LAUSR

Zeolites are widely recognised as effective adsorbents for the removal of organic pollutants from aqueous sources. However, their intrinsic powder form makes their application restricted by the arduous filtration-recovery process and their decreased activity due to aggregation. Herein, we report the organic structure directing agent (OSDA) free and binder-free preparation of ZSM-5@silica beads for organic pollutant sequestration exemplified by the aniline removal. All silica beads were prepared by employing ion exchange resin beads as a macro-template and further used to prepare a ZSM-5@silica composite. First, anion exchange resin beads were charged with silica by ion exchange. Second, the anion exchange resin was eliminated by high temperature combustion leaving behind an all-silica replica. The all-silica replica was partially transformed into ZSM-5 by hydrothermal treatment. ZSM-5 was synthesized from the OSDA-free system, thus avoiding high temperature calcination of the composite. The effect of the crystallization temperature (120, 150, and 170 °C) on the formation of ZSM-5 was studied. The physicochemical properties of the obtained beads were determined using different characterization methods such as powder X-ray diffraction (XRD), scanning-electron microscopy (SEM), N2 adsorption–desorption isotherms, and thermogravimetry (TG). The ZSM-5@silica composite demonstrated a remarkable capacity, outpacing most silica-based adsorbents and modified zeolitic materials, re-usability and retained spherical shape. The binder-free zeolite shaping technology offers a green and straightforward method for preparing zeolite-based adsorbents for the removal of organic pollutants from waste water.