The mechanism of anionic polyacrylamide adsorption on the montmorillonite surface in the presence of Cr(VI) ions.

The anionic polyacrylamide AN PAM (with various contents of carboxyl groups) adsorption mechanism on the montmorillonite surface was examined. The effect of hazardous chromium(VI) ions addition was studied. The anionic polyacrylamide is a popular soil flocculant, commonly used to prevent erosion of arable soils. On the other hand, polymeric macromolecules can increase the accumulation of various toxic substances, such as heavy metal ions (among others Cr(VI) ions) in soil minerals. For this purpose the adsorption properties of soil mineral - montmorillonite in relation to mixed system containing AN PAM and Cr(VI) ions was investigated. The impact of solution pH, order of individual adsorbates addition, chromium(VI) ions concentration and anionic groups content in the polymeric macromolecules were determined. The montmorillonite was characterized using the low-temperature nitrogen adsorption/desorption method, XRF, FTIR and SEM techniques. In turn, the adsorption and electrokinetic properties of examined montmorillonite - AN PAM - Cr(VI) systems were examined by means of spectrophotometry, potentiometric titration and microelectrophoresis methods.