Abstract
Paper sludge ash was converted into a zeolitic product with high cation exchange capacity (CEC) through acid leaching. The raw ash was treated with 1 M HCl, 1 M HNO3 and 1 M CH3COOH solutions. Ca and Mg were more easily extracted from the ash than Si and Al, and the Ca extractions using HCl and HNO3 were higher than that from CH3COOH. Element extractions and leachant pH in the HCl and HNO3 solutions were similar and steady state was achieved after 2 hours of leaching. A zeolitic product was synthesized from the 2-hour 1 M HCl ash leach by reaction of the residue with 2.5 M NaOH solution (80°C, 24 hours). Zeolite-A was synthesized from leached ash, and the CEC of the zeolite produced from leached ash (130 cmol/kg) was higher that that from raw ash (40 cmol/kg), and similar to that obtained when leaching ash for 24 hours.
