Mechanistic and thermodynamic studies of oxyanion sorption by various synthetic Mg/Al layered double hydroxides
Goh, Kok Hui
Date of Issue2009
School of Materials Science and Engineering
In this study, Mg/Al layered double hydroxides (LDHs) were investigated for their potential in scavenging several harmful oxyanions from aqueous solution. LDHs could effectively remove oxyanions and the selectivity of LDHs was governed by both the valencies and the ionic radii of the oxyanions. LDHs prepared by the fast coprecipitation with hydrothermal treatment (FCHT) method and sol-gel with solvothermal treatment method (SGST) had higher oxyanion (i.e. arsenate) removal efficiency than those prepared by the conventional routes, owing to their lower carbonate content, higher surface area, larger pore volume, larger pore size, and nanocrystalline characteristic. The sorption of arsenate by FCHT-LDH was found primarily due to anion exchange mechanism and might involve a secondary sorption mechanism. The negative DG° for arsenate sorption confirmed the spontaneity of the removal process. The positive values of DH° and DS° provided further evidence of the anion exchange process in the removal mechanism.
DRNTU::Engineering::Materials::Testing of materials
Water science & technology
© 2009 IWA Publishing. This is the author created version of a work that has been peer reviewed and accepted for publication by Water Science & Technology, IWA Publishing. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [http://dx.doi.org/10.2166/wst.2009.072].