Buriti biomass as catalysts based on activated carbon/Fe3O4 for ciprofloxacin removal by heterogeneous photo-Fenton process

Abstract

In this study, activated carbon (AC) from Buriti biomass decorated with magnetite (Fe3O4) nanoparticles was produced as a new material to be applied in ciprofloxacin (CIP) removal using photo-Fenton-based process. All materials (identified as AC1, AC3 e AC4) were initially carbonized with H2SO4 at 100 °C for 24 h in an activating agent/biomass ratio of 0.85. Subsequently, AC3 and AC4 materials suffered a new heat treatment at 300 °C (AC3) and 400 °C (AC4) respectively, resulting in materials of low porosity. The Fe3O4 nanoparticles were produced by co-precipitation method and the catalysts were identified as AC1/F, AC3/F and AC4/F. The materials were characterized by TGA-DSC, MEV-EDS, porosimeter, FT-IR and point of zero charge (pHPZC). To evaluate the catalytic performance of the ACs/F in the removal of CIP as an emerging pollutant, a study using heterogeneous photo-Fenton process at pH 2.0, 7.0 and 10 was performed. It was found that the AC4/F catalyst at pH 2.0 was the most efficient material, achieving 100 % of CIP removal, monitored by UV–Vis. The pathway mechanism observed seems to be highly dependent on the greater interaction capacity of H2O2 and less dependent on the CIP adsorption with the hybrid surface catalyst, i.e. AC and Fe3O4. The total organic carbon (TOC) study for the AC4/F catalyst at pH 2.0 showed 71.8 % of CIP mineralization and residual iron content below the levels set by the Brazilian Environmental Legislation (15 mg L−1).