Goethite is one of the most important heavy metal host minerals. Root exudates are the active organic component in rhizosphere. The effect of root exudates on adsorption behavior of heavy metals on soil or minerals is still little known. The present study showed that adsorption of Cd2+was inhibited in the presence of Helianthus annuus. Adsorption capacity of Cd2+to goethite increased with increasing of the initial solution pH. Root exudates reduced Cd2+adsorption capacity at all experimental pH. Both the Langmuir and the Freundlich isotherms represented well the experimental data and the pseudo-second order equation described well the kinetic data. Isothermal and kinetic studies showed that root exudates inhibited adsorption strength and adsorption rate. Adsorption of Cd2+on goethite is a endothermic process whereas the spontaneity of the reaction was reduced in the presence of root exudates.
HUANG Cheng-Ling, ZHANG Dao-yong, PAN Xiang-Liang
. Effects of Root Exudates from Helianthus annuus on Adsorption of Ca2+ on Goethite[J]. SCIENTIA GEOGRAPHICA SINICA, 2009
, 29(3)
: 455
-460
.
DOI: 10.13249/j.cnki.sgs.2009.03.455
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