Evaluation of the adsorption potential of iron mining tailing and its effect on raphanus sativus germination

Abstract

The objective of this work was to evaluate the physicochemical and adsorptive characterization of Fe tailing collected in the district of Brumadinho; and verify its effect on Raphanus sativus germination. The material was collected on the surface layer (0-20 cm) and disintegrated for pH, redox potential – Eh, electrical conductivity – EC, OM, cation exchange capacity – CEC, specific surface area – SSA and functional groups characterization. Adsorption studies were conducted using methylene blue (MB). The results of the adsorption studies were analyzed using kinetic models (Elovich, pseudo-first order – PFO and pseudo-second order – PSO) and isotherm models (Freundlich, Langmuir and Sips). The tailing has an acidic pH (5.60), negative ΔpH (-0.30) and low CEC (1.85 cmolc g-1). A high MB adsorption efficiency (96%) was verified. The Elovich model (0.9248<R2<0.9858) best represented the chemical kinetics, and the Freundlich model best describes the MB adsorption process in the tailing (R2 = 0.9609). The maximum adsorption capacity (qm) was equal to 15.08 mg g-1. The presence of Fe tailing positively influenced the germination of R. sativus seeds (73.8%), but stem and root growth were inferior when compared to seedlings cultivated in compost substrate. It is concluded that the material has favorable cationic adsorption capacity, which can benefit soil fertilization. However, R. sativus development was minor in Fe tailing substrate, probably due to low CEC, OM and nutrient availability.