Preparation and application of 4-amino-4'-nitro azobenzene modified chitosan as a selective adsorbent for the determination of Au

Crosslinked chitosan was modified with 4-amino-4'-nitroazobenzene and characterized by FT-IR and SEM. The adsorption of Au(III) and Pd(II) was optimum at pH 3.0 for Au(III) and at pH 2.0 for Pd(II), where maximum mass adsorption were 69.93 mg g.sup.-1 and 58.58 mg g.sup.-1, respectively. The adsorption isotherms obey the Langmuir equation in case of Au(III), and the Freundlich and Langmuir equations in case of Pd(II). The adsorption kinetics follows a pseudo-second-order model. This new adsorbent shows high affinity for Au(III) and Pd(II), while the adsorption is negligible for K, Na and Ca and no adsorption of several other metal ions occurs. The method was successfully applied to the determination and separation of Au(III) and Pd(II) in aqueous samples and ore.