Abstract
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 (R2) 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.Keywords: Citrus paradisi, biosorption, metal ions, characterization, mechanism.
Highlights
The degradation of natural waters with several heavy metal contaminants, have been found to be emanating mostly from mining waste and industrial discharges (Baig et al, 1999)
Characterization: Phytochemical screening of the grapefruit mesocarp revealed the presence of tannin (0.25%), alkaloid (7.28%), saponin (23.10%) and cyanogenic glycoside (0.14 mg/kg)
Examination of the Fourier Transform Infra – Red (FTIR) spectrum generated showed the presence of ionizable functional groups which are able to interact with the Pb (II) and Ni (II) ions (Pradhan and Singh, 2007; Bueno et al, 2008; Sun et al, 2008; Ertugay and Bayhan, 2008)
Summary
The degradation of natural waters with several heavy metal contaminants, have been found to be emanating mostly from mining waste and industrial discharges (Baig et al, 1999). These toxic materials cause problems to the entire ecosystem. Heavy metal pollution has become a global issue owing to the fact that it threatens human health and the ecosystem. Their presence over permissible levels in drinking water may cause adverse effects on human biochemical dynamics (Dahiya et al, 2008). The effect of heavy metals on man cannot be neglected because exposure to these contaminants even at low concentration in the environment can cause severe dysfunction in the renal, reproductive and central nervous systems (Manaham, 2004)
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