Abstract
In this study, palygorskite clay calcinated at different temperatures from 200 to 900 °C was used as adsorbent to remove
phosphate from aqueous solutions. The crystal structure and the surface property of the thermally modified material was
investigated to determinate the relationship between the adsorption capacity of the adsorbent and the changes of the crystal
structure and surface property. The results indicate that palygorskite clay calcinated at 700 °C had the highest adsorption
capacity. Complete dehydroxylation destroyed the crystal structure and Al coordination was changed from octahedral to
tetrahedral and further to a small amount of penta-coordination. The thermally modified adsorbent material was amorphous. All
these structure changes enhanced the activity of Al and phosphate adsorption.