiment results and photogenerated carrier migration paths: 1) There is optical complementarity between SMO and CN, which is represented by redshifted absorption edge, narrowed band gap and weaken PL intensity. 2) The key active site on the SMOCN composite surface is photogenerated carriers in Cip photocatalytic degradation, which given full play to the direct synergistic catalytic effect between SMO and CN heterojunction. 3) The direct Z-scheme mechanism preserves the carriers of SMOCN with effective photo-redox function, promotes their separation and prolongs their lifetime.

A Graphene/ZnO/ZnS/MoS2 Heterojunction with Excellent Photocatalytic Activity

AbstractIn this work, a well‐defined flower‐like ZnO (ZnO−F) was prepared through the precipitation method, and a graphene/ZnO/ZnS/MoS2 heterojunction (GR/ZnO−H) was fabricated using the hydrothermal approach. The morphological, compositional, and optical characteristics of the prepared materials were systematically investigated employing various analytical techniques. The photodegradation performance of these materials were assessed through methylene blue (MB) photodegradation experiments. Remarkably, GR/ZnO−H exhibited superior photodegradation efficacy compared to both pure ZnO−F and ZnO/ZnS/MoS2 heterojunctions, with a degradation rate reaching 98.8 % within 240 minutes. The examination of the photocatalytic mechanism revealed that superoxide anions (O2⋅−), hydroxyl radicals (⋅OH), and holes (h+) are the principal photocatalytic active species during MB degradation. This investigation unveils a highly effective photoregenerative material with promising applications in wastewater treatment.

Influence of Hydrothermal Temperature on the Physical Characteristics and Photocatalytics Activity of TiO2 for Degradation of Amoxicillin

Titanium dioxide (TiO2) is a photocatalyst material widely used for environmental remediation applications. In this research, TiO2 material was synthesized using the hydrothermal method at various temperatures (150°C, 180°C, and 200°C). Based on the Fourier-transform infrared (FTIR) data, it was found that all the synthesized materials showed similar absorption peaks, and Ti-O-Ti bonds were detected, which is a characteristic of TiO2. X-ray diffraction (XRD) analysis showed that all the synthesized materials were TiO2 anatase with different crystalline sizes. The synthesized TiO2 using the hydrothermal temperature of 180°C showed the smallest crystalline size of 86.81 nm. Based on the analysis of the band gap energy, it was found that wider band gap energy was obtained at higher hydrothermal temperatures. The band gap energies of the synthesized materials are 3.18 eV, 3.19 eV, and 3.21 eV for hydrothermal temperatures of 150°C, 180°C, and 200°C, respectively. The photocatalytic activity of the three synthesized materials was tested in the photodegradation experiment of amoxicillin under ultraviolet (UV) irradiation. As a result, it was found that TiO2 synthesized at 180°C has the highest photocatalytic activity by degrading 100% of amoxicillin compounds within 120 minutes.

Removal of bisphenol a micropollutants released from plastic waste using Pt-ZnO photocatalyst.

Plastic pollution is becoming increasingly severe and is attracting global attention. One of its consequences is the recent discovery of micropollutant discharge into water, with Bisphenol A (BA-MP) being a typical example. This study utilizes an advanced oxidation process based on Pt-doped ZnO photocatalyst to remove BA-MP. Health concerns related to the release of BA-MP from plastic waste are discussed. Besides, the results of the photodegradation experiment show that the Pt-ZnO photocatalyst can remove 94.1% of BA-MP within 60min when exposed to solar light. Moreover, after five reuse cycles, Pt-ZnO retains a high BA-MP removal efficiency of 71.2%, and its structure remains largely unchanged compared to the original material. The removal efficiency of BA-MP leaching from plastic waste was measured at 98.8%, confirming the suitability of Pt-ZnO for the treatment of micropollutants. Furthermore, this study also highlights the prospects and challenges of using Pt-ZnO for the treatment of micropollutants discharged from plastic waste.

Nanostructured Mn@NiO composite for addressing multi-pollutant challenges in petroleum-contaminated water

Efficient catalysts play a pivotal role in advancing eco-friendly water treatment strategies, particularly in the removal of diverse organic contaminants found in water-petroleum sources. This study addresses the multifaceted challenges posed by contaminants, encompassing a spectrum of heavy metals such as As, Cd, Cr, Mn, Mo, Ni, Pb, Sb, Se, and Zn alongside pollutants like oily water (OIW), total suspended solids (TSS), chemical oxygen demand (COD), dyes, and pharmaceuticals, posing threats to both aquatic and terrestrial ecosystems. Herein, we present the synthesis of biogenically derived Mn@NiO nanocomposite (NC) photocatalysts, a sustainable methodology employing an aqueous Rosmarinus officinalis L. extract, yielding particles with a size of 36.7 nm. The catalyst demonstrates exceptional efficacy in removing heavy metals, achieving rates exceeding 99–100% within 30 min, alongside notable removal efficiencies for OIW (98%), TSS (87%), and COD (98%). Furthermore, our photodegradation experiments showed remarkable efficiencies, with 94% degradation for Rose Bengal (RB) and 96% for methylene blue (MB) within 120 min. The degradation kinetics adhere to pseudo-first-order behavior, with rate constants of 0.0227 min−1 for RB and 0.0370 min−1 for MB. Additionally, the NC exhibits significant antibiotic degradation rates of 97% for cephalexin (CEX) and 96% for amoxicillin (AMOX). The enhanced photocatalytic performance is attributed to the synergistic interplay between the Mn and NiO nanostructures, augmenting responsiveness to sunlight while mitigating electron-hole pair recombination. Notably, the catalyst demonstrates outstanding stability and reusability across multiple cycles, maintaining its stable nanostructure without compromise.Graphical

Synthesis and characterisation of Ag-Cu-co-Doped WO3 @Carbeneous materials composites for waste water treatment

Nanoparticles of tungsten oxide are widely used in advanced chemical processes but the application of tungsten oxide (WO3) in photocatalysis is limited. To increase their application in photocatalysis, nanostructured tungsten oxide (W-1) is co-doped with silver and copper (W-2), and nanocomposites with g-C3N4 (W-3) and CNTs (W-4) are synthesized. Structural, elemental, and morphological analyses of prepared samples were carried out using different characterization techniques like XRD, SEM, FTIR, EDX, and Mott-Schottky. The bandgap of WO3 is 2.75 eV which is reduced to 2.32 eV by doping and composite formation. The degradation of crystal violet and chlorpyrifos is done to check the photocatalytic performance of prepared materials under the light bulb energy. Photodegradation experiment shows 83.33 % and 41 % degradation of CV and chlorpyrifos respectively. The higher degradation ability is shown by CNTs composites because they have smaller crystallite size (12.81 nm) as compared to other photocatalysts. In the presence of CNTs, the rate of recombination of holes and electrons decreases, resulting in the enhancement of photocatalytic activity. The research reveals that W-4 exhibits promising potential for applications in the photodegradation of organic wastes.

Construction of novel S-defects rich ZnCdS nanoparticles for synergistic visible light assisted photocatalytic degradation of rhodamine B: Insights into mechanism, pathway and by-products toxicity evaluation

The contamination of wastewater by azo dyes indicates serious environmental risks. Currently, industries worldwide use approximately 700,000 tons of these dyes annually, making their removal a significant challenge. In photocatalysis research, a prominent area of dedication to the advancement of visible light photocatalysis aims to achieve superior performance in overall activity. In this study, we fabricated ZnCdS nanoparticles (NPs) via a simple co-precipitation strategy, and sulphur (S)-defect-rich ZnCdS NPs (D-ZnCdS) were created through the ball milling method. These S-defect nanoparticle (NPs) catalysts were utilized for rhodamine B (RhB) dye photocatalytic degradation experiment. (XRD) X-ray diffractometer, X-ray photoelectron spectroscopy (XPS), surface-enhanced Raman spectroscopy, and photoluminescence (PL) spectroscopy characterization studies explained the induced S-defect rich in D-ZnCdS NPs. Further, the morphological, band gap determination, and photogenerated charge carrier recombination efficiency were studied using different analytical and spectroscopic characterization techniques. The Brunauer-emmett-teller (BET) results indicate the increased surface area of D-ZnCdS NPs thereby providing more active sites. The photocatalytic degrading efficiency of D-ZnCdS over RhB explains the complete degradation of pollutants within 260 min. This enhancement in the catalytic process is attributed to the increased absorption of photon energy from the visible light and large defect-rich active sites. Further, the involvement of hydroxyl (*OH) and superoxide radicals (O2*-) in the degradation of RhB along with the presence of sulphur defects, significantly improves the charge transfer in ZnCdS NPs. The involvement of certain factors like pH, ions, NCs catalyst and different RhB concentrations on RhB degradation was investigated. Additionally, D-ZnCdS NPs showed stable degrading capability even after six consecutive cycles of catalytic RhB degradation. The by products formed during the RhB photodegradation experiment were identified using Gas chromatography-mass spectrometer (GC-MS) analysis, and toxicity in fish, daphnia, and algae was examined using the Ecological structure-activity relationships (ECOSAR) program. From the above findings, the current research work provides a new strategy for utilizing defect-engineered D-ZnCdS NPs as a promising catalyst for various environmental remediation applications and paves a ways for manufacturing innovation.

The development and application of Cu@TiO2@SAPO-34 as better photocatalyst towards degradation of various pollutants

The study developed a novel Cu@TiO2@SAPO-34 nanocomposite for photocatalytic mortification of organic pollutants using modified hydrothermal synthesis. The material was characterized using XRD, BET, XPS, SEM, TEM, UV–vis, and Photoluminescence spectroscopy, confirming high pollutant absorption and photocatalytic capability. The structural analysis identified the emergence of monoclinic CuO and pure anatase phase TiO2, with ligands matching the formation of SAPO-34 at various planes of 2theta degrees. Also, species of Cu-SAPO-34 (35.43 and 65.88°) and TiO2-SAPO-34 (25.56°) were identified. The BET analysis indicated a narrow pore size distribution of 5.59 nm for Cu@TiO2@SAPO-34, with a high surface area to volume ratio of 145.7868 m2. g−1. The optical property analysis revealed that TiO2 exhibited light absorption mainly in the visible region, while Cu@TiO2@SAPO-34 exhibited early adsorption in the ultraviolet region and extended to the visible regions. This was accompanied by a concomitant decrease in band gap energy from 3.09 eV for TiO2 to 2.61 eV for Cu@TiO2@SAPO-34. The Photodegradation experiment demonstrated that TiO2 nanoparticles achieved 83 % degradation of methylene blue (MB) dye solution after 120 minutes under ultraviolet irradiation, while the Cu@TiO2@SAPO-34 composite achieved 98 % within 30 minutes. The novel nanocomposite material was further tested for real wastewater treatment, self-cleaning of the coated film, and nature of wettability, which all confirmed that the novel Cu@TiO2@SAPO-34 composite is superhydrophilic and a better photocatalyst for degrading organic contaminants. The study details the Photodegradation reaction mechanism for the Cu@TiO2@SAPO-34 nanocomposite, comparing it to TiO2 under UV–vis irradiation, and proposes a chabazite-related structure using Biovia Materials Studio 2020.

High-Resolution Mass Spectrometry Combined with Reactive Oxygen Species Reveals Differences in Photoreactivity of Dissolved Organic Matter from Microplastic Sources in Aqueous Environments.

Microplastics (MPs)-derived dissolved organic matter (MPs-DOM) is becoming a non-negligible source of DOM pools in aquatic systems, but there is limited understanding about the photoreactivity of different MPs-DOM. Herein, MPs-DOM from polystyrene (PS), polyethylene terephthalate (PET), poly(butylene adipate-co-terephthalate) (PBAT), PE, and polypropylene (PP), representing aromatic, biodegradable, and aliphatic plastics, were prepared to examine their photoreactivity. Spectral and high-resolution mass spectrometry analyses revealed that PS/PET/PBAT-DOM contained more unsaturated aromatic components, whereas PE/PP-DOM was richer in saturated aliphatic components. Photodegradation experiments observed that unsaturated aromatic molecules were prone to be degraded compared to saturated aliphatic molecules, leading to a higher degradation of PS/PET/PBAT-DOM than PE/PP-DOM. PS/PET/PBAT-DOM was mainly degraded by hydroxyl (•OH) via attacking unsaturated aromatic structures, whereas PE/PP-DOM by singlet oxygen (1O2) through oxidizing aliphatic side chains. The [•OH]ss was 1.21-1.60 × 10-4 M in PS/PET/PBAT-DOM and 0.97-1.14 × 10-4 M in PE/PP-DOM, while the [1O2]ss was 0.90-1.35 × 10-12 and 0.33-0.44 × 10-12 M, respectively. This contributes to the stronger photoreactivity of PS/PET/PBAT-DOM with a higher unsaturated aromatic degree than PE/PP-DOM. The photodegradation of MPs-DOM reflected a decreasing tendency from aromatic-unsaturated molecules to aliphatic-saturated molecules. Special attention should be paid to the photoreactivity and environmental impacts associated with MPs-DOM containing highly unsaturated aromatic compounds.

Effect of Multiple Acceptor Structures in Electron Transport Materials on Operational Lifetime of Blue Thermally Activated Delayed Fluorescence Organic Light‐Emitting Diodes

AbstractRecent advances in organic light‐emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF)‐assisted fluorescence (TAF) attest to the great promise of this technology in practical use. However, the simultaneous realization of high efficiency and device durability in blue OLEDs remains a significant challenge. Clarification of the degradation mechanisms correlated to molecular structure and device configuration is the key to extending the device lifetime. In this study, electron transport materials incorporating two triazine units in close proximity are adopted to use in hole‐blocking and electron‐transporting layers, resulting in superior device performances. In addition, a modified photodegradation experiment reveals that the degradation origins closely relate to charge carriers. The optimization of the device according to the obtained findings leads to 4.5 times extension in the lifetime of the TAF‐OLED using a multiple resonance emitter. These results also provide guidelines for designing robust electron transport materials for blue OLEDs.

A simple methodology for in situ study of microplastics’ aggregation

AbstractDue to the critical impacts of microplastic (MP) aggregation on their fate, mobility, and bioavailability, this study developed a simple approach to examine their aggregation under varying water chemistry and MPs’ surface aging conditions. An accelerated photodegradation experiment was conducted for 6 weeks. The water chemistry conditions varied by altering pH, using natural organic matter (NOM), and conducting experiments in ultrapure water and synthetic stormwater. The surface chemistry analysis of photodegraded MPs revealed the formation of carbonyl and vinyl functional groups. Zeta potential measurements revealed a more negative surface charge for photodegraded MPs compared to new MPs. The aggregation kinetics of MPs were studied by comparing the number of MP clusters formed over time after intense dispersion in water. The results showed that the presence of NOMs reduces the aggregation tendency of new low‐density polyethylene MPs due to enhanced steric hindrance and electrostatic repulsion. However, variations of pH and utilizing synthetic stormwater versus ultrapure water did not alter the aggregation kinetics of new MPs. The aggregation behavior of photodegraded MPs was significantly different from new MPs. A greater tendency for aggregation of photodegraded MPs was found in the stormwater compared to the ultrapure water. This study contributes to a better understanding of the transport and fate of MPs within the aqueous environment and their subsequent environmental risks.