Adsorption of Cr(VI) on cross-linked chitosan beads

A possibility of Cr(VI) removal by the adsorption method is discussed in the paper. An adsorbent were hydrogel chitosan beads are produced by the phase inversion method (by changing pH). The possibility of removing Cr(VI) ions by both pure chitosan hydrogel and its chelate compounds (chitosan cross-linked with Cu(II) and Ag(I) ions) was investigated. The adsorption proceeded from the solutions of potassium dichromate and ammonium dichromate (NH4)(2)Cr2O7 and K2Cr2O7 . The process rates and adsorption isotherms were determined and described by relevant equations. The process rate was described by the pseudo- and second-order equations, and adsorption equilibria by the Langmuir equations. A slight advantageous change in adsorption properties of chitosan beads was revealed after cross-linking (for chromium concentration up to 10 g/dm(3)). A maximum adsorption was 1.1 g(Cr)/g chitosan. Results of the studies show that chitosan hydrogel proves useful in the removal of Cr(VI) ions, additionally, cross-linking with Cu(II) and Ag(I) ions has an advantageous effect in the case of low-concentrated solutions.