Relative metal ion sorption on natural and engineered sorbents: Batch and column studies

The sorptive capacity of four sorbent materials (hydroxy-apatite, clinoptilolite, an organoclay, and an organoclay/anthracite blend) was determined for five metals: Cd, Cr, Cu, Ni, and Zn, by performing column and batch sorption isotherm tests. Hydroxy-apatite exhibited the largest sorption capacity for all materials tested, followed by clinoptilolite, the organoclay, and the organoclay/anthracite blend. In general, the increase in sorptive capacity for all materials was related to an increase in measured surface area. Although the organoclay and organoclay/anthracite blend had a lower sorptive capacity than the other materials tested, they show promise as sorbents for mixed effluent streams consisting of both organic contaminants and low levels of heavy metals.