Phenanthrene Sorption on Kaolin-HA, Montmorillonite-HA and Goethite-HA

Abstract: In order to study the interactions between humic acid and soil minerals on the sorption of hydrophobic organic pollutants (HOCs), kaolin, montmorillonite and goethite were selected to be synthesized with HA and the resulted complexes were characterized by FTIR, XRD and DSC for their morphological and structure. The effect of different solution chemistry on phenanthrene sorption on HA and mineral-HA complexes were studied. The results show that the glass transition temperature changed from 64.6℃(HA) to 32.6℃(kaolin-HA), 51.5℃(goethite-HA), 16.5℃ and 77.7℃(montmorillonite-HA), suggesting the change of HA structure. The Koc value of phenanthrene adsorption by mineral-HA complexes were about 50% less than that of HA and the sorption linearity increased. HA and three mineral-HA complexes in Na+ solution showed higher Koc value than that in Ca2+ solution. While, the ionic strength showed different influences in phenanthrene sorption on HA and 3 mineral-HA complexes. Lower pH favored the sorption of phenanthrene on the 3 mineral-HA complexes, and montmorillonite-HA exhibited the greatest sorption affinity for phenanthrene at pH 4. The results of this research could help to elucidate the transport and transformation of HOCs in soils and sediments.