Removal of Zinc Ions from Acid Aqueous Solutions and Acid Mine Drainage Using Zeolite-Bearing Tuff

Zeolite-bearing tuff (stilbite) was shown to be an effective and efficient adsorbent for treating acid mine drainage (AMD). We tested the adsorption of zinc ions from a synthetic acid aqueous solution and AMD from the Sasa mine. The concentration of zinc ions in the AMD decreased from 2.219 to 0.564 mg/dm 3 (74% removal). The solution pH, prior to treatment with the zeolite-bearing tuff, was 3.90, and following treatment, it was 5.36. The physical and chemical properties of the tuff were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. The concentrations of dissolved metal ions before and after treatment was determined by AES—ICP. The tuff’s maximum capacity was determined in equilibrium studies. Experimental data were fitted to adsorption models; the best fit was obtained with the Freundlich adsorption isotherm.