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Photocatalytic degradation of acetaminophen over Ag, Au and Pt loaded TiO2 using solar light
摘要： The sustainability and feasibility of using solar irradiation instead of UV light in photocatalysis is a promising approach for water remediation. In this study, photocatalytic degradation (PCD) of a widely used analgesic and antipyretic drug, acetaminophen (AP), with noble metal loaded TiO2 photocatalysts (Ag/TiO2, Au/TiO2 and Pt/TiO2) was investigated in aqueous suspension using solar light. The deposition of noble metals (Ag, Au and Pt) onto the TiO2 surface enhanced the PCD of AP under different operating conditions including pH, surfactants and drug excipients. However, lower degradation rate constants of AP were obtained under simulated and direct solar light as compared to UV light. The degradation mechanism of AP under UV as well as simulated solar light was found to follow similar, though not identical, reaction pathways leading to hydroxylated intermediates (e.g. 4-acetamidoresorcinol (4-AR), 4-acetamidocatechol (4-AC) and hydroquinone (HQ)) through competitive routes. The PCD of AP followed a pseudo first order kinetics according to Langmiur-Hinshelwood model. Noble metal (Ag, Au and Pt) loaded TiO2 photocatalysts can be used effectively to degrade AP in water under both solar and UV light.
关键词： Solar light,Hydroxyl radical,Noble metal,Acetaminophen,TiO2
更新于2025-09-19 17:15:36
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Synthesis and Properties of Highly Sensitive Ether Ring Fused <i>O</i>-Acyloxime Esters as Photoradical Initiator
摘要： High sensitivity of O-acyloxime ester, which is widely used as a photo radical polymerization initiator for color resist, was investigated. Introduction of an ether ring structure to the periphery of oxime was aimed at increasing rigidity of dye scaffold. As a result, the absorption spectrum at i-line (365 nm) became sharp, the absorption efficiency was greatly improved, and the sensitivity was increased by about five times as much as conventional linear type oximes by improving the radical generation quantum yield.
关键词： Photoradical initiator,i-Line,High sensitivity,Radical curing reaction,Ether ring-fused structure,Carbazole dye,O-Acyloxime ester
更新于2025-09-19 17:15:36
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Photocatalyzed thiol-alkene coupling: Mechanistic study and polymer synthesis
摘要： Due to the “click” chemistry characteristics of the thiol–ene reaction, these transformations have been gaining an increasing amount of attention in current chemical research. The high efficiency and selectivity of these transformations have been useful for many areas of study, from small molecule organic synthesis, to polymer synthesis and functionalization, to bioconjugation reactions. In this work, a study of a novel method of photochemical thiol–ene reactions using alkyl halides and an tris [2-phenylpyridinato-C2,N]iridium(III) (Ir(ppy)3) photocatalyst is investigated. This process is shown to progress rapidly and has the benefit of low catalyst and initiator concentrations relative to reagents as well as mild conditions associated with photochemical processes. To understand the mechanism of this process, catalyst and initiator concentrations and other reaction conditions are varied. To demonstrate the utility of this process, a step-growth thiol–ene polymer is synthesized using dithiol and diene monomers and a crosslinked polymer network is synthesized as well.
关键词： thiol–ene,radical reactions,step-growth polymerization,polymer network,photochemistry
更新于2025-09-19 17:15:36
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Photoredox catalyzed generation of acetonyl radical in flow: theoretical investigation and synthetic applications
摘要： A Hydrogen Atom Transfer (HAT) step from acetone allowed the smooth generation of acetonyl radical, that was then exploited as synthon in the mild formation of C–C bonds under flow conditions. The process was promoted by aryl radicals photocatalytically generated via Single Electron Transfer (SET) reduction of arenediazonium salts. The mechanism has been investigated by a combined experimental and computational approach and further supported by deuterium labelling experiments.
关键词： Arenediazonium salts,Hydrogen Atom Transfer (HAT),Acetonyl radical,Photocatalysis,Aryl radicals
更新于2025-09-19 17:15:36
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Simultaneous measurement of CO and OH in flames using a single broadband, femtosecond laser pulse
摘要： In this short communication, we report simultaneous measurement of CO and OH in flames using a single femtosecond (fs)-duration laser source. Two-photon excitation of CO A 1 (cid:2) ←← X 1 ?+ (3,0), (4,0) and (5,0) bands and single-photon excitation of OH A 2 ?+ ← X 2 (cid:2) (1,0) band are achieved simultaneously using one fs-duration laser pulse near 283 nm. Subsequently, crosstalk-free, laser-induced fluorescence (LIF) emissions are detected from the v’ = 3, 4 and 5 upper vibrational levels of CO in the 200–230 nm region, and (1,1) and (0,0) bands of OH near the 310-nm region. A detailed spectroscopic investigation of CO in a gas cell is followed by simultaneous detection of CO and OH in C 2 H 4 /air flames. The measured CO and OH profiles as a function of flame equivalence ratio agree well with equilibrium calculations. The present study extends the applicability of broadband fs-LIF imaging of OH in flames, and reveal an alternate method to obtain heat release rate in turbulent flames via simultaneous OH and CO measurements.
关键词： Femtosecond diagnostics,Carbon monoxide,Laser-induced fluorescence,Hydroxyl radical
更新于2025-09-19 17:13:59
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Photocontrolled Iodine-Mediated Green Reversible-Deactivation Radical Polymerization of Methacrylates: Effect of Water in the Polymerization System
摘要： Photocontrolled iodine-mediated reversible-deactivation radical polymerization (RDRP) is a facile and highly efficient access to precision polymers. Herein, a facile photocontrolled iodine-mediated green RDRP strategy was successfully established in water by using 2-iodo-2-methylpropionitrile (CP-I) as the initiator and water-soluble functional monomers including poly(ethylene glycol) methyl ether methacrylate (PEGMA), 2-hydroxyethyl methacrylate (HEMA), and 2-hydroxypropyl methacrylate (HPMA) as the model monomers under blue-light-emitting diode (LED) irradiation at room temperature. Well-defined polymers (PPEGMA, PHEMA, PHPMA) with narrow polydispersities (1.09?1.21) were obtained, and amphiphilic block copolymers which can form nanospheres in situ in water (PPEGMA-b-poly(benzyl methacrylate) (PPEGMA-b-PBnMA) and PPEGMA-b-PHPMA) were prepared. To explore the role of water in our polymerization, control experiments were successfully carried out by using oil-soluble monomer methyl methacrylate (MMA) with the help of trace amounts of water. Notably, the green solvent—water—has an additionally positive effect in accelerating the polymerization and makes our polymerization system an environmentally friendly polymerization system. Therefore, this simple strategy conducted in the presence of water enables the green preparation of well-defined water-soluble or water-insoluble polymers and clean synthesis of amphiphilic copolymer nanoparticles in situ.
关键词： blue-light-emitting diode,water-soluble functional monomers,amphiphilic block copolymers,green solvent,RDRP,Photocontrolled iodine-mediated reversible-deactivation radical polymerization
更新于2025-09-19 17:13:59
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Controlled synthesis of azobenzene-containing block copolymers both in the main- and side-chain from SET-LRP polymers via ADMET polymerization
摘要： Novel ABA triblock copolymer contained azobenzene (azo) chromophores both in the main- and side-chain was designed and synthesized via combination of single electron transfer-living radical polymerization (SET-LRP) and acyclic diene metathesis (ADMET) polymerization. The α-bromoester end group of side-chain azo-polymer prepared in SET-LRP system using acrylate bearing azo group as monomer was reacted with potassium acrylate to yield azo-polymer with the chain end of α-acrylate, which acted as a monofunctional macromolecular chain stopper for subsequent ADMET polymerization of azo-functionalized α,ω-diene monomer to finally controllable synthesize ABA triblock azo-copolymer. The diluted solutions of main-chain ADMET azo-homopolymer, side-chain SET-LRP azo-homopolymer, and main-side chains azo-copolymer exhibited different photoisomerization behaviors (maximum absorption and rate of photoisomerization) under the irradiation of UV and visible light. All these interesting results could provide a guide for the design of photosensitive materials.
关键词： photoresponsive polymer,Single electron transfer-living radical polymerization,acyclic diene metathesis polymerization
更新于2025-09-19 17:13:59
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Time-resolved laser-flash photolysis Faraday rotation spectrometer: a new tool for total OH reactivity measurement and free radical kinetics research
摘要： The total OH reactivity (k’OH) is an important parameter for quantitative assessment of the atmospheric oxidation capacity. Although laboratory measurement of k’OH has been achieved 20 years ago, the instruments required are often costly and complex. Long-term atmospheric observations remain challenging and elusive. In this work, a novel instrument combining laser-flash photolysis with a mid-infrared Faraday rotation spectrometer (LFP-FRS) has been developed for the measurement of k’OH and for studying gas phase free radical kinetics. The reactor is composed of a Herriott-type optical multipass cell, and OH radicals were generated by flash photolysis of ozone with a 266 nm pulsed Nd:YAG laser. The decay of the OH signal was directly measured with a time-resolved FRS spectrometer at 2.8 μm. The overlapping pathlength between the pump beam and probe beam was 25 m. High performance was achieved by subtracting the signals before and after flash photolysis to eliminate interferences caused by H2O absorption and background drift. The optimum precisions (1σ) of OH concentration and k’OH measurement were 4×106 molecule cm-3 and 0.09 s-1 over data acquisition times of 56 s and 112 s, respectively. The performance of the system was evaluated by the reaction of OH with CO and NO. The measured rate coefficients (kOH+CO and kOH+NO) were in good agreement with values reported in the literature. The developed LFP-FRS provides a new, high precision, and highly selective tool for atmospheric chemistry research of OH radicals and other transient paramagnetic free radicals such as HO2 radicals.
关键词： atmospheric oxidation capacity,total OH reactivity,laser-flash photolysis,free radical kinetics,Faraday rotation spectrometer
更新于2025-09-19 17:13:59
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Sulfur determination in laser-induced breakdown spectroscopy combined with resonance Raman scattering
摘要： Sulfur is an essential element in industry, but it is difficult to be detected by laser-induced breakdown spectroscopy (LIBS). In this work, the disulfide radical Raman scattering was observed in sulfur plasma by combining LIBS with resonance Raman scattering (LIBS-RRS). Sulfur has been ablated by a focused laser beam to generate plasma, in which some sulfur atoms were combined to form disulfide radicals. The disulfide radical resonance Raman was excited by a 306.4 nm wavelength laser and observed at 710 and 1420 cm?1 Raman shift. Using different contents of sulfur mixed with alumina (Al2O3) powder, both LIBS and LIBS-RRS calibrations were obtained at the same ablation laser energy. The calibration curve of sulfur atomic emission S I 921.28 nm was set up, and the linear coefficient (R2) was 0.285 and the detection limit (LoD) was 13.092 wt %. While the R2 was 0.966 and LoD was 0.118 wt % for S2 710 cm?1 in LIBS-RRS. The results indicate that disulfide radical Raman scattering by LIBS-RRS is promising for the determination of sulfur content and the diagnosis of molecular evolution in plasma.
关键词： LIBS,Disufide radical,Resonance Raman sacttering
更新于2025-09-19 17:13:59
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A three dimensional meshfree-simulation of the selective laser sintering process with constant thermal coefficients applied to nylon 12 powders
摘要： 3D printing is an intersting process in the context of creating original objects.Selective laser sintering printers use a laser to fuse polyamide particles together with specific resin and heat. The difference in temperature between the different areas in the process causes the appearance of deformations, the objective of this work is the modeling of the thermal SLS phenomenona, by following the evolution of the temperature as a function of time.This model is based on the resolution of the heat conduction equation coupling with convection and radiation conditions with a distribution heat source and constant thermal coefficients by the meshless method based on radial basis function , the result of this study,will be presented and compared with other works.
关键词： heat transfer,Meshfree method,radical basis function (RBF),thermal modeling,selective laser sintering(SLS)
更新于2025-09-19 17:13:59