Preconcentration and determination of Cu (II) from aqueous samples using functionalized sawdust and comparison with synthetic functionalized sorbents

The efficiency of indigenous functionalized sorbent (sawdust functionalized with polyaniline) was compared with synthetic functionalized sorbents (Dowex functionalized with 8-hydroxyquinoline (Dowex-8HQ) and α-nitroso-β-naphthol (Dowex-αNβN)) for preconcentration and determination of Cu (II) from aqueous samples. The synthetic functionalized sorbents and indigenous functionalized sorbent were characterized using FTIR. Different parameters like pH, equilibration time and sample volume were investigated for maximum sorption of Cu (II). Isotherm studies showed that the sorption data fitted well into Langmuir isotherm for the sawdust functionalized with polyaniline. Freundlich isotherm was followed for Dowex-8HQ and Dowex-αNβN. Four types of kinetic equations were applied to the data, and it was observed that sorption of Cu (II) followed second-order kinetics. Thermodynamically, the sorption of Cu (II) on these three sorbents was found to be exothermic and spontaneous. For maximum recovery of Cu (II) from loaded sorbents, different parameters like shaking time, eluent type, concentration and volume were investigated, and 89% Cu (II) was recovered from loaded sawdust functionalized with polyaniline and Dowex-8HQ. The interference studies showed the selectivity of sawdust functionalized with polyaniline for Cu (II) in comparison to synthetic functionalized sorbents. Thus, Cu (II) can be easily removed from aqueous samples in the presence of foreign ions.