Preparation of adsorbents from agro-industrial wastes and their application in the removal of Cd2+ and Pb2+ ions from a binary mixture: Evaluation of ionic competition

Abstract:

Adsorbents were prepared from agro-industrial wastes for the removal of Cd²⁺ and Pb²⁺ ions from a binary mixture. Of all the adsorbents prepared, that activated with H<inf>3</inf>PO<inf>4</inf> obtained from peanut shell (AQ<inf>ps</inf>) had the highest adsorptive capacity as regards the removal of both metal ions. The operating conditions established were: pH 5.0; 2 g<inf>adsorbent</inf> L<inf>solution</inf>^‐1 and 50 rpm. The kinetic showed rapid adsorption, and the equilibrium was reached in 3 min. Both pseudo-first-order and pseudo-second-order models represented the experimental data with R² values > 0.91 and χ²< 0.0001 for all the concentrations studied. The extended Langmuir model fitted the experimental data, obtaining R² = 0.90, with q<inf>max</inf> of 0.7 ± 0.3 mmol g^‐1 and K<inf>EL</inf> of 5.0 ± 3.6 L mmol^‐1 for Cd²⁺ and q<inf>max</inf> of 0.7 ± 0.1 mmol g^‐1 and K<inf>EL</inf> 40.5 ± 14.9 L mmol^‐1 for Pb²⁺. A decreasing trend in adsorptive capacity was also observed when the temperature was increased, indicating exothermic adsorption. During the evaluation of adsorbent recovery, when the volume of the eluent was five times smaller than that of the adsorbate, maximum desorption of 84.5 % for Cd²⁺ and 73.3 % for Pb²⁺ was obtained. In view of the above, AQ<inf>ps</inf> showed potential for simultaneous removal of Cd²⁺ and Pb²⁺ ions from aqueous media.

Año de publicación:

2022

Keywords:

• Extended Langmuir model
• Agro-industrial residue
• Binary mixture
• Desorption

Fuente:

scopus

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