Sodium percarbonate: an alternative oxidizing agent applied for the degradation of amoxicillin antibiotic in wastewaters using advanced oxidation processes

Advanced oxidation processes have presented promise results for the treatment of wastewaters from pharmaceutical industries, often using ultraviolet-visible radiation (UV-vis) and commercial/industrial aqueous solutions as sources of hydrogen peroxide (H2O2), which present several handling difficulties. In this context, sodium percarbonate (SPC) is an interesting alternative source of H2O2. So, in this work, SPC was studied for the degradation of amoxicillin antibiotic (AMX, 100 mgC L-1) by different processes (UV-Vis; UV-Vis/H2O2; SPC and photo-Fenton). Initially, the influences of pH, type of iron ions and the presence and absence of UV-vis radiation were studied. After this step, a modified photo-Fenton process was investigated, using the experimental design technique, evaluating the ferric ion initial concentration ([Fe3+]) (0.26-1.56 mmol L-1) and the molar flow of H2O2 (0.730-2.205 mmol H2O2 min(-1)), obtained from a SPC acidified aqueous solution, as independent variables. The better operating condition was found under a high [Fe2+] (1.56 mmol L-1) and a moderate molar flow of H2O2 (1.47 mmol min(-1)), obtaining 83% of organic carbon removal in 60 min. However, using a low Fe3+ concentration, it was obtained a mineralization of 78.1%, at the same molar flow of H2O2 and reaction time. This result was very important aiming future industrial applications, because, at this condition, the concentration of iron ions is below the maximum limit allowed for emission of wastewaters in receiving bodies, according to the Brazilian environmental legislation, not requiring the use of additional processes to remove residual iron, leading to lower operating costs.