Li Qilin, Snoeyink Vernon L, Campos Carlos, Mariñas Benito J
Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana 61801, USA.
Environ Sci Technol. 2002 Apr 1;36(7):1510-5. doi: 10.1021/es010870w.
This study investigated displacement of atrazine by the strongly competing fraction of natural organic matter (NOM) in batch and continuous-flow powdered activated carbon/PAC) adsorption systems. Due to the displacement effect, atrazine adsorption capacity in a continuous flow PAC/microfiltration (MF) system, where the carbon retention time is greater than the hydraulic retention time, decreased with time or NOM throughput. The capacity was lower than that measured in a batch reactor or predicted by the equivalent background compound-ideal adsorbed solution theory (EBC-IAST) method. A mathematical model previously developed to simulate the adsorption process in the PAC/MF system was modified to take into account the displacement effect. Two types of PACs were tested using a range of influent atrazine concentrations and carbon doses. The extent of atrazine displacement by NOM was found to depend on the type of PAC, while the rate of displacement was a function of PAC type as well as carbon dose. The PAC lost its adsorption capacity for atrazine faster at a lower carbon dose. PAC B, which has a higher percentage of mesopores, lost more atrazine adsorption capacity but at a slower rate than PAC A.
本研究在间歇式和连续流粉末活性炭（PAC）吸附系统中，考察了天然有机物（NOM）的强竞争组分对阿特拉津的置换作用。由于置换效应，在炭停留时间大于水力停留时间的连续流PAC/微滤（MF）系统中，阿特拉津的吸附容量随时间或NOM通量的增加而降低。该容量低于在间歇式反应器中测得的值，也低于用等效背景化合物-理想吸附溶液理论（EBC-IAST）方法预测的值。对先前开发的用于模拟PAC/MF系统中吸附过程的数学模型进行了修正，以考虑置换效应。使用一系列进水阿特拉津浓度和炭剂量对两种类型的PAC进行了测试。发现NOM对阿特拉津的置换程度取决于PAC的类型，而置换速率则是PAC类型和炭剂量的函数。在较低的炭剂量下，PAC对阿特拉津的吸附容量丧失得更快。具有较高比例中孔的PAC B，其阿特拉津吸附容量损失更多，但速率比PAC A慢。
