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The photosensitized transformation of organic chemicals is an important degradation mechanism in natural surface waters, aerosols, and water films on surfaces. Dissolved organic matter including humic-like substances (HS), acting as photosensitizers that participate in electron transfer reactions, can generate a variety of reactive species, such as OH radicals and excited triplet-state HS (3HS*), which promote the degradation of organic compounds. We use phthalate esters, which are important contaminants found in wastewaters, landfills, soils, rivers, lakes, groundwaters, and mine tailings. We use phthalate esters as probes to study the reactivity of HS irradiated with artificial sunlight. Phthalate esters with different side-chain lengths were used as probes for elucidation of reaction mechanisms using 2H and 13C isotope fractionation. Reference experiments with the artificial photosensitizers 4,5,6,7-tetrachloro-2′,4′,5′,7′-tetraiodofluorescein (Rose Bengal), 3-methoxy-acetophenone (3-MAP), and 4-methoxybenzaldehyde (4-MBA) yielded characteristic fractionation factors (−4 ± 1, −4 ± 2, and −4 ± 1‰ for 2H; 0.7 ± 0.2, 1.0 ± 0.4, and 0.8 ± 0.2‰ for 13C), allowing interpretation of reaction mechanisms of humic substances with phthalate esters. The correlation of 2H and 13C fractions can be used diagnostically to determine photosensitized reactions in the environment and to differentiate among biodegradation, hydrolysis, and photosensitized HS reaction.

Tire wear particles (TWPs) represent one of the major anthropogenic pools of particles ending up in the environment. They contain a large variety of chemicals, a part of which may be released into the environment through leaching, although the influence of sunlight and other environmental factors during this process is still unclear. This laboratory study compares the leaching of organic compounds from TWP in seawater in the dark and under artificial sunlight for (i) cryo-milled tire tread (CMTT), (ii) ‘virgin’ crumb rubber (VCR) and (iii) crumb rubber immersed in the sea for ≥ 12 months prior to the experiments (WCR). Leachates were analyzed for dissolved organic carbon (DOC) and 19 tire-derived chemicals, benzothiazoles and phenylguanidines as well as phenylendiamines by liquid chromatography-high resolution-mass spectrometry. For DOC and most chemicals, the amounts released decreased in the order CMTT > VCR > WCR and increased when leaching occurred under artificial sunlight. Sunlight also led to the formation of 23 transformation processes related to 1,3-diphenylguanidine (DPG). In contrast, 4-hydroxydiphenylamine (4-HDPA) and N-(1,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine quinone (6-PPDQ) were found in lower amounts upon sunlight exposure. The 19 quantified chemicals, however, did only account for 6 – 55% of the DOC in the leachates; most of the DOC, thus, remained unexplained. This study highlights that the amount of chemicals leached from tire particles depends upon their aging history and may be modulated by environmental conditions.

Dissolved organic matter (DOM) is a complex mixture of thousands of natural molecules that undergo constant transformation in the environment, such as sunlight induced photochemical reactions. Despite molecular level resolution from ultrahigh resolution mass spectrometry (UHRMS), trends of mass peak intensities are currently the only way to follow photochemically induced molecular changes in DOM. Many real-world relationships and temporal processes can be intuitively modeled using graph data structures (networks). Graphs enhance the potential and value of AI applications by adding context and interconnections allowing the uncovering of hidden or unknown relationships in data sets. We use a temporal graph model and link prediction to identify transformations of DOM molecules in a photo-oxidation experiment. Our link prediction algorithm simultaneously considers educt removal and product formation for molecules linked by predefined transformation units (oxidation, decarboxylation, etc.). The transformations are further weighted by the extent of intensity change and clustered on the graph structure to identify groups of similar reactivity. The temporal graph is capable of identifying relevant molecules subject to similar reactions and enabling to study their time course. Our approach overcomes previous data evaluation limitations for mechanistic studies of DOM and leverages the potential of temporal graphs to study DOM reactivity by UHRMS.

We explore a series of furan-based non-fullerene acceptors and report their optoelectronic properties, solid-state packing, photodegradation mechanism and application in photovoltaic devices. Incorporating furan building blocks leads to the expected enhanced backbone planarity, reduced band gap and red-shifted absorption of these acceptors. Still, their position in the molecule is critical for stability and device performance. We found that the photodegradation of these acceptors originates from two distinct pathways: electrocyclic photoisomerization and Diels–Alder cycloaddition of singlet oxygen. These mechanisms are of general significance to most non-fullerene acceptors, and the photostability depends strongly on the molecular structure. Placement of furans next to the acceptor termini leads to better photostability, well-balanced hole/electron transport, and significantly improved device performance. Methylfuran as the linker offers the best photostability and power conversion efficiency (>14 %), outperforming all furan-based acceptors reported to date and all indacenodithiophene-based acceptors. Our findings show the possibility of photostable furan-based alternatives to the currently omnipresent thiophene-based photovoltaic materials. © 2023 Wiley-VCH GmbH.

Photocatalytic degradation of bisphenol A (BPA) was investigated using commercial TiO2 P25 nanoparticles supported on natural zeolite clinoptilolite (Cli). Employing ultrasound assisted solid-state dispersion method hybrid photocatalyst containing 20 wt% of TiO2, marked TCli-20, was prepared. The structural, morphological and surface properties, and particle size distribution of TCli-20 were studied by X-ray powder diffraction, Fourier transform infrared spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy, scanning electron microscopy with energy dispersive spectroscopy, atomic force microscopy, Brunner-Emmet-Teller method and laser diffraction. The results revealed a successful loading of TiO2 P25 nanoparticles on Cli surface and the preservation of both zeolitic structure and optical properties of TiO2. The influence of catalyst dose, pH value and the addition of hydrogen peroxide (H2O2) was evaluated. The optimal reaction conditions were 2 g/L of catalyst at near-neutral conditions (pH = 6.4) for complete BPA (5 mg/L) photodegradation after 180 min of exposure to simulated solar light. The addition of H2O2 was beneficial for the degradation process and led to the removal of BPA after 120 min of irradiation. BPA removal (60% for 180 min of irradiation) was reduced when TCli-20 was tested in bottled drinking water due to the presence of bicarbonate ions which acted as scavengers for hydroxyl radicals. Even though the photocatalytic activity of TCli-20 decreased after several cycles of usage, 70% of BPA was still successfully degraded during the fourth cycle. The reusability study showed easy separation, stability and good photocatalytic ability of investigated cost-effective hybrid photocatalyst. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

Environmental management demands innovative techniques for its protection and treatment. The essential agreement of the modern world is to overcome every issue in a sustainable way. The two major financial problems in this area are water pollution and material corrosion. Persistent, organic compounds such as pesticides have devastating effects on the water ecosystem. This problem can be solved by applying advanced treatment processes (ATPs) like membrane separation and photocatalysis. Additionally, the corrosion of metal materials needs to be prevented to preserve natural resources and reduce environmental concerns. Therefore, researchers are trying to develop tunable, multifunctional materials with broad applications. Employed materials in these operations must fulfill high criteria, like durability, stability, and chemical and optical activity, to make specified processes efficient and viable. Electroconductive polymers (ECPs) can meet the aforementioned standards. The most used ECP is polyaniline (PANI), due to its catalytic and electrochemical performances. These two properties are beneficial for both water purification and anticorrosion applications. The objectives of the paper are to represent various PANI-based composites utilized in the removal of different classes of pesticides during wastewater treatment by adsorption or photocatalytic degradation. Further corrosion inhibition, utilizing PANI-based inhibitors, will be discussed as well.

Many efforts have been devoted to produce green materials and technology to prevent and minimize the adverse effects on the environment and human health caused primarily by population growth and industrial progress. Over the past years, the use of zeolites has attracted considerable attention as both an economically and environmentally friendly option. Zeolites are crystalline, hydrated aluminosilicates with an open-framework structure. Unique structural features make them very useful ion-changers, adsorbents and catalysts. The catalytic use of zeolites has expanded from traditional use in the petrochemical industry and refineries to use in the catalytic degradation of various environmental pollutants and the synthesis of fine chemicals. In recent times, progress on the use of zeolites has been achieved in biomass conversion to fuels and valuable industrial bio-based chemicals. This review highlights the recent advances in the catalytic application of clinoptilolite (CLI), the most abundant and explored natural zeolite. The main goal of the review is to give the current state of CLI applications and insights into CLI catalytic performance, which opens possibilities for a variety of applications.

Environmental and human health are seriously threatened by organic dye pollution. Many efforts have been made to find effective and safe methods of eliminating these contaminants. To mitigate these effects, the hydrothermal method was used to effectively generate a ternary kind of Dy2WO6-ZnO embedded in graphene oxide (DWZG) nanocomposites, which were used to degrade the pollutant. Powder X-ray diffraction (XRD) investigation confirms the crystalline character of the as-prepared DWZG nanocomposite. The Dy2WO6-ZnO composition on the graphene oxide (GO) layer is shaped like a combination of algae (Dy2WO6) and clusters (ZnO), as shown by scanning electron microscopy (SEM). X-ray photoelectron spectroscopy (XPS) investigation revealed the composition of elements and oxidation state of C, Dy, O, W and Zn elements. Methylene blue (MB) was chosen as the organic dye target for photocatalytic degradation using the produced nanocomposites. MB is degraded with a photocatalytic efficiency of 98.2% in about 30 min using a DWZG catalyst. Based on the result of the research entitled "Reactive Oxidative Species," the primary reactive species involved in the MB degradation are photo-generated (OH)-O-& BULL; and O-2(& BULL;-) radicals. The recycle test was also successful in evaluating the catalysts' long-term viability as well as their reusability., QC 20230714

In this study, we utilized calcination and simple impregnation methods to successfully fabricate bare g-C3N4 (GCN) and x% Ag/g-C3N4 (x% AgGCN) composite photocatalysts with various weight percentages (x = 1, 3, 5, and 7 wt.%). The synthesized bare and composite photocatalysts were analyzed to illustrate their phase formation, functional group, morphology, and optical properties utilizing XRD, FT-IR, UV-Vis DRS, PL, FE-SEM, and the EDS. The photodegradation rate of MO under solar light irradiation was measured, and the 5% AgGCN composite photocatalyst showed higher photocatalytic activity (99%), which is very high compared to other bare and composite photocatalysts. The MO dye degradation rate constant with the 5% AgGCN photocatalyst exhibits 14.83 times better photocatalytic activity compared to the bare GCN catalyst. This photocatalyst showed good efficiency in the degradation of MO dye and demonstrated cycling stability even in the 5th successive photocatalytic reaction cycle. The higher photocatalytic activity of the 5% AgGCN composite catalyst for the degradation of MO dye is due to the interaction of Ag with GCN and the localized surface plasmon resonance (SPR) effect of Ag. The scavenger study results indicate that O2 •− radicals play a major role in MO dye degradation. A possible charge-transfer mechanism is proposed to explain the solar-light-driven photocatalyst of GCN.

Photocatalytic degradation of bisphenol A (BPA) was investigated using commercial TiO2 P25 nanoparticles supported on natural zeolite clinoptilolite (Cli). Employing ultrasound assisted solid-state dispersion method hybrid photocatalyst containing 20 wt% of TiO2, marked TCli-20, was prepared. The structural, morphological and surface properties, and particle size distribution of TCli-20 were studied by X-ray powder diffraction, Fourier transform infrared spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy, scanning electron microscopy with energy dispersive spectroscopy, atomic force microscopy, Brunner-Emmet-Teller method and laser diffraction. The results revealed a successful loading of TiO2 P25 nanoparticles on Cli surface and the preservation of both zeolitic structure and optical properties of TiO2. The influence of catalyst dose, pH value and the addition of hydrogen peroxide (H2O2) was evaluated. The optimal reaction conditions were 2 g/L of catalyst at near-neutral conditions (pH = 6.4) for complete BPA (5 mg/L) photodegradation after 180 min of exposure to simulated solar light. The addition of H2O2 was beneficial for the degradation process and led to the removal of BPA after 120 min of irradiation. BPA removal (60% for 180 min of irradiation) was reduced when TCli-20 was tested in bottled drinking water due to the presence of bicarbonate ions which acted as scavengers for hydroxyl radicals. Even though the photocatalytic activity of TCli-20 decreased after several cycles of usage, 70% of BPA was still successfully degraded during the fourth cycle. The reusability study showed easy separation, stability and good photocatalytic ability of investigated cost-effective hybrid photocatalyst. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

Many efforts have been devoted to produce green materials and technology to prevent and minimize the adverse effects on the environment and human health caused primarily by population growth and industrial progress. Over the past years, the use of zeolites has attracted considerable attention as both an economically and environmentally friendly option. Zeolites are crystalline, hydrated aluminosilicates with an open-framework structure. Unique structural features make them very useful ion-changers, adsorbents and catalysts. The catalytic use of zeolites has expanded from traditional use in the petrochemical industry and refineries to use in the catalytic degradation of various environmental pollutants and the synthesis of fine chemicals. In recent times, progress on the use of zeolites has been achieved in biomass conversion to fuels and valuable industrial bio-based chemicals. This review highlights the recent advances in the catalytic application of clinoptilolite (CLI), the most abundant and explored natural zeolite. The main goal of the review is to give the current state of CLI applications and insights into CLI catalytic performance, which opens possibilities for a variety of applications.

[Abstract] An innovative bulky photocatalyst for water decontamination has been developed. The semiconductor (TiO2) is homogeneously distributed in an aggregating material through the whole piece. This design prevents the activity reduction usually observed in supported catalysts due to the loss of the photoactive layer, and facilitates its recovery for an easy reuse, which is a recurrent problem dealing with nanoparticles. The photocatalyst combines the excellent properties of TiO2 with those of a natural clay, which serves as binder, slows down the phase transition of anatase to rutile upon calcination, and has a synergetic function. The photocatalyst has been prepared in the form of small pellets with an Ecuadorian clay and TiO2 in the commercial form of P25 by evenly dry mixing, forming a paste with water, and subsequent extrusion, drying and calcination at 600 °C. The photodegradation of phenol, as a model pollutant, has been achieved by using this aggregate material in a flow reactor with artificial UVA-Vis radiation, and reused without any significant loss of activity. The photocatalyst showed an optimum activity at a 40% clay / 60% P25 ratio, while higher calcination temperatures had a negative effect on its performance.

[Abstract] This study reports the performance of a three-step lab-scale system including a hybrid digester (HD), a vertical flow (VF) constructed wetland, and a photodegradation (PD) lamp, with two different arrangements regarding the position of the recirculation point. In addition to total suspended solids (TSS), chemical oxygen demand (COD), and nitrogen compounds, removal of the following pollutants was investigated: paracetamol (ACE), ofloxacin (OFL), caffeine (CAF), ketoprofen (KET), ibuprofen (IBU), clofibric acid (ACB), bisphenol A (BPA), and sotalol (SOT). An excellent performance of HD was achieved on the elimination of TSS (82.2 ± 18.5% on average) and COD (63.9 ± 4.1%). TSS and COD removal increased to 91.2 ± 0.4% and 83.4 ± 2.9%, respectively, for the combined HD–VF system. Ammonia removal was 57.0 ± 7.8% in the VF unit while significant denitrification occurred in the HD. The overall HD–VF–PD system achieved mean removals of 100% for OFL, KET, SOT, and IBU, 98 ± 2% for ACE, 87 ± 8% for CAF, 81 ± 38% for ACB and 26 ± 9% for BPA. The removal of ACE, OFL, CAF, and IBU was mostly by biodegradation in the HD and VF units while the PD unit was responsible for the removal of KET, ACB, and SOT.

This study investigates the toxicity of methanolic extracts obtained from compostable plastics (BPs) and conventional plastics (both virgin and recycled). Additionally, it explores the potential influence of plastic photodegradation and composting on toxic responses using a battery of in vitro assays conducted in PLHC-1 cells. The extracts of BPs, but not those of conventional plastics, induced a significant decrease in cell viability (<70%) in PLHC-1 cells after 24 h of exposure. Toxicity was enhanced by either photodegradation or composting of BPs. Extracts of conventional plastics, and particularly those of recycled plastics, induced 7-ethoxyresorufin-O-deethylase (EROD) activity and micronucleus formation in exposed cells, indicating the presence of significant amounts of CYP1A inducers and genotoxic compounds in the extracts, which was enhanced by photodegradation. These findings highlight the importance of investigating the effects of degradation mechanisms such as sunlight and composting on the toxicity of BPs. It is also crucial to investigate the composition of newly developed formulations for BPs, as they may be more harmful than conventional ones.

The study of photodegradation processes concerns many fields, including those of cultural heritage, the food industry, and water purification. In each of these areas, different questions concerning photodegradation arise, but generally, they are related to either (i) the prevention of photodegradation aiming to avoid loss or change of properties, such as color, taste or smell, or (ii) the exploitation of photodegradation for removal of potentially harmful compounds in, e.g., drinking water. Studying light-induced degradation (LID) reactions is challenging and often it is difficult to establish a strong link between the degradation and the starting products. Several techniques and approaches for studying photodegradation had been developed previously, but these can be laborious and prone to errors. A solution to this could be found in a comprehensive, automated device that enables simultaneous sample irradiation of compounds in solution and chemical analysis in real-time and after photodegradation. The need for such an analytical platform is clarified in Chapter 1. The ‘Toolbox for studying the Chemistry Of Light-induced Degradation’ (TooCOLD) project envisioned to develop an integrated device. It would encompass a light-exposure cell, allow in-situ spectroscopic monitoring of the irradiated sample and on-line coupling to liquid chromatography (LC) with diode array detection (DAD) and mass spectrometry (MS) for direct identification of degradation products formed during irradiation. This thesis describes the step-wise development of such an automated device employing a gas-permeable liquid-core waveguide (LCW) as a light-exposure cell, a sample handler, a spectrograph for in-situ absorption spectroscopy, and switching valves for coupling to LC-DAD-QTOFMS. The full device was applied to study the photodegradation of several compounds to evaluate and demonstrate its analytical performance. Ideally, parameters that affect photodegradation should be known to aid the desi

Due to the rapid development of industry and growth of population, water consumption is increased. Beside this, releasing of xenobiotics, which represent significant pollutants into watercourse, like heavy metal ions, pesticides, paints, and solvents, made this problem much bigger. Therefore, they can enter into aquatic organisms directly from industrial plants or into human bodies indirectly through agricultural products. New technologies, including photocatalytic decomposition, are necessary for wastewater treatment as a highly efficient and low-cost process. Photocatalysis implies the degradation of various types of harmful organic substances to simple molecules such as CO2, SO2, ions, and water. The applied process has no detrimental effect on the environment and does not require additional chemicals for precipitation of the products. In this work, photodegradation of the pesticide difenoconazole (DFC) using a TiO2-based photocatalyst was examined using doubled wall thermoregulated quartz reactor. As a replacement for UVC radiation, solar imitated Ultra Vitalux (UV) lamp (300W) was used. Determination of DFC concentration was performed using a UV method. Degradation kinetics follows pseudo-first order. After 120 minutes, the DFC was completely degraded. Chemical oxygen demand (COD) also confirmed that successfully indicating that this process can be used in treating of industrial wastewater.

Nanoemulsion technique based on Ouzo effect was applied for the fast and simple synthesis of Ag3PO4 at room temperature. X-ray powder diffraction analysis and Raman spectroscopy reviled that synthesized powder was single-phase. Using scanning electron microscopy analysis, it was found that the synthesized Ag3PO4 particles were near-spherical shape with an average diameter of 100 nm. The high value for the specific surface area of obtained powder was measured by Brunauer–Emmet–Teller method. Finally, the Ag3PO4 product was used as a photocatalyst for the photodegradation of crystal violet dye in an aqueous solution. Nanoemulsion strategy procedure provides a simple pathway to obtain a highly efficient single-phase Ag3PO4 photocatalyst.

Cerium (Ce) and europium (Eu)-doped TiO₂ thin films were obtained by sol-gel dip-coating technique. SEM micrographs showed that the surfaces are covered by agglomerated particles due to the repeating coating process. XRD patterns showed the presence of TiO₂ anatase phase. Raman spectra revealed that the peaks recorded at 146 cm⁻¹(Eg) and 397 cm⁻¹(B1g) were related to the anatase phase. EIS measurements proved that Ce-TiO2 (1wt%) and Eu-TiO₂ (0.1wt%) photocatalysts possessed a lower electron transfer resistance than pure TiO₂, which can lead to effective separation of electron/ hole pairs during the photoreactions. The photoactivity of Ce and Eu-doped TiO₂ was investigated by the degradation of amido black10B dye (AB) under UV excitation and varying the initial pH and concentrations. It was found that Eu-TiO₂ (0.1wt%) exhibited higher photocatalytic activity, reaching a first-order reaction rate of kapp(0.036min-1), t1/2 was around 12 min and AB removal was 98.94%, under optimal pH of 3.5 and AB concentration of 10ppm compared to (t1/2 = 45 min, t1/2=30 min), (kapp = 0.022 min-1, kapp = 0.026min-1) and AB removal (94.78%, 96.44%), respectively for pure TiO₂ and Ce-TiO₂ (1wt%). Further increase in Eu/Ce amount up to optimal concentration (1wt% Ce and 0.1wt% Eu) led to a decrease in the AB removal. The mineralization of AB using Eu-TiO₂ photocatalyst was confirmed by HPLC analysis.

The development of analytical methodologies to monitor different antibiotic families in water and the implementation of alternatives for their efficient elimination are a great challenge. The aim of this research was to develop a method based on solid-phase extraction followed by ultra-high performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry to analyse multi-class antibiotics, including macrolides, cephalosporins, fluoroquinolones, sulfonamides and diaminopyrimidines, in waters. Several parameters affecting the extraction such as the sample pH, type of sorbent and cartridge, elution volume and breakthrough volume were optimized. The method was validated in real samples, and matrix effect was assessed, demonstrating that the use of isotopically labelled surrogate compounds was mandatory to avoid standard addition calibration for each individual samples. Urban and hospital wastewater samples, as well as natural waters, were analysed, confirming the presence of 12 of the 14 target compounds at concentrations up to 3.5 µg L−1. Non-target analysis based on data-independent workflow was also performed, enabling the identification of 94 pollutants. Preliminary photodegradation experiments were also assessed, revealing the total removal of many target compounds after the first 5–10 min of UVC irradiation. In addition, 20 by-products formed after photolysis could be identified using a non-target approach

In a photoelectrochemical (PEC) cell, the production of solar fuels such as hydrogen is often accompanied either by the oxidation of water or by the oxidation of organic substrates. In this study, we report bromide-mediated PEC oxidation of alkenes at a mesoporous BiVO4 photoanode and simultaneous hydrogen evolution at the cathode using water as an oxygen source. NaBr as a redox mediator was demonstrated to play a dual role in the PEC organic synthesis, which facilitates the selective oxidation of alkenes into epoxides and suppresses the photocorrosion of BiVO4 in water. This method enables a near-quantitative yield and 100% selectivity for the conversion of water-soluble alkenes into their epoxides in H2O/CH3CN solution (v/v, 4/1) under simulated sunlight without the use of noble metal-containing catalysts or toxic oxidants. The maximum solar-to-electricity efficiency of 0.58% was obtained at 0.39 V vs Ag/AgCl. The obtained epoxide products such as glycidol are important building blocks of the chemical industry. Our results provide an energy-saving and environment-benign approach for producing value-added chemicals coupled with solar fuel generation., QC 20230613

Biodegradable polymers complement recyclable materials in battling plastic waste because some products are difficult to recycle and some will end up in the environment either because of their application or due to wear of the products. Natural biopolymers, such as cellulose, are inherently biodegradable, but chemical modification typically required for the obtainment of thermoplastic properties, solubility, or other desired material properties can hinder or even prevent the biodegradation process. This Review summarizes current knowledge on the degradation of common cellulose derivatives in different laboratory, natural, and man-made environments. Depending on the environment, the degradation can be solely biodegradation or a combination of several processes, such as chemical and enzymatic hydrolysis, photodegradation, and oxidation. It is clear that the type of modification and especially the degree of substitution are important factors controlling the degradation process of cellulose derivatives in combination with the degradation environment. The big variation of conditions in different environments is also briefly considered as well as the importance of the proper testing environment, characterization of the degradation process, and confirmation of biodegradability. To ensure full sustainability of the new cellulose derivatives under development, the expected end-of-life scenario, whether material recycling or "biological"recycling, should be included as an important design parameter., QC 20230612

Dissolved organic matter (DOM) plays a central role in the biogeochemistry of aquatic ecosystems and is an important flux of carbon (C) from terrestrial to aquatic systems. Wetlands are rich sources of DOM to downstream waters, but the origins of wetland DOM and its role in biogeochemical processes in wetlands and downstream are not fully understood. To better understand the role of wetlands in mediating the movement and transformation of organic matter between terrestrial and aquatic ecosystems, I characterized the chemical composition and the microbial and photochemical reactivity of wetland DOM in a depressional wetland setting in the interior Delmarva Peninsula. I used laboratory experiments to understand DOM reactivity. I characterized sensitivity to photodegradation, concluding most wetland DOM was somewhat sensitive though site differences affected sensitivity. In another experiment, wetland DOM showed little biodegradability, but C losses to microbes were enhanced after photodegradation. This suggested photochemical and biological degradation may have interacted to influence wetland DOM composition within wetlands and in downstream waters. I also found terrestrial sources of DOM (plant and soil leachates) were more biodegradable than wetland surface water. I concluded wetland DOM was largely comprised of leftover material from previous microbial metabolism in soils or wetland water. To characterize wetland DOM and explore its environmental influences, I undertook a field sampling campaign of 22 wetlands over 18 months. Samples were characterized using a suite of DOM measurements, and variability in these data was modeled using water level, regional air temperature, a proxy for site canopy cover, estimated photosynthetically active radiation, and others. DOM varied considerably seasonally and among sites, and modeling suggested that complex seasonal and site-related interactions influenced DOM, not including water level. This research indicates that depressio

Bilirubin has been clinically confirmed as a liver function biomarker and used in a number of prognostic scoring systems for patients with cirrhosis and neonatal hyperbilirubinemia. Within clinical settings, optical and chemical methods are used to determine the blood bilirubin concentration, using complex, costly, and bulky instruments. This, combined with the expertise needed to operate these instruments, means that existing bilirubinometric technologies do not lend themselves to applications outside the clinics within the community settings. Consequently, blood bilirubin concentration is typically assessed intermittently, which results in missed episodes that may benefit from timely clinical interventions. This thesis outlines the development of a point-of-care (PoC) system to measure bilirubin in the blood. The system is developed using commercially available optoelectronic and microelectronic components, with an emphasis on low cost and ease of use. Two possible bilirubin level measurement approaches have been investigated: 1) the multi-wavelength method and 2) the photodegradation kinetics approach. The multi-wavelength method uses distinct optical signatures of bilirubin to implement a system based on dual-wavelength absorption measurement. A benchtop optical system was designed and implemented for bilirubin measurement using 470 nm (analytical wavelength) and 525 nm (reference wavelength). In contrast, the photodegradation kinetics approach uses bilirubin degradation under blue light to estimate its levels by analysing the variation in its spectrophotometric characteristics. A new kinetic model for degradation reaction is introduced to model the photodegradation kinetic results. Results show that bilirubin degrades exponentially with residual absorbance at long degradation times. The variations in the spectrophotometric characteristics of bilirubin were then used to estimate bilirubin levels. Building on the two approaches, the feasibility of combining both

Triclosan, an antimicrobial agent incorporated in personal care and consumer products, is used to prevent bacterial contamination and material biodegradation. However, various studies have shown that triclosan exhibits toxic effects to aquatic species, persists in the environment, and poses as an endocrine disruptor. Triclosan can be leached from untreated wastewater and wastewater treatment plant effluent into ocean surface water as a contaminant. Consequently, it can become aerosolized in sea spray aerosol (SSA) and undergo degradation in the atmosphere to produce potentially more toxic transformation products, such as dichlorodibenzo-p-dioxin and chlorophenols. To understand the lifetime of triclosan in the aerosol phase in SSA, this research focuses on quantifying the kinetics and degradation lifetimes of triclosan with respect to heterogeneous oxidation by hydroxyl radicals (OH) and photosensitization reactions involving chromophoric dissolved organic matter (CDOM) mixed with inorganic salts that coexist in SSA. A potential aerosol mass oxidation flow reactor (PAM-OFR), used to simulate aerosol aging, is coupled with an extractive electrospray ionization high-resolution time-of-flight mass spectrometer (EESI-HR-ToF-MS) to study triclosan degradation kinetics and its transformation products in the aerosol phase in near real time. Results indicate that the reactive uptake of OH by single-component triclosan aerosol proceeds with a diffusion-corrected uptake coefficient of 0.15 ± 0.04. In the presence of humic acid, a CDOM proxy, the OH reactive uptake coefficient decreased to 0.09 ± 0.04, suggesting that CDOM inhibits triclosan degradation in the presence of OH radicals. Furthermore, the addition of the inorganic salt, NaCl, to the triclosan system increased the effective uptake coefficient to 0.29 ± 0.08. 2,8 dichlorodibenzo-p-dioxin (2,8 DCDD), a toxic transformation product, was potentially detected by the EESI-HR-ToF-MS in the aerosol phase indicating photode

In this work, the behavior of Eucalyptus globulus unpreserved wood exposed outdoor for a year in La Plata city, Argentina, was evaluated. The evolution of color and defects presence were analyzed, and also their relationship with some climatic variables and the wood moisture content. Fifty-four samples (2.5 cm x 12 cm x 50 cm) were placed in an outdoor exhibitor with a 45º inclination (north), in which color (CIELab*), moisture content and defects were determined monthly. A sample without outdoor exposure was considered as control. After 150-180 days starting the test, the values of L*, a* and b* reached values close to the minimum (49.22; -6.5; -1.90, respectively). At the end, the colorimetric parameters showed significant changes with respect to the initial values (∆L*=22.55; ∆a*=5.41; ∆b*=16.64; ∆E*total=29.10) and to the control. The values of solar radiation and rainfall did not significantly influence the color, while the temperature affected the parameter a*. The moisture content of wood correlated with the presence of some defects, but it was not correlated with the color. Weathering caused loss of natural color, acquiring a grayish tone (a* and b* close to 0 = achromatic and L*=47.6) and increasing the level of cracking; the first 150 days of exposure were key in this process, En el presente trabajo se evaluó el comportamiento de la madera de Eucalyptus globulus sin preservar, expuesta a la intemperie durante un año en la ciudad de La Plata, Argentina. Se analizó la evolución del color y la presencia de defectos, y su relación con algunas variables climáticas y con el contenido de humedad de la madera. Se colocaron 54 muestras (2,5 cm x 12 cm x 50 cm) en un expositor exterior con inclinación de 45º (norte) y sobre ellas se determinó mensualmente color (CIELab*), humedad y defectos. Una muestra sin exposición fue considerada testigo. Entre los 150-180 días de comenzar el ensayo, los parámetros L*, a* y b* alcanzaron valores cercanos al mínimo (49,22; -6,5; -1,90 respectivamente); al finalizar presentaron cambios significativos respecto a los valores iniciales (∆L*=22,55; ∆a*=5,41; ∆b*=16,64; ∆E*total=29,10) y al testigo. Los valores de radiación solar y precipitaciones no influyeron significativamente en el color mientras que la temperatura afectó al parámetro a*. El contenido de humedad de la madera se correlacionó con la presencia de algunos defectos, pero no afectó al color. El intemperismo provocó pérdida del color natural, adquiriendo un tono grisáceo (a* y b*cercanos a 0=acromático y L*=47,6) y aumentó el agrietado, siendo los primeros 150 días de exposición claves en este proceso

The photolysis of amlodipine (AML) as a ubiquitous pollutant in natural water has been extensively studied. Montmorillonite (MMT), a major component of suspended particles in surface aquifers, plays key roles in the natural transportation and transformation of organic contaminants in the environment. However, literature has scarcely focused on whether and how suspended particles affect the phototransformation of AML. This study systematically investigated the phototransformation behavior of AML in MMT suspensions under simulated sunlight. The results obtained showed that MMT significantly enhanced the photolysis of AML. The photodegradation of AML in 0.05 g/L MMT suspension reached 92.2 % after 3 h irradiation under the simulated sunlight. The photodecomposition followed the pseudo-first-order kinetic with a rate constant of 0.803 h−1 in the presence of 0.05 g/L MMT, which is about 19 times larger than that in the absence of MMT (0.0421 h−1). Further mechanistic investigation suggested that MMT accelerated the photolysis of AML by the formation of surface complexes between cationic amino groups of AML and the negatively charged sites on MMT surface, which greatly facilitated light absorption and electron transfer for the production of cationic radical AML+·. Meanwhile, the hydroxyl radicals generated by irradiated MMT also played an important role in the photocatalytic degradation of AML. The probable photodegradation pathways of AML in MMT suspension further supported the proposed mechanisms. The toxicity evaluation of phototransformation products of AML with ECOSAR program indicated that photolysis could reduce its potential threats. These findings reveal an important and previously overlooked phototransformation mechanisms of AML in the presence of MMT clays, which is of importance in assessing the environmental fate of other similar organic contaminants. © 2021 Elsevier Ltd

Nano-sized semiconductor photocatalysts are known for their promising and economical remediation approach to environmental pollution under visible light irradiation. In this study, a facile strategy was adopted to develop the zirconium oxide/cadmium sulfide nanocomposite through a co-precipitation method for degradation of three aromatic dyes under visible light. The synthesized photocatalyst was characterized using powder X-ray diffraction, Fourier-transform infrared spectroscopy, Scanning electron microscopy, UV–Visible spectroscopy, Cyclic voltammetry, and Electrochemical impedance spectroscopy. The zirconium oxide/cadmium sulfide heterostructure nanocomposite was tested for photocatalytic degradation of Direct Violet-9, Methyl Violet, and Congo Red. The composite exhibited photocatalytic degradation efficiency of 95.5%, 91%, and 84% for Direct Violet-9, Methyl Violet, and Congo Red, respectively under visible light. The high degradation efficiency of the photocatalyst for multiple dyes was found to be mainly due to the suppression of charge carrier recombination.

In this work, the behavior of Eucalyptus globulus unpreserved wood exposed outdoor for a year in La Plata city, Argentina, was evaluated. The evolution of color and defects presence were analyzed, and also their relationship with some climatic variables and the wood moisture content. Fifty-four samples (2.5 cm x 12 cm x 50 cm) were placed in an outdoor exhibitor with a 45º inclination (north), in which color (CIELab*), moisture content and defects were determined monthly. A sample without outdoor exposure was considered as control. After 150-180 days starting the test, the values of L*, a* and b* reached values close to the minimum (49.22; -6.5; -1.90, respectively). At the end, the colorimetric parameters showed significant changes with respect to the initial values (∆L*=22.55; ∆a*=5.41; ∆b*=16.64; ∆E*total=29.10) and to the control. The values of solar radiation and rainfall did not significantly influence the color, while the temperature affected the parameter a*. The moisture content of wood correlated with the presence of some defects, but it was not correlated with the color. Weathering caused loss of natural color, acquiring a grayish tone (a* and b* close to 0 = achromatic and L*=47.6) and increasing the level of cracking; the first 150 days of exposure were key in this process, En el presente trabajo se evaluó el comportamiento de la madera de Eucalyptus globulus sin preservar, expuesta a la intemperie durante un año en la ciudad de La Plata, Argentina. Se analizó la evolución del color y la presencia de defectos, y su relación con algunas variables climáticas y con el contenido de humedad de la madera. Se colocaron 54 muestras (2,5 cm x 12 cm x 50 cm) en un expositor exterior con inclinación de 45º (norte) y sobre ellas se determinó mensualmente color (CIELab*), humedad y defectos. Una muestra sin exposición fue considerada testigo. Entre los 150-180 días de comenzar el ensayo, los parámetros L*, a* y b* alcanzaron valores cercanos al mínimo (49,22; -6,5; -1,90 respectivamente); al finalizar presentaron cambios significativos respecto a los valores iniciales (∆L*=22,55; ∆a*=5,41; ∆b*=16,64; ∆E*total=29,10) y al testigo. Los valores de radiación solar y precipitaciones no influyeron significativamente en el color mientras que la temperatura afectó al parámetro a*. El contenido de humedad de la madera se correlacionó con la presencia de algunos defectos, pero no afectó al color. El intemperismo provocó pérdida del color natural, adquiriendo un tono grisáceo (a* y b*cercanos a 0=acromático y L*=47,6) y aumentó el agrietado, siendo los primeros 150 días de exposición claves en este proceso

In this work, Ag-doped ZnO nanoparticles are obtained via pulsed laser ablation of the Ag-coated ZnO target in water. The ratio of Ag dopant in ZnO nanoparticles strongly depends on the thickness of the Ag layer at the ZnO target. Synthesized nanoparticles were characterized by XRD, XPS, SEM, EDS, ICP-OES, and UV–VIS spectrophotometry to obtain their crystal structure, elemental composition, morphology and size distribution, mass concentration, and optical properties, respectively. The photocatalytic studies showed photodegradation of methylene blue (MB) under UV irradiation. Different ratios of Ag dopant in ZnO nanoparticles influence the photodegradation rate. The ZnO nanoparticles doped with 0.32% silver show the most efficient photodegradation rate, with the chemical reaction constant of 0.0233 min−1. It exhibits an almost twice as large photodegradation rate compared to pure ZnO nanoparticles, showing the doping effect on the photocatalytic activity.

Spray pyrolysis was used to deposit CeO2–TiO2 coatings on stainless steel substrates. The addition of CeO2 to TiO2 changes morphology of the coatings, causing the surface to become laced and some CeO2 ions are incorporated into TiO2 crystal lattice. Part of CeO2 is highly dispersed on the surface of TiO2. The XPS showed the simultaneous existence of Ce4+ and Ce3+ on coating surface. As the CeO2 content in composites increases from 0.5 to 20%, the band gap decreases from 3.16 to 2.88 eV, respectively. The photoactivities in the degradation of methyl orange and lindane were significantly influenced by the content of Ce in composite. For methyl orange photodegradation, the highest activity had coating with CeO2 content of 2 wt%. In contrast, the activity of coatings in lindane photodegradation gradually decreases as the CeO2 content increases. However, efficiency of CeO2–TiO2 coatings remained satisfactory for application in process of lindane degradation. Lindane conversion at 6 h of irradiation is in the range from 88% for pure TiO2 to 60% for CeO2–TiO2 coating with CeO2 content of 20 wt%. Photodegradation of lindane was enhanced on pure TiO2 sites, while methyl orange degradation is highest on composite CeO2/TiO2 species with CeO2 content of 2 wt%.

Magnetorheological elastomer (MRE) materials have the potential to be used in a wide range of applications that require long-term service in hostile environments. These widespread applications will result in the emergence of MRE-specific durability issues, where durability refers to performance under in-service environmental conditions. In response, the outdoor tropical climatic environment, combined with the effects of weathering, will be the primary focus of this paper, specifically the photodegradation of the MRE. In this study, MRE made of silicone rubber (SR) and 70 wt% micron-sized carbonyl iron particles (CIP) were prepared and subjected to mechanical and rheological testing to evaluate the effects under natural weathering. Magnetorheological elastomer samples were exposed to the natural weathering conditions of a tropical climate in Kuala Lumpur, Malaysia, for 30 days. To obtain a comprehensive view of MRE degradation during natural weathering, mechanical testing, rheology, and morphological evaluation were all performed. The mechanical and rheological properties test results revealed that after 30 days of exposure and known meteorological parameters, Young's modulus and storage modulus increased, while elongation at break decreased. The degradation processes of MRE during weathering, which are responsible for their undesirable change, were given special attention. With the help of morphological evidence, the relationship between these phenomena and the viscoelastic properties of MRE was comprehensively defined and discussed.

Many chemical reactions contain heterogeneous reagents, products, byproducts, or catalysts, making their transposition from batch to continuous-flow processing challenging. Herein, we report the use of a photochemical rotor–stator spinning disk reactor (pRS-SDR) that can handle and scale solid-containing photochemical reaction conditions in flow. Its ability to handle slurries was showcased for the TiO2-mediated aerobic photodegradation of aqueous methylene blue. The use of a fast rotating disk imposes high shear forces on the multiphase reaction mixture, ensuring its homogenization, increasing the mass transfer, and improving the irradiation profile of the reaction mixture. The pRS-SDR performance was also compared to other lab-scale reactors in terms of water treated per reactor volume and light power input.

In this work, Ag-doped ZnO nanoparticles are obtained via pulsed laser ablation of the Ag-coated ZnO target in water. The ratio of Ag dopant in ZnO nanoparticles strongly depends on the thickness of the Ag layer at the ZnO target. Synthesized nanoparticles were characterized by XRD, XPS, SEM, EDS, ICP-OES, and UV–VIS spectrophotometry to obtain their crystal structure, elemental composition, morphology and size distribution, mass concentration, and optical properties, respectively. The photocatalytic studies showed photodegradation of methylene blue (MB) under UV irradiation. Different ratios of Ag dopant in ZnO nanoparticles influence the photodegradation rate. The ZnO nanoparticles doped with 0.32% silver show the most efficient photodegradation rate, with the chemical reaction constant of 0.0233 min−1. It exhibits an almost twice as large photodegradation rate compared to pure ZnO nanoparticles, showing the doping effect on the photocatalytic activity.

CaO nanoparticles sized ca. 26 nm were organically modified with oleic acid (Ol-CaO), and both were incorporated into PLA at concentrations of 5 and 8 wt.% by a melting process. Modification of nanoparticles improved the distribution into PLA, as seen by transmission electron microscopy (TEM). Thermal analysis revealed that the presence of Ol-CaO in the PLA matrix promoted a decrease ca. 13% in the glass transition temperature (T). The thermal stability of the PLA/Ol-CaO decreased ca. 23% compared to the neat PLA due to the catalytic activity from nanoparticles, while Vickers Microhardness (HV) for nanocomposites PLA/Ol-CaO increased ca. 9%, compared with the neat PLA, due to the good dispersion of modified-surface Ol-CaO nanoparticles in PLA. PLA/Ol-CaO nanocomposites reached 99.9% of antimicrobial effectiveness against E. coli for nanoparticles content above 8 wt.%. From photodegradation tests under irradiation during five days, it was verified that the presence of CaO nanoparticles accelerated the photodegradation of the polymer matrix nanoparticles into PLA promoted a decreasing ca. 13% of Tg and an increase in the degree of crystallinity (Xc) (ca. 7%), compared to PLA/CaO without irradiation. Besides, the viscosity molecular weight (M¯v) of PLA/CaO showed a higher decrease than neat PLA after irradiation, and SEM analysis showed that the nanocomposites presented cavities around the nanoparticles after irradiation. Our results showed that incorporating CaO nanoparticles into the PLA polymer matrix allows future development of more sustainable materials as nanocomposites for food packaging or medical devices.

Nano-sized semiconductor photocatalysts are known for their promising and economical remediation approach to environmental pollution under visible light irradiation. In this study, a facile strategy was adopted to develop the zirconium oxide/cadmium sulfide nanocomposite through a co-precipitation method for degradation of three aromatic dyes under visible light. The synthesized photocatalyst was characterized using powder X-ray diffraction, Fourier-transform infrared spectroscopy, Scanning electron microscopy, UV–Visible spectroscopy, Cyclic voltammetry, and Electrochemical impedance spectroscopy. The zirconium oxide/cadmium sulfide heterostructure nanocomposite was tested for photocatalytic degradation of Direct Violet-9, Methyl Violet, and Congo Red. The composite exhibited photocatalytic degradation efficiency of 95.5%, 91%, and 84% for Direct Violet-9, Methyl Violet, and Congo Red, respectively under visible light. The high degradation efficiency of the photocatalyst for multiple dyes was found to be mainly due to the suppression of charge carrier recombination.

The photolysis of amlodipine (AML) as a ubiquitous pollutant in natural water has been extensively studied. Montmorillonite (MMT), a major component of suspended particles in surface aquifers, plays key roles in the natural transportation and transformation of organic contaminants in the environment. However, literature has scarcely focused on whether and how suspended particles affect the phototransformation of AML. This study systematically investigated the phototransformation behavior of AML in MMT suspensions under simulated sunlight. The results obtained showed that MMT significantly enhanced the photolysis of AML. The photodegradation of AML in 0.05 g/L MMT suspension reached 92.2 % after 3 h irradiation under the simulated sunlight. The photodecomposition followed the pseudo-first-order kinetic with a rate constant of 0.803 h−1 in the presence of 0.05 g/L MMT, which is about 19 times larger than that in the absence of MMT (0.0421 h−1). Further mechanistic investigation suggested that MMT accelerated the photolysis of AML by the formation of surface complexes between cationic amino groups of AML and the negatively charged sites on MMT surface, which greatly facilitated light absorption and electron transfer for the production of cationic radical AML+·. Meanwhile, the hydroxyl radicals generated by irradiated MMT also played an important role in the photocatalytic degradation of AML. The probable photodegradation pathways of AML in MMT suspension further supported the proposed mechanisms. The toxicity evaluation of phototransformation products of AML with ECOSAR program indicated that photolysis could reduce its potential threats. These findings reveal an important and previously overlooked phototransformation mechanisms of AML in the presence of MMT clays, which is of importance in assessing the environmental fate of other similar organic contaminants. © 2021 Elsevier Ltd

Many chemical reactions contain heterogeneous reagents, products, byproducts, or catalysts, making their transposition from batch to continuous-flow processing challenging. Herein, we report the use of a photochemical rotor–stator spinning disk reactor (pRS-SDR) that can handle and scale solid-containing photochemical reaction conditions in flow. Its ability to handle slurries was showcased for the TiO2-mediated aerobic photodegradation of aqueous methylene blue. The use of a fast rotating disk imposes high shear forces on the multiphase reaction mixture, ensuring its homogenization, increasing the mass transfer, and improving the irradiation profile of the reaction mixture. The pRS-SDR performance was also compared to other lab-scale reactors in terms of water treated per reactor volume and light power input.

Spray pyrolysis was used to deposit CeO2–TiO2 coatings on stainless steel substrates. The addition of CeO2 to TiO2 changes morphology of the coatings, causing the surface to become laced and some CeO2 ions are incorporated into TiO2 crystal lattice. Part of CeO2 is highly dispersed on the surface of TiO2. The XPS showed the simultaneous existence of Ce4+ and Ce3+ on coating surface. As the CeO2 content in composites increases from 0.5 to 20%, the band gap decreases from 3.16 to 2.88 eV, respectively. The photoactivities in the degradation of methyl orange and lindane were significantly influenced by the content of Ce in composite. For methyl orange photodegradation, the highest activity had coating with CeO2 content of 2 wt%. In contrast, the activity of coatings in lindane photodegradation gradually decreases as the CeO2 content increases. However, efficiency of CeO2–TiO2 coatings remained satisfactory for application in process of lindane degradation. Lindane conversion at 6 h of irradiation is in the range from 88% for pure TiO2 to 60% for CeO2–TiO2 coating with CeO2 content of 20 wt%. Photodegradation of lindane was enhanced on pure TiO2 sites, while methyl orange degradation is highest on composite CeO2/TiO2 species with CeO2 content of 2 wt%.

The photolysis of amlodipine (AML) as a ubiquitous pollutant in natural water has been extensively studied. Montmorillonite (MMT), a major component of suspended particles in surface aquifers, plays key roles in the natural transportation and transformation of organic contaminants in the environment. However, literature has scarcely focused on whether and how suspended particles affect the phototransformation of AML. This study systematically investigated the phototransformation behavior of AML in MMT suspensions under simulated sunlight. The results obtained showed that MMT significantly enhanced the photolysis of AML. The photodegradation of AML in 0.05 g/L MMT suspension reached 92.2 % after 3 h irradiation under the simulated sunlight. The photodecomposition followed the pseudo-first-order kinetic with a rate constant of 0.803 h−1 in the presence of 0.05 g/L MMT, which is about 19 times larger than that in the absence of MMT (0.0421 h−1). Further mechanistic investigation suggested that MMT accelerated the photolysis of AML by the formation of surface complexes between cationic amino groups of AML and the negatively charged sites on MMT surface, which greatly facilitated light absorption and electron transfer for the production of cationic radical AML+·. Meanwhile, the hydroxyl radicals generated by irradiated MMT also played an important role in the photocatalytic degradation of AML. The probable photodegradation pathways of AML in MMT suspension further supported the proposed mechanisms. The toxicity evaluation of phototransformation products of AML with ECOSAR program indicated that photolysis could reduce its potential threats. These findings reveal an important and previously overlooked phototransformation mechanisms of AML in the presence of MMT clays, which is of importance in assessing the environmental fate of other similar organic contaminants. © 2021 Elsevier Ltd

This work investigates the reaction of 1-vinyl-2-pyrrolidinone (VP) and 2-piperazin-1-yletanamine (PPE) under UV radiation. Both substances are high-volume production chemicals (production >1000 tons/year) widely used in polymers, coatings and a wide array of applications, which have been classified as mobile chemicals and which can then lead to the formation of persistent and mobile transformation products (TPs). Thus, their reaction with UV light was studied by means of liquid chromatography-quadrupole-time-of-flight-mass spectrometry (LC-QTOF-MS). Both compounds presented a high reactivity, the VP quantum yield was 0.28 mol/E; whereas, PPE had a quantum yield notably higher than 1 (16 mol/E). Five and 7 TPs were identified for VP and PPE, respectively. Some of them had been already reported in literature due to sunlight photodegradation or other oxidation processes, but most of them are reported here for the first time. Finally, the acute and chronical toxicity of precursors and TPs were estimated using two quantitative structure-activity relationship (QSAR) software tools which led to some discrepancies in the estimations, pointing to the need for experimental toxicity assays for these compounds

In this work, the role of moisture in photo-ageing was discussed for the case of an acrylic-urethane network. Ageing behaviours were characterised by Fourier transform infra-red spectroscopy, positron annihilation lifetime spectroscopy, sol-gel analysis, and differential scanning calorimetry. Two common features between dry and wet photo-ageing, namely, decrease in the mean free volume and increase in the glass transition temperature were observed as photo-oxidation progressed. The characteristics of the final internal structure of the wet photo-aged sample differed from those of the dry photo-aged sample. Although the dry photo-aged samples suggested network densification due to extensive crosslinking formation, wet photo-ageing led to an inhomogeneous structure wherein the average molar mass between crosslinks (at a scale of several nanometres) increased and some domains crosslinked at the sub-nanoscale. Considering the physical (plasticisation) and chemical (hydrolysis) effects induced by water, a possible mechanism for the evolution of the macromolecular architecture was proposed for photo-ageing in dry and wet environments.

In this work, the role of moisture in photo-ageing was discussed for the case of an acrylic-urethane network. Ageing behaviours were characterised by Fourier transform infra-red spectroscopy, positron annihilation lifetime spectroscopy, sol-gel analysis, and differential scanning calorimetry. Two common features between dry and wet photo-ageing, namely, decrease in the mean free volume and increase in the glass transition temperature were observed as photo-oxidation progressed. The characteristics of the final internal structure of the wet photo-aged sample differed from those of the dry photo-aged sample. Although the dry photo-aged samples suggested network densification due to extensive crosslinking formation, wet photo-ageing led to an inhomogeneous structure wherein the average molar mass between crosslinks (at a scale of several nanometres) increased and some domains crosslinked at the sub-nanoscale. Considering the physical (plasticisation) and chemical (hydrolysis) effects induced by water, a possible mechanism for the evolution of the macromolecular architecture was proposed for photo-ageing in dry and wet environments.

Titanium (IV) isopropoxide (TTIP) was used to synthesize GO/TiO2 thin films using a sol-gel spin-coating method onto a glass substrate, undergoing an heat tretment at 350 °C. Several amounts of graphene oxide (GO) (0-20mg) were weighed into a sol solution of TiO2 to produce GO/TiO2 thin films. The thin film samples were characterized by X-ray diffraction (XRD) to analyze the samples’ phase and by scanning electron microscopy (SEM) to analyze the samples’ microstructure. Physical testing such as water contact angle (WCA) was analyzed using an optical microscope with J-Image software. In contrast, the optical band gap and photodegradation of methylene blue under sunlight irradiation of the thin film was analyzed using UV-VIS spectrophotometry. GO5 thin film sample showed low-intensity anatase phase formation, where the microstructure revealed a larger surface area with the addition of GO. WCA reveals that GO/TiO2 thin film exhibits super hydrophilic properties where the angle decreases from 37.83° to 4.11°. The optical result shows that GO has improved the absorption edges by expanding into visible regions. Moreover, due to the existence of GO 3.30 eV band gap energy of TiO2 decreases from to 3.18 eV obtained by GO5. The improved adsorption edge allows Ti3+, O2 and interstitial states to be formed in low valence states with energy underneath than in the TiO2 band gap. Therefore, the photodegradation of methylene blue (MB) dye increases from 48 % to 59 % in the GO/TiO2 thin film.

Apart from some strongly fluorescent wood species, the general fluorescence of wood has long been ignored. Recent studies suggest that each species has a distinct fluorescence, originating from both basic components and characteristic extractives. However, wood colour and fluorescence rapidly change upon exposure to sunlight. In this study, 288 samples of Acer pseudoplatanus, Quercus robur, Picea abies and Juglans nigra were irradiated with different bands of ultraviolet (UV) and visible (VIS) light. Photosensitivity was examined in regards of colour, infrared absorbance (FTIR), and fluorescence imaging. UV light caused strong yellowing in all examined species, mostly correlating with lignin degradation, carbonyl formation and the appearance of a broad banded fluorescence emission. VIS light above 420 nm, however, caused different, partly contradicting effects in colour and fluorescence, and did not affect lignin. Juglans nigra proved to be most sensitive towards VIS- induced yellowing and bleaching. The main new finding of this study is that the native long wave fluorescence of wood was strongly decreased by VIS-irradiation above 510 nm wavelength in all samples. This effect was not species-specific, probably originating from a cross-species wood component. The results have potential impacts on non-destructive image-based evaluation methods and wood identification.

Pure, Sn and Sr doped Cadmium Sulphide photocatalysts were prepared by chemical coprecipitation method with different proportion of dopant (CdxSrySn1-x+yS). The prepared samples were characterised by SEM (Scanning Electron Microscopy), EDX (Energy Dispersive X-Ray Diffraction, and XRD (X-Ray diffraction) spectroscopy. Structural and optical study reveals, the size and band gap was reduced than pure CdS. Photocatalytic degradation experiments were carried out in UV-Photo reactor for degradation study and in sunlight. The photocatalytic activity of Sr and Sn doped Cadmium Sulphide was studied by changing the factors pH, light intensity, catalyst loading and reuse of photocatalyst were studied by the degradation of R6G dye. The photocatalytic activity doped CdS and undoped CdS was compared by means of oxidative photocatalytic degradation of R6G dye. Doped Cadmium Sulphide photocatalyst was observed more effective and efficient than undoped Cadmium Sulphide.

This work develops a kinetic model that allow to predict the water toxicity and the main degradation products concentration of aqueous solutions containing 4-chlorophenol oxidised by UV/H2O2. The kinetic model was developed grouping degradation products of similar toxicological nature: aromatics (hydroquinone, benzoquinone, 4-chlorocatechol and catechol), aliphatics (succinic, fumaric, maleic and malonic acids) and mineralised compounds (oxalic, acetic and formic acids). The degradation of each group versus time was described as a mathematical function of the rate constant of a second-order reaction involving the hydroxyl radical, the quantum yield of lump, the concentration of the hydroxyl radicals and the intensity of the emitted UV radiation. The photolytic and kinetic parameters characterising each lump were adjusted by experimental assays. The kinetic, mass balance and toxicity equations were solved using the Berkeley Madonna numerical calculation tool. Results showed that 4-chlorophenol would be completely removed during the first hour of the reaction, operating with oxidant molar ratios higher than R=200 at pH6.0 and UV=24 W. Under these conditions, a decrease in the rate of total organic carbon (TOC) removal close to 50% from the initial value was observed. The solution colour, attributed to the presence of oxidation products as p-benzoquinone and hydroquinone, were oxidised to colourless species, that resulted in a decrease in the toxicity of the solutions (9.95 TU) and the aromaticity lost.