Preparation, characterization and physicochemical study of 3-amino propyl trimethoxy silane-modified kaolinite for Pb(II) adsorption

Modification of Indonesian kaolinite with 3-amino propyl trimethoxy silane (APTES) was investigated for use as an adsorbent for the removal of Pb(II) from aqueous solutions. This research aimed to evaluate the effect of the amount of APTES on the surface properties and adsorption capability. Characterization of the materials was conducted by X-ray diffraction, Fourier transform-infrared (FT-IR) analysis, gas sorption analysis and scanning electron microscopy (SEM). In addition, the adsorption kinetics were also studied.The results show that that modification leads to no significant change in the surface profile or crystallinity by the modification, while a higher amount of Pb(II) (from 5 to 140 mg/L) led to an approximately sevenfold increase of adsorption by modified kaolinite compared to raw kaolinite. FTIR analysis suggests the presence of a chemical interaction on the active surface of modified kaolinite. The adsorption obeys pseudo first-order kinetics and was fit to the Dubinin-Radushkevich isotherm model. Keywords: Adsorption, Isotherm, Kaolinite, Surfactan