RESUMO
The treatment of pharmaceutical industrial wastewaters, containing the antibiotic amoxicillin (218.29â mg L-1), via some advanced oxidation processes (POA), was studied. The H2O2 photolysis process presented the highest percentage of mineralization (97%), after the total reaction time (180â min). However, the photo-Fenton process showed the highest organic carbon removal rate, mineralizing 65% of the initial concentration, in 30â min. Because of this fact, this process was studied in more detail. The initial concentration of ferrous ions (0.03-1.00â mmol L-1) did not affect the performance of the photo-Fenton process, possibly operating using concentrations of below 15â mg L-1 (0.27â mmol L-1), that is the iron content limit for discharging wastewaters established in the Brazilian environmental legislation. Furthermore, experiments were performed according to the composite experimental design technique (Doehlert matrix), analyzing the following variables: (i) the inlet molar flow rate of H2O2 (FH2O2 ) and (ii) the initial concentration of ferrous ions ([Fe2+]). Besides that, the initial mineralization rate and the total organic carbon removal percentages, measured at 5, 10, 15 and 30â min of reaction, were chosen as the response variables. It was observed that FH2O2 was the most important variable in relation to the initial degradation rate. In the optimal conditions (FH2O2 = 3.27â mmol min-1 and [Fe2+] = 0.27â mmol L-1), the photo-Fenton process achieved a percentage of organic carbon removal of 84%, in only 30â min of reaction, presenting an interesting potential for real industrial applications, combined, or not, with conventional technologies (as biological treatments, for example).