Adsorption of Heavy Metals in Contaminated Water Using Zeolite Derived from Agro-Wastes and Clays: A Review

Table 4

Summary of SEM analysis of zeolites.

Zeolite	Raw material	Synthesis method	Observations	References
FAU-type zeolite	Coal fly ash	Alkaline fusion + hydrothermal treatment	High water content and longer ageing time resulted to better defined zeolite	[209]
K-ZFA Zeolite	Coal fly ash	Hydrothermal alkaline treatment	The material showed low degree agglomeration	[210]
Zeolite A	Natural Sudanese montmorillonite clay	Alkali fusion	Uniform particle morphology.; Small particle size in the range 3.72–8.61 μm	[211]
Magnetic NaA Zeolite	Natural kaolin	Hydrothermal treatment	Crystals with the same cubic morphology and almost same diameter (2 μm)	[71]
Cancrinite	Natural Tunisian clay	High pressure hydrothermal treatment	Symmetric hexagonal needlelike shapes	[212]