Hall T, Breysse P, Corn M, Jonas L A
Johns Hopkins University School of Hygiene and Public Health, Baltimore, MD 21205.
Am Ind Hyg Assoc J. 1988 Sep;49(9):461-5. doi: 10.1080/15298668891380079.
A recent trend in occupational safety and health has focused on the use of respiratory protective equipment to supplant engineering controls as the primary means of protecting workers from toxic substances. Respirator adsorbent cartridges have been demonstrated to have a finite capacity to adsorb toxic vapors. The knowledge of when this limit is approached or has been exceeded is crucial to the user. The Wheeler kinetic breakthrough model has been shown to describe accurately organic vapor penetration through beds of activated carbon. The model, however, does not account for competitive adsorption of water vapor or other organic vapors. The investigations reported here demonstrate the effect of adsorbed water vapor on the kinetic adsorption parameters (kinetic rate constant and kinetic saturation capacity) of the Wheeler equation. Adsorbent beds were equilibrated at varying concentrations of water vapor and then challenged with carbon tetrachloride vapor-laden air. Dry carbon had an initial rate constant of 62.5 s-1 and a kinetic adsorption capacity of 0.36 g of adsorbed CCl4/gram (g/g) of adsorbent. These parameters decreased in proportion to the amount of water vapor adsorbed, with the minimum predicted values occurring at 100% relative humidity. The minimum experimental value for the kinetic rate constant was 17.6 s-1, a decrease of 73% from the dry carbon values. The minimum predicted value for the kinetic adsorption capacity was 0.16 g/g, a decrease of 45%.
职业安全与健康领域最近的一个趋势是，将呼吸防护设备作为保护工人免受有毒物质侵害的主要手段，以取代工程控制措施。已证实呼吸器吸附滤筒吸附有毒蒸汽的能力有限。了解何时接近或超过这一限度对使用者至关重要。惠勒动力学穿透模型已被证明能准确描述有机蒸汽透过活性炭床层的情况。然而，该模型没有考虑水蒸气或其他有机蒸汽的竞争性吸附。此处报告的研究表明了吸附的水蒸气对惠勒方程动力学吸附参数（动力学速率常数和动力学饱和容量）的影响。吸附剂床层在不同浓度的水蒸气中进行平衡，然后用载有四氯化碳蒸汽的空气进行冲击。干燥的活性炭初始速率常数为62.5 s-1，动力学吸附容量为0.36克吸附的四氯化碳/克吸附剂（g/g）。这些参数与吸附的水蒸气量成比例下降，在相对湿度为100%时出现预测的最小值。动力学速率常数的最小实验值为17.6 s-1，比干燥活性炭的值下降了73%。动力学吸附容量的最小预测值为0.16 g/g，下降了45%。
