Effect of Acid Treatment and Alkali Treatment on Nanopore Properties of Selected Minerals

Abstract

Bentonite, biotite, illite, kaolin, muscovite, vermiculite and zeolite were acidified or alkalized with HCl orNaOH of concentrations 0.0, 0.1, 1.0 and 5.0 mole dm−3 at room temperature for 2 weeks and converted into Ca homoionic forms. Low-temperature nitrogen and room-temperature water-vapor adsorption-desorption isotherms were used to characterize the mineral pores of radii between 1 and 30 nm. Nanopore volumes, size distributions, average radii and fractal dimensions were calculated. Values calculated from the nitrogen isotherms differed from those derived from water-vapor data. With an increase of the acid-treatment concentration, the pore volumes measured using both adsorption techniques increased markedly for all minerals. The pore radii measured from nitrogen isotherms appeared to decrease for all minerals except zeolite, while the pore radius calculated from water-vapor data increased in most cases. The fractal dimension measured from water vapor isotherms decreased in all cases indicating smoothing of the mineral surfaces and decrease in pore complexity. No well defined trends in any of the pore parameters listed above were noted under alkaline treatment. In the reaction of each mineral with acid and alkali treatments, the individual character of the mineral and the presence of impurities seems important.

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

“…During the acid treatment, many changes occurred in the aluminosilicate structure due to dissolution of structural ions and the rearrangement of the structure (Korichi et al, 2009). The acid treatment firstly rendered the surface of clay mineral acidic, then it leached metal ions from the clay mineral lattice leading to an increase of the external surface area of the clay mineral and introduces permanent mesoporosity (Jozefaciuk and Sarzynska, 2006). The extent of these changes depended on different parameters such as the geographical origin of the clay mineral, the type of the used acid, its concentrations, temperature and time of acid activation (Noyan et al, 2007;Amari et al, 2010;Komadel and Madejová, 2013;Kooli and Liu, 2013).…”

“…The adsorption properties depended in many factors, among them the specific surface area, and many studies have related the increase or the decrease of adsorption capacity to the surface areas of the adsorbent materials (Yang et al, 2008). The specific surface area of clay mineral could be enhanced by different methods, such as pillaring process (Kloprogge et al, 2005), acid activation (Jozefaciuk and Sarzynska, 2006).…”

Effect of structure and acidity of acid modified clay materials on synthesis of octahydro-2H-chromen-4-ol from vanillin and isopulegol

“…1) 10.0, d (002) 5.0 Å), and a possible 7% illite-smectite mixed-layered mineral (IS MLM) with d (001) 11.0 Å, were detected. Acid activation of kaolin by 0.5 mol/dm 3 HCl leads to the complete disappearance of calcite and IS MLM reflections, indicating the dissolution of these minerals.…”

“…1) [8][9][10]. The strong bands in the region of 1000-1120 cm −1 can characterize Si-O stretching in untreated kaolinite.…”

Surface Chemistry and Porosity of Natural and Activated Aluminosilicate from Montmorillonite and Clinoptilolite

“…Physicochemical and surface properties of clay minerals are determined by their porous structure and different active sites on the surface such as exchangeable cations, coordinatively unsaturated ions Al , acid/basic hydroxyl groups and oxygen anions [8,9]. In order to produce tailor-made catalysts and sorbents, montmorillonite-and clinoptilolite-containing clays are activated by various methods of treatment, such as thermal treatment [10], ion exchange [11,12], treatment with acids [13,14] and alkalis [15,16]. Currently, montmorillonite minerals are often modified in such processes as grafting [17], silylation [18] or intercalation [19,20] due to their capability to swell.…”