Abstract
The present study was carried out on the effect of acid leaching on the modification and structure alteration of montmorillonite. A nanostructured, activated material was prepared by selective leaching of pure smectite clay with different concentrations of sulfuric acid (1 - 10 N/L) at 85°C for 120 min using a solid/liquid ratio of 1:20 and a reflux system. The Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-Ray diffraction (XRD) techniques were used for the characterization and study of the acid-treated montmorillonite clay. Chemical structure of specimens was distinguished by FTIR. The results showed that the formation of Si-OH bonds and leaching of Al3+ ions increased progressively with severity of the acid treatment. As the FTIR studies indicated, acid treatment led to the removal of the octahedral Al3+ cations and an increase in the Si-OH bonds. The morphological alteration of the untreated and treated montmorillonite was investigated by using TEM and SEM. X-ray fluorescence (XRF) analysis revealed a considerable decrease in the relative content of Al by increasing the acid strength. Moreover, the XRD results showed that the treatment using highly concentrated acid resulted in the formation of an amorphous silica phase.
Highlights
Montmorillonite is one of the clay materials widely used for a large number of applications
One type of the clay from the smectite family is the montmorillonite (MMT) which was found for the first time at montmorillon in France and formed of very soft phillosilicates with a monoclinic crystal system [1]
The Fourier transform infrared (FTIR) spectrum confirmed that the original structure of the montmorillonite was not fully destroyed, and the Si tetrahedral layers of the clay were only affected at a high acid concentration
Summary
Montmorillonite is one of the clay materials widely used for a large number of applications. This abundant (plentiful) raw material is highly valued for its reactive and sorptive properties, which depend strongly on its large surface area and its tendency to adsorb molecules at interlayer sites. MMT is derived from weathering of volcanic ash like other types of smectites It is a 2:1 clay meaning that has two silica tetrahedral sheets and a central alumina octahedral sheet between them. We can improve specific surface area, pore volume, acidity, activated sites and adsorption capacity, exchangeable ion capacity, and other applicable characteristic of the clay materials [4,5,6,7,8,9].
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