steeply to reach a maximum value of around 99% at pH 11. The lower desorption percentage in the pH range of 2-8 can be attributed to the combination of hydrogen bonding and electrostatic forces operating for he interaction of XG with alumina surface in that pH regime. On the other hand,the electrostatic forces of repulsion beyong pH 9,result in the higher percentage desorption in the pH region of 9-11.