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Separation and purification of carbon nanotubes using froth flotation with three sequential pretreatment steps of catalyst oxidation, catalyst removal, and silica dissolution
Author(s) -
Lertrojanachusit Nattapong,
Pornsunthorntawee Orathai,
Kitiyanan Boonyarach,
Chavadej Jittipan,
Chavadej Sumaeth
Publication year - 2013
Publication title -
asia‐pacific journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.348
H-Index - 35
eISSN - 1932-2143
pISSN - 1932-2135
DOI - 10.1002/apj.1727
Subject(s) - dissolution , catalysis , chemistry , carbon nanotube , pulmonary surfactant , carbon fibers , inorganic chemistry , chemical engineering , nuclear chemistry , organic chemistry , materials science , biochemistry , composite number , engineering , composite material
Carbon nanotubes (CNTs) with a carbon content of 3% were synthesized via the disproportionation of CO over a CoMo/SiO 2 catalyst. The proposed purification technique consisted of four sequential steps: oxidative treatment, acid leaching, silica dissolution, and froth flotation. The as‐synthesized CNTs were oxidized at 250 °C before being treated with a 5‐ m HCl solution at 80 °C and a sonication time of 6 h, resulting in a catalyst removal of 90% and an increase in carbon content to 4%. For the silica dissolution, the CNTs were treated with a 0.5‐ m NaOH solution at 70 °C and a sonication time of 12 h, leading to a silica removal of 70% and an increase in carbon content to 35%. The froth flotation technique was employed to separate the CNTs from the remaining silica using two types of surfactants: linear ethoxylated alcohol with an average degree of polymerization of 7 and a linear alkyl chain of 12–14 carbon number (Surfonic L24‐7) and sodium dodecyl benzene sulfonate (SDBS). The separation performance was maximized at a Surfonic L24‐7‐to‐SDBS molar ratio of 1 : 12 with a total surfactant concentration of 230 mg/L, yielding a carbon content of 76%. © 2013 Curtin University of Technology and John Wiley & Sons, Ltd.