首页|Preparation of adsorbents from agro-industrial wastes and their application in the removal of Cd~(2+) and Pb~(2+) ions from a binary mixture: Evaluation of ionic competition
Preparation of adsorbents from agro-industrial wastes and their application in the removal of Cd~(2+) and Pb~(2+) ions from a binary mixture: Evaluation of ionic competition
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Adsorbents were prepared from agro-industrial wastes for the removal of Cd~(2+) and Pb~(2+) ions from a binary mixture. Of all the adsorbents prepared, that activated with H3PO4 obtained from peanut shell (AQ_(ps)) had the highest adsorptive capacity as regards the removal of both metal ions. The operating conditions established were: pH 5.0; 2 g_(adsorbent) L_(solution)~(-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 R~2 values > 0.91 and χ~2< 0.0001 for all the concentrations studied. The extended Langmuir model fitted the experimental data, obtaining R~2 = 0.90, with q_(max) of 0.7 ± 0.3 mmol g~(-1) and K_(EL) of 5.0 ± 3.6 L mmol~(-1) for Cd~(2+) and q_(max) of 0.7 ± 0.1 mmol g~(-1) and K_(EL) 40.5 ± 14.9 L mmol~(-1) for Pb~(2+). 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 Cd~(2+) and 73.3 % for Pb~(2+) was obtained. In view of the above, AQ_(ps) showed potential for simultaneous removal of Cd~(2+) and Pb~(2+) ions from aqueous media.
Agro-industrial residueBinary mixtureDesorptionExtended Langmuir model
V.H. Santos、G.E. do Nascimento、D.C. Silva Sales
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Departamento de Engenharia Quimica, Universidade Federal de Pernambuco, Av. Prof. Arthur de Sa, s/n, 50740-521, Recife, PE, Brazil
Polytechnic School of Pernambuco, University of Pernambuco, Rua Benfica, 455, Madalena, 50720-001, Recife, PE, Brazil
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