Modification of smectite structure by sulfuric acid and characteristics of the modified smectite

Abstract

Bentonite samples from Petrovac and Aleksinac were treated with sulfuric acid of different molarities. Differences in structure and texture of the initial and modified bentonite were determined by chemical analysis and Xraypowder diffraction (XRPD), infra-red spectroscopy (FTIR), scanning electron microscopy (SEM) and physisorption nitrogen at −196°C. Sulfuric acid caused an exchange of Al3+, Fe3+ and Mg2+ with H+ ions which led to a modification of the smectite crystalline structure. The Mg and Fe substitution in the octahedral sheet promoted the dispersion of those layers and forming of amorphous silicon. The sequence according to which the cations left the octahedral sheets was as follows: Mg2+>Fe3+>Al3+. The sulfuric acid activated bentonites exhibiting a lower cation exchange capacity (CEC) and а change of specific surface area (SBET) from 6 to 387 for bentonite from Petrovac and from 44 to 1784 m2 g-1 for bentonite from Aleksinac, positioning them as an excellent absorber in wine technology and in the protection of soil and environment

Effect of acid activation of Saudi local clay mineral on removal properties of basic blue 41 from an aqueous solution

“…These observations were in good agreement with those reported in the literature (Kooli et al, 2009;Tomić et al, 2011), and it was due to the partial dissolution layers of clay mineral during the activation process.…”

Experimental Study of Montmorillonite Structure and Transformation of its Properties under the Treatment of Inorganic Acid Solutions

“…Such a decrease of CEC under the treatment with inorganic acid solutions (e.g, HCl and H2SO4) was described by other researchers [33]. Cation exchange capacity of bentonite clays is connected not only with montmorillonite content, but also with the particularities of its structure.…”

“…A lot of attention in the works devoted to the acid treatment of natural bentonite clay was paid to the issues of activation -improving the properties of modified clays in comparison with natural clays [33,34,35]. An increase of specific surface area and pore volume is observed in the course of conducted experiments (Table 1).…”

Experimental Study of Montmorillonite Structure and Transformation of Its Properties under Treatment with Inorganic Acid Solutions

“…Such a decrease of CEC under the treatment with inorganic acid solutions (e.g., HCl and H 2 SO 4 ) was described by other researchers [12]. Cation exchange capacity of bentonite clays is connected not only to montmorillonite content but primarily, to such structural particularities as layer charge and its distribution among octahedral sheets.…”

“…The most aggressive environment for bentonite clays is acid solutions. A number of processes take place under acid treatment and lead to a significant transformation of the structure and properties of montmorillonite bentonite clays [11][12][13][14]. A significant increase in the specific surface of the acid-modified clays promotes wide use of such material for removal of heavy metals, radionuclides and for oil refining [15][16][17][18][19].…”