Identification Of By-products Research Articles

Monitoring Epoxidized Soybean Oil Degradation Using Liquid Chromatography-Mass Spectrometry and In Silico Spectral Libraries.

Epoxidized soybean oil (ESO) is routinely used as a bioderived plasticizer and stabilizer in polyvinyl chloride (PVC), as it prolongs material integrity during dehydrochlorination. During this process, the epoxide moieties of ESO are progressively converted to chlorohydrins, which amplify ESO's inherent structural complexity. Past characterization efforts utilized separation-mass spectrometry (MS) analysis of the hydrolyzed acyl chains to simplify the complexity. However, this approach significantly increases the complexity of sample preparation and cannot directly monitor the chlorination of individual ESO species during aging. Here, we present a comprehensive LC-MS/MS data acquisition and in silico spectral library identification workflow optimized for intact ESO byproduct analysis. Detailed MS/MS fragmentation rules derived from synthesized standards were coupled with improved fragment ion intensity modeling capabilities to generate a high-fidelity spectral library for rapid ESO byproduct identification. Identification confidence was further bolstered by using retention time modeling to filter spurious MS/MS matches. Finally, we paired this informatic approach with an optimized extraction procedure and reversed-phase separation to generate a detailed timeline of more than 400 ESO species and byproducts during PVC thermal aging. These developments significantly improve our ability to detect, characterize, and understand ESO degradation in complex PVC formulations with new levels of molecular resolution.

Exploring the photocatalytic degradation mechanism for low-density polyethylene utilizing Bi4Ti3O12 nanoflower catalyst

The escalating presence of microplastics (MPs), specifically low-density polyethylene (LDPE), in various ecosystems has sparked considerable environmental and health concerns. These persistent pollutants, due to their small size and resistance to degradation, pose a serious threat to both ecosystems and human health. This study explores the efficacy of Bi4Ti3O12 nanoflower as a photocatalyst in the photocatalytic degradation of LDPE MPs under the influence of a 300 W xenon lamp. Bi4Ti3O12, synthesized via a hydrothermal method, showcases a unique layered perovskite structure that enhances photocatalytic activity by promoting the separation of photogenerated electrons and holes. The degradation efficacy was significantly superior, with LDPE MPs experiencing a weight loss of 38.27 % in 6 hours, outperforming the reported photocatalysts within a shorter timeframe. Through comprehensive analytical techniques, including SEM, XRD, FTIR, XPS, and GC-MS, the study delineates the structural, morphological, and chemical changes of LDPE MPs, highlighting the critical role of reactive oxygen species such as •OH, •O2−, and 1O2 in the degradation process through active species detection and capture experiments. The identification of various degradation by-products suggests the conversion of LDPE MPs into small molecular substances such as esters and aromatic compounds, which are then further oxidized to CO2 and H2O by •OH, •O2−, and 1O2, significantly increasing the degradability and availability of LDPE MPs. Ultimately, the present work not only sheds light on the photocatalytic degradation mechanisms but also highlights the innovative potential of Bi4Ti3O12 nanoflowers as a catalyst for reducing microplastic pollution, setting a foundation for future advancements in environmental cleanup technologies.

Mechanistic insights on interactions of dissolved organic matter with chemical oxidants: quantification of reactive sites and identification of oxidation byproducts*)

Mechanistic insights on interactions of dissolved organic matter with chemical oxidants: quantification of reactive sites and identification of oxidation byproducts^*)

Removal of benzophenone-4 via chlorination and advanced oxidation processes in aqueous solution: kinetics, by-product identification, and mechanistic studies.

Benzophenone-4 (BP-4) is one of the UV filters widely used in personal care products (PCPs). BP-4 has been identified as an emergent contaminant detected in influent and effluent of wastewater treatment plants (WWTPs) at high concentrations showing that conventional treatment is unable to remove it, subsequently, the presence of BP-4 in surface water is inevitable. In this study, we focus on the degradation of this compound by chlorine, and we report the efficiency of its removal from water by applying two advanced oxidation processes UV/TiO2 and UV/H2O2 aiming to achieve a superior mineralization result. The study was performed in purified water (pH = 6.5, temperature = 25 °C) with an initial concentration of BP-4 similar to that detected in WWTPs (10 mg/L). The results showed that 76% of BP-4 was degraded after 80 min of reaction with chlorine leading to the formation of one by-product persistent in the solution. The oxidation by UV/TiO2 and UV/H2O2 led to a total removal of BP-4 and their generated by-products after 50 and 10 min of reactions, respectively. The kinetic study showed that BP-4 degradation by UV/H2O2 and UV/TiO2 followed pseudo-first-order reaction kinetics and the apparent rate constants (kapp) were determined to be 0.48 min-1 and 0.08 min-1, respectively. The degradation of BP-4 by chlorine followed first-order reaction kinetics with kapp = 0.02 min-1. The identification of by-product structures was performed using liquid chromatography with electrospray ionization and tandem mass spectrometry (MS/MS. The fragmentation of BP-4 and by-product ions at different collision energies allowed to propose the pathways of degradation and to predict the toxicity using a silico toxicity program which confirmed a higher toxicity of all generated by-products.

Determination of ω-end functionalities in tailored poly(2-alkyl-2-oxazoline)s by liquid chromatography and mass spectrometry.

The in-depth analytical characterization of polymers, in particular regarding intended biomedical applications, is becoming increasingly important to elucidate their structure-property relationships. Specifically, end group analysis of e.g. polymers featuring a 'stealth effect' towards the immune system is of particular importance because of their use in coupling reactions to bioactive compounds. Herein, we established a liquid chromatography (LC) protocol to analyse bicyclo[6.1.0]nonyne-functionalized poly(2-alkyl-2-oxazoline)s (POx)s as promising functional polymers that can be applied in strain-promoted click reactions. This work involved the synthesis of poly(2-methyl-2-oxazoline) (PMeOx) and poly(2-ethyl-2-oxazoline) (PEtOx) by living cationic ring-opening polymerization (CROP) with different molar masses ranging from 2 up to 17.5 kDa and, to our knowledge, the first liquid chromatographic analysis of PMeOx. The developed analytical protocol enables the quantitative determination of post-polymerization reaction sequences with respect to the conversion of the ω-end groups. All synthesized polymers were straightforwardly analysed on a C18-derivatized silica monolithic column under reversed-phase chromatographic conditions with a binary mobile phase gradient comprising a mixture of acetonitrile and water. Subsequent mass spectrometry of collected elution fractions enabled the confirmation of the desired ω-end group functionalities and the identification of synthetic by-products.

A critical review of advances in tumor metabolism abnormalities induced by nitrosamine disinfection by-products in drinking water.

Intensified sanitation practices amid the recent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak might result in the increased release of chloramine disinfectants into surface water, significantly promoting the formation of nitrosamine disinfection by-products (DBPs) in drinking water. Unfortunately, these nitrosamine DBPs exhibit significant genotoxic, carcinogenic, and mutagenic properties, whereas chlorinating disinfectants remain in global practice. The current review provides valuable insights into the occurrence, identification, contamination status, exposure limits, and toxicity of the new unregulated disinfection by-products (nitrosamine DBPs) in drinking water. As a result, concentrations of nitrosamine DBPs far exceed allowable limits in drinking water, and prolonged exposure has the potential to cause metabolic disorders, a critical step in tumor initiation and progression. Importantly, based on recent research, we have concluded the role of nitrosamines DBPs in different metabolic pathways. Remarkably, nitrosamine DBPs can induce chronic inflammation and initiate tumors by activating sphingolipid and polyunsaturated fatty acid metabolism. Regarding amino acid and nucleotide metabolism, nitrosamine DBPs can inhibit tryptophan metabolism and de novo nucleotide synthesis. Moreover, inhibition of de novo nucleotide synthesis fails to repair DNA damage induced by nitrosamines. Additionally, the accumulation of lactate induced by nitrosamine DBPs may act as a pivotal signaling molecule in communication within the tumor microenvironment. However, with the advancement of tumor metabolomics, understanding the role of nitrosamine DBPs in causing cancer by inducing metabolic abnormalities significantly lags behind, and specific mechanisms of toxic effects are not clearly defined. Urgently, further studies exploring this promising area are needed.

Application of artificial intelligence for the optimization of advanced oxidation processes to improve the water quality polluted with pharmaceutical compounds

Sulfamethoxazole and metronidazole are emerging pollutants commonly found in surface water and wastewater. These compounds have a significant environmental impact, being necessary in the design of technologies for their removal. Recently, the advanced oxidation process has been proven successful in the elimination of this kind of compounds. In this sense, the present work discusses the application of UV/H2O2 and ozonation for the degradation of both molecules in single and binary systems. Experimental kinetic data from O3 and UV/H2O2 process were adequately described by a first and second kinetic model, respectively. From the ANOVA analysis, it was determined that the most statistically significant variables were the initial concentration of the drugs (0.03 mmol L−1) and the pH = 8 for UV/H2O2 system, and only the pH (optimal value of 6) was significant for degradation with O3. Results showed that both molecules were eliminated with high degradation efficiencies (88–94% for UV/H2O2 and 79–98% for O3) in short reaction times (around 30–90 min). The modeling was performed using a quadratic regression model through response surface methodology representing adequately 90 % of the experimental data. On the other hand, an artificial neural network was used to evaluate a non-linear multi-variable system, a 98% of fit between the model and experimental data was obtained. The identification of degradation byproducts was performed by high-performance liquid chromatography coupled to a time mass detector. After each process, at least four to five stable byproducts were found in the treated water, reducing the mineralization percentage to 20% for both molecules.

Site-selective benzylic C-H hydroxylation in electron-deficient azaheterocycles.

Benzylic C-H bonds can be converted into numerous functional groups, often by mechanisms that involve hydrogen atom transfer as the key bond breaking step. The abstracting species is most often an electrophilic radical, which makes these reactions best suited to electron-rich C-H bonds to achieve appropriate polarity matching. Thus, electron deficient systems such as pyridine and pyrimidine are relatively unreactive, and therefore underrepresented in substrate scopes. In this report, we describe a new method for heterobenzylic hydroxylation-essentially an unknown reaction in the case of pyrimidines-that makes use of an iodine(III) reagent to afford very high selectivity towards electron-deficient azaheterocycles in substrates with more than one reactive position and prevents over-oxidation to carbonyl products. The identification of key reaction byproducts supports a mechanism that involves radical coupling in the bond forming step.

Simulated solar-driven photo-assisted anodic oxidation of sulfadiazine by C3N4 modified Ti3+ self-doping TiO2 nanotube arrays

In this study, a C3N4 modified Ti3+ self-doping TiO2 nanotube arrays (C3N4-Ti3+/TiO2-NTA) material was innovatively fabricated using a three-step procedure consisting of anodization, chemical vapor deposition, and in-situ cathodic polarization. Simultaneously introducing C3N4 and Ti3+ significantly enhanced the light absorption property and charge separation efficiency of TiO2-NTA, while also increasing the oxygen evolution overpotential to 2.61 V vs the silver/silver chloride electrode. C3N4-Ti3+/TiO2-NTA with excellent optoelectronic properties was first applied as an anode in the simulated solar-driven photo-assisted anodic oxidation (PAO) system. It was found that the PAO system for the degradation of sulfadiazine (SDZ) exhibited 12.1-fold and 1.9-fold higher activity compared to the photocatalytic system and the anodic oxidation system alone, respectively, indicating the optoelectronic synergistic interactions over C3N4-Ti3+/TiO2-NTA. Quenching experiments and electron spin resonance results suggested that main reactive species during the degradation of SDZ by the PAO system were hydroxyl radical and superoxide radical. Additionally, three possible degradation pathways of SDZ by the PAO were proposed based on the identification of intermediate byproducts and theoretical calculation. Furthermore, the biosafety evaluation revealed a significant reduction in the biological toxicity of intermediate byproducts of SDZ. These findings provide new insights into the design and manufacturing of novel anode material for efficient degradation of recalcitrant pollutants in practical applications under solar irradiation.

Property-microstructure analysis and statistical qualification of MgB2 bulks: An investigation via micrograph feature extraction

In the pursuit of high-quality superconductors for stable operation at cryogenic temperatures, the understanding of process-structure-property relationships is crucial to device performance reproducibility and scalability. In this manuscript, we propose an indirect image-based method to evaluate statistical relationships between the ex-situ characterization results (i.e., superconducting, and mechanical properties) and microstructural distribution of MgB2 bulks produced via Spark Plasma Sintering. This study utilizes bulks processed under similar temperature profiles and sintering time, but different uniaxial loads and powder modalities. Considering the microstructure as the centerpiece between the MgB2 sintering thermodynamics and yielded macroscopic properties, multiple cross-sectional SEM micrographs of bulks MgB2 undergo an automated process that comprise image thresholding, segmentation, masking, and filtering to enable the identification of microstructural defects and byproducts. The statistical analysis establishes the relationship between processing conditions, bulk microstructural distributions, and ex-situ characterization results. Lastly, morphological analysis of the bulk cross-section microstructures indicates the effectiveness of the proposed method in identifying and statistically quantifying property variation in MgB2 bulk properties.

An integrated approach for the assessment of the electrochemical oxidation of diclofenac: By-product identification, microbiological and eco-genotoxicological evaluation

Diclofenac (DCF), a contaminant of emerging concern, is a non-steroidal anti-inflammatory drug widely detected in water bodies, which demonstrated harmful acute and chronic toxicity toward algae, zooplankton and aquatic invertebrates, therefore its removal from impacted water is necessary. DCF is recalcitrant toward traditional treatment technologies, thus, innovative approaches are required. Among them, electrochemical oxidation (EO) has shown promising results. In this research, an innovative multidisciplinary approach is proposed to assess the electrochemical oxidation (EO) of diclofenac from wastewater by integrating the investigations on the removal efficiency and by-product identification with the disinfection capacity and the assessment of the effect on environmental geno-toxicity of by-products generated through the oxidation.The electrochemical treatment successfully degraded DCF by achieving >98 % removal efficiency, operating with NaCl 0.02 M at 50 A m−2. By-product identification analyses showed the formation of five DCF parental compounds generated by decarboxylic and CN cleavage reactions.The disinfection capacity of the EO technique was evaluated by carrying out microbiological tests on pathogens generally found in aquatic environments, including two rod-shaped Gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli), one rod-shaped Gram-positive bacterium (Bacillus atrophaeus), and one Gram-positive coccus (Enterococcus hirae).Eco-toxicity was evaluated in freshwater organisms (algae, rotifers and crustaceans) belonging to two trophic levels through acute and chronic tests. Genotoxicity tests were carried out by Comet assay, and relative expression levels of catalase, manganese and copper superoxide dismutase genes in crustaceans. Results highlight the effectiveness of EO for the degradation of diclofenac and the inactivation of pathogens; however, the downstream mixture results in being harmful to the aquatic ecosystem.

84 Advances, Challenges and Prospects for the Sustainable Use of the chigüiro in Colombia

Abstract The sustainable use of chigüiro or capybara is a strategy proposal to prevent the decline of the species population by maintaining and conserving appropriate habitats, reducing illegal capture, promoting its recognition, and achieving a better distribution of its benefits and its environmental services. The objective of this work is to present the progress made toward the sustainable use of capybaras in Colombia. The biological information compiled during the last 15 years indicates that the density of the populations of this species is heterogeneous throughout the flooded savannahs with space-time variations between < 1 individual/ha, and up to 6 individual/ha. These variations are associated with strong climatic variations, changes in habitat quality, and the impact of a series of conditioning factors, both natural (water availability over time) and anthropogenic origin (hunting, land use, eventual competition with cattle, and the incidence of burning). Commercial hunting as a sustainable strategy includes the identification of various products and by-products of the species, as well as its linkage in Bioeconomy projects (Figure 1) through the compliance of associated normative, the reinforcement of environmental authorities, an effective communication strategy and user commitment. Capybara meat is characterized by having a low-fat content and a protein ratio greater than 20%; and its carcass meat performance is between 44% and 53%. In addition to the training in the preparation of various meat by-products and the analysis and processing of the fur, there is an updated market study that includes an interview phase, a pilot test of exploitation, yields and tastings for approach to the actor of the commercial chain and meet future investors or buyers. With these results, a financial model was formulated with all the necessary costs to make use of the Chigüiro products. Additionally, a prototype processing plant was designed and it has three mobile components (A, B, C); two complementary fixed structures (D, E) and a module for the processing of by-products and waste (Figure 2). Finally, linking capybara population concentration points within ecotourism activities will expand the options for its use and conservation of the Chigüiro population and its habitats. Among the actual limitations for Chigüiro use we have the delay in issuing the resolution for the allocation of the global utilization quota, and the modification of the closure to increase the period of use. These resolutions will encourage the participation of other users and local investors, which is expected to reduce the transformation of natural ecosystems and their associated biodiversity.

Evaluation of Azolla filiculoides potential in pyrene and phenanthrene accumulation and phytoremediation in contaminated waters

Polycyclic aromatic hydrocarbons (PAHs) are a serious threat to the health of the environment. This study investigated the potential of Azolla filiculoides for the uptake, accumulation, and biodegradation of phenanthrene and pyrene. A- filiculoides plants were treated with 10 and 30 mg L−1 concentrations of phenanthrene and pyrene for the experimental duration of ten days. Phenanthrene and pyrene concentrations were measured using the high-performance liquid chromatography (HPLC) technique. Identification of the intermediate by-products resulting from the biological degradation of PAHs was performed by gas chromatography-mass spectrometry (GC/MS). The quantities of phenanthrene and pyrene in the ten-day treatments with 10 and 30 mg L−1 were 0.007 and 0.011 mg g−1 FW, and 0.048 and 0.079 mg g−1 FW, respectively. The growth parameters in the plants such as fresh weight, dry weight and RFN as well as the content of photosynthetic pigment of the plant decreased significantly compared to the control sample (p < 0.05). Ten compounds were identified from the plant tissue during the decomposition of pyrene and phenanthrene, and none of the PAHs were identified in the aquatic environment. Therefore, the use of A-filiculoides for phytoremediation of water resources contaminated with PAHs is an effective and promising method.

Multivariate effect of inorganic wastewater matrix on the removal of pesticides by solar photo-Fenton

An amount of works has reported the effect of wastewater matrix composition on pollutants removal by different AOPs. The biggest challenge is that each wastewater source has a challenging composition (organic and inorganic compounds, pollutants, etc.) and not only the concentration of all these species but also the interaction between them may affect the effectiveness of the studied process. This work has been carried out to evaluate the photo-degradation kinetics of six different pesticides (flutriafol, imidacloprid, myclobutanil, pirimicarb, thiamethoxam and triadimenol) by solar photo-Fenton (SPF) process at acidic pH. First, oxidant concentration (H2O2) was optimized with an actual WWTP effluent. Then, the process was validated with two different secondary and tertiary WWTP effluents, in which main intermediate transformation by-products were identified. Finally, the effect of the inorganic water matrix components (bicarbonate, chloride, sulphate, nitrate and phosphate) was evaluated by a multivariate analysis. Once H2O2 has been optimized at 30 mg L−1, the photo-degradation efficiency of pesticides in real wastewater samples was compared. DOC content of both secondary and tertiary WWTP effluents was dropped by 67%. The identification of the main intermediate transformation by-products (such as 1H-1,2,4-triazole, desmethyl-formamido pirimicarb, thiamethoxam urea, chloronicotinic acid and imidacloprid urea) was reviewed. Following, the multivariate analysis on pesticides photo-degradation, generally, predicted four significant effects in common for the studied pesticides: a positive effect (interaction bicarbonate/nitrate) and three negative ones (chloride, phosphate and the interaction chloride/sulphate); among others. In addition, optimum values of inorganic ion concentrations, to obtain an optimum desirability on studied pesticides removal by SPF at acidic pH, were also evaluated.

Pulsed versus direct current electrochemical co-catalytic peroxymonosulfate-based system: Elevated degradation and energy efficiency with enhanced oxidation mechanisms

In this work, the pulsed electrochemical (PE) system was investigated to activate peroxymonosulfate (PMS) with the addition of Fe(III) to achieve efficient degradation of sulfamethoxazole (SMX) with reduced energy consumption, in comparison with the direct current (DC) electrochemical system. The operational conditions of PE/PMS/Fe(III) system were optimized as 4 kHz pulse frequency, 50% duty cycle, and pH 3, at which 67.6% reduction of energy consumption and enhanced degradation performance were achieved compared to the DC/PMS/Fe(III) system. Results of electron paramagnetic resonance spectroscopy analysis and quenching and chemical probe experiment revealed the presence of •OH, SO4•−, and 1O2 in the system, with •OH being the dominant role. The concentrations of these active species were averagely 15 ± 1% higher in the PE/PMS/Fe(III) system than those of the DC/PMS/Fe(III) system. Identification of SMX byproducts was achieved based on high resolution mass spectrometry analysis to predict the degradation pathways. The SMX byproducts could eventually be eliminated by the PE/PMS/Fe(III) system with extended treatment time. Overall, the PE/PMS/Fe(III) system was demonstrated with high energy and degradation performance, and is appear to be an robust strategy for practical treatment of wastewater.

Degradation of carbamazepine by the photo-Fenton process. Approach towards the elucidation of degradation by-products

Carbamazepine (CBZ) is a pollutant of emerging concern because of its adverse effects associated. This work deals with the degradation of 1 mg L-1 of CBZ by the photo-Fenton process in water to discern the potential of this advanced oxidation process for the elimination of this persistent pollutant. For this purpose, the operating conditions were optimized using a central composite design of experiments, testing the influence of ferrous ion (Fe2+) and hydrogen peroxide (H2O2) concentrations on the degradation of CBZ. As a result, 96.4% of CBZ removal was obtained under optimal operating conditions (0.750 mg L-1 and 0.2 mg L-1 of H2O2 and Fe2+, respectively). In addition, the effect of the initial concentration of the target drug on the oxidation capacity of the photo-Fenton process was assessed by analyzing the removal kinetic constant. This value was achieved through a pseudo-first order model and resulted to be 0.0182 µmol L-1 min−1. Additionally, the degradation of CBZ in surface water was evaluated, obtaining an elimination of 74.4%. Finally, the identification of some CBZ by-products was carried out, being one of them purified and elucidated by means of the nuclear magnetic resonance technique and mass spectrometry. The referred degradation by-product was identified for the first time as 2,2′-aminodibenzaldehyde. In this regard, the photo-Fenton process is concluded to be able of degrading CBZ in natural surface water.

Fe(II) activated calcium peroxide/peroxymonosulfate: A practical system for phenanthrene degradation and upholding ecological pH

Groundwater contamination by polycyclic aromatic hydrocarbons (PAHs) can have adverse effects on both the subsurface environment and human health. This study aimed to demonstrate the degradation of PHE using a coupled oxidant system, that involves simultaneous injection of Fe(II) and oxidants, CaO2 (CP) and peroxymonosulfate (PMS). To ensure the environmental compatibility, coupled oxidant strategy was proposed to maintain the pH level between 6.0 and 8.0 following the treatment process. The influence of reaction conditions including concentration of PMS, CP, and Fe(II) concentrations, initial pH, anions, and humic acid on PHE degradation were assessed. Scavenger experiments and electron spin resonance (ESR) analysis confirmed that hydroxyl radical (HO−) and non-radical singlet oxygen (1O2) were the primary reactive oxygen species (ROS) in the reported system. PHE degradation mechanism in the coupled oxidant system was proposed based on by-products identification. In addition, the CP/PMS/Fe(II) system showed promising degradation performance for naphthalene and pyrene, indicating the proposed strategy could be a viable option for removing a broad spectrum of PAHs. Finally, the coupled oxidant system was optimized to achieve best PHE removal efficiency under natural groundwater (NGW) conditions.

Photocatalytic degradation of diclofenac using a novel double Z-scheme catalyst (O-g-C3N4/ZnO/TiO2@halloysite nanotubes): Degradation mechanism, identification of by-products and environmental implementation

It is challenging and expensive to synthesize multivariate composites with high photocatalytic efficiency and recyclability. Herein, a novel direct double Z-scheme O-g-C3N4/ZnO/TiO2@halloysite nanotubes (HNTs) photocatalyst was synthesized using a simple and low-cost method to degrade and mineralize diclofenac (DCF). During 50 min, O-g-C3N4/ZnO/TiO2@HNTs degraded DCF completely at pH 6.83, 10 mg/L DCF concentration, and 1.0 g/L catalyst, which was 1.66 and 2.4 times higher than ternary O-g-C3N4/ZnO/TiO2 and O-g-C3N4/HNTs/TiO2. Under the same conditions, 35.12 % of DCF was removed from urban wastewater. A negative effect of anions on the process was observed as follows: CO32− > HPO42− > Cl− > NO3−. Under the same conditions, 39.23 % of total organic carbon (TOC) was removed. Moreover, Mott-Schottky analysis and active species trapping experiments were performed to investigate the photodegradation mechanism systematically. It was observed that O2− played a minor part in the photodegradation process, while hole and OH were the more critical reactive species. Several intermediate compounds formed during the photocatalytic reaction were identified by LC-MS analysis. The results showed that a simple design and synthesis of multi-component complex catalysts presented a new insight into removing emerging pollutants from the aquatic environment and apprehending the enhanced photocatalytic mechanism.

Thiol Reactome: A Nontargeted Strategy to Precisely Identify Thiol Reactive Drinking Water Disinfection Byproducts.

The precise identification of predominant toxic disinfection byproducts (DBPs) from disinfected water is a longstanding challenge. We propose a new acellular analytical strategy, the 'Thiol Reactome', to identify thiol-reactive DBPs by employing a thiol probe and nontargeted mass spectrometry (MS) analysis. Disinfected/oxidized water samples had reduced cellular oxidative stress responses of 46 ± 23% in Nrf2 reporter cells when preincubated with glutathione (GSH). This supports thiol-reactive DBPs as the predominant drivers of oxidative stress. This method was benchmarked using seven classes of DBPs including haloacetonitriles, which preferentially reacted with GSH via substitution or addition depending on the number of halogens present. The method was then applied to chemically disinfected/oxidized waters, and 181 tentative DBP-GSH reaction products were detected. The formulas of 24 high abundance DBP-GSH adducts were predicted, among which nitrogenous-DBPs (11) and unsaturated carbonyls (4) were the predominant compound classes. Two major unsaturated carbonyl-GSH adducts, GSH-acrolein and GSH-acrylic acid, were confirmed by their authentic standards. These two adducts were unexpectedly formed from larger native DBPs when reacting with GSH. This study demonstrated the "Thiol Reactome" as an effective acellular assay to precisely identify and broadly capture toxic DBPs from water mixtures.

Waste to drugs: identification of pyrolysis by-products as antifungal agents against Cryptococcus neoformans

The fungi, Cryptococcus neoformans cause major infections such as cryptococcal meningitis and cryptococcosis. Therefore, we explored the use of Thioredoxin reductase (Trr1) from C. neoformans as a gene target for the development of novel antifungal agents. Trr1 plays an essential role in the survival in the oxidative environment of macrophages and is important for the virulence of C. neoformans. During the thermochemical conversion (pyrolysis) of lignocellulosic biomass (LCB), a cocktail of compounds is produced by the decomposition and degradation. In general, LCB-derived cocktail of compounds is a rich source of aromatic compounds that have been shown to be antifungal in nature. Usually, the aqueous phase produced during biomass pyrolysis is generally regarded as waste. Here, we used Parthenium hysterophorus biomass as the antifungal source and obtained the aqueous phase after pyrolysis. Using GC-MS analysis of the aqueous phase collected from P. hysterophorus biomass revealed the presence of a large number of aromatic and organic compounds. Using virtual screening, the compounds present in the aqueous phase were docked against Trr1 using GLIDE. Two promising candidates were analyzed further by performing molecular dynamics simulation using GROMACS, to establish stable interactions. We validated the computational results with clustering analysis. We report that 2,4-Di-tertbutyl phenol and 1H-Pyrazole, 4-ethyl-3,5-dimethyl have a potent antifungal property and we postulate that they could be a potent antifungal agent against Trr1 of C. neoformans.