Sorption characteristics of aqueous copper onto residue generated in ammoniacal leaching of manganese nodules

Abstract

The present paper reports the studies on copper removal from its aqueous solution using residue generated in the process of reduction roast- ammonia leaching of manganese nodules. The leached residue was washed with water to remove the entrapped liquor containing metals from leaching operation, dried and used for adsorption of aqueous Cu(II) under varying experimental conditions. The particle size analyses of manganese nodule residue (wMNR) showed very fine particles with mean diameters (d50) of 17.8 µm. The BET surface area of wMNR was found to be 66.7 m2g-1. Adsorption studies of copper aqueous solution by batch equilibrium method indicated that the equilibrium was attained within 4 h. The percentage of Cu(II) adsorption increased with increase of leached residue dose but decreased with increase of initial Cu(II) concentrations. The adsorption was found to be dependent on initial pH of Cu(II) solution, which increased with increase in initial pH. During uptake of Cu(II), various metal ions, especially Mn and Fe, were found to be released from leached residue, which decreased with increase of pH. Pseudo second-order kinetics was applicable for the Cu(II) adsorption. Adsorption data were satisfactorily fitted to the Langmuir isotherms. The maximum adsorption capacity determined by Langmuir isotherm was found to be 26.95 mg g-1 at pH 5.5 and 303 K. Thus the leach residue found to be useful for removal of heavy metal like copper from the industrial effluent.