Microwave-assisted post treatment to make hydrophobic zeolite Beta for aromatics adsorption in aqueous systems

Abstract

Adsorption capacity of zeolitic adsorbents for organic pollutants can be affected severely under humid conditions and/or in aqueous systems. This study presents the development of hydrophobic Beta zeolites using a microwave-assisted post-synthetic treatment method (i.e., microwave-assisted chelation, MWAC) for adsorption removal of organics (benzene and phenol as the models) in aqueous systems. MWAC treatment enabled the dealumination of Beta zeolites in only one minute whilst increasing its hydrophobicity. Based on the characterization data, the mechanism for the hydrophobization of Beta zeolite was proposed. The influence of hydrophobicity, porosity and the property of organic molecules on adsorption behaviours were systematically studied, showing that the most hydrophobic Beta zeolite presented the highest benzene adsorption capacity per surface area of 2.87 × 10−3 mmol/m2 (at 1.0 g/L initial concentration). TGA and multi-cycle regeneration/adsorption experiments were employed to assess the regeneration and reusability of the adsorbents, and the results suggested that the modified Beta zeolites could be regenerated easily with the preserved physiochemical properties and adsorption capacity. The developed method and the associated zeolitic materials could be developed further for making high-performance hydrophobic zeolitic adsorbents for applications in organics removal from aqueous media.