Author: Li, L.Y.

Source: Environmental Technology, Volume 27, Number 7, July 2006 , pp. 811-822(12)

Publisher: Taylor and Francis Ltd

Abstract:

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.

Keywords: CLAY MINERALS; DESORPTION; HEAVY METALS; SODIUM ION; ACID LEACH

Document Type: Research article

Publication date: 2006-07-01

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