Adsorção de fósforo em matriz produzida a partir de resíduo da indústria de fundição

Abstract

This study aimed to apply the adsorption process to an aqueous solution containing phosphorus. The adsorbent tested was the residual smoke from the electric arc furnace was used in the production of a matrix capable of adsorbing phosphorus from aqueous solutions, and the adsorption process was evaluated. For this, a physical and chemical characterization was performed, including analyzes of SEM and EDX. The influence of pH (3,5, 5 and 8), temperature (25, 35 and 45 ° C), and the initial concentration of phosphorus in the solution (10, 20, 30, 40, 50 mg L -1 ) was investigated through of a series of equilibrium adsorption experiments in a bath system. The characterization indicated a structure with microparticles and the absence of pores, as well as iron and oxygen compounds that can be associated with iron oxides, that promote the adsorption. The results obtained from the equilibrium experiments indicated a multi-layer adsorption behavior, in which two adsorption steps were identified: (i) monolayer adsorption, with a binding energy characteristic of the coexistence of chemisorption and physisorption; (ii) multilayer adsorption, favored by acid pH, with physical binding due to less intense interactions. The model that presented the best fit for the adsorption kinetics data was the Avrami model, whose transformation rates are low at the beginning and close to equilibrium at the end of the process. The process has been shown to be dependent on pH and temperature since different pH and temperature have different phosphorus and iron species in the solution that can bind or repel. Thus, the proposed adsorption system proved efficient and can be used for the removal of phosphorus from aqueous solutions.