TY - JOUR
T1 - New principals on the adsorption of alkyl compound by Mg–Al oxide
T2 - Adsorption kinetics and equilibrium studies
AU - Kameda, Tomohito
AU - Umetsu, Mami
AU - Kumagai, Shogo
AU - Yoshioka, Toshiaki
N1 - Publisher Copyright:
© 2016 Elsevier B.V.
Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2017/1/5
Y1 - 2017/1/5
N2 - The uptake of ethylsulfate (ES−), hexylsulfate (HS−), and dodecylsulfate (DS−) anions by Mg–Al oxide in aqueous solution was examined through adsorption equilibrium and kinetic modelling. The removal of ES−, HS−, and DS− by Mg–Al oxide proceeded as diffusion-controlled reactions exhibiting Langmuir-type adsorption isotherms. The maximum amounts of adsorption are ordered as DS− > HS− > ES−. Mg–Al oxide preferentially reacts with the organic anion with lower charge density, because the effect of hydrophobic interactions in these cases is stronger than that of electrostatic interactions. In the first stage of reaction, Mg–Al oxide, which is prepared by the thermal decomposition of Mg–Al layered double hydroxides (LDHs) intercalated with CO32− (CO3·Mg–Al LDH), rehydrates and combines with alkylsulfate to reconstruct the LDH structure. Then the alkylsulfate anions intercalated in the interlayer of the LDH attracted other anions in the solution via hydrophobic interactions, thereby promoting their removal by Mg–Al oxide. DS− was removed with the highest efficiency followed by HS−, because the hydrophobic attraction between DS− anions is stronger than that between HS−, which is stronger than that between ES−. At low initial concentrations (C0), the intercalated alkylsulfates are likely oriented parallel to the brucite-like host layers of Mg–Al LDH. With increasing C0, pairs of alkyl chains in DS− and HS− may overlap due to the hydrophobic interaction, while the alkyl chains in DS− are likely arranged perpendicular to the host layers to form bilayers.
AB - The uptake of ethylsulfate (ES−), hexylsulfate (HS−), and dodecylsulfate (DS−) anions by Mg–Al oxide in aqueous solution was examined through adsorption equilibrium and kinetic modelling. The removal of ES−, HS−, and DS− by Mg–Al oxide proceeded as diffusion-controlled reactions exhibiting Langmuir-type adsorption isotherms. The maximum amounts of adsorption are ordered as DS− > HS− > ES−. Mg–Al oxide preferentially reacts with the organic anion with lower charge density, because the effect of hydrophobic interactions in these cases is stronger than that of electrostatic interactions. In the first stage of reaction, Mg–Al oxide, which is prepared by the thermal decomposition of Mg–Al layered double hydroxides (LDHs) intercalated with CO32− (CO3·Mg–Al LDH), rehydrates and combines with alkylsulfate to reconstruct the LDH structure. Then the alkylsulfate anions intercalated in the interlayer of the LDH attracted other anions in the solution via hydrophobic interactions, thereby promoting their removal by Mg–Al oxide. DS− was removed with the highest efficiency followed by HS−, because the hydrophobic attraction between DS− anions is stronger than that between HS−, which is stronger than that between ES−. At low initial concentrations (C0), the intercalated alkylsulfates are likely oriented parallel to the brucite-like host layers of Mg–Al LDH. With increasing C0, pairs of alkyl chains in DS− and HS− may overlap due to the hydrophobic interaction, while the alkyl chains in DS− are likely arranged perpendicular to the host layers to form bilayers.
KW - Adsorption
KW - Alkylsulfate
KW - Equilibrium
KW - Kinetics
KW - Mg–Al oxide
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U2 - 10.1016/j.colsurfa.2016.10.063
DO - 10.1016/j.colsurfa.2016.10.063
M3 - Article
AN - SCOPUS:85002246065
VL - 513
SP - 348
EP - 354
JO - Colloids and Surfaces A: Physicochemical and Engineering Aspects
JF - Colloids and Surfaces A: Physicochemical and Engineering Aspects
SN - 0927-7757
ER -