Simultaneous adsorption of polycyclic aromatic hydrocarbons (PAHs) on biochar from sewage sludge.

Abstract

PAHs are organic pollutants of great environmental persistence. This study produced biochar of sewage sludge from a treatment plant and used it as an adsorbent in a complex system containing 16 priority PAHs. The biochar was characterized by the morphology and elemental composition (SEM/EDS), specific surface area, and pore size using N₂ adsorption-desorption (BET/BJH), crystallinity (DRX), functional groups (FTIR), and thermogravimetric degradation (DSC/DTG). The dosage effect showed that 90% of the PAHs were removed when SSB was 2 g L^-1. Kinetic assays were performed using different SSB dosages. The most adequate model to represent the kinetic results was the Elovich. The adsorption capacity and removal percentage of the 16 emerging organic polycyclic aromatic hydrocarbons cited by the US EPA were evaluated individually. The highest adsorption capacity was verified for fluoranthene, pyrene, and phenanthrene, respectively, evidencing the electivity of this material for these compounds.