title: Displacement effect of NOM on atrazine adsorption by PACs with different pore size distributions.
abstract: 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.
authors: Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana 61801, USA.
authors: Qilin
authors: Q
authors: Li
authors: Vernon L
authors: VL
authors: Snoeyink
authors: Carlos
authors: C
authors: Campos
authors: Benito J
authors: BJ
authors: Mariñas
mesh_terms: D000327:Adsorption; D001280:Atrazine / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D006540:Herbicides / Q000737:chemistry*; D008962:Models, Theoretical; D009930:Organic Chemicals; D014874:Water Pollutants, Chemical; D018508:Water Purification
chemical_list: D006540:Herbicides; D009930:Organic Chemicals; D014874:Water Pollutants, Chemical; D002244:Carbon; D001280:Atrazine