Chromium(VI) and lead(II) accumulation at the montmorillonite/aqueous solution interface in the presence of polyacrylamide containing quaternary amine groups

Nowadays, due to increasing environment pollution, the amount of heavy metals in soil becomes higher and higher. The introduced metals are usually toxic and harmful for plants and animals. Taking this fact into account, in this paper it was checked if common clay mineral – montmorillonite, modified by soil flocculant (cationic polyacrylamide, CT PAM) can immobilize chromium(VI) and lead(II) ions and thus decreases their bioavailability. The adsorbed amounts of polymer, ions and polymer/ions on the montmorillonite surface were measured spectrophotometrically. The electrical double layer structure formed around montmorillonite particles without and with heavy metal ions/polymer was also determined. The obtained results indicate that cationic polyacrylamide captures both lead and chromium ions and increases their adsorbed amount on the montmorillonite surface. Thus, the cationic flocculant usage may enhance the heavy metal immobilization.