Influence of hydrophilicity on adsorption of caffeine onto montmorillonite

Abstract

Some types of montmorillonite containing different interlayer ions were prepared and the changes in the interlayer spacings, the hydrophilicity, and the characteristics of adsorption of caffeine in solution were observed. Ion exchange treatments were performed using Li, Na, K, Rb, Cs, Mg, Ca, Sr, or Ba. As a result, Li-and Na-type montmorillonite showed larger interlayer distance (1.31-1.53 nm), than K, Rb, and Cs-type montmorillonite (1.23-1.26 nm). In the measurement of hydrophilicity using a pulse NMR-based particle interface analyzer, Li-and Na-type montmorillonite showed higher hydrophilicity. In addition, K Lang , which indicates the interaction with caffeine, was 0.25-0.32 l/mmol, which is lower than K-, Rb-, and Cs-type montmorillonite (1.14-1.60 l/mmol). It is possible that adsorption of water molecules inhibits caffeine from adsorbing. Because of the difficulty of exchange between caffeine and water molecules in interlayer of the Li-and Na-type montmorillonite, the interaction with caffeine decreased. Alternatively, another possibility is that when highly hydrophilic montmorillonite retains many water molecules, the caffeine adsorption sites are blocked by water molecules. In either case, hydrophilicity has a large influence on the adsorption of caffeine onto montmorillonite.

Caffeine removal using Elaeis guineensis activated carbon: adsorption and RSM studies

“…It is present in beverages such as coffee, teas, chocolates, and soft drinks. The metabolism of this substance is rapid where only a small amount (1-10%) is excreted (Thorn et al 2012;Portinho et al 2017;Beltrame et al 2018;Ptaszkowska-Koniarz et al 2018;Yamamoto et al 2018;González et al 2019). Many pharmaceutical compounds, such as caffeine, are considered water contaminants and classified as emerging pollutants.…”

A Review of Caffeine Adsorption Studies onto Various Types of Adsorbents

“…It is also possible to change the naturally hydrophilic character of smectite clay minerals into organophilic, making them act as adsorbents for organic compounds. e intercalation of surfactant cations (quaternary ammonium salts) into layers of clay minerals not only changes the surface properties but also increases the interlamellar distance (basal spacing) of the layers, thus easing the adsorption of organic molecules [42,59,[127][128][129][130][131]. Bentonite (a montmorillonite) and saponite are the most frequently used clays as caffeine adsorbents.…”

“…Regarding aluminosilicates (Table 9), smectite minerals-such as montmorillonite and saponite and their modifications, organoclays, or thermally treated smectites-show a good caffeine adsorption capacity (99.0-143.7 mg/g), with the advantage of being abundant and low-cost materials [22,43,130,131]. Although aluminosilicates have a low SSA in comparison with activated carbons, sepiolite and bentonite have a good adsorption capacity for caffeine.…”

Caffeine vehiculation into alpha-zirconium phosphate: a multifunctional intercalation product and its application for modified topical release

“…The water molecules are located in the zeolitic cavities of the interlayer region 21 . In the past, several authors have reported that caffeine can be successfully intercalated in lamellar solids reaching interesting goals [22][23][24][25][26][27]28 . Herein we report the first intercalation of CAF on ZrP, obtaining an intercalation product that has been successfully used to prepare a stable emulsion.…”