Decaying leaves have been proven capable of partially removing lead from polluted water. Several factors affecting the removal process have been studied. These include the concentration of lead ions, concentration of leaves, drying leaves, degree of crushing of leaves, leaf extracts, pH, agitation and presence of competing and of complexing agents. The relative capability of some common types of leaves for the removal of lead from water has been studied.
The release of lead from leaves saturated with lead ions has been studied under the effect of varying pH, addition of competing ions and the addition of complexing agents.
The results of the present work indicate that the interaction between lead ions and leaves is mainly an adsorption process and fit the Freundlich adsorption isotherm whose parameters have also been calculated. A fractional order of reaction (0.7) has been determined for the reaction between lead ions and leaves using two methods of evaluation. A mechanism in which film diffusion being the most probable limiting step has been suggested.
Journal of Environmental Science and Health, Part A, Volume 29, Issue 10 December 1994 , pages 2087 - 2114