Low Volatile Organic Compounds Research Articles

Real-World Emission Characteristics of Full-Volatility Organics Originating from Nonroad Agricultural Machinery during Agricultural Activities.

Nonroad agricultural machinery (NRAM) emissions constitute a significant source of air pollution in China. Full-volatility organics originating from 19 machines under 6 agricultural activities were measured synchronously. The diesel-based emission factors (EFs) for full-volatility organics were 4.71 ± 2.78 g/kg fuel (average ± standard deviation), including 91.58 ± 8.42% volatile organic compounds (VOCs), 7.94 ± 8.16% intermediate-volatility organic compounds (IVOCs), 0.28 ± 0.20% semivolatile organic compounds (SVOCs), and 0.20 ± 0.16% low-volatility organic compounds (LVOCs). Full-volatility organic EFs were significantly reduced by stricter emission standards and were the highest under pesticide spraying activity. Our results also demonstrated that combustion efficiency was a potential factor influencing full-volatility organic emissions. Gas-particle partitioning in full-volatility organics could be affected by multiple factors. Furthermore, the estimated secondary organic aerosol formation potential based on measured full-volatility organics was 143.79 ± 216.80 mg/kg fuel and could be primarily attributed to higher-volatility-interval IVOCs (bin12-bin16 contributed 52.81 ± 11.58%). Finally, the estimated emissions of full-volatility organics from NRAM in China (2021) were 94.23 Gg. This study provides first-hand data on full-volatility organic EFs originating from NRAM to facilitate the improvement of emission inventories and atmospheric chemistry models.

Volatility of aerosol particles from NO3 oxidation of various biogenic organic precursors

Abstract. Secondary organic aerosol (SOA) is formed through the oxidation of volatile organic compounds (VOCs), which can be of both natural and anthropogenic origin. While the hydroxyl radical (OH) and ozone (O3) are the main atmospheric oxidants during the day, the nitrate radical (NO3) becomes more important during the nighttime. Yet, atmospheric nitrate chemistry has received less attention compared to OH and O3. The Nitrate Aerosol and Volatility Experiment (NArVE) aimed to study the NO3-induced SOA formation and evolution from three biogenic VOCs (BVOCs), namely isoprene, α-pinene, and β-caryophyllene. The volatility of aerosol particles was studied using isothermal evaporation chambers, temperature-dependent evaporation in a volatility tandem differential mobility analyzer (VTDMA), and thermal desorption in a filter inlet for gases and aerosols coupled to a chemical ionization mass spectrometer (FIGAERO-CIMS). Data from these three setups present a cohesive picture of the volatility of the SOA formed in the dark from the three biogenic precursors. Under our experimental conditions, the SOA formed from NO3 + α-pinene was generally more volatile than SOA from α-pinene ozonolysis, while the NO3 oxidation of isoprene produced similar although slightly less volatile SOA than α-pinene under our experimental conditions. β-Caryophyllene reactions with NO3 resulted in the least volatile species. Four different parameterizations for estimating the saturation vapor pressure of the oxidation products were tested for reproducing the observed evaporation in a kinetic modeling framework. Our results show that the SOA from nitrate oxidation of α-pinene or isoprene is dominated by low-volatility organic compounds (LVOCs) and semi-volatile organic compounds (SVOCs), while the corresponding SOA from β-caryophyllene consists primarily of extremely low-volatility organic compounds (ELVOCs) and LVOCs. The parameterizations yielded variable results in terms of reproducing the observed evaporation, and generally the comparisons pointed to a need for re-evaluating the treatment of the nitrate group in such parameterizations. Strategies for improving the predictive power of the volatility parameterizations, particularly in relation to the contribution from the nitrate group, are discussed.

Effect of Synthetic Low-Odor Thiol-Based Hardeners Containing Hydroxyl and Methyl Groups on the Curing Behavior, Thermal, and Mechanical Properties of Epoxy Resins

A novel thiol-functionalized polysilsesqioxane containing hydroxyl and methyl groups was synthesized using a simple acid-catalyzed sol–gel method to develop an epoxy hardener with low odor, low volatile organic compound (VOC) emissions, and fast curing at low temperatures. The synthesized thiol-based hardeners were characterized using Fourier transform infrared spectroscopy, nuclear magnetic resonance, thermogravimetric analysis (TGA), and gel permeation chromatography and compared with commercially available hardeners in terms of odor intensity and VOC emissions using the air dilution olfaction method and VOC analysis. The curing behavior and thermal and mechanical properties of the epoxy compounds prepared with the synthesized thiol-based hardeners were also evaluated. The results showed that synthetic thiol-based hardeners containing methyl and hydroxyl groups initiated the curing reaction of epoxy compounds at 53 °C and 45 °C, respectively. In contrast, commercial thiol-based hardeners initiated the curing reaction at 67 °C. Additionally, epoxy compounds with methyl-containing synthetic thiol-based hardeners exhibited higher TGA at a 5% weight loss temperature (>50 °C) and lap shear strength (20%) than those of the epoxy compounds with commercial thiol-based hardeners.

Methodological advances to improve repeatability of SOA generation in environmental chambers

Most laboratory atmospheric chamber studies probing the chemical and physical properties of secondary organic aerosol (SOA) perform such experiments with mixing ratios of volatile organic compounds (VOCs) above atmospheric relevance (≳50 ppbv). When performing ozonolysis of biogenic VOCs at mixing ratios of atmospheric relevance (≲10 ppbv), a major hinderance on the repeatability of replicate experiments is due to the limitations of conventional VOC injection techniques. To overcome these limitations, two novel components (stop/flow and split valves) were embedded in a conventional VOC injection setup, thereby permitting the use of higher VOC volumes of injection to attain low VOC mixing ratios, and the delivery of the VOC to the environmental chamber as a short, discrete pulse for subsequent reaction. Implementation of these novel VOC injection components has resulted in improvements in variability between replicate chamber experiments of up to a factor of 7 with respect to particle number, mass, and size distributions at both high and low VOC mixing ratios (50 and 10 ppbv, respectively). These improvements permit extension of quantitative measurements of SOA formation to VOC mixing ratios at or near atmospheric levels, where new particle formation (NPF) and SOA mass loading are typically within experimental variability.

Saturation vapor pressure characterization of selected low-volatility organic compounds using a residence time chamber

Abstract. Saturation vapor pressure (psat) is an important thermodynamic property regulating the gas-to-particle partitioning of organic compounds in the atmosphere. Low-volatility organic compounds (LVOCs), with sufficiently low psat values, primarily stay in the particle phase and contribute to aerosol formation. Obtaining accurate information on the psat of LVOCs requires volatility measurements performed at temperatures relevant to atmospheric aerosol formation. Here, we present an isothermal evaporation method using a residence time chamber to measure psat for dry single-compound nanoparticles at 295 K. Our method is able to characterize organic compounds with psat spanning from 10−8 to 10−4 Pa at 295 K. The compounds included four polyethylene glycols (PEGs: PEG6, PEG7, PEG8, and PEG9), two monocarboxylic acids (palmitic acid and stearic acid), two dicarboxylic acids (azelaic acid and sebacic acid), two alcohols (meso-erythritol and xylitol), and one ester (di-2-ethylhexyl sebacate). There was a good agreement between our measured psat values and those reported by previous volatility studies using different measurement techniques, mostly within 1 order of magnitude. Additionally, quantum-chemistry-based COSMOtherm calculations were performed to estimate the psat values of the studied compounds. COSMOtherm predicted the psat values for most of the studied compounds within 1 order of magnitude difference between the experimental and computational estimates.

Effect of SEBS Molecular Structure and Formula Composition on the Performance of SEBS/PP TPE for Automotive Interior Skin.

The hydrogenated styrene-butadiene-styrene block copolymer (SEBS)/Polypropylene (PP)-blended thermoplastic elastomer (TPE) is an ideal material for automotive interior skin applications due to its excellent elasticity, weather resistance, and environmentally friendly characteristics such as low odor and low volatile organic compounds (VOC). As a thin-wall injection-molded appearance skin product, it requires both high fluidity and good mechanical properties with scratch resistance. To optimize the performance of the SEBS/PP-blended TPE skin material, an orthogonal experiment and other methods were employed to investigate the impact of the formula composition and raw material characteristics, such as the styrene content and molecular structure of SEBS, on the TPE's final performance. The outcomes revealed that the ratio of SEBS/PP had the most significant influence on the mechanical properties, fluidity, and wear resistance of the final products. The mechanical performance was enhanced by increasing the PP content within a certain range. The degree of sticky touch on the TPE surface was increased as the filling oil content increased, causing the increase in sticky wear and the decrease in abrasion resistance. When the SEBS ratio of high/low styrene content was 30/70, the TPE's overall performance was excellent. The different proportions of linear/radial SEBS also had a significant effect on the final properties of the TPE. The TPE exhibited the best wear resistance and excellent mechanical properties when the ratio of linear-shaped/star-shaped SEBS was 70/30.

Sensitivity of pollutant concentrations in urban streets to asphalt and traffic-related emissions

The higher concentrations of atmospheric particles, such as black carbon (BC) and organic matter (OM), detected in streets compared to the urban background are predominantly attributed to road traffic. The integration of this source of pollutant in air quality models nevertheless entails a high degree of uncertainty and some other sources may be missing. Through sensitivity scenarios, the impacts on pollutant concentrations of sensitivities related to traffic and road-asphalt emissions are evaluated. The 3D Eulerian model Polair3D and the street network model MUNICH are applied to simulate various scenarios and their impacts at the regional and local scales. They are coupled with the modular box model SSH-aerosol to represent formation and aging of primary and secondary gas and particles. Traffic emissions are calculated with the COPERT methodology. Using recent volatile organic compound speciations for light vehicles with more detailed information pertaining to intermediate, semi- and low-volatile organic compounds (I/S/LVOCs) leads to limited reductions of OM concentrations (10% in streets). Changing the method of estimating I/S/LVOC emissions leads to an average reduction of 60% at emission and a decrease of the OM concentrations of 27% at the local scale. An increase in 219% of BC emissions from tire wear, consistent with the uncertainties found in the literature, doubles the BC concentrations at the local scale, which remain underestimated compared to observations. I/S/LVOC emissions are several orders of magnitude higher when considering emissions from road asphalt due to pavement heating and exposure to sunlight. However, simulated concentrations of PM at the local scale remain within acceptable ranges compared to observations. These results suggest that more information is needed on I/S/LVOCs and non-exhaust sources (tire, brake and road abrasion) that impact the particle concentration. Furthermore, currently unconsidered emission sources such as road asphalt may have non-negligible impacts on pollutant concentrations in streets.

Characteristics of the Low Molecular Weight Metabolome of Potamogeton Natans L. (Potamogetonaceae) from Lakes of Different Trophic State (Karelian Isthmus, Northwest Russia)

The qualitative and quantitative component composition of low molecular weight volatile organic compounds (VOCs) of the essential oil of the floating-leaf pondweed (Potamogeton natans L., Potamogetonaceae family) growing in various lakes of the Karelian Isthmus (North-West of the Russian Federation) in the fruiting stage was investigated in detail for the first time by gas chromatography-mass spectrometry. The low molecular weight metabolome (LMWM) of P. natans contained 138 components, 128 of which were identified. VOCs belonging to esters, alcohols, and various functional groups dominated the LMWM of floating leaf pondweed from mesotrophic and eutrophic lakes. A significant similarity was found between the component composition of VOCs of floating leaf pondweed from mesotrophic and eutrophic lakes. Many of the substances found in the LMWM of P. natans can be attributed to biologically active compounds. This opens up prospects for the use of this plant (particularly manool and ecdysteroids from its LMWM) for various economic applications as a valuable natural raw material. Due to the characteristic of the floating leaf pondweed's substantial resistance of its LMWM to the factor of the trophic status of the lakes, it is feasible to use it as an ecological indicator of significant disruptions in aquatic environments.

Multifunctional Layer-by-Layer Coating Based on a New Amphiphilic Block Copolymer via RAFT-Mediated Polymerization-Induced Self-Assembly Process.

In this hi-tech world, the "smart coatings" have sparked significant attention among materials scientists because of their versatile applications. Various strategies have been developed to generate smart coatings in the past 2 decades. The layer-by-layer (LbL) technique is the most commonly employed strategy to produce a smart coating for suitable applications. Here, we present a smart coating with healing, antifogging, and fluorescence properties fabricated by the LbL assembly of an anionic amphiphilic block copolymer latex and cationic inorganic POSS (polyhedral-oligomeric-silsesquioxane) nanoparticles. In this case, a new anionic block copolymer (BCP), {poly(sodium styrene sulfonate)-block-poly[2-(acetoacetoxy)ethyl methacrylate]}, (PSS-b-PAAEMA) was synthesized via surfactant-free RAFT-mediated emulsion polymerization using the PISA technique. The PSS-b-PAAEMA was characterized by 1H NMR, dynamic light scattering, scanning electron microscopy, and transmission electron microscopy analyses as well as by UV-vis and photoluminescence spectroscopy. For LbL coating fabrication, an amine-modified glass was successively dipped in the anionic latex and cationic POSS solution. The transparent coating exhibited good fluorescence properties under UV light (blue color). The antifogging performance of the coating was also investigated using both cold-warm and hot-vapor techniques. Additionally, the coating surface showed a significant healing activity with a healing efficiency of >75% through ionic interaction. Thus, this finding provides a simple low volatile organic compound (VOC) water-based LbL coating with multifunctional properties that can be a potential material for versatile applications.

Method Development for Detecting Low Level Volatile Organic Compounds (VOCs) among Workers and Residents from a Carpentry Work Shop in a Palestinian Village.

Volatile organic compounds (VOCs) are considered a major public health concern in industrial location areas. The presence of exposure to (VOCs) has raised concern regarding the health effects caused by chronic human exposure as this will increase cancer diseases in the village. An analytical method has been developed and modified to help us detect 38 VOCs in the blood of 38 volunteers who are related to a carpentry shop at the parts-per-trillion level. To measure and evaluate the potential risk, several devices, such as portable passive monitors and air-collected samples, in addition to blood concentration, were used to study three different occupational groups. Ten of the volunteers are employees at the shop, 10 volunteers live very close to the shop, and 10 of them are students in an elementary school very close to the shop. In this study, we developed an automated analytical method using headspace (HS) together with solid-phase microextraction (SPME) connected to capillary gas chromatography (GC) equipped with quadrupole mass spectrometry (MS). The detection limits for the method used were measured in the range from 0.001 to 0.15 ng/L, using linear calibration curves that have three orders of magnitude. The detected concentrations ranged from 3 ng L-1 for trichloroethene to 91 ng L-1 for toluene and 270 ng L-1 for 2,4-diisocyanate, which was derived from the paint solvents used for the wood in the carpentry shop and the paints on the walls. More than half of all assessed species (80%) had mean concentration values less than 50 ng L-1, which is the maximum allowed for most VOCs. The major chemical types among the compounds quantified will be those we found in our previous study in the surrounding air of a carpentry workshop in Deir Ballout in Palestine, which were toluene diisocyanate and butyl cyanate. Some were found to be highly present air. Most of the measurements were below the guidelines of the World Health Organization (WHO). Despite the fact that this study only involved a small number of smokers, smoking was found to be connected with several blood and breath components. This group includes unsaturated hydrocarbons (1,3-butadiene, 1,3-pentadiene, 2-butene), furans (2,5-dimethylfuran), and acetonitrile. The proposed classification of measured species into systemic (blood-borne) and exogenous volatiles is strictly hypothetical, as some species may have several origins.

Brown Coal and Logwood Combustion in a Modern Heating Appliance: The Impact of Combustion Quality and Fuel on Organic Aerosol Composition.

Residential heating with solid fuels is one of the major drivers for poor air quality in Central and Eastern Europe, and coal is still one of the major fuels in countries, such as Poland, the Czech Republic, and Hungary. In this work, emissions from a single-room heater fueled with brown coal briquettes (BCBs) and spruce logs (SLs) were analyzed for signatures of inorganic as well as semivolatile aromatic and low-volatile organic constituents. High variations in organic carbon (OC) emissions of BCB emissions, ranging from 5 to 22 mg MJ-1, were associated to variations in carbon monoxide (CO) emissions, ranging from 900 to 1900 mg MJ-1. Residential BCB combustion turned out to be an equally important source of levoglucosan, an established biomass burning marker, as spruce logwood combustion, but showed distinct higher ratios to manosan and galactosan. Signatures of polycyclic aromatic hydrocarbons emitted by BCB combustion exhibited defunctionalization and desubstitution with increasing combustion quality. Lastly, the concept of island and archipelago structural motifs adapted from petroleomics is used to describe the fraction low-volatile organic compounds in particulate emissions, where a transition from archipelago to island motifs in relation with decreasing CO emissions was observed in BCB emissions, while emissions from SL combustion exhibited the island motif.

Single-atom Pt-CeO2/Co3O4 catalyst with ultra-low Pt loading and high performance for toluene removal

The design and manufacture of high activity and thermal stability catalysts with minimal precious metal loading is essential for deep degradation of volatile organic compounds (VOCs). In this paper, a novel single-atom Pt-CeO2/Co3O4 catalyst with ultra-low Pt loading capacity (0.06 wt%, denoted as 0.06Pt-SA) was fabricated via one-step co-precipitation method. The 0.06Pt-SA exhibited excellent toluene degradation activity of T90 = 169 °C, matched with the nanoparticle Pt-supported CeO2/Co3O4 catalyst with more than six times higher Pt loading (0.41 wt%, denoted as 0.41Pt-NP). Moreover, the ultra-long durability (toluene conversion remains 99% after 120 h stability test) and excellent toluene degradation ability in a wide space speed range of 0.06Pt-SA were superior to that of 0.41Pt-NP catalyst. The excellent performance was derived from the strong metal-support interaction (SMSI) between the single atomic Pt and the carrier, which induced more Pt0 and Ce3+ for oxygen activation and more Co3+ for toluene removal. The in situdiffuse reflectance infrared spectroscopy (DRIFTS) experiments confirmed that the conversion of intermediates was accelerated in the reaction process, thereby promoting the toluene degradation. Our results should inspire the exploitation of noble single-atomic modification strategy for developing the low cost and high performance VOCs catalyst.

Airborne dimethyl sulfide (DMS) cues dimethylsulfoniopropionate (DMSP) increases in the intertidal green alga Ulva fenestrata

Although the use of airborne molecules as infochemicals is common in terrestrial plants, it has not been shown to occur in an ecologically relevant context in marine seaweeds. Like terrestrial plants, intertidal plants spend part of their lives emersed at low tide and release volatile organic compounds (VOCs) into the air when they are grazed or physiologically stressed. We hypothesized seaweeds could use airborne VOCs as infochemicals and respond to them by upregulating a keystone defensive metabolite, dimethylsulfoniopropionate (DMSP). We conducted laboratory and field experiments in which Ulva fenestrata was exposed to airborne dimethyl sulfide (DMS), a volatile antiherbivore and antioxidant metabolite released when the seaweed is grazed or physiologically stressed. In the laboratory, U. fenestrata exposed to DMS had 43–48% higher DMSP concentrations, relative to controls, 6–9 days after exposure. In the field, U. fenestrata 1 m downwind of DMS emitters had 19% higher DMSP concentrations than upwind seaweeds after 11 days. To our knowledge, this is the first demonstration of a marine plant using an airborne molecule released when damaged to elicit defensive responses. Our study suggests that the ability to detect airborne compounds has evolved multiple times or before the divergence of terrestrial plants and green algae.

Development of a Moisture Pretreatment Device for the Accurate Quantitation of Water-Soluble Volatile Organic Compounds in Air

In air pollutant monitoring using sensors, moisture can adversely affect the analytical accuracy of volatile organic compounds (VOCs). Therefore, a new moisture pretreatment device (KPASS–Odor) for analyzing VOCs in the air was developed, based on frost and created by a desublimation process inside a cold tube. The performance of KPASS–Odor was compared with conventional devices (i.e., a NafionTM dryer and a cooler) through the measurements of low water-soluble VOCs (i.e., benzene, toluene, ethyl benzene, p-xylene, and styrene) and relatively high ones (i.e., methyl-ethyl ketone, methyl isobutyl ketone, butyl acetate, and isobutyl alcohol) using gas chromatography (GC) and sensor methods. Regarding the GC method, the recovery rates for KPASS–Odor and the cooler were >95% and >80%, respectively, at a flow rate of 500 mL/min for all compounds. For the NafionTM dryer, the recovery rates differed between low and high water-soluble compounds, which exhibited the rates ≥88% and ≤86%, respectively. In terms of the sensor method, the VOC recovery rates of KPASS–Odor and the NafionTM dryer were found to be >90% and <50%, respectively. Therefore, KPASS–Odor was determined to be the most suitable moisture pretreatment device for highly soluble VOCs of concern in this study.

Research Progress of SOA Formation from Anthropogenic VOCs Under Complex Pollution Condition

Although the air quality in China has been greatly improved in recent years, the air pollution remains severe. The annual mean PM2.5 concentrations have not met the second grade of the National Ambient Air Quality Standards in China and are still much higher than the guideline value of the World Health Organization. Thus, the PM2.5 concentration needs to be further reduced. Secondary organic aerosol (SOA) is an important component of PM2.5 and has an important impact on air quality, global climate change, and human health. Therefore, understanding the formation mechanism of SOA is an important basis to control SOA and further reduce PM2.5. As an important precursor of SOA, volatile organic compounds (VOCs) can be oxidized by oxidants such as ·OH, NO3[KG-*2/3]·, Cl·, and O3 to generate low volatile organic compounds and further to form SOA through gas-particle partitioning, homogeneous nucleation, aqueous phase reaction, and heterogeneous reaction processes. The formation of SOA can be affected by many factors, such as the types and initial concentrations of VOCs, VOCs/NOx ratios, relative humidity (RH), temperature (T), seed aerosols, oxidants, aqueous phase process, and photochemical process. The observed SOA concentration is always underestimated by air quality models because a comprehensive understanding of the complexity of SOA chemical composition and formation mechanisms is still lacking, especially that under the highly complex air pollution conditions in China. Therefore, the formation mechanism and influencing factors of SOA under highly complex air pollution conditions have become an important concern in the field of atmospheric sciences. Recently, much laboratory work has focused on the formation of SOA under complex conditions. The research progress of SOA formation from different anthropogenic VOCs are reviewed here, and the methods used and the impact of different influencing factors on SOA formation are introduced. Finally, the key scientific issues that exist in the research of the SOA mechanism at present are put forward, and the future research direction is projected.

Weekend-weekday variations, sources, and secondary transformation potential of volatile organic compounds in urban Zhengzhou, China

Periodical changes of human activities cause weekend-weekday differences of volatile organic compounds (VOCs) and nitrogen oxides (NO + NO2 = NOx) emissions, which induce urban ozone (O3) pollution and secondary organic aerosol (SOA) in fine particulate (with aerodynamic diameters ≤2.5 μm; PM2.5). However, influences of weekend-weekday differences in primary emissions on the production of secondary pollutants remain unknown. The TROPOspheric Monitoring Instrument and surface observations are carried to simultaneously monitor VOCs, NO2, O3, and PM2.5 concentrations in urban Zhengzhou, China during the weekend and the weekday. Reductions in anthropogenic activities result in atmospheric VOCs and NO2 reductions during the weekend. The ratios of formaldehyde columns to NO2 columns during the weekend afternoon and the weekday afternoon (0.53 and 0.39, respectively) are less than 2.30, indicating the O3 formation under the VOC-limited regime. Lower total VOCs (TVOCs) mixing ratios but higher ratios of TVOCs mixing ratios to NO2 mixing ratios during the weekend afternoon perform faster photochemical O3 production. In contrast, higher TVOCs mixing ratios are responsible for higher SOA formation during the weekday. Based on the positive matrix factorization model and VOCs reactivities, solvent usage, vehicle exhaust, and industrial sources are majorly responsible for SOA (80.1%) and O3 (79.9%) formation potential. To reduce O3 concentrations during the weekend and SOA concentrations during the weekday collaboratively, solvent, vehicle, and industrial activities should be transformed from weekday to weekend.

Characteristics and environmental and health impacts of volatile organic compounds in furniture manufacturing with different coating types in the Pearl River Delta

Volatile organic compounds (VOCs) are essential pollutants affecting ambient air quality. In the Pearl River Delta of China, furniture manufacturing contributes significantly to VOCs emissions, mainly from coatings. Therefore, the source substitution of coatings is the most effective way to reduce VOCs emissions. In this study, eight typical furniture enterprises with five different coatings types (traditional solvent coatings (solvent and solvent ultraviolet (UV) coatings) and low VOCs content coatings (waterborne, waterborne UV, and powder coatings)) were selected for field monitoring to reveal differences in VOCs emission characteristics, environmental impacts and health risks between traditional solvent coatings and low-VOCs coatings. The results showed that solvent coating VOCs have the highest concentration (143.32 mg/m3) and are much higher than that of solvent UV coating (45.96 mg/m3) and other coatings (≤11.81 mg/m3). The highest proportion of VOCs of solvent (UV) coating is aromatic hydrocarbons (50.73% (44.05%)). While oxygenated VOCs rank first in low-VOCs coatings (47.81%–59.20%). Compared with other coatings, the solvent coating has the greatest contribution to the formation potential of ozone and secondary organic aerosols. Meanwhile, the solvent coating has the highest carcinogenic risk of ethylbenzene in the spraying workshop (8.53 × 10−6), and only solvent coating in the spraying workshop has the non-carcinogenic risk of xylene (1.07). Finally, through scenario analysis, the environmental benefits of low-VOCs coatings substituting solvent coating were quantified. The study will help accelerate the process of source substitution of coatings and promote cleaner production in the furniture industry.

Synergistic enhancement of flame retardancy of epoxy resin by layered zirconium phenylphosphate modified layered double hydroxides

While water-based epoxy coatings have been welcomed by the market due to their excellent environmental performance and low volatile organic compounds emission, its poor flame retardancy has led to limited applications. Herein, the catalytic char formation effect of zirconium phenylphosphonate (ZrPP) and the excellent flame retardant properties of layered double hydroxide (LDH) were fully combined to obtain a high-performance composite flame retardant coating. Specifically, polydopamine (PDA) with excellent adhesion properties was encapsulated on the surface of LDH to enhance its dispersibility in water. The introduction of PDA provided abundant active sites for the adsorption of ZrPP precursor cations, which contributed to the uniform loading of ZrPP on LDH to obtain well-structured LDH@PDA@ZrPP (LPZP) hybrids. The synergistic effect of LDH and ZrPP on the flame retardant properties of the epoxy resin matrix was investigated. The LPZP4%/EP sample showed the lowest backside temperature (173.6 °C), maximum expansion height (25.10 mm) and expansion rate (20.10), proving its highest thermal insulation effect. In the TGA test, the residual char of LPZP4%/EP increased to 26.8 %, proving the excellent thermal stability of the coating. The SEM images showed that the internal char layer of the composite coating formed a honeycomb network structure, which increased the heat absorption property of the char layer.

Divergent summertime surface O3 pollution formation mechanisms in two typical Chinese cities in the Beijing-Tianjin-Hebei region and Fenwei Plain

Recently, severe summertime ozone (O3) pollution has swept across most areas of China, especially the Beijing-Tianjin-Hebei (BTH) region and Fenwei Plain. By focusing on Beijing and Yuncheng, which are two typical cities in the BTH region and the Fenwei Plain, we intended to reveal the neglected fact that they had disparate emission features and atmospheric movements but suffered from similar high-O3 pollution levels. Field observations indicated that Yuncheng had lower volatile organic compound (VOC) and NOx concentrations but higher background O3 levels. The model simulation verified that both photochemical reactions and net O3 generation were stronger in Beijing. Ultimately, faster net O3 generation rates (8.4 ppbv/h) plus lower background O3 values in Beijing and lower net O3 generation rates (6.2 ppbv/h) plus higher background O3 values in Yuncheng caused both regions to reach similar O3 peak values in July 2020. However, different O3 control measures were appropriate for the two cities according to the different simulated O3-VOCs-NOx responses. Additionally, as surface O3 levels are greatly affected by the ongoing O3 production/depletion process that occurs in three dimensions, exploring the effects of spatially distributed O3 on surface O3 should be high on the agenda in the future.

Designing a Coupling Agent with Aliphatic Polyether Chain and Exploring Its Effect on Silica/Natural Rubber Nanocomposites under the Action of Non-Rubber Contents.

In order to prepare engineering tires with lower rolling resistance and better wet slip resistance in a more environmentally friendly way. In this study, a series of low volatile organic compound (VOC) Mx-Si69 coupling agents (x = 1, 2, 3, 4, 5, 6, which means the number of ethoxy group in bis-(γ-triethoxysilylpropyl)-tetrasulfide (Si69) substituted by the aliphatic polyether chain) were applied to silica/NR nanocomposites to prepare tire tread with excellent performance. Firstly, M1-Si69 was substantiated as the best choice of Mx-Si69 and Si69 to achieve comprehensive optima in the mechanical properties of silica/NR nanocomposites characterized by dynamic and static mechanical properties. Afterwards, the modification of silica with M1-Si69 induced by Non-Rubber Contents (NRCs) in silica/NR nanocomposites was revealed by comparing the filler network, micromorphology, and mechanical properties of isoprene rubber (IR) and NR nanocomposites. Furthermore, compared with Si69, the M1-Si69 coupling agent was found to conspicuously reduce the energy loss and improve the safety performance of engineering tires according to evaluations of the rolling resistance and dynamic thermomechanical properties of the silica/NR nanocomposites. Finally, the critical function of M1-Si69 in reducing ethanol (a kind of volatile organic compound (VOC)) emissions from the reaction of coupling agent and silica was disclosed by gas chromatography-mass spectrometry.