Organic Exfoliation of Hydrophilic Bentonite using Aliquat 336 and Isobutyl(Trimethoxy)Silane to Enhance its Activity Toward pH-Dependent Adsorption of Epigallocatechin Gallate

The most potent and significant polyphenolic molecule from tea catechins is epigallocatechin gallate (EGCG); it has potential anti-cancer and anti-inflammatory properties. Methods are needed to mitigate its presence in the environment and protect humans from exposure. The objective of the present study was to investigate a functionalized, low-cost clay mineral as an adsorbent for the tea polyphenol EGCG. Hydrophilic bentonite (Bn) was functionalized using Aliquat 336 (A336) and isobutyl(trimethoxy)silane (IBTS). The degree of clay functionalization depended on the extent of introduction of alkyl linkages between the superimposed clay layers. Results revealed that Aliquat 336 functionalized clay (A336-Bn) exhibited maximum thermal stability at 500°C and it is a promising adsorbent for ECGC with a maximum adsorption capacity of 196.26 mg/g at equilibrium. Experimental data were analyzed using pseudo-first order and pseudo-second order models. Adsorption isotherms were interpreted from the Freundlich adsorption isotherm.