-
Water Research Oct 2023Confronted with the imperative crisis of water quality deterioration, the pursuit of state-of-the-art decontamination technologies for a sustainable future never stops.... (Review)
Review
Confronted with the imperative crisis of water quality deterioration, the pursuit of state-of-the-art decontamination technologies for a sustainable future never stops. Fitting into the framework of suitability, advanced oxidation processes have been demonstrated as powerful technologies to produce highly reactive radicals for the degradation of toxic and refractory contaminants. Therefore, investigations on their radical-induced degradation have been the subject of scientistic and engineering interests for decades. To better understand the transient nature of these radical species and rapid degradation processes, laser flash photolysis (LFP) has been considered as a viable and powerful technique due to its high temporal resolution and rapid response. Although a number of studies exploited LFP for one (or one class of) specific reaction(s), reactions of many possible contaminants with radicals are largely unknown. Therefore, there is a pressing need to critically review its implementation for kinetic quantification and mechanism elucidation. Within this context, we introduce the development process and milestones of LFP with emphasis on compositions and operation principles. We then compare the specificity and suitability of different spectral modes for monitoring radicals and their decay kinetics. Radicals with high environmental relevance, namely hydroxyl radical, sulfate radical, and reactive chlorine species, are selected, and we discuss their generation, detection, and implications within the frame of LFP. Finally, we highlight remaining challenges and future perspectives. This review aims to advance our understandings of the implementation of LFP in radical-induced transient processes, and yield new insights for extrapolating this pump-probe technique to make significant strides in environmental implications.
Topics: Photolysis; Chlorides; Chlorine; Halogens; Lasers
PubMed: 37672949
DOI: 10.1016/j.watres.2023.120526 -
Pest Management Science Sep 2020Chlorothalonil is a conventional chloroaromatic fungicide and is toxic to many aquatic species. This study was designed to investigate the effects of six flavonoids on...
BACKGROUND
Chlorothalonil is a conventional chloroaromatic fungicide and is toxic to many aquatic species. This study was designed to investigate the effects of six flavonoids on the photolysis of chlorothalonil under sunlight and artificial light.
RESULTS
Flavonoids sensitized the photolysis of chlorothalonil under sunlight and artificial light by 6.7-18.3 and 2.4-7.5 times, respectively, in comparison with a flavonoid-free control. Photosensitization effect of each of the six flavonoids was greater under sunlight irradiation than under high-pressure mercury lamp irradiation. Cyanidin showed greater photosensitization effects than luteolin, galangin, quercetin, morin and kaempferol. Chlorothalonil underwent photo-reductive dechlorination and no hydrolysis product was formed in the presence of flavonoids. Hydroxyl and hydrogen radicals were detected in the absence and presence of cyanidin, respectively, under light irradiation.
CONCLUSION
The photosensitization effect of flavonoids on chlorothalonil photolysis is apparently related to flavonoid structure and might be due to their hydrogen donation capacity. These results highlight benefit of using flavonoids to manage aquatic pollution and reduce aquatic toxicity, and have great relevance in predicting the degradation kinetics and biological impacts of chlorothalonil in surface water. © 2020 Society of Chemical Industry.
Topics: Flavonoids; Kinetics; Nitriles; Photolysis; Water; Water Pollutants, Chemical
PubMed: 32246548
DOI: 10.1002/ps.5842 -
Environmental Science & Technology Apr 2020Secondary organic aerosol (SOA) accounts for a large fraction of the tropospheric particulate matter. Although SOA production rates and mechanisms have been extensively...
Secondary organic aerosol (SOA) accounts for a large fraction of the tropospheric particulate matter. Although SOA production rates and mechanisms have been extensively investigated, loss pathways remain uncertain. Most large-scale chemistry and transport models account for mechanical deposition of SOA but not chemical losses such as photolysis. There is also a paucity of laboratory measurements of SOA photolysis, which limits how well photolytic losses can be modeled. Here, we show, through a combined experimental and modeling approach, that photolytic loss of SOA mass significantly alters SOA budget predictions. Using environmental chamber experiments at variable relative humidity between 0 and 60%, we find that SOA produced from several biogenic volatile organic compounds undergoes photolysis-induced mass loss at rates between 0 and 2.2 ± 0.4% of nitrogen dioxide (NO) photolysis, equivalent to average atmospheric lifetimes as short as 10 h. We incorporate our photolysis rates into a regional chemical transport model to test the sensitivity of predicted SOA mass concentrations to photolytic losses. The addition of photolysis causes a ∼50% reduction in biogenic SOA loadings over the Amazon, indicating that photolysis exerts a substantial control over the atmospheric SOA lifetime, with a likely dependence upon the SOA molecular composition and thus production mechanisms.
Topics: Aerosols; Air Pollutants; Models, Chemical; Particulate Matter; Photolysis; Volatile Organic Compounds
PubMed: 32154714
DOI: 10.1021/acs.est.9b07051 -
ACS Macro Letters Apr 2021Herein, we demonstrate that the photochemical cleavage of linear polymers containing a midchain photocleavable moiety strongly depends on the chain length. Based on an...
Herein, we demonstrate that the photochemical cleavage of linear polymers containing a midchain photocleavable moiety strongly depends on the chain length. Based on an -nitrobenzyl (NB) difunctional reversible addition-fragmentation chain-transfer agent, well-defined poly(methyl acrylate)s ( = 1.59-67.6 kg mol, = 1.3-1.4) were synthesized following a core-first approach. Photolysis at λ = 350 nm of the -nitrobenzyl moiety led to the generation of equally sized polymer segments. The rate of NB-driven polymer fragmentation, which can be well described by first-order kinetics, strongly increases with increasing molecular weight in a nonlinear fashion, potentially caused by entropic considerations and is compared to the ideal chain model. The current study thus demonstrates that polymer photolysis is dependent on the polymer chain length, with critical implications for photocleavable network design.
Topics: Molecular Weight; Photolysis; Polymers
PubMed: 35549234
DOI: 10.1021/acsmacrolett.1c00057 -
Journal of Photochemistry and... Jan 2020The photolysis of thiochrome (THC), an oxidation product of thiamine (vitamin B) (THE), used for its fluorimetric assay, has been studied in the pH range 7.0-12.0. THC...
The photolysis of thiochrome (THC), an oxidation product of thiamine (vitamin B) (THE), used for its fluorimetric assay, has been studied in the pH range 7.0-12.0. THC undergoes photooxidation to oxodihydrothiochrome (ODTHC) which is oxidized to a non-fluorescent compound (OP1) on UV irradiation. The kinetics of the consecutive first-order reactions: THC→kODTHC→kOP1, has been evaluated and the values of first-order rate constants, k (0.58-4.20 × 10, s) and k (0.05-2.03 × 10, s), at pH 7.0-12.0 have been determined. The rates of degradation of THC and ODTHC are enhanced with pH and the second-order rate constants k' and k' for the OH ion-catalyzed reaction are in the range of 0.002-58.3 M s. The quantum yields of the photolysis of THC and ODTHC in the pH range 7.0-12.0 have been determined. THC, ODTHC and OP1 have been identified by chromatographic, spectrometric and fluorimetric methods. THC and ODTHC have similar fluorescence characteristics and emit at 450 and 445 nm, respectively. THC, ODTHC and OP1 with distinct absorption maxima (370, 344 and 290 nm, respectively) have been determined by a newly developed and validated multicomponent spectrometric method during the photolysis reactions. The on-line formation of THC by the photooxidation of THE may lead to the degradation of THC and give erroneous results in the fluorimetric assay of THE. A scheme for the photolysis reactions of THC in aqueous solution is presented.
Topics: Catalysis; Fluorometry; Hydrogen-Ion Concentration; Kinetics; Oxidation-Reduction; Photolysis; Thiamine; Ultraviolet Rays
PubMed: 31927488
DOI: 10.1016/j.jphotobiol.2019.111766 -
Environmental Science & Technology Jul 2021Nitrates formed on mineral dust through heterogeneous reactions in high NO areas can undergo photolysis to regenerate NO and potentially interfere in the photochemistry...
Nitrates formed on mineral dust through heterogeneous reactions in high NO areas can undergo photolysis to regenerate NO and potentially interfere in the photochemistry in the downwind low NO areas. However, little is known about such renoxification processes. In this study, photolysis of various nitrates on different mineral oxides was comprehensively investigated in a flow reactor and in situ diffuse reflectance Fourier-transform infrared spectroscopy (in situ DRIFTS). TiO was found much more reactive than AlO and SiO with both NO and HONO as the two major photolysis products. The yields of NO and HONO depend on the cation basicity of the nitrate salts or the acidity of particles. As such, NHNO is much more productive than other nitrates like Fe(NO), Ca(NO), and KNO. SO and water vapor promote the photodegradation by increasing the surface acidity due to the photoinduced formation of HSO/sulfate and H, respectively. O enables the photo-oxidation of NO to regenerate nitrate and thus inhibits the NO yield. Overall, our results demonstrated that the photolysis of nitrate can be accelerated under complex air pollution conditions, which are helpful for understanding the transformation of nitrate and the nitrogen cycle in the atmosphere.
Topics: Nitrates; Nitrogen Oxides; Oxides; Photolysis; Silicon Dioxide
PubMed: 34132529
DOI: 10.1021/acs.est.1c02182 -
Chemosphere Jan 2022Colloids, such as natural particulate matter and microplastics, can play a significant role in the fate and transport of organic contaminants. Specifically, these small...
Colloids, such as natural particulate matter and microplastics, can play a significant role in the fate and transport of organic contaminants. Specifically, these small nano-to micron-sized particles provide large surface area; thus, particle-aqueous interfacial chemistry becomes significant. In this work, we present an experimental investigation of interfacial photokinetics of malachite green cation (MG) adsorbed at the surface of polystyrene carboxyl (PSC) microspheres suspended in aqueous solution. Second harmonic generation (SHG), an interfacial selective laser spectroscopic tool, has been used to probe the buried interface. It is revealed that relative to the bulk, photoinduced degradation of MG is accelerated by approximately 10-fold at this noncatalytic particle surface. By measuring the SHG-based surface electronic spectra, we have also demonstrated that N-demethylated intermediates of MG remain at the interface until they are further decomposed. MG exhibits a bathochromic shift at the interface. Together with strong binding affinity and faster initial rate of photodegradation of MG at the interface, this work highlights that adsorption and surface photolysis are important pathways by which organic compounds can be transformed within the aquatic environment. Moreover, this research also stimulates further questions on the enrichment of reactive species at the colloidal-aqueous interface and their influence on facilitating decompositions of organic pollutants.
Topics: Microplastics; Photolysis; Plastics; Rosaniline Dyes
PubMed: 34461340
DOI: 10.1016/j.chemosphere.2021.131953 -
Nature Communications Dec 2023Prodrug photolysis enables spatiotemporal control of drug release at the desired lesions. For photoactivated therapy, near-infrared (NIR) light is preferable due to its...
Prodrug photolysis enables spatiotemporal control of drug release at the desired lesions. For photoactivated therapy, near-infrared (NIR) light is preferable due to its deep tissue penetration and low phototoxicity. However, most of the photocleavable groups cannot be directly activated by NIR light. Here, we report a upconversion-like process via only one step of energy transfer for NIR light-triggered prodrug photolysis. We utilize a photosensitizer (PS) that can be activated via singlet-triplet (S-T) absorption and achieve photolysis of boron-dipyrromethene (BODIPY)-based prodrugs via triplet-triplet energy transfer. Using the strategy, NIR light can achieve green light-responsive photolysis with a single-photon process. A wide range of drugs and bioactive molecules are designed and demonstrated to be released under low-irradiance NIR light (100 mW/cm, 5 min) with high yields (up to 87%). Moreover, a micellar nanosystem encapsulating both PS and prodrug is developed to demonstrate the practicality of our strategy in normoxia aqueous environment for cancer therapy. This study may advance the development of photocleavable prodrugs and photoresponsive drug delivery systems for photo-activated therapy.
Topics: Prodrugs; Photolysis; Drug Delivery Systems; Photosensitizing Agents; Energy Transfer
PubMed: 38062051
DOI: 10.1038/s41467-023-43805-y -
Molecules (Basel, Switzerland) Nov 2022The mechanism of photolytic degradation of 2-4-6-trinitrotoluene (TNT) by UVA−visible light (>320 nm) in ethanolic, aqueous-ethanolic, and aqueous solutions was...
Photolysis by UVA-Visible Light of TNT in Ethanolic, Aqueous-Ethanolic, and Aqueous Solutions According to Electrospray and Aerodynamic Thermal Breakup Droplet Ionization Mass Spectrometry.
The mechanism of photolytic degradation of 2-4-6-trinitrotoluene (TNT) by UVA−visible light (>320 nm) in ethanolic, aqueous-ethanolic, and aqueous solutions was investigated by electrospray and aerodynamic thermal breakup droplet ionization mass-spectrometric analyses. For the photolysis, a DRK-120 mercury-quartz lamp was used. Products of the photolysis reaction were compared with known products of TNT transformation in the environment. Because the photochemistry of some compounds in alcohols (in contrast to aqueous solutions) features a transfer of electrons from the solvent to the light-excited compound, we believe that the efficiency of photolysis (polymerization) of TNT in ethanol and aqueous-ethanolic solutions is based on this mechanism.
Topics: Photolysis; Trinitrotoluene; Light; Mass Spectrometry; Water; Ethanol
PubMed: 36432093
DOI: 10.3390/molecules27227992 -
Advanced Healthcare Materials Mar 2021Light-controlled sequential photolysis from a single nanoparticle is a challenge for controlled release. A wavelength-selective sequential photolysis from single gold...
Light-controlled sequential photolysis from a single nanoparticle is a challenge for controlled release. A wavelength-selective sequential photolysis from single gold nanoparticles is reported for the first time. In particular, it is also demonstrated that such nanoparticle can be used to sequentially release two payloads in living cells. In principle, this system can be extended to sequential release of multiple different types of payloads by rational design of diverse photocleavable linkers. It is expected that this work can provide a new tool for better orderly controlling cellular events that request high spatiotemporal manners.
Topics: Gold; Metal Nanoparticles; Nanoparticles; Photolysis
PubMed: 33034955
DOI: 10.1002/adhm.202000321