Abstract

DIAZ, Carlos et al. Study of the biosorption of chromium (VI) on crosslinked-quaternary chitosan for their application on the bioremediation of waster waters. Rev. Soc. Quím. Perú [online]. 2013, vol.79, n.4, pp.304-318. ISSN 1810-634X.

In this work, the stoichiometric amounts of the amino-quaternaries and cross-linker were studied to produce the most stable cross-linked quaternary Chitosan (QC2). Preliminary assays were carried out to test the improvement in their mechanical and chemical properties (extreme conditions, surface area and thermogravimetry). Then, the adsorption of chromium (VI) on the QC2 was studied at changing experimental conditions like: pH, adsorbent dose, initial chromium concentration and ionic strength. Moreover, the kinetics of the process was also evaluated as well as the optimization, the desorption of chromium (VI) from the adsorbent for metal recovery and adsorbent recycling. Finally, was characterized by using instrumental techniques such as FTIR, SEM. These tools allowed us to investigate the adsorption mechanism. The calculated parameters indicate a high adsorbent/adsorbato affinity for QC2 with a maximum adsorption capacity of 208 mg g^-1 for Cr (VI), elucidating its potential use for the removal of chromium from aqueous solutions. Also showed a pseudosecond order adsorption kinetics with a velocity constant of 0.289 g.mg^-1.min^-1. Desorption of chromium was efficiently accomplish with a mixture of 1M of NaCl and NaOH, reaching a recovery up to 99.78% of the initial metal concentration at pH 4.5. Finally, high ionic strength shows an effect on the adsorption of chromium (VI) onto the studied adsorbents.

Keywords : Chitosan quaternary; quaternary crosslinked chitosan; chromium VI; adsorption isotherms; biosorption.

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