Adsorption of anionic surfactant sodium dodecyl sulfate onto alpha alumina with small surface area

Adsorption of sodium dodecyl sulfate (SDS) onto large α-alumina beads was systematically analyzed as functions of pH and NaCl concentration. The maximum adsorption density of SDS onto α-Al 2 O 3 increases with decreasing pH due to the increase in equilibrium surface charge. Adsorption isotherms at d...

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Bibliographic Details
Published in:Colloid and polymer science 2015-01, Vol.293 (1), p.217-227
Main Authors: Pham, Tien Duc, Kobayashi, Motoyoshi, Adachi, Yasuhisa
Format: Article
Language:English
Subjects:
Adsorption
Beads
Characterization and Evaluation of Materials
Chemistry
Chemistry and Materials Science
Complex Fluids and Microfluidics
Density
Food Science
Isotherms
Mathematical models
Nanotechnology and Microengineering
Original Contribution
Physical Chemistry
Polymer Sciences
Sodium dodecyl sulfate
Soft and Granular Matter
Strength
Surface chemistry
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Summary:Adsorption of sodium dodecyl sulfate (SDS) onto large α-alumina beads was systematically analyzed as functions of pH and NaCl concentration. The maximum adsorption density of SDS onto α-Al 2 O 3 increases with decreasing pH due to the increase in equilibrium surface charge. Adsorption isotherms at different salt concentrations demonstrated a common intersection point (CIP) corresponding to charge neutralization. The obtained comprehensive data clarified the applicability of two-step adsorption and four-region models to describe the adsorption isotherms of SDS onto α-Al 2 O 3 beads. Also, proton adsorption isotherms upon SDS uptake onto α-Al 2 O 3 can be fitted by two-step adsorption model with almost the same parameters of surfactant adsorption for 0.001 and 0.01 M NaCl. Our finding indicates that proton adsorption takes place onto the adsorbed SDS. After passing through CIP, proton adsorption onto α-Al 2 O 3 increases at low ionic strength while the amount of proton adsorption does not change for 0.1 M NaCl. Adsorption amount of proton as a function of SDS adsorption shows that only hemimicelles are plausible for case of low ionic strength. The increase in the proton adsorption is not significant at high ionic strength, suggesting the presence of admicelles on the surface of α-Al 2 O 3 beads.
ISSN:0303-402X
1435-1536
DOI:10.1007/s00396-014-3409-3