Ni(II) and Cu(II) binding properties of native and modified sugar beet pulp

The abilities of native and modified sugar beet pulps to remove Ni(II) and Cu(II) ions from aqueous solutions were compared. Their preparation by chemical treatments (saponification, hot 0.05 M HCl and cold 0.05 M NaOH extractions) is described. The sugar composition, which was strongly affected during these modifications, is discussed in terms of metal sorption efficiencies. The influence of these modifications was also evaluated by comparing the content of the functional groups determined by potentiometric titration, and the rate and extent of Cu(II) and Ni(II) uptakes onto the raw and modified materials. Nickel and copper sorptions were fast and complete within 30 min and the kinetic parameters were calculated using a second order model. The equilibrium data fitted well with the Langmuir model and showed the affinity order of the materials for the metal ions. The base-extracted pulp and saponified pulp exhibited the highest Ni(II) and Cu(II) ion uptakes among the materials tested.