Preparation of biosorbents from the Jatoba (Hymenaea courbaril) fruit shell for removal of Pb(II) and Cd(II) from aqueous solution

In this study, the biosorption properties of Jatoba (Hymenaea courbaril) fruit shell for removal of Pb(II) and Cd(II) ions from aqueous solutions, and its potential as a low-cost biosorbent for water treatment, were investigated. The Jatoba fruit shell (JBin) was subjected to different treatments with heated water (JBH2O) and sodium hydroxide (JBNaOH) to modify its surfaces and improve its adsorption properties. The chemical modification of the surfaces of the resulting materials was confirmed by analyzing the compositions and structural features of the raw material and the chemically treated materials using SEM, FTIR, 13C NMR, and pHpzc. The ability of the biosorbents to remove the metal ions was investigated with batch adsorption procedures. The adsorption data were then examined in detail by applying adsorption models of Langmuir, Freundlich, and Dubinin-Radushkevich. The results showed that the experimental data were best described by the Langmuir model for the Pb-JBin and Cd-JBNaOH systems, the Freundlich model for the Pb-JBH2O and Pb-JBNaOH systems, and the Dubinin-Radushkevich model for Cd-JBin and Cd-JBH2O systems. The maximum adsorption capacities of JBNaOH obtained using the Langmuir model reached values of 30.27 and 48.75 mg g−1 for Cd(II) and Pb(II), respectively. The adsorption kinetic studies showed that the pseudo-second-order model was the best fitted to the experimental data, and adsorptions for Pb-JBH2O and Cd-JBH2O are controlled by intraparticle diffusion mechanism.