Ni(II)-CITRATE COMPLEX SORPTION ONTO CHITOSAN

摘要

The use of metal complexes in industry complicates metal recovery by commonly used means, i.e. precipitation in the form of insoluble compounds and sorption on natural and synthetic sorbents. Investigation of Ni(II)-citrate and Cu(II)-EDTA complexes sorption of widely used in electronics industry and printed circuit board industry on chitosan has shown that is possible to remove both metal ions and ligands from solution. During the sorption the prevailing accumulation of ligands takes place. The sorption of heavy metal ions depends on the amounts of sorbed ligands. The higher is the amount of sorbed ligand the less is the amount of sorbed metal ions in heavy metal ion complex solution. The heavy metal sorption from complex solution proceeds according to Freundlich isotherm equation and pseudo-second order rate model indicating a complicated sorption process. The sorption capacity depends on pH and metal and ligand concentrations in solutions. Ni(II)-citrate can be desorbed in acidic solutions. The use of electrolysis enables to deposit nickel on the cathode, to destroy citrate on the anode and thus to regenerate chitosan.