Hard-core/zeolitized-shell beads obtained by surface zeolitization of activated clay particles

This work presents a novel and cost-effective procedure that improves the reactivity of kaolinitic clay particles toward generation millimetric hard-core/zeolitized-shell units. The obtained particulate material is ready to use as ion exchanger beads in fixed adsorption bed. Starting from properly activated, millimeter-sized units, transition their external surface towards new crystalline ordering could be induced. Na 2 CO 3 alkaline activation treatment applied previously calcined allowed obtaining different levels NaAlSiO 4 polymorphs on particles, which are easily transformed zeolitic products. By varying synthesis conditions, FAU LTA zeolite structures were successfully hardened reaching conversions close 90%. starting clay, pretreated clays, products after hydrothermal characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive microanalysis (EDX). versatility method exemplified adsorbents specifically designed for retention Cd 2+ Ni contaminating ions. A total removal was achieved at 150 min initial 40 ppm solutions, being 98% 94% 120 solutions cadmium nickel, respectively. • Millimetric clay. Millimeter-sized adsorbent suitable packed-bed columns. High efficiency achieved.