Removal of multiple-metals from contaminated clay minerals.
Clay minerals spiked with multi-component metal ions (Cu(+2), Cd(+2), Pb(+2)) were decontaminated using different soil washing solutions. The desorption characteristics were determined by batch acid leaching with various acids. Removal of Cu(2+), Cd(+2) and Pb(+2) ions from variable charge minerals (e.g. kaolinite) required much less effort than their removal from constant-charge minerals (e.g. illite). The surface charge of a clay mineral had an important influence. When the numbers of H+ and Na+ ions available in the soil were increased by adding a buffer solution such as NaOAc-HOAc, heavy metals adsorbed on the clay surface transferred to the pore fluid. When more H+ or Na+ ions were available in the pore fluid, more Cu(+2), Cd(+2) and Pb(+2) ions were released into the equilibrium solution. Decreasing the pH led to more removal of heavy metal ions from kaolinite. The presence of Na+ ions facilitated the removal of heavy metals from contaminated illite. The selectivity for desorption was in the order Cu(+2) > Cd(+2) > Pb(+2) for all washing solutions investigated.
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Department of Civil Engineering, The University of British Columbia, 2010-6250 Applied Science Lane, Vancouver, British Columbia, Canada V6T 1Z4.
D000042:Absorption; D000538:Aluminum Silicates / Q000737:chemistry; D002104:Cadmium / Q000737:chemistry; D000077215:Clay; D003300:Copper / Q000737:chemistry; D006801:Humans; D007220:Industrial Waste; D007854:Lead / Q000737:chemistry; D019216:Metals, Heavy / Q000737:chemistry*; D008906:Mining; D012989:Soil Pollutants / Q000737:chemistry*
D000538:Aluminum Silicates; D007220:Industrial Waste; D019216:Metals, Heavy; D012989:Soil Pollutants; D002104:Cadmium; D007854:Lead; D003300:Copper; D000077215:Clay