Sorption of heavy metals from gold mining wastewater using chitosan

• This study is concerned with the use of chitosan produced from shrimp shell waste for the removal of Cu(II), Hg(II), Pb(II) and Zn(II) from gold ore tailing solutions containing cyanide. This work involved the study of equilibrium and kinetic adsorption, the physicochemical characterization of mining effluents and desorption using different regenerating solutions. The experimental results showed that the adsorption capacity of chitosan is a function of the solution pH and that the optimum pH for these metallic ions is 6, except for Hg (pH 4). The equilibrium data were described using the Langmuir, Freundlich, Redlich-Peterson and SIPS isotherm models. The Langmuir equation was used to find the maximum adsorption capacity for Cu (79.94 mg/g), Hg (109.55 mg/g), Pb (58.71 mg)g) and Zn (47.15 mg/g). To determine the rate-controlling mechanism for metallic ion adsorption, pseudo-first-order, pseudo-second-order and the Elovich equation kinetic models were tested with experimental adsorption kinetic data. Tests conducted with gold ore tailing solutions indicated that chitosan is effective to remove these metallic ions above 70%. Desorption studies revealed that the regeneration of chitosan saturated with these metallic ions depends on the type and concentration of the regenerating solution ((NH(4))(2)SO(4), H(2)SO(4), HCl, NaOH and NaCl).

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Kemiteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Chemical Engineering (hsv//eng)

Nyckelord

Adsorption equilibrium

Adsorption kinetics

Desorption

Heavy metal

Mining effluents

Shrimp shells

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