Humic acid coated Fe 3O 4 magnetic nanoparticles as highly efficient Fenton-like catalyst for complete mineralization of sulfathiazole

Abstract

Humic acid coated Fe 3O 4 magnetic nanoparticles (Fe 3O 4/HA) were prepared for the removal of sulfathiazole from aqueous media. Fe 3O 4/HA exhibited high activity to produce hydroxyl ( OH) radicals through catalytic decomposition of H 2O 2. The degradation of sulfathiazole was strongly temperature-dependent and favored in acidic solution. The catalytic rate was increased with Fe 3O 4/HA dosage and H 2O 2 concentration. When 3 g L −1 of Fe 3O 4/HA and 0.39 M of H 2O 2 were introduced to the aqueous solution, most sulfathiazole was degraded within 1 h, and >90% of total organic carbon (TOC) were removed in the reaction period (6 h). The major final products were identified as environmentally friendly ions or inorganic molecules (SO 4 2−, CO 2, and N 2). The corresponding degradation rate ( k) of sulfathiazole and TOC was 0.034 and 0.0048 min −1, respectively. However, when 3 g L −1 of bare Fe 3O 4 were used as catalyst, only 54% of TOC was eliminated, and SO 4 2− was not detected within 6 h. The corresponding degradation rate for sulfathiazole and TOC was 0.01 and 0.0016 min −1, respectively. The high catalytic ability of Fe 3O 4/HA may be caused by the electron transfer among the complexed Fe(II)-HA or Fe(III)-HA, leading to rapid regeneration of Fe(II) species and production of OH radicals.