The surface characteristics of
Citrus paradisi
(grapefruit mesocarp biomass) on
the biosorption of Ni (II) and Pb (II) ions from aqueous solution were studied adopting a
batch reactor technique. The dried grapefruit mesocarp biomass was characterized using
phytochemical screening and Fourier Transform Infra – Red (FTIR) Spectroscopy.
The results of the characterization revealed the presence of alkaloids, tannins, saponins,
cyanogenic glycosides. Furthermore, the FTIR spectrum pattern of the biomass showed broad
and sharp absorption peaks indicating the existence of functional groups like – OH, C=O,
C-H, C-O, N-H, etc. The biosorption process was found to be pH, time and concentration
dependent. The rate of biosorption was higher in Ni (II) ion than Pb (II) ion. The result of the
equilibrium modeling showed that the biosorption process fitted well with the Freundlich
isotherm equation indicating a muiltilayer biosorption. The mechanism of the biosorption
process followed pseudo – second – order kinetic model equation with correlation coefficient
(R
2) of 0.999 for Ni (II) ion and 0.991 for Pb (II) ion respectively. Thermodynamic
parameters determined showed that the biosorption of Ni (II) and Pb (II) ions on the surface
of the biomass was an exothermic and spontaneous process. The rate of biosorption was found
to decrease with increasing temperature. The results showed that the dried grapefruit
mesocarp biomass was efficient and effective in the biosorption of Ni (II) and Pb (II) ions and
is recommended to be applied in wastewaters.
