THE EFFECTS OF NATURAL ZEOLITE ON TAILING REMEDIATION
When concentrations of pollutants exceed a certain level and present a threat to the environment or human health, remediation action are necessary (Misaelides, 2011). This process consists of two approaches: the extraction of pollutants from soil and water as well as the reduction of their mobility (Misaelides, 2011). While several products have been utilized for these purposes, the use of zeolite is a low-cost solution that provides a high sorption capacity with the ability to adjust the pH of soil and water systems. The application of natural zeolites to remediation processes is based on their ion exchange properties.
A study by Motsi et al. (2009) studied the adsorption behavior of natural zeolite to determine its applicability in treating acid mine drainage containing lead, copper, zinc and magnesium. Researchers examined the rate of adsorption and the uptake at equilibrium in single and multi-component solutions. The results showed rapid uptake during the first 40 minutes, corresponding to an 80 percent total removal (Motsi et al., 2009). Following this initial uptake, the rate of absorption decreased. However, the overall results demonstrated that natural zeolite has significant potential as an alternative, low cost material in the treatment of acid mine drainage (Motsi et al., 2009).
Cui et al. (2006) explored a novel process for high-capacity remediation of acid rock drainage. The results indicated that using clinoptilolite in a slurry bubble column approached equilibrium after 30 minutes. Also, the adsorption of metal ions occurred within 10 minutes. The researchers found that smaller particles of clinoptilolite showed significantly higher capacity and rates of adsorption than larger particles. Finally, the adsorption of clinoptilolite particles differed for various metal ions, with a normalized order of iron, aluminum, copper, zinc, magnesium, and manganese.
Li et al. (2007) examined clinoptilolite’s adsorptive capacity for aluminum, copper, iron, and zinc ions based on equilibrium tests using acid rock drainage. The results indicated that clinoptilolite adsorbed the four metals within 30 minutes. It also removed 64% of copper, 82% of iron, and 89% of aluminum. The researchers also found that clinoptilolite treated at a pH 1-5 for 144 hours showed minimal changes in its overall structure and remained stable. The results point to zeolite’s potential as a heavy metal adsorbent.