Avaliação das diferentes frações da Moringa oleifera na remoção de metais potencialmente tóxicos em água

Abstract

There is a great number of polluting agents of water resources, and among them the present work highlights toxic metals. These compounds have high toxicity even at low concentrations, mainly due to their bioaccumulation characteristic and difficulty in degradation. Biosorption of potentially toxic metals has been shown to be an alternative in the treatment of contaminated water, because it is a technique that is fast and low-cost. In this sense, in relation to other possible biosorbents, Moringa oleifera residues stand out, which have a large amount of pores and surface area, indicating a powerful adsorption capacity for the treatment of surface water and effluents, being an alternative to conventional treatments. Therefore, this work proposed the evaluation of the efficiency of moringa biomass in its fractions (pod, seed, seed husk and leaf) in the removal of lead, barium and nickel from water. Adsorption tests were carried out according to the adopted experimental design, to evaluate the following variables: type and amount of biomass, diameter of biomass particles and different initial concentrations of metal. The results showed removals of 99.8% of Ba2+ using the moringa seeds, 99.0% of Pb2+ using the seed husks, and 85.8% of Ni2+ using the leaves. Adsorption tests were also carried out in a multi-element solution and the results showed a possible competitiveness between the ions, where Pb2+ showed to have a greater affinity with the studied biosorbent, with higher removal percentages. Among the evaluated metals, Ni2+ had the lowest removal efficiencies. The samples that showed better removal percentages according to the experimental design were analyzed according to the Freundlich and Langmuir adsorption isotherm models at three temperatures and showed a better fit to the Freundlich model.