Abaie Elham, Kumar Manish, Garza-Rubalcava Uriel, Rao Balaji, Sun Yilang, Shen Yuexiao, Reible Danny
Department of Civil, Environmental and Construction Engineering, Texas Tech University, Lubbock, TX 79409, United States.
Department of Chemical Engineering, Texas Tech University, Lubbock, TX 79409, United States.
Environ Adv. 2024 Jul;16. doi: 10.1016/j.envadv.2024.100520. Epub 2024 Mar 15.
Chlorinated volatile organic compounds (CVOCs) are often found in combination with 1,4-dioxane which has been used as a solvent stabilizer. It would be desirable to separate these compounds since biodegradation of 1,4-dioxane follows an aerobic pathway while anaerobic conditions are needed for biodegrading CVOCs. Conventional adsorbents such as activated carbon (AC) and carbonaceous resins have high adsorption capacities for 1,4-dioxane and CVOCs but lack selectivity, limiting their use for separation (Liu et al., 2019). In the current work, two macrocyclic adsorbents, β-CD-TFN and Res-TFN, were examined for selective adsorption of chlorinated ethenes in the presence of 1,4-dioxane. Both adsorbents exhibited rapid adsorption of the CVOCs and minimal adsorption of 1,4-dioxane. Res-TFN had a higher adsorption capacity for CVOCs than β-CD-TFN (measured linear partition coefficient, K 2140 -9750 L⋅kg versus 192-918 L⋅kg for 1,1, DCE, cis-1,2-DCE and TCE, respectively) and was highly selective for CVOCs(TCE K ~117 K for 1,4-dioxane). By comparison, TCE and 1,4-dioxane adsorption on AC was approximately equal at 100 µg⋅L and approximately 1/3 of the adsorption of TCE on the Res-TFN. The greater adsorption and selectivity of Res-TFN suggest that it can be used as a selective adsorbent to separate CVOCs from 1,4-dioxane to allow separate biodegradation.
氯化挥发性有机化合物（CVOCs）常常与曾用作溶剂稳定剂的1,4 - 二氧六环同时存在。分离这些化合物是很有必要的，因为1,4 - 二氧六环的生物降解遵循好氧途径，而CVOCs的生物降解则需要厌氧条件。传统吸附剂如活性炭（AC）和碳质树脂对1,4 - 二氧六环和CVOCs具有高吸附容量，但缺乏选择性，这限制了它们用于分离的用途（Liu等人，2019年）。在当前工作中，研究了两种大环吸附剂β - CD - TFN和Res - TFN在1,4 - 二氧六环存在下对氯乙烯的选择性吸附。两种吸附剂对CVOCs都表现出快速吸附，而对1,4 - 二氧六环的吸附极少。Res - TFN对CVOCs的吸附容量高于β - CD - TFN（测得的线性分配系数，对于1,1 - 二氯乙烯、顺式 - 1,2 - 二氯乙烯和三氯乙烯，分别为2140 - 9750 L·kg对192 - 918 L·kg），并且对CVOCs具有高度选择性（三氯乙烯对1,4 - 二氧六环的K约为117）。相比之下，在100 µg·L时，三氯乙烯和1,4 - 二氧六环在AC上的吸附大致相等，且三氯乙烯在Res - TFN上的吸附约为其在AC上吸附的1/3。Res - TFN更大的吸附量和选择性表明它可作为选择性吸附剂用于从1,4 - 二氧六环中分离CVOCs，以实现分别进行生物降解。
