Competitive adsorption of copper and lead ions on an iron-coated sand from water

Iron oxides are good adsorbents for some metal ions. However, the adsorbent properties of these oxides are not fully exploited in water or wastewater operations because of difficulties associated with their separation from the aqueous phase. An oven process with agitators for applying an iron oxide coating onto the sand surface to utilize the adsorbent properties of the coating and filtration properties of the sand media was developed. The competitive adsorption of iron-coated sand for copper and lead ions from water was investigated by batch and column experiments. Among the two metal ions studied, the coated sand has greater affinity for the removal of lead ions compared to copper ions at a concentration of 5×0-5M, 1×10-4M and an interval of pH=2.5∼6.5. Adsorption behaviors of copper and lead ions at the iron oxide/water interface could be proved to form chemisorption through the SEM/EDAX analysis. From the column experiment results, both copper and lead ions could be removed simultaneously by the iron-coated sand in a continuous treatment unit.