C1 coupling reactions over zeolite catalysts are central to sustainable chemical production strategies. However, questions persist regarding the involvement of CO in ketene formation, and the impact of this elusive oxygenate intermediate on reactivity patterns. Using operando photoelectron photoion coincidence spectroscopy (PEPICO), we investigate the role of CO in methyl chloride conversion to hydrocarbons (MCTH), a prospective process for methane valorization with a reaction network akin to methanol to hydrocarbons (MTH) but without oxygenate intermediates. Our findings reveal the transformative role of CO in MCTH at the low pressures, inducing ketene formation in MCTH and boosting olefin production, confirming the Koch carbonylation step in the initial stages of C1 coupling. We uncover pressure-dependent product distributions driven by CO-induced ketene formation, and its subsequent desorption from the zeolite surface, which is enhanced at low pressure. Inspired by the above results, extension of the co-feeding approach to CH3OH as another simple oxygenate showcases the additional potential for improved catalyst stability in MCTH at ambient pressure.

Advanced oxidation processes (AOPs) have been widely used in water and wastewater treatment and have shown excellent performance in remediating contaminated water. However, their oxidation byproducts, including halogenated organics, have recently attracted increasing attention. Alkyl halides are among the most important environmental pollutants in nature. Here, we report a Fenton-like reaction in which alkyl halides can form during the photodegradation of aliphatic carboxylic acids in the presence of Fe(III) and halides. Chloromethane, chloroethane, and 1-chloropropane were produced from the degradation of acetic acid, propionic acid and n-butyric acid, respectively. CH3Cl, CH2Cl2 and CHCl3 were all identified as the products of acetic acid with the yields of approximately 5.1%, 0.2% and 0.005%, respectively. It was demonstrated that hydroxyl radicals, halogen radicals and alkyl radicals were involved in the formation of alkyl halides. A possible mechanism of chloromethane formation was proposed based on the results. In real samples of saline water, the addition of carboxylic acid and Fe(III) significantly promoted the generation of CH3Cl under xenon lamp irradiation. The results indicated that the coexistence of Fe(III), halides and carboxylic acids enhanced the photochemical release of alkyl halides. The reactions described in this paper may contribute to knowledge on the mechanism of halogenated byproduct formation during AOPs.

In this study, a novel tin oxide/nitrogen-doped graphene quantum dot nanocomposite (SnO2-NDGQD) and 1-methyl-3-octylimidazolinium chloride (1M3OICl) ionic liquid amplified carbon paste electrode (CPE) was fabricated as an efficient and fast-response sensor to determine daunorubicin, an anticancer drug. The electrochemical characteristics of daunorubicin at the surface of the 1M3OICl/SnO2-NDGQD/CPE was explored via various voltammetric methods. The high-resolution transmission electron microscope (HR-TEM) images were recorded to examine the morphological structure of the as-synthesized nanocomposites. The 1M3OICl/SnO2-NDGQD/CPE offered a wide linear concentration of 0.001-280.0 μM with a low detection limit of 0.40 nM at the optimized experimental conditions using square wave voltammetric (SWV) method. In a nutshell, the developed electrode illustrated outstanding selectivity in the presence of interfering agents and long-term stability. The1M3OICl/SnO2-NDGQD/CPE was used as new and powerful analytical tool for determination of daunorubicin in real samples with recovery range 98.75%-104.8%.

OBJECTIVE: A simple and robust head space/gas chromatography with flame ionisation sensor (HS/GC/FIS) approach for the trace evaluation of carcinogenic impurity, methyl chloride, in trimetazidine dihydrochloride (TRD) drug ingredient and its formulation is described.
METHODS: This HS/GC/FIS approach was based on separation and analysis of CH3Cl content on DB-624 [75.0m - length, 0.53mm - internal diameter, 3.0μm - film thickness] column using nitrogen as carrier gas flowing through the column at 3mL/min stream rate. Detection of eluted CH3Cl was accomplished with flame ionization sensor at a set temperature of 260̊C.
RESULTS: The optimised HS/GC/FIS methodological approach was thoroughly validated, demonstrating that it was linear with range of 5.0ppm to 1508.4ppm, sensitive with detection limit of 1.65ppm and quantification limit of 5.01ppm, reproducible with RSD values of 2.10-2.35%, accurate with recoveries of 81.9-99.0%, robust with percent variation of 7.5-12.22% with respect to changes in oven temperature, injector temperature, detector temperature and practical for regular TRD quality control.
CONCLUSIONS: The findings revealed that with this optimised HS/GC/FIS methodological approach, the trace amounts of carcinogenic impurity (methyl chloride) in TRD drug ingredient and formulation could be successfully measured.

Chemical emissions from two new memory foam mattresses were evaluated in a simulated consumer use environment over the course of 32 days. Passive 12- and 24-h samples (n = 62) were collected for various VOCs. Airborne concentrations of chemicals associated with the mattresses (2-propanol, acetone, chloromethane, toluene, and ΣVOC) peaked during the first day after installation and progressively decayed over the course of the following 31 days. Emission rates were derived using a two-phase, double exponential source decay model paired with a one-compartment generalized indoor air quality model; short- and long-term emission half-lives for individual chemicals were on the order of hours (approximately 4 or 12 h) and days (approximately 24 days), respectively. Model-estimated average ΣVOC concentrations for the 32-day period of the study were approximately 20 and 33 μg/m3 for Mattress 1 and 2, respectively, while the modeled one-year average concentrations were 2.7 and 4.2 μg/m3, respectively. First-year trends for both mattresses were qualitatively similar, with the sum of 2-propanol, acetone, chloromethane, and toluene contributing to approximately 81% and 95% of the first-year ΣVOC concentration of Mattress 1 and 2, respectively. The airborne concentrations of individual chemicals and ΣVOC measured and modeled in this study were well below available health-based benchmarks for individual chemicals and within available indoor air quality recommendations for ΣVOC, suggesting that it is unlikely that the use of the models of mattresses evaluated in this study would pose a health risk to consumers.

Chlorine (Cl) in the terrestrial environment is of interest from multiple perspectives, including the use of chloride as a tracer for water flow and contaminant transport, organochlorine pollutants, Cl cycling, radioactive waste (radioecology; 36Cl is of large concern) and plant science (Cl as essential element for living plants). During the past decades, there has been a rapid development towards improved understanding of the terrestrial Cl cycle. There is a ubiquitous and extensive natural chlorination of organic matter in terrestrial ecosystems where naturally formed chlorinated organic compounds (Clorg) in soil frequently exceed the abundance of chloride. Chloride dominates import and export from terrestrial ecosystems while soil Clorg and biomass Cl can dominate the standing stock Cl. This has important implications for Cl transport, as chloride will enter the Cl pools resulting in prolonged residence times. Clearly, these pools must be considered separately in future monitoring programs addressing Cl cycling. Moreover, there are indications that (1) large amounts of Cl can accumulate in biomass, in some cases representing the main Cl pool; (2) emissions of volatile organic chlorines could be a significant export pathway of Cl and (3) that there is a production of Clorg in tissues of, e.g. plants and animals and that Cl can accumulate as, e.g. chlorinated fatty acids in organisms. Yet, data focusing on ecosystem perspectives and combined spatiotemporal variability regarding various Cl pools are still scarce, and the processes and ecological roles of the extensive biological Cl cycling are still poorly understood.

Methyl chloride (CH3Cl) and methyl bromide (CH3Br) are the predominant carriers of natural chlorine and bromine from the troposphere to the stratosphere, which can catalyze the destruction of stratospheric ozone. Here, penguin colony soils (PCS) and the adjacent tundra soils (i.e., penguin-lacking colony soils, PLS), seal colony soils (SCS), tundra marsh soils (TMS), and normal upland tundra soils (UTS) in coastal Antarctica were collected and incubated for the first time to confirm that these soils were CH3Cl and CH3Br sources or sinks. Overall, tundra soil acted as a net sink for CH3Cl and CH3Br with potential flux ranges from -18.1 to -2.8 pmol g-1 d-1 and -1.32 to -0.24 pmol g-1 d-1, respectively. The deposition of penguin guano or seal excrement into tundra soils facilitated the simultaneous production of CH3Cl and CH3Br and resulted in a smaller sink in PCS, SCS, and PLS. Laboratory-based thermal treatments and anaerobic incubation experiments suggested that the consumption of CH3Cl and CH3Br was predominantly mediated by microbes while the production was abiotic and O2 independent. Temperature gradient incubations revealed that increasing soil temperature promoted the consumption of CH3Cl and CH3Br in UTS, suggesting that the regional sink may increase with Antarctic warming, depending on changes in soil moisture and abiotic production rates.

Chloromethane (CH3Cl) is the most abundant long-lived chlorinated organic compound in the atmosphere and contributes significantly to natural stratospheric ozone depletion. Salt marsh ecosystems including halophyte plants are a known source of atmospheric CH3Cl but estimates of their total global source strength are highly uncertain and knowledge of the major production and consumption processes in the atmosphere-halophyte-soil system is yet incomplete. In this study we investigated the halophyte plant, Salicornia europaea, and soil samples from a coastal salt marsh site in Sardinia/Italy for their potential to emit and consume CH3Cl and using flux measurements, stable isotope techniques and Arrhenius plots differentiated between biotic and abiotic processes. Our laboratory approach clearly shows that at least 6 different production and consumption processes are active in controlling atmospheric CH3Cl fluxes of a salt marsh ecosystem. CH3Cl release by dried plant and soil material was substantially higher than that from the fresh material at temperatures ranging from 20 to 70 °C. Results of Arrhenius plots helped to distinguish between biotic and abiotic formation processes in plants and soils. Biotic CH3Cl consumption rates were highest at 30 °C for plants and 50 °C for soils, and microbial uptake was higher in soils with higher organic matter content. Stable isotope techniques helped to distinguish between formation and degradation processes and also provided a deeper insight into potential methyl moiety donor compounds, such as S-adenosyl-l-methionine, S-methylmethionine and pectin, that might be involved in the abiotic and biotic CH3Cl production processes. Our results clearly indicate that cycling of CH3Cl in salt marsh ecosystems is a result of several biotic and abiotic processes occurring simultaneously in the atmosphere-plant-soil system. Important precursor compounds for biotic and abiotic CH3Cl formation might be methionine derivatives and pectin. All formation and degradation processes are temperature dependent and thus environmental changes might affect the strength of each source and sink within salt marsh ecosystems and thus considerably alter total fluxes of CH3Cl from salt marsh ecosystems to the atmosphere.

Here, a bioinspired strategy is used to prepare well-ordered nanotubular structures, as observed in animals and plants, such as gecko toe pads or corals. The nanotubes are obtained by templateless electropolymerization of thieno[3,4-b]thiophene-based monomers with various aromatic groups in an organic solvent (dichloromethane). The most interesting and robust structures were obtained with carbazole and pyrene substituents to the base monomer structure, since these groups participate significantly in the polymerization and also have strong π-stacking interactions. The addition of water to electropolymerization solvent significantly impacted the formation of nanotubes, as it caused the release of a significant amount of H2 and O2 bubbles, depending on the electropolymerization method. Identifying templateless approaches to vary nanotubular structures is very interesting, as these materials are sought-after for applications in water harvesting systems. This article is part of the theme issue \'Bioinspired materials and surfaces for green science and technology (part 3)\'.

Methyl chloride (CH3Cl) is presently understood to arise from biotic and abiotic processes in marine systems. However, the production of CH3Cl via photochemical processes has not been well studied. Here, we reported the production of CH3Cl from humic acid (HA) in sunlit saline water and the effects of the concentration of HA, chloride ions, ferric ions and pH were investigated. HA in aqueous chloride solutions or natural seawater were irradiated under an artificial light, and the amounts of CH3Cl were determined using a purge-and-trap and gas chromatography-mass spectrometry. CH3Cl was generated upon irradiation and its amount increased with increasing irradiation time and the light intensity. The formation of CH3Cl increased with an increase of HA concentration ranging from 2 mg L-1 to 20 mg L-1 and chloride ion concentration ranging from 0.02 mol L-1 to 0.5 mol L-1. The photochemical production of CH3Cl was pH-dependent, with the highest amount of CH3Cl generating near neutral conditions. Additionally, the generation of CH3Cl was inhibited by ferric ions. Finally, natural coastal seawater was irradiated under artificial light and the concentration of CH3Cl rose significantly. Our results suggest that the photochemical process of HA may be a source of CH3Cl in the marine environment.