Ultraviolet Photolysis Research Articles

Insight into the mechanisms of trichloronitromethane formation by vacuum ultraviolet: QSAR model and FTICR-MS analysis

Vacuum ultraviolet (VUV) photolysis is recognized as an environmental-friendly treatment process. Nitrate (NO3−) and natural organic matter (NOM) are widely present in water source. We investigated trichloronitromethane (TCNM) formation during chlorination after VUV photolysis, because TCNM is an unregulated highly toxic disinfection byproduct. In this study: (1) we found reactive nitrogen species that is generated under VUV photolysis of NO3− react with organic matter to form nitrogen-containing compounds and subsequently form TCNM during chlorination; (2) we found the mere presence of 0.1 mmol/L NO3− can result in the formation of up to 63.96 µg/L TCNM; (3) we found the changes in pH (6.0-8.0), chloride (1-4 mmol/L), and bicarbonate (1-4 mmol/L) cannot effectively diminish TCNM formation; and, (4) we established the quantitative structure-activity relationship (QSAR) model, which indicated a linear relationship between TCNM formation and the Hammett constant (σ) of model compounds; and, (5) we characterized TCNM precursors in water matrix after VUV photolysis and found 1161 much more nitrogen-containing compounds with higher aromaticity were generated. Overall, this study indicates more attention should be paid to reducing the formation risk of TCNM when applying VUV photolysis process at scale.

Electrochemical-assisted ultraviolet light coupled peroxodisulfate system to degrade ciprofloxacin in water: Kinetics, mechanism and pathways

The persulfate advanced oxidation is an emerging and efficient pollutant treatment method, but usually requires the help of other materials or energy to catalyze and produce highly oxidizing active substances. In this paper, electrochemical-assisted ultraviolet light coupled peroxodisulfate system (E-UV-PDS) was used to degrade ciprofloxacin (CIP), and it was determined that electrolysis and ultraviolet photolysis were synergistic by calculation. The effects of initial pH, voltage, peroxodisulfate dosage, CIP concentration and coexisting anions on the degradation process were explored. The quenching experiments showed that 1O2, ⋅OH and SO4−⋅ were the main active oxygen species. Under the following conditions, ultraviolet light = 6 W, voltage = 4 V, [peroxodisulfate] = 20 mM, [pH]0 = 7 and [CIP] = 100 mgL−1, the degradation rate of CIP reached about 100% after 120 min, and the influence of inorganic anions was also discussed. Several intermediate products were identified by LC-MS, and three degradation pathways were speculated for CIP degradation. Finally, economic evaluation of the E-UV-PDS system was made, and it was useful to construct environmentally friendly and low-cost catalytic processes for the efficient degradation of organic pollutants.

Total organic fluorine (TOF) analysis by completely converting TOF into fluoride with vacuum ultraviolet

Quantifying total organic fluorine (TOF) in water is vital in monitoring the occurrence and persistence of all fluorine-containing organic compounds in the environment, while currently most studies focus on analyzing individual fluorine-containing organic compounds. To fill the technology gap, we herein proposed to convert TOF completely into fluoride with vacuum ultraviolet (VUV) photolysis, followed by analysis of fluoride with ion chromatography. Results showed that the tailored VUV photoreactor achieved satisfying recoveries of fluorine from ten model TOF compounds not only in ultrapure water (83.9 ± 2.0% to 109.4 ± 0.8%) but also in real water samples (92.1 ± 1.0%–106.2 ± 15.7%). Unlike other ultraviolet-based processes that favor alkaline conditions, this VUV process preferred either neutral or acidic conditions to defluorinate selected compounds. While the mechanisms remain to be explored in the future, it has been evidenced that the photo-degradation and photo-defluorination rates of these TOF compounds varied significantly among compounds and operation conditions. The method obtained a method detection limit (MDL) of 0.15 μg-F/L, which is lower than the MDLs of many other TOF analytical methods, along with excellent calibration curves for concentrations ranging from 0.01 to 10.0 mg-F/L. Notably, minimizing fluoride in sample prior to photoconversion was necessary to avoid subtraction-induced errors for TOF measurement, especially when the fluoride/TOF ratio was high. The robust VUV is also green for sample pretreatment due to its unreliance of chemicals or additives.

Catalytic oxidation of acetone in air over Ag modified CeO2 catalysts under VUV irradiation: Comparison of different treatment process, performance, and mechanism studies

In this study, the performance of different treatment processes, including UV photolysis, ozonation, UV photolysis + ozonation, and vacuum ultraviolet (VUV) photolysis for oxidation of acetone in the presence and absence of Ag modified CeO2 photocatalysts was investigated. The as-synthesized catalysts were characterized using XRD, XPS, Raman Spectroscopy, BET, SEM, HRTEM, and EDX techniques. The attained data showed that by introducing Ag nanoparticles into the CeO2 network, the oxygen storage capability of the catalyst increases, which facilitates the generation of oxygen vacancies leading to the activation of lattice oxygen. The mechanism of the acetone oxidation and the contribution of each participating reaction mechanism were determined. The obtained results indicated that the VUV treatment system shows the best performance among different treatment processes, leading to more than 40% acetone conversion at room temperature. Moreover, the addition of Ag/CeO2 photocatalysts to the VUV treatment process not only increases the acetone conversion up to 76% but also, by involving the catalytic ozonation as a participating acetone oxidation pathway, can eliminate the generated ozone during the treatment process. The results revealed that adding Ag to CeO2 photocatalyst under VUV irradiation oxidized the produced CO, significantly improving the reaction selectivity and leading the acetone degradation reactions to total oxidation level of up to 96%. The stability of the Ag/CeO2 photocatalysts under VUV irradiation was investigated, and an in-situ regeneration process was employed for suppressing the catalyst deactivation process. The durability tests showed more than 73% acetone oxidation even after three consecutive runs and 990 min irradiation.

UV/Chlorine Process: An Efficient Advanced Oxidation Process with Multiple Radicals and Functions in Water Treatment.

Because of the deterioration of global water quality, the occurrence of chemical and microbial contaminants in water raises serious concerns for the health of the population. Identifying and developing effective and environmentally friendly water treatment technologies are critical to obtain clean water. Among the various technologies for the purification of water, ultraviolet photolysis of chlorine (UV/chlorine), an emerging advanced oxidation process (AOP), has multiple functions for the control of contaminants via the production of hydroxyl radicals (HO·) and reactive chlorine species (RCS), such as Cl·, ClO·, and Cl2·-.This Account centers around the radical chemistry of RCS and HO· in different water matrices and their roles and mechanisms in the abatement of contaminants. The concentrations of Cl·, ClO·, and Cl2·- are comparable to or higher than those of HO· (10-14 to 10-13 M). The reactivities of RCS are more selective than HO· with a broader range of second-order rate constants (k). The k values of Cl· toward most aromatics are higher or similar as compared to those of HO·, while those of Cl2·- and ClO· are less reactive but more selective toward aromatics containing electron-donating functional groups. Their major reaction mechanisms with Cl· are electron transfer and addition, while those with ClO· and Cl2·- primarily involve electron transfer. As for aliphatics, their reactivities with both HO· and RCS are much lower than those of aromatics. The reaction mechanisms for most of them with Cl· and Cl2·- are hydrogen abstraction, except for olefins, which are addition. In addition, RCS greatly contribute to the inactivation of microbial contaminants.Toward future application, the UV/chlorine process has both pros and cons. Compared with the traditional HO·-based AOP of UV/H2O2, UV/chlorine is more efficient and energy-saving for oxidation and disinfection, and its efficiency is less affected by water matrix components. However, the formation of toxic byproducts in UV/chlorine limits its application scenarios. In dissolved organic matter (DOM)-rich water, the formation of halogenated byproducts is enhanced in UV/chlorine. In the presence of ammonia, reactive nitrogen species (RNS) (e.g., ·NO and ·NO2) are involved, and highly toxic nitro(so) products such as nitro(so)-phenolics and N-nitrosodimethylamine are generated. For a niche application, the UV/chlorine process is recommended to be utilized in water with low levels of DOM and ammonia.Strategies should be developed to make full use of highly reactive species (RCS and HO·) for the abatement of target contaminants and to reduce the formation of toxic byproducts. For example, the UV/chlorine process can be used in tandem with other treatments to create multiple barriers for the production of safe water. In addition, halogen radicals are very important in ecosystems as well as other areas such as medical therapy and organic synthesis. UV/chlorine is the most efficient homogeneous system to generate halogen radicals, and thus it provides a perfect system to investigate the fates of halogen radicals for interdisciplinary research.

Preliminary studies of photolysis and TiO2-montomorillonite-immobilised photocatalysis processes for the degradation of organic pollutants in water treatment

Organic compounds are the most diverse group of contaminants. The largest anthropogenic source of these contaminants in water is municipal and industrial wastewater. One of the indicators of surface water pollution is biological oxygen demand (BOD). Purifying water from organic micropollutants is a serious challenge and requires the development of newer and more effective methods. The removal of such contaminants is most effective only in advanced oxidation processes (AOP), which include UV photolysis and photocatalysis. The presented results are from preliminary research to evaluate the effectiveness of water treatment by ultraviolet (UV) photolysis and photocatalysis. Treatment efficiency was evaluated on the basis of changes in the BOD index before and after the advanced oxidation process of raw water. The values of the BOD5 index determined in accordance with PN-EN 25813:1997. The exposure time of the samples was a maximum of 60 minutes. The tested material was water samples taken from the Rudawa River, which is one of the drinking water sources for Krakow. The initial BOD5 value (expressed as concentration of O2) for all samples was about 8 mg/L but it has decreased to over 2 mg/L due to AOP processes. This means that after an hour, more than 75% of organic compounds present in the raw water were removed. For photocatalysis (TiO2-MMT), the exposure time of the samples was a maximum of 35 minutes. Water samples taken from the Rudawa River were also used as test material. The initial BOD5 value for all samples was about 9 mg/L but it has decreased to about 4 mg/L due to the photocatalysis process. This means that after 35 minutes, 55% of the organic compounds present in the raw water were removed.

In-situ removal of residual antibiotics (enrofloxacin) in recirculating aquaculture system: Effect of ultraviolet photolysis plus biodegradation using immobilized microbial granules

The misuse of antibiotics and ineffective treatment in aquaculture cause serious environmental problems. The closed-loop design of recirculating aquaculture systems (RAS) enables the effective use of antibiotics and rapid removal of antibiotic residues. Hitherto, few studies have been carried out on these. This study aims to examine the feasibility of rapid in-situ removal of residual antibiotics in RAS using integrated process and characterize the operational parameters. The fate of the selected antibiotic enrofloxacin (ENR) in different units of a laboratory-scale RAS was investigated with photolysis pretreatment followed adsorption-biodegradation of photolysis intermediates by immobilized microgranules. The degradation kinetics was also characterized. The results indicated that the ultraviolet (UV) device in RAS played an important role in ENR removal. The wavelength and light intensity were crucial for the removal efficiency of ENR. The F− produced by defluorination could reproduce the effect of the decomposition of ENR by UV photolysis. The UV photolysis products of ENR had a positive relationship with photolysis time, indicating incomplete decomposition of ENR. Under optimal condition (UV 80 W/254 nm and flow rate of 60 L/h), the ratio of BOD5 to COD (B/C) after photolysis increased from 0.041 to 0.28, which supported biodegradation. The photolysis products were partially adsorbed by activated carbons in the immobilized microbial granules and then biodegraded by microbes of the granules. Based on this study, a four-step process was proposed for the control of residual antibiotics in RAS.

Hydrocarboxyl Radical as a Product of α-Alanine Ultraviolet Photolysis.

UV photodissociation of α-alanine was studied by parahydrogen matrix isolation infrared spectroscopy. The temporal behavior of Fourier transform infrared spectra revealed that UV irradiation at 213 nm yielded the HOCO radical as a direct photoproduct from the S2 excited state. The concentration of HOCO quickly approached a steady state due to secondary photodissociation of HOCO to produce CO2 + H or CO + OH. On the other hand, no photoproducts were detected by S1 excitation at 266 nm. Irradiation of fully deuterated α-alanine at 213 nm yielded ∼2 times more cis-DOCO radicals than the lower energy isomer trans-DOCO, indicating that the conformation of the hydroxyl group is fairly well-preserved upon photodissociation of α-alanine. The present study suggests that HOCO may be a good tracer species in the search for amino acids in interstellar space.

Application-Scale Parametric Evaluation of Ultraviolet Photolysis (UV) and UV/H2O2 for the Degradation of Neutral Pharmaceuticals in Municipal Wastewaters

AbstractThe removal of 10 pharmaceuticals and 3 of their metabolites from municipal wastewater by ultraviolet irradiation at a wavelength of 254 nm (UVC) and UV/H2O2 were investigated in this study...

Rapid photodegradation of organic micro-pollutants in water using high-intensity pulsed light

The rising concentration of organic micro-pollutants (OMPs) in water resources has become a major concern for aquatic ecosystems and human health. Advanced oxidation processes (AOPs), based on ultraviolet (UV) photolysis and photochemical reactions, have been suggested for the degradation of various micropollutants present in water and wastewater. However, the application of these methods on large scale is limited due to the long treatment times. Here we evaluate the efficiency of high-intensity pulsed light treatment (HIPL) for the degradation of organic compounds in aqueous conditions. A solution containing 11 OMPs was treated with short (<2 ms) and high-intensity light pulses produced by a Xenon flash lamp. It was observed that the HIPL parameters, such as the number of pulses and optical energy dose, have a significant impact on the efficiency of the treatment. The main advantage of HIPL is the fast kinetics that allows efficient photodegradation of OMPs from the aqueous solution rapidly and within milliseconds. The present work showcases the potential of HIPL technique for the post-treatment of contaminated water containing pharmaceuticals and endocrine disruptor compounds.

Ultraviolet photolysis of monochloro-p-benzoquinone (MCBQ) in aqueous solution: Theoretical investigation into the dechlorination

In this work, the UV-induced transformation of monochloro-p-benzoquinone (MCBQ) in aqueous solution has been systematically investigated through quantum chemical calculations. During the UV irradiation at 253.7 nm, the first triplet state of MCBQ (3MCBQ*) was from the intersystem crossing of its first excited singlet state (1MCBQ*). In aqueous solution, the nucleophilic attack of OH− on carbon atoms in 3MCBQ* was the central reaction. The addition of OH− to olefinic carbon atoms was much more kinetically feasible than that to carbonyl carbon atoms, even though the carbonyl carbon atoms were more positively charged. Moreover, OH− preferred to add to the ortho-position of C–Cl bond, where the unchlorinated atom was more negatively charged than the chlorinated one. The UV photolysis of the primary intermediate (HO-CBQ) was not the same as that of MCBQ. The attack of OH− on the para-position of C–Cl bond was the most efficient pathway. The addition of OH− to the chlorinated atom of 3HO-CBQ* was much more efficient than that in the case of 3MCBQ*, which reveals that more UV irradiation may promote the dechlorination. The findings in the present study may be helpful to enrich the understanding of the halobenzoquinones transformation in aqueous solution.

Degradation and toxicity of the antidepressant fluoxetine in an aqueous system by UV irradiation

Fluoxetine (FLU), a selective serotonin reuptake inhibitor, is commonly found in aquatic environments. Ultraviolet (UV) photolysis is widely used to remove certain pharmaceuticals from water and wastewater. The present study aimed to investigate the toxicity of FLU and its transformed products formed during UV photolysis by using zebrafish embryos (Danio rerio) as a model. The degradation rates of FLU for five days were approximately 63.6% ± 2.14%, 84.6% ± 0.99%, and 97.5% ± 0.25% after 15, 30, and 60 min of UV irradiation, respectively. Furthermore, the degradation mechanism was explored using LC-MS measurements and density flooding theory (DFT) theoretical calculations. Comprehensive toxicity preassessment of FLU and its degradation products was carried out using the T.E.S.T. software. The effects of physiological and biochemical parameters and neuron- and apoptosis-related gene expression were examined in zebrafish embryos exposed to non-irradiated (0-min) and irradiated (15, 30- and 60-min) solutions from 4 h post-fertilization (hpf) to 120 hpf. The hatching time of zebrafish embryos exposed to the non-irradiated solution (0-min) and irradiated solution (60-min) was delayed, their heart rate at 48 and 72 hpf increased, and their body length at 120 hpf decreased. Significant differences were found between the non-irradiated (0-min) and UV-irradiated (15- or 30-min) groups. A dynamic response involving acetylcholinesterase (AChE) and superoxide dismutase (SOD) activity was also observed in the non-irradiated and UV-irradiated groups. During the UV treatment experiments, the expression levels of neuron-related and apoptosis-related genes were significantly reduced over time alongside the formation of FLU degradation products. Overall, this study provides new concepts to remove and assess the toxicity of emerging contaminants in aquatic environments and highlights the need to consider the formation and persistence of toxic transformation products.

Advances in Vacuum Ultraviolet Photolysis in the Postharvest Management of Fruit and Vegetables Along the Value Chains: a Review

Advances in Vacuum Ultraviolet Photolysis in the Postharvest Management of Fruit and Vegetables Along the Value Chains: a Review

Insights into stress degradation behavior of gibberellic acid by UHPLC Q-Exactive Orbitrap mass spectrometry

Gibberellic acid (GA3) is widely applied in agriculture and food worldwide. Profiling the degradation products and their formation pattern under stress are helpful for deeply understanding GA3 regulating plant physiology and GA3 safety in agricultural crops. This study firstly investigated the degradation behavior of GA3. Different stress factors such as light, pH and temperatures were investigated through photolysis and hydrolysis experiments. Five degradation products were identified using ultra high-performance liquid chromatography Q-Exactive Orbitrap mass spectrometry (UHPLC Q-Exactive Orbitrap MS). Three degradation products were produced under ultraviolet photolysis conditions. Two isomers (iso-GA3 and gibberellenic acid) were formed under alkaline conditions. In order to characterize each degradation product, complete mass fragmentation pathways of all analytes were initially established. These results could provide a practical reference for the safety of agricultural products and the guidance for scientific application of GA3 and proposed storage conditions of GA3.

Ultraviolet photolysis of four typical cardiovascular drugs: mechanisms, influencing factors, degradation pathways, and toxicity trends.

The cardiovascular drugs (CDDs), such as metoprolol (MET), atenolol (ATE), bezafibrate (BZB), and atorvastatin (ATO), have been frequently detected in the water environment. They can cause potential threats to the ecological environment and human health due to their "pseudo-persistence" effect. In this study, the photolysis kinetics, degradation mechanisms, by-products, influencing factors, and acute toxicity of these four typical CDDs under polychromatic ultraviolet irradiation (200-400 nm) were investigated. The results showed that the photolysis of ATE, BZB, MET, and ATO all followed pseudo-first-order kinetics, and their average photon quantum yields of the wavelength studied were 0.14×10-2, 0.33×10-3, 0.78×10-4, and 0.24×10-4 mol einstein-1, respectively. Singlet oxygen (1O2), hydroxyl radical (·OH), and the triplet-excited state of the cardiovascular drug (3CDD*) were all involved in the photolysis while 1O2 was the dominator. The effects of NO3-, Cl-, HCO3-, and humic acid (HA) on the photolysis were the combination of light-shielding, quenching, and excitation of reactive species. Seven, four, four, and nine photolysis products of ATO, BZB, ATE, and MET were identified, respectively, and their possible degradation pathways were proposed. The acute toxicity of ATE was basically unchanged during photolysis; however, ATO, BZB, and MET toxicity all increased due to the generation of ketonization and hydroxylation products.

Degradation of ibuprofen by photo-based advanced oxidation processes: exploring methods of activation and related reaction routes

Several homogeneous photo-based advanced oxidation processes-namely photolysis, photo-oxidation, and photo-Fenton oxidation—were investigated for the elimination of ibuprofen in water. The effects of several operating parameters, such as the lamp type (low or medium pressure mercury, xenon-arc), the concentration of hydrogen peroxide (0.5 to 7 times the stoichiometric amount required for mineralization), and the concentration of Fenton reagent, were quantified. Photo-Fenton oxidation was also combined with low-frequency sonication to investigate possible synergistic interactions. Ibuprofen degradation under ultraviolet photolysis and ultraviolet/hydrogen peroxide oxidation followed pseudo-first-order kinetics with respect to the pollutant concentration and the apparent rate constant increased with lamp power (6–10 W) and oxidant concentration. Photo-Fenton oxidation under ultraviolet light (L1 lamp, 254 nm, 6 W) and visible light (L2 lamp, 360–740 nm, 150 W) led to complete ibuprofen removal after 3 h, but the mineralization yield of the L1/Fenton process (82%) was higher than that of the L2/Fenton process (59%) because of the effects of ultraviolet/hydrogen peroxide oxidation in the former. Coupling L2/Fenton with sonication improved the degradation rate of the molecule at low Fenton reagent concentration, but the beneficial effect of ultrasound on ferrous iron regeneration vanished when the iron to ibuprofen molar ratio was close to 1. An overall reaction scheme for ibuprofen degradation is proposed based on the transformation products detected during these processes.

Sublimation of Laboratory Ices Millimeter/Submillimeter Experiment (SubLIME): Structure-specific Identifications of Products from UV-photolyzed Methanol Ice

Abstract Submillimeter/far-IR spectroscopy was used to detect and quantify organic molecules sublimated after the ultraviolet photolysis (at 12 K) and warm-up (up to 300 K) of a methanol (CH3OH) ice sample. Eleven sublimated photoproducts were uniquely identified: carbon monoxide (CO), formaldehyde (H2CO), ketene (C2H2O), acetaldehyde (CH3CHO), ethylene oxide (CH2OCH2), vinyl alcohol (CH2CHOH), ethanol (CH3CH2OH), dimethyl ether (CH3OCH3), methyl formate (HCOOCH3), glycolaldehyde (HOCH2CHO), and acetone ((CH3)2CO). Two additional products were detected in the photolyzed ice by Fourier-transform infrared (FTIR) spectroscopy: carbon dioxide (CO2) and methane (CH4). The rotational temperatures and gas densities were calculated for the organics containing two or more C atoms via a rotation diagram analysis, and the gas-phase submillimeter/far-IR technique was used in tandem with mass spectrometry and FTIR spectroscopy of the ice during photolysis. The abundance ratios of the sublimated species (normalized to methanol) were compared to those observed in hot cores (Orion-KL, Sagittarius B2(N), and IRAS 16293-2422(B)) and in comets C/2014 Q2 (Lovejoy) and 67P/Churyumov–Gerasimenko.

Degradation of Congo red by UV photolysis of nitrate: Kinetics and degradation mechanism

The efficiency of Congo red (CR) removal by low-pressure ultraviolet photolysis of nitrate (UV/NO3−) process was investigated in this study. Results showed that CR degradation through direct UV (254 nm) photolysis could be ignored, but CR was obviously removed in UV/NO3− process. Moreover, the contributions of UV, NO2 and OH to the degradation of CR were explored to be roughly 0.63%, 17.46% and 81.90%, respectively. In addition, the observed pseudo-first-order rate constants for the degradation of CR (kobs) were assessed by the effects of different water matrices and operation conditions, including NO3− dosage, CR concentration, solution pH, chloride ion (Cl−), natural organic matter (NOM) and carbonate/bicarbonate (CO32−/HCO3−). The kobs was increased by nearly 12.9 times with the addition of NO3− dosage from 1 mM to 200 mM due to the generation of more active components (e.g., OH and NO2). Higher doses of CR reduced the kobs, which could be attributed to the filter effects of CR on UV irradiation. Although the photolysis of NO3− could be expedited under acidic conditions, the kobs was decelerated because of the protonation of CR (pKa = 4.1, 25 °C). While in alkaline conditions, the kobs was also reduced as the decrease in redox potential of OH. The presence of Cl− (0–7 mM) exhibited no scavenging effect on the kobs, which suggested the secondary radicals (i.e., chlorine radicals (e.g., Cl, Cl2−)) could oxidize CR effectively. NOM restricted the degradation of CR significantly, resulting from the filter effects of NOM (ε = 0.11 LmgC−1cm−1) on UV and the effects of radical scavenging. The kobs was improved obviously with the participation of CO32−/HCO3− (0–7 mM), ascribing to the oxidation of carbonate radical (CO3−) and the increased steady state concentration of NO2. The degradation of CR in UV/NO3− process has the potential for practical applications in real water. Furthermore, eight intermediates were proposed by Liquid chromatography-tandem mass spectrometry (LC-MS/MS). Hydroxylation, nitrification and other aromatic products in the reaction of CR with OH and/or NO2 were readily produced by H-abstraction, addition reaction and electron transfer.

A slow and clean fluorine atom beam source based on ultraviolet laser photolysis

A slow and clean fluorine atom beam source is one of the essential components for the low-collision energy scattering experiment involving fluorine atom. In this work, we describe a simple but effective photolysis fluorine atom beam source based on ultraviolet laser photolysis, the performance of which was demonstrated by high-resolution time-of-flight spectra from the reactive scattering of F+HD. This beam source paved the way for studies of low energy collisions with fluorine atoms.

Dual-Functional Phosphorene Nanocomposite Membranes for the Treatment of Perfluorinated Water: An Investigation of Perfluorooctanoic Acid Removal via Filtration Combined with Ultraviolet Irradiation or Oxygenation.

Nanomaterials with tunable properties show promise because of their size-dependent electronic structure and controllable physical properties. The purpose of this research was to develop and validate environmentally safe nanomaterial-based approach for treatment of drinking water including removal and degradation of per- and polyfluorinated chemicals (PFAS). PFAS are surfactant chemicals with broad uses that are now recognized as contaminants with a significant risk to human health. They are commonly used in household and industrial products. They are extremely persistent in the environment because they possess both hydrophobic fluorine-saturated carbon chains and hydrophilic functional groups, along with being oleophobic. Traditional drinking water treatment technologies are usually ineffective for the removal of PFAS from contaminated waters, because they are normally present in exiguous concentrations and have unique properties that make them persistent. Therefore, there is a critical need for safe and efficient remediation methods for PFAS, particularly in drinking water. The proposed novel approach has also a potential application for decreasing PFAS background levels in analytical systems. In this study, nanocomposite membranes composed of sulfonated poly ether ether ketone (SPEEK) and two-dimensional phosphorene were fabricated, and they obtained on average 99% rejection of perfluorooctanoic acid (PFOA) alongside with a 99% removal from the PFOA that accumulated on surface of the membrane. The removal of PFOA accumulated on the membrane surface achieved 99% after the membranes were treated with ultraviolet (UV) photolysis and liquid aerobic oxidation.