Copper sorption on chitin and acid-washed shrimp shells from Palinurus elephas: isotherm and kinetic studies

Abstract

The removal of toxic heavy metals species from aqueous solutions is the concern of this paper which investigates the sorption kinetics and equilibriums in the uptake of copper(II) by low-cost chitinous adsorbents prepared from Algerian shrimp (Palinurus elephas) shell waste. Acid-washed shrimp shells and chitin biosorbents resulted from the bulk treatment of the waste with 1.2 M HCl and 1 M NaOH that aims to the demineralization and the deproteinization of raw biomass. Elements analysis experiments showed that such treatments led to a significant increase in nitrogen content in the biomaterial. In fact, this finding proved that nitrogen chemical moieties (amine and acetamide) are likely the key parameters in copper(II)-binding phenomena. Maximum adsorption yields at pH 4 were found to be 16 mg g−1 for acid-washed shrimp shells and 24 mg g−1 for chitin but many times more with chitosan (about 150 mg g−1). Besides, kinetic measurements of copper(II) sorption onto the various biomaterials were fitted properly to the pseudo-second-order model and the Langmuir equation applied to the isotherms modeling.