Abstract
The review emphasizes on synthesis, characterization, and application of zeolite. Zeolite is a hydrated aluminosilicate having a tetrahedral structural framework; it contains channels and cages which are occupied by exchangeable active metal ions and water molecules. Zeolite was synthesized through different synthesis methods, particularly, hydrothermal and green synthesis methods. The review also has tried to address the structure of zeolite such as morphology, functional group, and particle size using different characterization methods as reported via different authors. The characterization results verify that zeolite shows many unique properties such as uniform pore size, acidic properties, thermal stability, mobile extra cation, hydrophilicity, and hydrophobicity. These lead to a number of applications in catalysis, water purification, adsorption, and agriculture.
Highlights
Zeolites are hydrated aluminosilicate that is made from tetrahedral alumina (AlO45-) and silica (SiO44-) through interlinkage of oxygen atoms [1, 2]. e term zeolite is derived from Greek words “Zeo” and Lithos” [3,4,5] which means boil and stone, respectively; zeolites have high ability of absorbing water and releasing it when they get heated [4]. ey have an open void with 3D crystal structure having aluminum, silicon, and oxygen coordination with active metals [5]
Each oxygen ion within Si-O and Al-O bonds connects with two cations and which are shared between two tetrahedron structures [6, 8]. is results in the tetravalent electroneutral Si in SiO4/2 and the trivalent negatively charged Al in AlO4/2 [9]. e negative charge and the pores of zeolites can be occupied by group IA or IIA metal ions and water molecule as it is denoted via the general formula, Mx/n {(Al2O)x (SiO2)y.zH2O} [10,11,12], where M represents an alkali or alkaline Earth cation, n represents the valence of the cation, z is the number of water molecules per unit cell, and x and y are the total numbers of tetrahedral per a unit cell
Nyankson et al [12] reported Zn (II) supported zeolite as the Zn-zeolite framework that generates a secondary pore; the secondary pore results larger surface area and has the ability to removal dyes, heavy metals, pesticides, and other pollutants from water [13, 29]. erefore, this review explores the synthesis, characterization, and applications of zeolite [13, 22, 29]
Summary
Zeolites are hydrated aluminosilicate that is made from tetrahedral alumina (AlO45-) and silica (SiO44-) through interlinkage of oxygen atoms [1, 2]. e term zeolite is derived from Greek words “Zeo” and Lithos” [3,4,5] which means boil and stone, respectively; zeolites have high ability of absorbing water and releasing it when they get heated [4]. ey have an open void with 3D crystal structure having aluminum, silicon, and oxygen coordination with active metals [5]. E other familiar zeolite is Zeolite A, which is synthesized from sodium aluminosilicate usually referred as zeolite NaA or zeolite 4A, represented by the formula Na12 (AlO2)12(SiO2)12·27H2O [14, 17] It is the type of synthetic zeolite that is used in detergent production for treatment of hard water. The cost comparison of obtaining a silica and alumina source from a chemical feedstock and kaolin/metakaolin has been carried out, and the result shows that zeolite A synthesized from clay has a comparative cost advantage of 15% over a commercial chemical such as sodium silicate [1, 3, 15]. Hydrothermal synthesis method of zeolite consists of two stages: the initial stage, formation of hydrated aluminosilicate gel, and the crystallization stage [4, 12]. Deng et al [17] synthesized zeolite
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