A quantitative property‐property relationship for the internal diffusion coefficients of organic compounds in solid materials

Indoor releases of organic chemicals encapsulated in solid materials are major contributors to human exposures and are directly related to the internal diffusion coefficient in solid materials. Existing correlations to estimate the diffusion coefficient are only valid for a limited number of chemical‐material combinations. This paper develops and evaluates a quantitative property‐property relationship (QPPR) to predict diffusion coefficients for a wide range of organic chemicals and materials. We first compiled a training dataset of 1103 measured diffusion coefficients for 158 chemicals in 32 consolidated material types. Following a detailed analysis of the temperature influence, we developed a multiple linear regression model to predict diffusion coefficients as a function of chemical molecular weight (MW), temperature, and material type (adjusted R² of .93). The internal validations showed the model to be robust, stable and not a result of chance correlation. The external validation against two separate prediction datasets demonstrated the model has good predicting ability within its applicability domain (>.8), namely MW between 30 and 1178 g/mol and temperature between 4 and 180°C. By covering a much wider range of organic chemicals and materials, this QPPR facilitates high‐throughput estimates of human exposures for chemicals encapsulated in solid materials.     

In‐vessel composting under air pressure of organic fraction of municipal solid waste in Azemmour,Morocco

This study aims to evaluate the performance of laboratory‐scale in‐vessel composting bioreactor for the Organic Fraction of Municipal Solid Waste treatment in Azemmour, Morocco. The bioreactor was specially designed and used for this study, and it was operated semicontinuously under 0.6 bar pressure. The evaluations studied included the operational indices, the compost maturity indices and the quality of the final compost. Obtained results showed that organic fraction of municipal solid waste could be composted successfully in 12 days. Moreover, high CO₂ generations involve high temperature and high internal air pressure change, revealing vigorous microbial activity. The final compost was satisfactory for its agricultural application.     

合成材料运动场地面层中挥发性有机化合物和二硫化碳释放量的同时测定方法

建立热脱附-气相色谱-质谱法同时测定合成材料运动场地面层中挥发性有机化合物和二硫化碳释放量的方法。采用三合一吸附管,DB-5MS UI柱作为色谱柱,对热脱附解吸条件,程序升温等参数进行优化。研究表明：本实验中挥发性有机化合物分离良好,间(对)二甲苯在(0.2～2.0)μg浓度范围内线性良好,其它8种物质在(0.1～1.0)μg浓度范围内线性良好,R²均大于0.99,检出限均小于0.01[mg/(m²·h)],满足GB 36246-2018标准的要求。本方法方便高效,结果准确可靠。     

Predicting the importance of oxidative aging on indoor organic aerosol concentrations using the two‐dimensional volatility basis set (2D‐VBS)

Organic aerosol (OA) is chemically dynamic, continuously evolving by oxidative chemistry, for instance, via hydroxyl radical (OH) reactions. Studies have explored this evolution (so‐called OA aging) in the atmosphere, but none have investigated it indoors. Aging organic molecules in both particle and gas‐phases undergo changes in oxygen content and volatility, which may ultimately either enhance or reduce the condensed‐phase OA concentration (C_OA). This work models OH‐induced aging using the two‐dimensional volatility basis set (2D‐VBS) within an indoor model and explores its significance on C_OA relative to prior modeling methodologies which neglect aging transformations. Lagrangian, time‐averaged, and transient indoor simulations were conducted. The time‐averaged simulations included a Monte Carlo procedure and sensitivity analysis, using input distributions typical of U.S. residences. Results demonstrate that indoors, aging generally leads to C_OA augmentation. The extent to which this is significant is conditional upon several factors, most notably temperature, OH exposure, and OA mass loading. Time‐averaged C_OA was affected minimally in typical residences (<5% increase). However, some plausible cases may cause stronger C_OA enhancements, such as in a sunlit room where photolysis facilitates significant OH production (~20% increase), or during a transient OH‐producing cleaning event (~35% peak increase).