Authors: Fengrong Zhang Na Du Haiping Li Shue Song Wanguo Hou
Publish Date: 2015/04/14
Volume: 293, Issue: 7, Pages: 1961-1969
Abstract
In this study the sorption of hexavalent chromium CrVI on a Mg6AlFelayered double hydroxide LDH and its calcined product layered double oxide LDO in aqueous solutions was investigated using a batch technique at various sorbent dosages C s A significant sorbent effect C seffect was observed in the sorption systems the sorption isotherms declined as C s increased The Langmuir and Freundlich isotherms can describe the sorption equilibriums at each given C s well but cannot describe the C seffect observed These C seffect data can be described by the surface component activity SCA model namely the LangmuirSCA and FreundlichSCA isotherms The C seffect in the LDO system is stronger than that in the LDH system which can be attributed to the higher specific surface area of the LDO than that of the LDH Furthermore the characteristic saturation sorption capacity of the LDO for CrVI which was obtained from the SCA model is higher than that of the LDH indicating that LDOs are more effective sorbents than LDHs are for heavy metal removal In addition the influences of pH and electrolyte NaNO3 concentration C NaNO3 on the C seffect were examined no significant effects were observed upon changing either the solution pH 5–9 or C NaNO3 0001–0100 mol/L This work improves our understanding of the C seffect phenomenon and confirms the applicability of the SCA model in describing sorption equilibriums with the C seffect
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