ATIVAÇÃO DE COMPOSTO ORGÂNICO COM ÁCIDO FOSFÓRICO E OS EFEITOS NA ADSORÇÃO DE Pb E Cd

ACTIVATION OF ORGANIC COMPOST WITH PHOSPHORIC ACID AND THE EFFECTS ON Pb AND Cd ADSORPTION.

Application of adsorbents derived from waste in contaminated areas remediation is aligned with sustainable development goals and circular economy principles. As chemical activation can result in increased adsorption capacity, it is an alternative to improve the performance of materials and enable their use. This study evaluated whether activated compost derived from the organic fraction of municipal solid waste would be an efficient and low-cost adsorbent. Chemical activation was performed by impregnating 1 mol L^-1 of phosphoric acid for 12 h at 25 °C. Characterization and batch equilibrium tests were carried out to confirm if chemical activation would positively affect the retention of lead (Pb) and cadmium (Cd). Surface functional groups and minerals were verified through Fourier Transform Infrared Spectroscopy (FTIR) and X-Ray Diffractometry (XRD) before and after batch equilibrium test. Removal percentages ranged from 52.49 to 91.22% for Pb (initial concentrations of 20.11 to 889.20 mg L^-1) and from 13.33 to 87.13% for Cd (initial concentrations from 1.56 to 667.50 mg L^-1). Compared to the original material, activation did not increase Cd adsorption capacity. However, was observed an improvement in adsorption performance for Pb between 76.86 and 443.30 mg L^-1. The Langmuir isotherm best fitted the experimental data obtained both for Pb and Cd.