Evaluation of the sorption properties of a Mexican clinoptilolite-rich tuff for iron, manganese and iron-manganese systems

In the present work a Mexican clinoptilolite-rich tuff was characterized, modified in its sodium form, and its sorption properties for the removal of iron and manganese from aqueous solutions were determined. The removal behavior of iron and manganese by the zeolitic material was performed in batch system. Clinoptilolite, heulandite, mordenite and quartz were found as the main components of the zeolitic material, the specific surface area for the sodium modified zeolitic material was higher than for the unmodified material. The maximum iron and manganese removal was found at initial pH value of 6.0. Iron was higher removed from the aqueous solutions than manganese by the sodium modified zeolitic material in single systems, in binary systems iron and manganese compete for the active sites of the zeolitic material, decreasing the removal of both metals. Sodium, calcium, potassium and magnesium were determined in the different zeolitic tuffs and it was found that mainly the ion exchange mechanism is responsible for manganese removal and precipitation for iron removal at pH 6.0. The kinetic results were best adjusted to the pseudo-second order model equation and the isotherms to the Freundlich isotherm model. Sodium modified zeolitic tuff removed more manganese and iron from aqueous solution than the unmodified material. These results showed that the Mexican clinoptilolite rich tuff in its sodium form could be used efficiently for the removal of iron and manganese from aqueous solutions in single and binary systems. (C) 2008 Elsevier Inc. All rights reserved.