Illite clay modified with hydroxyapatite – innovative perspectives for soil remediation from lead(II)

Abstract

Clay with its properties plays an important role in various processes including those which are related to soil fertility and solution of environmental pollution problems. Clay is a widespread natural resource which can be applied for diverse purposes - from construction material and production of ceramics to medicine and cosmetics. Clay is also studied to seek new approaches for use of raw local resources around the world. In this study, clay was modified by using calcium and sodium chloride, nitric acid (protonation), iron oxyhydroxide and potassium dihydrogen phosphate in different proportions of Ca/P molar ratio. Modified clay was prepared and characterized by X-ray powder diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface measurement analysis and methylene blue spectrophotometric method. Preliminary studies for sorption of lead (II) in spiked solutions as well as leaching tests were performed for soil samples spiked with Pb (II) amended with modified clay. Sorption of Pb (II) on modified clay surface is based mainly on reactions of physical capture on complicately structured surface and ion exchange reactions. Modified illite clay can be seen as perspective soil amendment for immobilization of lead in soil.