Modeling description and spectroscopic evidence of surface acid–base properties of natural illites

Sensitivity of the acid–base properties of clays to the methods of preparation and measurement

“…After acid treatment, the PZNPC (see Section 3.3 for the definition) ranged between 4 and 5, and after subsequent washing they were shifted toward pH 8. The complete purification procedure is mostly used by authors who intent to study the properties of the clay mineral, whereas other authors investigate the raw material or nonhomoionized material [38][39][40].…”

“…The reference titration curve can also be modeled using the speciation constants of the dissolved species [39]. However, this method does not take into account the variation of the amount of dissolved species according to the pH.…”

“…Quantification of this contribution from the pH and the amounts of released elements is theoretically possible by using the corresponding thermodynamic constants. Such an approach was followed by Liu [39] and Lu and Smith [40] by introducing the interactions between soluble Al 3+ and H 4 SiO 4 in the model calculations. However, in the general case, the above aspects are only rarely taken into account in the acid-base studies on clays, despite the variety aqueous monomeric, polymeric, and combined species that may be formed during titration.…”

Surface binding site analysis of Ca2+-homoionized clay–humic acid complexes

“…The morphology of the illite crystal and the complexity of its surface suggest a number of surface reactive sites, including weakly acidic basal planes and amphoteric silanol and aluminol sites on the edge surface [16][17][18][19]. For the most part, however, because of the clay structural complexity and the limited ability of current surface complexation models (SCMs), and optimization routines such those included, for example, in the FITEQL Ò code [20], to predict the number of reactive sites, two binding sites have been assumed on clay mineral surfaces [16,17,21,22]. In order to better understand the nature of metal and organic matter complexation to clays, not only the number of available sites, but their most accurate apparent pK a values and concentrations must be first defined.…”

Illite-supported nanoscale zero-valent iron for removal of 238U from aqueous solution: characterization, reactivity and mechanism

“…As shown in Fig. 2a, the main peaks at 2h of 8.91°, 20.94°and 26.72°are the characteristic diffraction peaks for natural illite [39]. The other peaks marked by Q are impurities corresponding to quartz.…”