Pecan Nutshell as Biosorbent to Remove Toxic Metals from Aqueous Solution

Abstract

In the present study we reported for the first time, the feasibility of pecan nutshell (PNS-Carya illinoensis) as an alternative biosorbent to remove Cr(III), Fe(III) and Zn(II) metallic ions from aqueous solutions. The ability of PNS to remove these metallic ions was investigated by using batch biosorption procedure. The effects, such as pH and the biosorbent dosage on the adsorption capacities of PNS were studied. Five kinetic models were tested, the adsorption kinetics being the better fitted one to the fractionary-order kinetic model.

The equilibrium data were fitted to Langmuir, Freundlich, Sips, and Redlich-Peterson isotherm models. Taking into account a statistical error function, the data were best fitted to Sips isotherm models. The maximum biosorption capacity of PNS were 93.01, 76.59, and 107.9 mg g⁻¹ for Cr(III), Fe(III), and Zn(II), respectively.

Keywords:

• Biosorption
• heavy metals
• low-cost adsorbent
• pecan nutshell

ACKNOWLEDGEMENTS

The authors are grateful to Ministério de Ciência e Tecnologia (MCT), to Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), and to Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) for financial support and fellowships. We are grateful to Centro de Microscopia Eletrônica (CME-UFRGS) for the use of the SEM microscope. We would also like to thank Perkin Elmer for donating impact beads utilized in the nebulizer of the Analyst 200 spectrometer.

Notes

∗Second stage.