Effects of environmental conditions on the emission and odor-active compounds from Fraxinus mandshurica Rupr

Comparative analysis of very volatile organic compounds and odors released from decorative medium density fiberboard using gas chromatography-mass spectrometry and olfactory detection

VVOCs with a retention range below C₆ have become one of the main indoor pollutants that negatively affect human health. Most studies have focused on the emission of VOCs from furniture and decorative materials, seldom consider VVOCs. To close this gap, a 15-L environmental chamber, combined with multi-absorbent tube, was used for gas sampling. Emissions of VVOCs and odors released from decorative medium density fiberboard (MDF) were measured using gas chromatography-mass spectrometry and olfactometry detection. The results demonstrated that multi-absorbent tubes had excellent capture capacity for low-molecular-weight VVOCs. Thickness and decorative materials had conspicuous effects on VVOCs and odor emissions. The total VVOCs (TVVOC) from 18-mm decorative MDF was consistently higher than that of 8-mm samples. The major VVOCs from these decorative MDF were alcohols, esters and ketones, which were the major odor contributors with high odor intensity values. VVOCs concentration generally increased as thickness increased, but it decreased after decorative treatment. Fruity and alcohol-like were the main odor impressions of 8-mm MDF, whereas sweet and fruity were the major odor impressions of 8-mm polyvinyl chloride decorative MDF (PVC-MDF) and melamine impregnated paper decorative MDF (MI-MDF). Fruity was the main odor impression of 18-mm decorative MDF. The overall odor intensity increased and the major odor impression may differ when thickness was changed. Both the MI and the PVC decorative materials blocked some odor emissions but did so to a greater extent with the former than with the latter. Identification and analysis of the composition of VVOCs can supplement a database structure network of volatile pollutants and establish a novel and feasible method to investigate low-molecular-weight substances from wooden materials and their products.

Comprehensive evaluation model for health grade of multi-component compound release materials based on fuzzy comprehensive evaluation with grey relational analysis

The selection of materials is a complex and elusive process due to the multiple factors related to health. For the effective selection of materials, a comprehensive model for evaluating the health grade of materials was proposed with the mathematical method of the fuzzy comprehensive evaluation (FCE) and grey relational analysis (GRA). A health evaluation procedure scheme of the AgBB as well as standards of the forestry industry of the People's Republic of China and standards of the health industry of the People's Republic of China were referred to during the process. Based on Qt technology, a computer program was developed to calculate the compound comprehensive evaluation models. The data of Choerospondias axillaris with different lacquers were used as practical examples firstly, and then, the emission and odor characteristics of Xylosma racemosum (Sieb. et Zucc.) Miq. with PU, UV, and waterborne coating were explored with the technology of GC-MS/O. Results showed that: a total of 21 odorants were identified from Xylosma racemosum with PU, UV, and waterborne coating. The health grade of three Xylosma racemosum samples was UV > waterborne > PU, with the health grade of UV coating being "A", and the boards with PU and the waterborne coating were "N", with a fuzzy comprehensive index of P_PU = 0.5151, P_{waterborne coatings=}0.4950. Based on the results, it is proved that the establishment of the comprehensive evaluation model based on FCE and GRA successfully converts qualitative evaluation into quantitative evaluation; in addition, effectively evaluates the health grade of materials. This study provides a better understanding of materials' health grades, which will aid consumers in reducing indoor air pollution and using their products properly.

Research on Very Volatile Organic Compounds and Odors from Veneered Medium Density Fiberboard Coated with Water-Based Lacquers

Very volatile organic compounds (VVOCs) are a group of important odor pollutants affecting indoor air quality that have been shown to be harmful to human health. A 15 L environmental chamber, combined with multi-bed tube was used to collect gases. Fifteen very volatile organic compounds (VVOCs), including 12 odor compounds, were identified from veneered medium density fiberboard coated with water-based lacquer (WB-MDF) using gas chromatography–mass spectrometry/olfactometry (GC-MS/O). The total very volatile organic compound (TVVOC) and total odor intensity (TOI) showed a decreasing trend over time, reaching equilibrium on day 28. TVVOC showed an overall slow-fast-slow emission profile, from day 3 to day 7, with a maximum decay rate of 29.7%. TOI showed the greatest rate of decline from day 1 to day 3, at approximately 12%. Alkane and alcohol VVOCs were the more abundant compounds, accounting for at least 60% and even up to 80% of the total. The major odor impression was fruity, with a highest odor rating of 6.6, followed by sweet, with an odor rating of 6.1. Although the odor impression changed from sweet to fruity over time, it seemed pleasant overall. The odor contributors were mainly alkanes, alcohols, esters, and ethers, which had relatively high odor intensities. The main odor-contributing substances were dichloromethane, ethanol, ethyl acetate, 2-methylacrylic acid methyl ester, and tetrahydrofuran. When WB-MDF is used for furniture or other decorative materials, it is strongly recommended that it be stored under ventilation for at least 28 days and the adoption of substitute solvents of lacquers, modified adhesives, and low-odor wood raw materials is recommended. These possible initiatives would contribute to the aim of building an environmentally friendly indoor environment.