Department of Civil and Environmental Engineering, Hanyang University, 222 Wangsimni-Ro, Seoul 04763, Republic of Korea.
Department of Civil and Environmental Engineering, Hanyang University, 222 Wangsimni-Ro, Seoul 04763, Republic of Korea.
Environ Res. 2019 Jan;168:96-108. doi: 10.1016/j.envres.2018.09.019. Epub 2018 Sep 17.
To effectively remove gaseous pollutants from air using sorbents, a thorough knowledge of the actual sorption performance is needed at ambient conditions rather than at unrealistically high-pressure conditions, as is commonly presented in the literature. To this end, the sorbent capacities of gaseous benzene were evaluated at a constant sorbent bed inlet pressure (50 ppm or ~5 Pa) in 1 atm of N, room temperature (298 K), a fixed flow rate (50 mL min), and equal outlet sampling intervals (5 min). The benzene adsorption patterns were investigated against six sorbent types in a total of 17 different forms: 1- zeolite in five forms: beads (ZB), ground to 212 µm (ZG212), beads ground to 300 µm (ZG300), coarsely ground/washed zeolite (ZWc), and coarsely ground/washed/thermally treated zeolite (ZTc), 2- activated carbon in two forms: 212 µm (ACd212) and granular (ACdg), 3- Carbopack-X (CX), 4- Tenax TA (TA), 5- used black tea leaves of 150 or 300 µm in three forms: dry (TD150/TD300), wet (TW150/TW300), and wet dust (TWd), and 6- used ground coffee in either dry (CD) or wet forms (CW). Accordingly, the largest adsorption capacities at 5 Pa (e.g., >10 mg g) were observed for ACd212 (79.1) and ACdg (73.6). Moderate values (e.g., 5 < < 10 mg g) were obtained for ZG212 (7.98), CX (6.79), ZG300 (5.70), and ZB (5.58), while the remainder were far lower at < 5 mg g (e.g., tea leaves, ground coffee, TA, ZWc, and ZTc). The experimental benzene capacities of the tested sorbents were further assessed by the Langmuir, Henry's law, Freundlich, Dubinin-Radushkevich, and Elovich isotherm models. The linearized Langmuir adsorption isotherms of ACd212, ACdg, and CX showed the presence of more than one adsorption site (i.e., retrograde at the lowest pressures and two others at higher pressures). However, TA, zeolite, tea leaves, and ground coffee exhibited a type-V isotherm, wherein the sorption capacity continued to increase with loaded volume (i.e., multilayer adsorption). Thus, ACd212 has the best figure-of-merit based on a high 10% breakthrough volume (BTV) and low cost for real-world applications.
为了在环境条件下（而不是文献中常见的不切实际的高压条件下）有效地从空气中去除气态污染物，需要对实际的吸附性能有深入的了解。为此，在 1 个大气压的 N2、室温（298 K）、固定的流速（50 mL min）和相等的出口采样间隔（5 min）下，评估了气态苯在恒定的吸附剂床入口压力（50 ppm 或~5 Pa）下对六种吸附剂的吸附容量。研究了六种吸附剂在 17 种不同形式下的苯吸附模式：1-沸石有五种形式：珠粒（ZB）、研磨至 212 µm（ZG212）、研磨至 300 µm（ZG300）、粗研磨/洗涤沸石（ZWc）和粗研磨/洗涤/热处理沸石（ZTc），2-活性炭有两种形式：212 µm（ACd212）和颗粒状（ACdg），3- Carbopack-X（CX），4- Tenax TA（TA），5- 150 或 300 µm 的用过的红茶有三种形式：干（TD150/TD300）、湿（TW150/TW300）和湿尘（TWd），6- 干（CD）或湿（CW）形式的用过的研磨咖啡。因此，在 5 Pa 时（例如，>10 mg g）观察到最大吸附容量的是 ACd212（79.1）和 ACdg（73.6）。ZG212（7.98）、CX（6.79）、ZG300（5.70）和 ZB（5.58）的吸附容量适中（例如，5 < < 10 mg g），而其余的吸附容量较低（<5 mg g）（例如，茶叶、研磨咖啡、TA、ZWc 和 ZTc）。通过 Langmuir、亨利定律、Freundlich、Dubinin-Radushkevich 和 Elovich 等温模型进一步评估了测试吸附剂的实验苯吸附容量。ACd212、ACdg 和 CX 的线性化 Langmuir 吸附等温线表明存在不止一个吸附位（即在最低压力下出现反演，在较高压力下出现另外两个吸附位）。然而，TA、沸石、茶叶和研磨咖啡表现出类型-V 等温线，其中吸附容量随着负载体积的增加而继续增加（即多层吸附）。因此，ACd212 具有基于高 10%突破体积（BTV）和低成本的最佳性价比，适用于实际应用。
