Electrochemical determination of Cu2+ complexation in the extract of E. crassipes by anodic stripping voltammetry

Abstract

Chemical speciation of copper and its total dissolved concentration in the aqueous extract of Eichhornia crassipes (E. crassipes) were investigated by DPASV titration with Cu. Values of speciation parameters, logKCuLi′ and [Li], were calculated using Scatchard linearization and nonlinear fitting with the assumption of two complexing ligands. The total dissolved copper [Cu]T in the acid digested extract was found to be 0.48 μM ± 0.032. Results obtained from the linear and nonlinear transformations revealed that there were two classes of very strong copper complexation with average logKCuL1′∼14.34(±0.01), logKCuL2′∼13.54(±0.04), [L1] ∼ 1.41 μM (±0.29) and [L2] ∼ 2.08 μM (±0.1), calculated from the two methods. This reflects the great affinity of E. crassipes toward eliminating Cu2+ from its aqueous environment, and converting Cu2+ into less toxic by chelation with natural ligands released from the plant tissues.

Keywords

• Speciation
• DPASV
• Eichhornia crassipes
• Copper