Uso de processo Fenton modificado para a degradação de compostos orgânicos

• Autor(a) principal: Sarmento, Antover Panazzolo
• Data de Publicação: 2013
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/773
• topic: Compostos orgânicos; Reação Fanton; Processos oxidativos avançados; Organic compounds; Reaction Fanton; Advanced oxidation processes; CNPQ::CIENCIAS AGRARIAS::ENGENHARIA AGRICOLA

In environmental engineering, it was agreed to use the term organic microcontaminants for the full range of organic substances resistant to biological degradation, highlighting various industrial chemicals, surfactants, pesticides, steroids, hormones and hygiene, beauty and cleaning products. These pollutants, because they are not biodegradable and present high toxicity, may be responsible or contribute to affect the organisms in the water, alter the organoleptic water characteristics and damage human health. The conventional water treatment, generally, presents unsatisfactory performance in the removal of micropollutants. An alternative to mitigate these contaminants are the advanced oxidation processes, which are based on the Fenton reaction (conventional and modified). The objective of this study was to evaluate the efficiency of modified Fenton processes in the degradation of three different types of organic micropollutants: (i) humic substances (humic acid), (ii) phenol and (iii) drugs (trimethoprim and sulfamethoxazole). At first, it was aimed the evaluation of Mn4+ usage as catalyst supporting to the Fenton reaction, and also the Fe2+ replacement with Fe3+, in humic acid degradation. Verified that Mn4+ and Fe3+ did not contribute to improve the degradation efficiency, in a second experiment, degrading phenol, Fe 2+ was determined as a source of iron and Mn2+ was used as a catalyst supporting to the reaction. Previously, it was verified that Mn2+ presents different behavior in different pH (3 and 5), in a third experiment of drugs degradation it was used Fe2+ and Mn2+, confirming the interaction between Mn2+ and the pH. All experiments analyzed the influence of the factors pH, reagent concentration and reaction time. The inferences were conducted using variance analysis, Pareto chart, response surface method and desirability function. The significance level of the statistical analyzes was 5%. The optimal condition for the humic acid degradation predicted is: pH 5, [H2O2] 210 mg L-1, [Fe2+] 30 mg L-1 and reaction time of 120 min. The optimum conditions for the phenol degradation in more acidic pH (3) was: [H2O2] 210 mg L-1, [Fe2+] 20, 40 or 60 mg L-1, [Mn2+] 60 mg L-1 and reaction time of 90 min, in less acid pH (5) it was observed that the conventional Fenton process was a more efficient alternative, being the optimum condition: [H2O2] 90 mg L-1, [Fe2+] 20 mg L-1 and reaction time of 30 min. The optimum condition for the trimethoprim degradation was: pH 5, [H2O2] 180 mg L-1, [Fe2+] 45 mg L-1 and the reaction time of 30 min. This thesis concluded that the Mn4+ and Fe3+ do not show efficiency in the Fenton process, is possible to use Mn2+ when the substrate to be treated exhibit lower pH (3) and both, the Fenton modified and Fenton processes, presented high degradation efficiency.