Biosorption of Cr(III) and Pb(II) by Schoenoplectus californicus and Insights into the Binding Mechanism

Tomás Agustín Rearte,Maria Luisa Andrade,Alicia Fabrizio De Iorio,Patricia Beatriz Bozzano

doi:10.1155/2013/851602

Abstract

Biosorption and desorption of chromium and lead on shoots biomass of Schoenoplectus californicus were investigated by performing batch sorption tests in different conditions of pH, biosorbent dose, and initial concentration in simple and binary solutions. Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm models were employed to describe sorption equilibrium. Filters and biomass were characterized before and after treatments by environmental scanning electron microscopy and X-ray energy-dispersive spectrometry. The optimal conditions for biosorption were found to be pH 5 for both metals. The contact time to reach pseudoequilibrium changed as a function of pH and the metal studied. The highest optimisation of biosorbent dose was 5 g L−1 at pH 7 and 15 g L−1 at pH 5 for both metals. The most effective extracting agents for lead and chromium proved to be HNO3 and NaOH, respectively. The recovery of lead was greater than of chromium because the Cr(III) sorption mechanisms involve a stronger binding energy than the mechanisms for Pb(II), such as in intern sphere complexes. Both metals accounted for a high % removal (>90%) under the best sorption conditions. The use of Schoenoplectus californicus proved to be an efficient and economical alternative for the treatment of effluents contaminated with lead and chromium.

Highlights

The release of heavy metals into bodies of water occurs due to the lack of previous treatments performed on industrial wastewater; this release is a serious problem because the persistence of heavy metals in the ecosystem and the transference into the several trophic levels implies a high risk to both wildlife and humans
The substrate is less susceptible to breakdown, indicating that this material features characteristics that allow it to be employed as an effective biosorbent
The Fourier transform infrared spectroscopy (FTIR) spectrum was measured within the range of 500–4000 cm−1 wavenumber

Summary

Introduction

The release of heavy metals into bodies of water occurs due to the lack of previous treatments performed on industrial wastewater; this release is a serious problem because the persistence of heavy metals in the ecosystem and the transference into the several trophic levels implies a high risk to both wildlife and humans. Considering the vast wastewater quantities, the current metal removal technologies are either not effective enough or are prohibitively expensive and inadequate. Biosorption technology based on the utilisation of dead biomass offers several major advantages, such as a lack of toxicity constraints, nonrequirement of nutrient supply, high availability and low cost of biomass, and recoverybound metal species [3]. Different types of biomass, such as algae, bacteria, fungi, and industrial and agricultural organic wastes, have been investigated for the removal of heavy metals from aqueous solutions [2,3,4,5,6,7]

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Results

Conclusion