Abstract

ESPINOSA-RODRIGUEZ, Miguel Ángel et al. Adsorption of Cd(ll) and Pb(ll) present in aqueous solution with nanche stone (Byrsonima crassifolia). Rev.Colomb.Quim. [online]. 2020, vol.49, n.2, pp.30-36. ISSN 0120-2804.  https://doi.org/10.15446/rev.colomb.quim.v49n2.80633.

The nanche stone is an agricultural residue that has great potential as adsorbent. Then, the adsorption capacity of Cd(II) and Pb(II) ions present in aqueous solution was evaluated, using the stone as adsorbent. The tests performed for this purpose were the determination of point of zero charge (pHPZC), determination of active sites (Boehm method and FTIR spectroscopy), and the development of the mathematical models of Langmuir, Freundlich, and Prausnitz-Radke through adsorption isotherms. The results obtained from the pHPZC of the nanche stone were in an acidic range (6,0), while the concentration of acid and basic sites were 0.1037 and 0.046 mol/g respectively. The infrared spectra (FTIR) detected acid functional sites associated with the phenol group, carboxylic acids, and lactones. Finally, the adsorption capacity of nanche stone to Cd(II) and Pb(II), increased with the pH, achieving percentages of removal up to 84% for Cd (II) to pH 8, and of 82% for Pb(II) to pH 5. In conclusion, the pH and the presence of acidic functional sites were decisive in the elimination of the Pb(II) and Cd(II) ions.

Keywords : agricultural residues; heavy metals; active sites.

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