LAUSR

Abstract The objective of this work is to enhance the adsorbing performance of the natural Egyptian phyllosilicate mineral, glauconite (greensand), through surface modification to obtain a particular combination of physical and chemical properties. It was found that Zn removal increased from 84% to 94%, while Pb removal varied from 96.67% to 99% by using 10–25 g/l modified glauconite in a solution having 50 mg/l Zn 2+ and 30 mg/l pb 2+ ions. Adsorption data were investigated using Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherms. Linear regression methods are used to determine adsorption capacities and optimum adsorption isotherms. R 2 value of Langmuir isotherm model for pb 2+ is higher than other models. The maximum monolayer coverage (Q o ) from Langmuir isotherm model was calculated to be 15.363 and 21.654 mg/g and the separation factor indicating a favorable sorption experiment is 0.0324 and 0.13207 for Zn 2+ and Pb 2+ respectively. Also from Freundlich isotherm model, the intensities of adsorption (n) that indicated favorable sorption are 1.3036 and 1.364 for Zn 2+ and Pb 2+ respectively. The heat of sorption process was calculated from Temkin isotherm model to be 6.44101 and 4.1353 J/mol for Zn 2+ and Pb 2+ respectively, that indicated to the physisorption process which B  D