Dissolution kinetics of sepiolite from Eskisehir (Turkey) in hydrochloric and nitric acids

Abstract

A B S T R A C T: Dissolution kinetics of sepiolite from Eskisehir (Turkey) have been investigated at various temperatures and particle sizes using dilute hydrochloric and nitric acids. Dissolution reaction rate constants were calculated and apparent activation energies were dependent on acid concentration. For both acids, apparent activation energy values reached a minimum of ~11 kcal/mol at an acid concentration of 0.75 u. For the second-order reaction which is independent of the acid concentration, the activation energy was 14.5 kcal/mol for both acids. The reaction rate constants were proportional to the acid concentrations, and inversely proportional to the square-root of the initial particle radii of the sepiolite.

A New Approach to Compositional Limits for Sepiolite and Palygorskite

“…Samples of sepiolite were prepared by cutting a fragment and coating it with Au. Palygorskite samples were first treated using the dodecylanunonium treatment (Abudelgawad et al, Mid-Atlantic Ridge (Hathaway and Sachs, 1965) Goles, South Serbia (Maksimovic and Radukic, 1961) Little Cottonwood, Utah, USA (Nagy and Bradley, 1955) Kuzuu District, Japan (Imai et al, 1969) Madriat, Sistriere (Caill~re, 1934a) Ampandrandava, Madagascar (Caill~re, 1936) Vasko (Caillbre, 1951) Eski~ehir, Turkey (Cetisli and Gedikbey, 1990) Amboseli, Kenya (Hay and Stoessell, 1984) Tintinara, South Australia (Rogers et al, 1956) Vallecas, Spain (Galfin and Castillo, 1984) Yunclillos, Toledo, Spain (Gal~in and Castillo, 1984) Ballarat, Inyo County, California (Post and Janke, 1984) Itukaichi, Tokyo, Japan (Nagata and Sakae, 1975) Toledo, Spain (L6pez Gonzfilez et al, 1981) Nye County, Nevada (Giiven and Carney, 1979) Vallecas, Spain (Fukushima and Okamoto, 1987) Vallecas, Spain (Gal~in, 1987) Vallecas, Spain (Vicente Rodrfguez et al, 1994) Ninetyeast Ridge, Indian Ocean (Argast, 1989) U.S.S.R. (Teodorovitch, 1961) Ankara, Turkey (Inukai et al, 1994) Southwest Konya, Anatolia, Turkey (Yeniyol, 1986) Vallecas, Spain (Komarneni et al, 1986) Ash Meadows, Nevada (Komarneni et al, 1986) Valdemoro, Spain (He et al, 1996) Vicalvaro, Madrid, Spain (Robertson and Stot, 1974) Amboseli, Kenya (Stoessell and Hay, 1978) Yavapai Country, Arizona, USA (Kauffman, 1943) Karasawa Mine, Japan (Takahashi, 1966) Mullion, Cornwall, England (Midgley, 1964) Yagca formation, Turkey (Yal~in and Bozkaya, 1995) Eski~ehir, Turkey (Yalqin nad Bozkaya, 1995) (2) from …”

Physical and catalytic characterization of smectites from Boa-Vista, Paraíba, Brazil

“…This behaviour is governed by the extent and nature of their external surface, which can be modified by suitable acid and thermal treatments. Acid and thermal treatments increase the catalytic and adsorbent activity of certain clay minerals, but further and stronger treatments decrease this activity [11,[15][16][17][18].…”

Acid Activation of a Ferrous Saponite (Griffithite): Physico-Chemical Characterization and Surface Area of the Products Obtained

“…Numerous papers about acid activation of montmorillonite (the principal silicate in the smectite group), sepiolite (a fibrous magnesic silicate), vermiculite and other silicates can be found in the literature (Lrpez Gonzfilez et al 1981;Mendioroz et al 1987;Cetisli and Gedikbey 1990;Suquet et al 1991;Pesquera et al 1992). However, in spite of the growing interest in the study of saponite, no references to acid activation of this silicate have been found.…”