Synthesis of coal-analcime composite from coal gangue and its adsorption performance on heavy metal ions.

An innovative adsorbent, "coal-analcime composite", was converted from coal gangue directly, that combined the adsorption effect of analcime and residual coal in coal gangue. The gangue was added silicon and alkali source, composite was synthesized under saturated steam pressure of 1 Mpa(187 °C) for 3 h. Moreover, the products generation mechanism and property have been explored by XRD, FTIR, Ar adsorption measurement. The characterization results showed that residual coal was modified after the hydrothermal alkali activation process, higher specific surface area and more extensive pore size distribution were obtained compared with pure analcime. Modified coal loaded on the surface of analcime enhanced the adsorption capacity of analcime, adsorption experiments showed that the chemo-adsorption occurred between heavy metal ions and composite, the maximum Pb exchange capacity reached as high as 268 mg/g.