Chemical characterization of polymer and chloride content in waste plastic materials using pyrolysis - direct analysis in real time - high-resolution mass spectrometry.

The increasing global demand for plastic has raised the need for effective waste plastic management due to its long lifetime and resistance to environmental degradation. There is a need for rapid plastic identification to improve the mechanical waste plastic sorting process. This study presents a novel application of Temperature-Programmed Desorption-Direct Analysis in Real Time-High Resolution Mass Spectrometry (TPD-DART-HRMS) that enables rapid characterization of various plastics.

Molecular insights into the composition, sources, and aging of atmospheric brown carbon.

The light-absorbing chemical components of atmospheric organic aerosols are commonly referred to as Brown Carbon (BrC), reflecting the characteristic yellowish to brown appearance of aerosol. BrC is a highly complex mixture of organic compounds with diverse compositions and variable optical properties of its individual chromophores. BrC significantly influences the radiative budget of the climate and contributes to adverse air pollution effects such as reduced visibility and the presence of inhalable pollutants and irritants.

Molecular Characterization and Photoreactivity of Organic Aerosols Formed from Pyrolysis of Urban Materials during Fires at the Wildland-Urban Interface.

Fires at the wildland-urban interface (WUI) are increasing in magnitude and frequency, emitting organic aerosol (OA) with unknown composition and atmospheric impacts. In this study, we investigated the chemical composition of OA produced through the 600 °C pyrolysis of ten urban materials in nitrogen, which were subsequently aged under UV light for 2 h. The analysis utilized ultrahigh-performance liquid chromatography (UHPLC) separation, coupled with a photodiode array (PDA) detector and a high-resolution mass spectrometer (HRMS) for molecular characterization.

Volatility Basis Set Distributions and Viscosity of Organic Aerosol Mixtures: Insights from Chemical Characterization Using Temperature-Programmed Desorption-Direct Analysis in Real-Time High-Resolution Mass Spectrometry.

Quantitative assessment of gas-particle partitioning of individual components within complex atmospheric organic aerosol (OA) mixtures is critical for predicting and comprehending the formation and evolution of OA particles in the atmosphere. This investigation leverages previously documented data obtained through a temperature-programmed desorption-direct analysis in real-time, high-resolution mass spectrometry (TPD-DART-HRMS) platform. This methodology facilitates the bottom-up construction of volatility basis set (VBS) distributions for constituents found in three biogenic secondary organic aerosol (SOA) mixtures produced through the ozonolysis of α-pinene, limonene, and ocimene.

Enhanced Light Absorption and Elevated Viscosity of Atmospheric Brown Carbon through Evaporation of Volatile Components.

Samples of brown carbon (BrC) material were collected from smoke emissions originating from wood pyrolysis experiments, serving as a proxy for BrC representative of biomass burning emissions. The acquired samples, referred to as "pyrolysis oil (PO)," underwent subsequent processing by thermal evaporation of their volatile compounds, resulting in a set of three additional samples with volume reduction factors of 1.33, 2, and 3, denoted as PO, PO, and PO.

Chemical characterization of microplastic particles formed in airborne waste discharged from sewer pipe repairs.

Microplastic particles are of increasing environmental concern due to the widespread uncontrolled degradation of various commercial products made of plastic and their associated waste disposal. Recently, common technology used to repair sewer pipes was reported as one of the emission sources of airborne microplastics in urban areas. This research presents results of the multi-modal comprehensive chemical characterization of the microplastic particles related to waste discharged in the pipe repair process and compares particle composition with the components of uncured resin and cured plastic composite used in the process.

Volatility Measurements of Individual Components in Organic Aerosol Mixtures Using Temperature-Programmed Desorption-Direct Analysis in Real Time-High Resolution Mass Spectrometry.

Atmospheric organic aerosols (OA) have profound effects on air quality, visibility, and radiative forcing of climate. Quantitative assessment of gas-particle equilibrium of OA components is critical to understand formation, growth, distribution, and evolution of OA in the atmosphere. This study presents a novel ambient pressure measurement approach developed and tested for untargeted screening of individual components in complex OA mixtures, followed by targeted chemical speciation of identified species and assessment of their physicochemical properties such as saturation vapor pressure and enthalpies of sublimation/evaporation.

Molecular and Structural Characterization of Isomeric Compounds in Atmospheric Organic Aerosol Using Ion Mobility-Mass Spectrometry.

Secondary organic aerosol (SOA) formed through multiphase atmospheric chemistry makes up a large fraction of airborne particles. The chemical composition and molecular structures of SOA constituents vary between different emission sources and aging processes in the atmosphere, which complicates their identification. In this work, we employ drift tube ion mobility spectrometry with quadrupole time-of-flight mass spectrometry (IM-MS) detection for rapid gas-phase separation and multidimensional characterization of isomers in two biogenic SOAs produced from ozonolysis of isomeric monoterpenes, d-limonene (LSOA) and α-pinene (PSOA).

Ice-nucleating agents in sea spray aerosol identified and quantified with a holistic multimodal freezing model.

Sea spray aerosol (SSA) is a widely recognized important source of ice-nucleating particles (INPs) in the atmosphere. However, composition-specific identification, nucleation processes, and ice nucleation rates of SSA-INPs have not been well constrained. Microspectroscopic characterization of ambient and laboratory-generated SSA confirms that water-borne exudates from planktonic microorganisms composed of a mixture of proteinaceous and polysaccharidic compounds act as ice-nucleating agents (INAs).

Secondary organic aerosol formation from atmospheric reactions of anisole and associated health effects.

Anisole (methoxybenzene) represents an important marker compound of lignin pyrolysis and a starting material for many chemical products. In this study, secondary organic aerosols (SOA) formed by anisole via various atmospheric processes, including homogeneous photooxidation with varying levels of OH• and NO and subsequent heterogeneous NO• dark reactions, were investigated. The yields of anisole SOA, particle-bound organoperoxides, particle-induced oxidative potential (OP), and cytotoxicity were characterized in view of the atmospheric fate of the anisole precursor.

Kinetics, Products, and Brown Carbon Formation by Aqueous-Phase Reactions of Glycolaldehyde with Atmospheric Amines and Ammonium Sulfate.

Glycolaldehyde (GAld) is a C water-soluble aldehyde produced during the atmospheric oxidation of isoprene and many other species and is commonly found in cloudwater. Previous work has established that glycolaldehyde evaporates more readily from drying aerosol droplets containing ammonium sulfate (AS) than does glyoxal, methylglyoxal, or hydroxyacetone, which implies that it does not oligomerize as quickly as these other species. Here, we report NMR measurements of glycolaldehyde's aqueous-phase reactions with AS, methylamine, and glycine.

Molecular investigation of the multi-phase photochemistry of Fe(III)-citrate in aqueous solution.

Iron (Fe) is ubiquitous in nature and found as Fe or Fe in minerals or as dissolved ions Fe or Fe in aqueous systems. The interactions of soluble Fe have important implications for fresh water and marine biogeochemical cycles, which have impacts on global terrestrial and atmospheric environments. Upon dissolution of Fe into natural aquatic systems, organic carboxylic acids efficiently chelate Fe to form [Fe-carboxylate] complexes that undergo a wide range of photochemistry-induced radical reactions.

Optical Properties of Secondary Organic Aerosol Produced by Photooxidation of Naphthalene under NOx Condition.

Secondary organic aerosols (SOAs) affect incoming solar radiation by interacting with light at ultraviolet and visible wavelength ranges. However, the relationship between the chemical composition and optical properties of SOA is still not well understood. In this study, the complex refractive index (RI) of SOA produced from OH oxidation of naphthalene in the presence of nitrogen oxides (NOx) was retrieved online in the wavelength range of 315-650 nm and the bulk chemical composition of the SOA was characterized by an online high-resolution time-of-flight mass spectrometer.

Solid organic-coated ammonium sulfate particles at high relative humidity in the summertime Arctic atmosphere.

SignificancePhysical and chemical properties of individual atmospheric particles determine their climate impacts. Hygroscopic inorganic salt particles mixed with trace amounts of organic material are predicted to be liquid under typical tropospheric conditions in the summertime Arctic. Yet, we unexpectedly observed a significant concentration of solid particles composed of ammonium sulfate with an organic coating under conditions of high relative humidity and low temperature.

Molecular Characterization of Water-Soluble Brown Carbon Chromophores in Snowpack from Northern Xinjiang, China.

This study reports molecular-level characterization of brown carbon (BrC) attributed to water-soluble organic carbon in six snowpack samples collected from northern Xinjiang, China. The molecular composition and light-absorbing properties of BrC chromophores were unraveled by application of high-performance liquid chromatography (HPLC) coupled to a photodiode array (PDA) detector and high-resolution mass spectrometry. The chromophores were classified into five major types, that is, (1) , (2) , (3) , (4) , and (5) .

Molecular Analysis of Secondary Brown Carbon Produced from the Photooxidation of Naphthalene.

We investigate the chemical composition of organic light-absorbing components, also known as brown carbon (BrC) chromophores, formed in a proxy of anthropogenic secondary organic aerosol generated from the photooxidation of naphthalene (-SOA) in the absence and presence of NO. High-performance liquid chromatography equipped with a photodiode array detector and electrospray ionization high-resolution mass spectrometer is employed to characterize -SOA and its BrC components. We provide molecular-level insights into the chemical composition and optical properties of individual -SOA components and investigate their BrC relevance.

Quantitative analysis of polycyclic aromatic hydrocarbons using high-performance liquid chromatography-photodiode array-high-resolution mass spectrometric detection platform coupled to electrospray and atmospheric pressure photoionization sources.

Polycyclic aromatic hydrocarbons (PAHs) are common pollutants present in atmospheric aerosols and other environmental mixtures. They are of particular air quality and human health concerns as many of them are carcinogenic toxins. They also affect absorption of solar radiation by aerosols, therefore contributing to the radiative forcing of climate.

Secondary organic aerosols produced from photochemical oxidation of secondarily evaporated biomass burning organic gases: Chemical composition, toxicity, optical properties, and climate effect.

Biomass burning (BB) is an important source of primary organic aerosols (POA). These POA contain a significant fraction of semivolatile organic compounds, and can release them into the gas phase during the dilution process in transport. Such evaporated compounds were termed "secondarily evaporated BB organic gases (SBB-OGs)" to distinguish them from the more studied primary emissions.

Photosensitized Reactions of a Phenolic Carbonyl from Wood Combustion in the Aqueous Phase-Chemical Evolution and Light Absorption Properties of AqSOA.

Guaiacyl acetone (GA) is a phenolic carbonyl emitted in significant quantities by wood combustion that undergoes rapid aqueous-phase oxidation to produce aqueous secondary organic aerosol (aqSOA). We investigate the photosensitized oxidation of GA by an organic triplet excited state (C*) and the formation and aging of the resulting aqSOA in wood smoke-influenced fog/cloud water. The chemical transformations of the aqSOA were characterized in situ using a high-resolution time-of-flight aerosol mass spectrometer.

Optical Properties of Secondary Organic Aerosol Produced by Nitrate Radical Oxidation of Biogenic Volatile Organic Compounds.

Nighttime oxidation of biogenic volatile organic compounds (BVOCs) by nitrate radicals (NO·) represents one of the most important interactions between anthropogenic and natural emissions, leading to substantial secondary organic aerosol (SOA) formation. The direct climatic effect of such SOA cannot be quantified because its optical properties and atmospheric fate are poorly understood. In this study, we generated SOA from the NO· oxidation of a series BVOCs including isoprene, monoterpenes, and sesquiterpenes.

Chemical Composition and Molecular-Specific Optical Properties of Atmospheric Brown Carbon Associated with Biomass Burning.

This study provides molecular insights into the light absorption properties of biomass burning (BB) brown carbon (BrC) through the chemical characterization of tar condensates generated from heated wood pellets at oxidative and pyrolysis conditions. Both liquid tar condensates separated into "darker oily" and "lighter aqueous" immiscible phases. The molecular composition of these samples was investigated using reversed-phase liquid chromatography coupled with a photodiode array detector and a high-resolution mass spectrometer.