Effect of Acid Treatment on the Physicochemical Characteristics and Sorption Capacity of a Natural Zeolite

Abstract

Mining is a very important industry for the development of emerging economies; however, it generates a large number of environmental externalities such as acid mine drainages; these have acid pH values and high heavy metal content. Although there are several methods for the elimination of metals in different solutions, they require a large economic investment. Recently, the use of adsorbent materials for the removal of heavy metals in acid drains such as agricultural by-products and natural zeolites has been developed as a cheaper alternative. In spite of the environmental benefits of using natural zeolites as adsorbent, one of the disadvantages is dealumination, which to a great extent could depend on the geological origin of the mineral that shapes some of its characteristics. This study characterized chemical and physical properties of natural and modified zeolites using various techniques, such as X-ray diffraction (XRD), N2 adsorption- desorption, inductively coupled plasma − optical emission spectroscopy (ICP-OES), and SEM-EDS to determine the effect of an acid treatment on the physical and chemical characteristics of a natural zeolite, correlating these with their sorption capacity. When giving acid treatment to a zeolite there are no significant changes in the crystal structure, the Si/Al ratio indicates a dealumination of the structure but with minimal changes, the surface area and density of the micropores increased considerably. A significant increase in the capacity of copper adsorption was registered. According to XRD, no significant changes occur to the structures.

Keywords: Dealumination; aluminosilicates; AMD; acid treatment; metal removal.

DOI: 10.7176/JEES/10-9-05

Publication date:September 30^th 2020