Nutshells as Efficient Biosorbents to Remove Cadmium, Lead, and Mercury from Contaminated Solutions

Abstract

The release of potentially toxic elements into the environment, and their effects on aquatic ecosystems still present a real threat. To avoid such contamination, the use of biological sorbents as an alternative to conventional and expensive water remediation techniques has been proposed. The present study evaluated the potential of 0.5 g L−1 of peanut, hazelnut, pistachio, walnut, and almond shells to remove the requisite concentrations of cadmium (Cd), lead (Pb), and mercury (Hg) from contaminated water. Hazelnut shells were identified as the sorbent with the highest potential and were evaluated in mono- and multi-contaminated mineral water. The influence of sorbent-intrinsic and solution-intrinsic characteristics were assessed. Differences among sorbents were attributed to varying percentages of their main components: cellulose, hemicellulose, and lignin. Matrix complexity increase caused a decrease in Cd removal, presumably due to the diminution in electrostatic interaction, and complexation with anions such as Cl-. When simultaneously present in the solution, contaminants competed, with Pb showing higher affinity to the sorbent than Hg. High efficiencies (>90%) obtained for hazelnut shells for all elements in ultrapure water and for Pb and Hg in mineral water) reveals the high potential of this low-cost and abundant waste for use in the remediation of contaminated waters (circular economy).

Utilization of <i>Ziziphus lotus</i> Fruit as a Potential Biosorbent for Lead (II) and Cadmium (II) Ion Removal from Aqueous Solution

“…Furthermore, the hydrated radius of Cd 2+ (0.426 nm) is greater than that of lead Pb 2+ (0.401 nm) (Cheng et al, 2021). All these factors could explain the preferential adsorption of lead compared to that of cadmium on the biosorbent surface (Dias et al, 2021).…”

Single and Ternary Removal of Heavy Metals from Aqueous Solution Using Fe3O4 Magnetic Nano-particles

“…Similarly, Xiaotao et al (2016) reported that Cd removal was not affected due to the presence of Hg in the binary system, while Hg was affected significantly. Dias et al (2021) found that the absorptivity of metals by hazelnut, peanut and walnut can be ranked as: Cd>Pb>Hg. Additionally, they found that the transition from single to ternary adsorption system resulted in a decrease in Hg and Cd removal by 14% and 7%, respectively, while Pb showed an insignificant change.…”

A Potencialidade das Macroalgas na Remoção de Elementos Terras Raras de Águas Contaminadas

“…A biossorção tem vindo a revelar-se como um método eficaz na remoção de elementos tóxicos presentes em soluções, nomeadamente quando estes se encontram em baixas concentrações. Nos últimos anos têm vindo a ser testados diferentes tipos de biossorventes, nomeadamente os constituídos por biomassa de algas, fungos, bactérias, resíduos de plantas e de animais, cascas e diversos outros [8,[11][12][13].…”