Separation Science and Technology, Vol.42, No.12, 2751-2766, 2007
Modification of single-walled carbon nanotubes for enhancing isopropyl alcohol vapor adsorption from air streams
Single-walled carbon nanotubes (SWCNTs) were oxidized by HCl, HNO3 and NaClO solutions and were selected as adsorbents to study their characterizations and adsorption properties of isopropyl alcohol (IPA) vapor from air streams. The physicochemical properties of SWCNTs were greatly changed after oxidation by HNO3 and NaClO solutions. These modifications include the increase in surface functional groups and surface basic sites, which enhance the chemisorption capacity of IPA, and the decrease in pore size and the increase in surface area of micropores, which improve the physisorption capacity of IPA. The maximum IPA adsorption capacities of SWCNTs, SWCNTs(HCl), SWCNTs(HNO3) and SWCNTs(NaClO) calculated by Langmuir model are 63.48, 54.34, 72.99, and 103.56 mg/g, respectively. The SWCNTs(NaClO) show the best performance of IPA removal and their adsorption mechanism appears mainly attributable to physical force with a relatively low influent IPA concentration but appears attributable to both physical and chemical forces with a relatively high influent IPA concentration.