Younjin Park

Removal of Co, Sr and Cs from aqueous solution using self-assembled monolayers on mesoporous supports

Sorptive removal of Co, Sr and Cs from aqueous solution by SAMMS was investigated. The single-solute sorption data were well fitted by the Freundlich, Langmuir and Dubinin-Radushkevich models (R2>0.95). The maximum sorption capacities (qmL) of the Langmuir model were in the order of Cs (1.14 mmol/g)>Co (0.20 mmol/g)≈Sr (0.195 mmol/g). The bi-solute competitive sorption of the metals was analyzed by the Langmuir, competitive Langmuir, modified extended Langmuir and P-factor models. The sorption of one metal was suppressed by the presence of competing metals. Sorptions of Co and Sr were strongly dependent on the initial solution pH but that of Cs was not. The calculated thermodynamic parameters such as ΔH0, ΔS0 and ΔG0 showed that sorption of Co onto SAMMS was endothermic, whereas those of Sr and Cs were exothermic. The negative ΔG0 values indicated all the sorption processes were spontaneous in nature.

Functionalized carbon nanotubes reinforced polymer electrolyte membranes prepared by a surfactant-assisted method for fuel cell applications

Functionalized carbon nanotubes (CNTs)/Nafion® nanocomposite membranes prepared by a surfactant-assisted method have been presented for fuel cell applications. 1 wt.% sulfonated CNTs (s-CNTs) and 1 wt.% oxidized CNTs (ox-CNTs) were reinforced into Nafion® membrane by adding 0.3 wt.% surfactant such as Cetyltrimethylammonium bromide (CTDMA), sodium dodecylbenzenesulfonate (SDBS), sodium 4-octylbenzoylsulfonate (SOBS) and hexadecyltrimethylammonium (HDTMA) in a solution casting procedure. The prepared s-CNTs or ox-CNTs reinforced Nafion® nanocomposites produced lower methanol uptake values than that of cast Nafion® while ion exchange capacity was maintained. Furthermore thermal property of the nanocomposites was enhanced.