Mild microwave-assisted synthesis of aluminum-pillared bentonites

Abstract

Two types of bentonites were modified using a cleaner method to prepare aluminum-pillared clays. This methodology involved a purifying stage, an intercalation process, and a microwave irradiation step at low energy power. Structural changes induced by pillaring process were demonstrated by thermal behavior, as well as morphological characterization. The effect of pillaring process on thermal stability of clays was studied, and the mass lost associated with the dehydroxylation of the octahedral clay sheets was not detected for modified bentonites. In addition, an analysis of their chemical composition and crystalline structure was also performed. Concerning industrial applications of these bentonites, two potential uses were proposed: (1) as reinforcement of different polymers matrices such as thermoplastic starch (TPS), high-density polyethylene (HDPE), and poly (styrene-b-butadiene-b-styrene), SBS; and (2) as removal agent for cadmium (Cd) species present in wastewaters. Bentonite particles reinforced thermoplastic starch matrix and increased ultraviolet barrier capacity of HDPE composites. Besides, bentonites improved the mechanical performance and modified barrier properties of SBS. Regarding effluents purification, an adequate Cd adsorption from aqueous solutions was observed (77%), proving their feasibility to be used as non-conventional removal agents.