ZEOLITE: ITS NATURAL OCCURRENCE AND APPLICATIONS: A MINI REVIEW Stephen Sunday EMMANUEL* and Ademidun Adeola ADESIBIKAN Department of Industrial Chemistry, University of Ilorin, P. M. B. 1515, Ilorin, Nigeria *Corresponding author:stephenemmanuel6011@gmail.com ABSTRACT This article presents a mini review on various applications of zeolites as a promising low cost microporous material in countless fields. Zeolites are hydrated aluminosilicates with full cross-linked open framework structures made up of corner sharing SiO4 and AlO4 tetrahedra and they belong to the family of microporous solids known as molecular sieves. However, currently, zeolite structure does not necessarily have to be composed of SiO4 and AlO4 tetrahedra, as numerous elements from the periodic table can now be an integral part of zeolite structural framework. Zeolites are formed in nature via volcanic action but can as well be synthesized or manufactured. The use of natural zeolites particularly for environmental applications in various fields has gained long standing interest in the science community because of their significant properties and global occurrence. Therefore, this mini review focus on the occurrence of zeolites and its various application in industries and medical field which will help future researchers to gain insight on next line of putative research avenues in application of zeolites. Keywords: Adsorption, ion exchange, microporous, occurrence, volcanic, zeolites. 1. Introduction Microporous materials are favorable key answer to global concerns and zeolite belong to this microporous solid family which is also known as molecular sieves [1]. The term ‘zeolite’ was firstly mentioned by Swedish mineralogist A. F. Cronstedt in 1756 as a name of an aluminosilicate mineral (stilbite) that seemed to steam when heated. The word zeolite is derived from the Greek word ‘zeo’ (boil) and ‘lithos’ (stone) [1], [2], [3]. Over the years about 50 natural and more than 200 synthetic zeolites have been identified as a separate group of minerals but unfortunately, natural zeolites cannot meet the huge demands in industry particularly in catalysis, therefore, synthetic zeolites are produced in large quantities [4]. The most common type of synthesized zeolites includes zeolites A, X, Y, L, ZSM-5 and the most common natural zeolites that have been identified during the past 20 decades include analcime, chabazite, clinoptilolite, erionite, ferrierite, heulandite, laumontite, mordenite, and phillipsite. They are widely used in industry as ion exchange resins, molecular sieves, sorbents and catalysts. Generally, zeolite contain silicon, aluminium and oxygen in their framework and cations, water and/or other molecules within their pores [4]. According to Bogdan et al., 2009 [1], zeolites are inorganic porous materials having a highly regular structure of pores and chambers that allow molecules to pass through and cause others to be either excluded or broken down. Their framework is crystalline and three dimensional networks of tetrahedra silica or alumina anions strongly bonded at all corners [1]. The general empirical formula of a zeolite can be represented as: Mx/n [(AlO2) x (SiO2) y] •wH2O [4], [5]. Where 'M' represents the exchangeable cations, commonly from the group I or II ions, although other metals, non- metals and organic cations may also balance the negative charge created by the presence of Al in the structure. ‘n’ is the valence of the cation M, w is the number of water molecules per unit cell, x and y are the total number of tetrahedral atoms per unit cell. The y/x ratio (Si/Al ratio) usually ranges from 1 to 5 or 10 to 100 for high silica zeolites [ 2], [4], [5].