Adsorption and Desorption of Bt protein (Cry 1Ab) on Clay Minerals and Amorphous Aluminosilicates

Studies on adsorption and desorption of Bt protein (Cry 1Ab) were carried out with clay minerals saturated with Zn, Cu and Co and also on synthetic amorphous aluminosilicates with different Si/Al molar ratios. Bt-protein adsorption was higher in montmorillonites; clays saturated with zinc and amorphous aluminosilicates with Si/Al=0 compared to others. The Langmuir adsorption isotherm fitted well in almost all the cases while the Freundlich isotherm failed to explain the fitness in some of the samples. Montmorillonites showed highest bonding energy and adsorption maxima and lowest free energy suggesting that the adsorption reaction was fast and spontaneous. With respect to desorption (10.0–31.6% in different reacting surfaces) of adsorbed Bt-protein, highest desorption was seen in from clay minerals saturated with Co and amorphous aluminosilicates with Si/Al ratio=2 compared to rest of the reacting surfaces.