title: Static and dynamic removal of aquatic natural organic matter by carbon nanotubes.
abstract: Carbon nanotubes (CNTs) were investigated for their capability and mechanisms to simultaneously remove colloidal natural organic matter (NOM) and humic substances from natural surface water. Static removal testing was conducted via adsorption experiments while dynamic removal was evaluated by layering CNTs onto substrate membranes and filtering natural water through the CNT-layered membranes. Analyses of treated water samples showed that removal of humic substances occurred via adsorption under both static and dynamic conditions. Removal of colloidal NOM occurred at a moderate level of 36-66% in static conditions, independent of the specific surface area (SSA) of CNTs. Dynamic removal of colloidal NOM increased from approximately 15% with the unmodified membrane to 80-100% with the CNT-modified membranes. Depth filtration played an important role in colloidal NOM removal. A comparison of the static and dynamic removal of humic substances showed that equilibrium static removal was higher than dynamic (p < 0.01), but there was also a significant linear relationship between static and dynamic removal (p < 0.05). Accounting for contact time of CNTs with NOM during filtration, it appeared that CNT mat structure was an important determinant of removal efficiencies for colloidal NOM and humic substances during CNT membrane filtration.
authors.affiliation: Center for Water and Health, Johns Hopkins University, Baltimore, MD 21205, USA.
authors.forename: Gaurav S
authors.initials: GS
authors.lastname: Ajmani
authors.affiliation: SD Center, KOLON Water & Energy Co., LTD., Seocho-3dong, Seocho-gu, Seoul 137-870, South Korea.
authors.forename: Hyun-Hee
authors.initials: HH
authors.lastname: Cho
authors.affiliation: Center for Water and Health, Johns Hopkins University, Baltimore, MD 21205, USA.
authors.forename: Talia E
authors.initials: TE
authors.lastname: Abbott Chalew
authors.affiliation: Center for Water and Health, Johns Hopkins University, Baltimore, MD 21205, USA.
authors.forename: Kellogg J
authors.initials: KJ
authors.lastname: Schwab
authors.affiliation: Center for Water and Health, Johns Hopkins University, Baltimore, MD 21205, USA; MWH, Lovettsville, VA 20180, USA.
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Jacangelo
authors.affiliation: Center for Water and Health, Johns Hopkins University, Baltimore, MD 21205, USA; State Joint Key Laboratory of Environmental Simulation and Pollution Control, School of Environment, Beijing Normal University, Beijing 100875, China. Electronic address: huanghaiou@bnu.edu.cn.
authors.forename: Haiou
authors.initials: H
authors.lastname: Huang
mesh_terms: D000327:Adsorption; D005374:Filtration / Q000295:instrumentation / Q000379:methods; D006812:Humic Substances; D037742:Nanotubes, Carbon; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D006812:Humic Substances; D037742:Nanotubes, Carbon; D014874:Water Pollutants, Chemical; D014867:Water
keywords: Carbon nanotube; Drinking water; Membrane filtration; Natural organic matter; Static adsorption