Emission factors and characteristics of volatile organic compounds (VOCs) from adhesive application in indoor decoration in China

Environmental and economic impact analysis of levying VOCs environmental protection tax in China

China is one of the largest volatile organic compounds (VOCs) emitters worldwide. The emission levels of and harm caused by VOCs have attracted much attention. China has implemented multiple policies for VOCs prevention and control but lacks economic control measures for VOCs In this study, the input-output (IO) price model was used to simulate and analyze the emission reduction and economic effects resulting from the imposition of a VOCs environmental protection tax (EPT) in 31 provinces in China. The results show that, first, the collection of a VOCs-EPT can achieve not only VOCs emission reductions but also the synergistic emission reductions of other major pollutants. Second, the collection of a VOCs-EPT could have a negative impact on the macroeconomy, i.e., the greater the tax scope and the higher the tax rate are, the greater the negative economic impact. Third, differences in the level of economic development, the structure of pollution emissions and the stringency of tax policies among regions would cause the emission reduction effect and related negative economic impact to vary across regions. Finally, the collection of a VOCs-EPT could have heterogeneous impacts on various industries, as high-emission industries would suffer greater negative impacts. Therefore, each region should set tax rates that match its provincial economic and environmental development levels. Furthermore, a VOCs-EPT can be levied on key industries, and reasonable preferential tax policies can be formulated to reduce negative macroeconomic benefits.

Self-assembly behavior and adhesive performance of imidazolium cation grafted cellulose nanocrystals in confined space

Confined evaporation-induced self-assembly (C-EISA) is a powerful technique to guide disordered nanoparticles into long-range organized structures. Herein, we investigate the C-EISA behavior of 1-butyl-3-vinylimidazolium cation ([VBIm]+) grafted cellulose nanocrystals (CNC-C) in a parallel-plates confined geometry. Interestingly, CNC-C can spontaneously assemble into maze-like patterns with branch dimensions on the micrometer scale and uniformly distributed throughout the confined space, which is completely different from the lamellar self-assembly patterns of unmodified CNCs. Combining in situ observations and microscopic characterization, we speculate that the formation of maze-like patterns originates from the reduction of colloidal stability induced by the grafted imidazolium cations. The electrostatic attraction between CNC-C aggregated bundles and glass substrates acts as anchor points, thereby leading to the unstable motion of the liquid-air menisci during the inward intrusion of air. Due to the physicochemical properties and unique C-EISA behavior, the CNC-C based adhesive can maintain adhesion at temperatures of ca. 200 °C, while rapidly debonding when immersed in water, demonstrating the potential to be used as stimuli-responsive temporary or removable adhesives. Furthermore, the strategy proposed in this work for achieving CNCs patterning is also promising to be extended to other anisotropic rod-shaped nanoparticles.

High-Performance Ir1/CeO2 Single-Atom Catalyst for the Oxidation of Toluene

The elimination of toluene is an obligatory target with increasing VOC emission in recent years. This study successfully prepared a single-atom Ir catalyst (Ir1/CeO2) by a simple incipient wetness impregnation method, confirmed by in situ CO DRIFTS and AC-HAADF-STEM. Compared to the cluster Ir catalyst (Ir/CeO2-C), Ir1/CeO2 exhibited excellent catalytic performance, stability, and water resistance for the oxidation of toluene. By Raman, H2-TPR, O2-TPD, and XPS experiments, abundant oxygen defects and a unique Ir3+-Ov-Ce3+ structure were formed for the Ir1/CeO2 sample because it had a lower oxygen vacancy formation energy. Furthermore, the DFT results revealed that the Ir1/CeO2 sample had a lower ring-opening energy barrier and adsorption energy of the ring-opening products, which was the rate-determining step for the oxidation of toluene. This work provides instructive insights into the construction of Ir/CeO2 catalysts for the highly efficient removal of VOCs.

A Knudsen diffusion model for predicting VOC emissions from porous wood-based panels based on porosimetry tests

Volatile organic compounds (VOCs) emitted from porous wood-based panels with fractal structure severely pollute indoor environment. Different from previous studies which the diffusion type of VOC in building materials is attributed to Fick diffusion, VOC emission from porous wood-based panels belongs to Knudsen diffusion is firstly determined by comparing the pore diameter of internal channel with VOC molecular free path in this paper. Therefore, a time fractional mass transfer model related to the fractal dimension has been proposed to analyze Knudsen diffusion characteristics firstly. This model considers areal porosity has an impact on surface emission. Analytical solution of the present model is obtained for the first time. Furthermore, it is proved that the finite difference scheme is solvable, unconditionally stable, and convergent, and numerical simulation result and experimental data match well. Moreover, the influences of the fractal dimension d_f, areal porosity ε, and delay time parameter λ on VOC emission are demonstrated and analyzed; results suggest that the higher ε and d_f, and lower λ promote VOC emission, which can provide guidance for improving indoor air quality.

Emission characteristics, risk assessment and scale effective control of VOCs from automobile repair industry in Beijing

Automobile repair is regarded as a typical domestic source of VOCs in China characterized by numerous sites, wide dispersion and intermittent VOCs emissions. It is of great importance to study and control VOCs from such activities. In this research, emission characteristics, risk assessment and scale effective control of VOCs from automobile repair in Beijing were studied. Results showed that coating spraying and baking were the main processes of VOCs and the major species determined were mostly oxygen-containing VOCs and aromatic hydrocarbons in the case of solvent-based coating usage. Meanwhile, alkanes were determined and accounted for 40 % of total VOCs emissions during the water-based coating spraying and baking. Generally, the total determined VOCs during the automobile repair processes were 1.06-1.27 mg/m³ and 2.93-53.46 mg/m³ for the usage of water-based and solvent-based paint, respectively. Health risk assessments indicated that the residents in the region about 30 m high within a radius of 20 m around the automobile repair plants might suffer from both serious non-carcinogenic and carcinogenic risk threats in the case of solvent-based coating usage in that the values of total hazard index (HI) represented by dichloropropane and acrolein were higher than 1 and the value of lifetime cancer risk (LCR) represented by dichloroethane was higher than 10^-5. Besides, those in the region about 30 m high and within a wider radius of 340 m might suffer from carcinogenic risk threat with a certain probability (LCR > 10^-6) no matter either solvent-based or water-based coatings were used. As for the scale control of VOCs from automobile repair, independent adsorption by activated carbon combined with mobile regeneration by catalytic combustion was also proposed as an efficient way.

Supramolecular interaction enabled preparation of high-strength water-based adhesives from polymethylmethacrylate wastes

The preparation of water-based adhesives with high bonding strength for various substrates is challenging. Moreover, to construct a sustainable society, it is highly desirable to develop a cost-effective way to achieve the reuse of plastic wastes. Herein, using polymethylmethacrylate (PMMA) chemicals or wastes as raw materials, water-based adhesives with high bonding strength for various substrates are prepared through a simple one-step hydrolysis strategy. The adhesives possess the maximum bonding strength of 7.1 MPa to iron, 4.2 MPa to wood, and ∼1.5 MPa to plastics. The adhesives have a world-record bonding strength to metal when compared with that of current reported water-based adhesives. Our method is low cost, simple, environmentally friendly, and suitable for large-scale industrial production. More importantly, using plastic wastes as raw materials opens up a new and low-cost way to turn wastes into valuables, which will greatly contribute to construct a sustainable society.

Characteristics, secondary transformation and odor activity evaluation of VOCs emitted from municipal solid waste incineration power plant

Volatile organic compounds (VOCs) emitted from municipal solid waste incineration power plant (MSWIPP) plays a significant role in the formation of O₃ and PM_2.5 and odor pollution. Field test was performed on four MSWIPPs in an area of the North China Plain. Nonmethane hydrocarbons (NMHCs) and 102 VOCs were identified and quantified. Ozone formation potential (OFP), secondary organic aerosol formation potential (SOAFP), and odor activity of the detected VOCs were evaluated. Results showed that the average concentration of NMHCs and VOCs were 1648.6 ± 1290.4 μg/m³ and 635.3 ± 588.8 μg/m³, respectively. Aromatics (62.1%), O-VOCs (16.0%), and halo hydrocarbons (10.0%) were the main VOCs groups in the MSWIPP exhaust gas. VOCs emission factor of MSWIPP was 2.43 × 10³ ± 2.27 × 10³ ng/g-waste. The OFP and SOAFP of MSWIPP were 960.18 ± 2158.17 μg/m³ and 1.57 ± 3.38 μg/m³, respectively. Acrolein as the dominant VOC species was the major odor contributor with a percentage of odor contribution of 65.9%. Benzene and 1,2,4-trimethylbenzene as the dominant VOC species were the main contributors of O₃ formation potentials, in which 1,2,4-trimethylbenzene was also the main contributors of SOA formation potential.

Comparison of multidimensional mass transfer models of formaldehyde emissions originating from different surfaces of wood-based panels

Indoor decoration causes a large amount of formaldehyde to be concurrently released from different surfaces of wood-based panels. However, this phenomenon has rarely been described with two- or three-dimensional mass transfer models. In this paper, multidimensional mass transfer models of formaldehyde emissions originating from different surfaces of building materials are first established. Moreover, mass balance integral equation is introduced. Experiments of formaldehyde emissions in the environmental chambers are numerically simulated by combining the parameter estimation method, composite Simpson formula and finite difference method, whose convergence and stability are verified. The results indicated that the proposed models suitably agreed with the experimental and literature data. Furthermore, the multidimensional mass transfer model confirmed that formaldehyde released from sides should not be ignored. Compared with the one-dimensional model, the three-dimensional model can more accurately simulate the release data of formaldehyde from wood-based panels. Subsequently, the variation trend between the chemical reaction formation rate and physical diffusion rate of formaldehyde is revealed.

Quantitation study on VOC emissions and their reduction potential for coking industry in China: Based on in-situ measurements on treated and untreated plants

Currently, the characteristics of volatile organic compounds (VOC) released from coking industry are still vague, and the widely used VOC emission factors (EFs) were still from the measurements of 1990s. Hence, focusing on coking industry, we conducted an in-situ measurement campaign in several typical plants, developed a set of VOC EFs for various release units, and estimated the current emission amounts and future reduction potentials of VOC in China. The measurements show that the levels of VOC in stationary units were 63.82-9563.93 μg·m^-3, and those surrounding fugitive units were 111.37-1436.36 μg·m^-3. VOC emissions from stationary units were directly calculated, which deducing EFs of 11.57, 15.51, 127.13, 0.28, 0.16 g·t^-1 coke respectively for coke charging, coke pushing, coke oven chimney, dry quenching, and wastewater treatment processes. Meanwhile, VOC emissions from fugitive units were simulated following the inverse dispersion method, which achieving EFs of 443.34 ± 66.31, 352.12 ± 65.81, and 718.56 ± 132.69 g·t^-1 coke respectively for the coke oven leakage, byproduct recovery with VOC treatment system, and byproduct recovery without VOC treatment system. Generally, the coking plants installing VOC treatment system had total VOC EF of 953.76 g·t^-1 coke, about 37.1% lower than those never considering VOC treatment (1516.25 g·t^-1 coke). According to these developed EFs, the VOC emission amount from coking industry in China were estimated, slightly decreasing from 623.54 to 578.17 Gg per year, although the coke production increasing from 410.86 to 418.26 Tg during 2015-2019. In future, according to the national industrial policies, regulations and standards, technical guidelines, the VOC reduction potential of this industry in China could reach 336.9 Gg, to which headstream adjustment, process improvement, and end-of-pipe control contributed about 21.4%, 31.6%, and 47.0%, respectively.

Hierarchical porous structure formation mechanism in food waste component derived N-doped biochar: Application in VOCs removal

Nitrogen-doped (N-doped) hierarchical porous carbon was widely utilized as an efficient volatile organic compounds (VOCs) adsorbent. In this work, a series of N-doped hierarchical porous carbons were successfully prepared from the direct pyrolysis process of three food waste components. The porous biochar that derived from bone showed a high specific surface area (1405.06 m²/g) and sizable total pore volume (0.97 cm³/g). The developed hierarchical porous structure was fabricated by the combined effect of self-activation (Carbon dioxide (CO₂) and water vapor (H₂O)) and self-template. The emission characteristics of activation gas analyzed by Thermogravimetric-Fourier transform infrared spectrometer (TG-FTIR) and the transformation of ash composition in the biochar help to illustrate the pore-forming mechanism. Calcium oxide (CaO) and hydroxylapatite were confirmed as the major templates for mesopores, while the decomposition processes of calcium carbonate (CaCO₃) and hydroxylapatite provided a large amount of activation gas (CO₂ and H₂O) to form micropores. The materials also obtained abundant N-containing surface functional groups (up to 7.84 atomic%) from pyrolysis of protein and chitin. Finally, the porous biochar showed excellent performance for VOCs adsorption with a promising uptake of 288 mg/g for toluene and a high adsorption rate of 0.189 min^-1. Aplenty of mesopores distributed in the materials effectively improved the mass transfer behaviors, the adsorption rate got a noticeable improvement (from 0.118 min^-1 to 0.189 min^-1) benefited from mesopores. Reusable potentials of the hierarchical porous carbons were also satisfying. After four thermal regeneration cycles, the materials still occupied 84.8%-87.4% of the original adsorption capacities.

Characterizing Key Volatile Pollutants Emitted from Adhesives by Chemical Compositions, Odor Contributions and Health Risks

As one of the major sources of volatile pollutants in indoor air, gaseous emissions from adhesives during interior decoration have attracted increasing concern. Identifying major volatile pollutants and the risk in adhesive gaseous emissions is of great significance, but remains rarely reported. In the present research, we assessed the major volatile pollutants emitted from white emulsion adhesive and silicone adhesive samples (n = 30) from three aspects: chemical composition, odor and health risk contributions. The results showed that a total of 21 volatile pollutants were detected. Significantly, xylene was the most concentrated compound from white emulsion adhesives, accounting for 45.51% of the total concentrations. Butanone oxime was the most concentrated compound in silicone adhesives, accounting for 69.86% of the total concentrations. The trends in odor concentration (evaluated by the odor activity value method) over time were well correlated with the total chemical concentrations. Xylene (58.00%) and butanone oxime (76.75%) showed the highest odor contribution, respectively. Moreover, from an integrated perspective of chemical emissions, odor and health risk contributions, xylene, ethylbenzene, ethyl acetate and benzene were identified as the key volatile pollutants emitted from the white emulsion adhesives, while butanone oxime, butanone, and ethanol were the key volatile pollutants emitted from the silicone adhesives. This study not only identified the key volatile pollutants but also provided characteristics of odor and health risks of gas emitted from adhesives.

VOCs characteristics and their ozone and SOA formation potentials in autumn and winter at Weinan, China

Frequent ozone and fine particulate matter (PM_2.5) pollution have been occurring in the Guanzhong Plain in China. To effectively control the tropospheric ozone and PM_2.5 pollution, this study performed measurements of 102 VOCs species from Sep.19-25 (autumn) and Nov.27-Dec. 8, 2017 (winter) at Weinan in the central Guanzhong Plain. The total volatile organic compounds (TVOCs) concentrations were 95.8 ± 30.6 ppbv in autumn and 74.4 ± 37.1 ppbv in winter. Alkanes were the most abundant group in both of autumn and winter, accounting for 33.5% and 39.6% of TVOCs concentrations, respectively. The levels of aromatics and oxygenated VOCs were higher in autumn than in winter, mainly due to changes in industrial activities and combustion strength. Photochemical reactivities and ozone formation potentials (OFPs) of VOCs were calculated by applying the OH radical loss rate (L_OH) and maximum incremental reactivity (MIR) method, respectively. Results showed that Alkenes and aromatics were the key VOCs in term ozone formation in Weinan, which together contributed 59.6% ̶ 65.3% to the total L_OH and OFP. Secondary organic aerosol formation potentials (SOAFP) of the measured VOCs were investigated by employing the fractional aerosol coefficient (FAC) method. Aromatics contributed 94.9% and 96.2% to the total SOAFP in autumn and winter, respectively. The regional transport effects on VOCs and ozone formation were investigated by using trajectory analysis and potential source contribution function (PSCF). Results showed that regional anthropogenic sources from industrial cities (Tongchuan, Xi'an city) and biogenic sources from Qinling Mountain influenced VOCs levels and OFP at Weinan. Future studies need to emphasize on meteorological factors and sources that impact on VOCs concentrations in Weinan.