Emprego de tratamentos oxidativos e osmose inversa para redução da ecotoxicidade do tensoativo cloreto de hexadeciltrimetilamônio

• Autor(a) principal: Paula, Mariana Silva de
• Data de Publicação: 2018
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/14316
• topic: Cationic Surfactant; Ozonation; Electro-Fenton; Reverse osmosis; Ecotoxicity.; Tensoativo catiônico; Ozonização; Eletro-Fenton; Osmose inversa; Ecotoxicidade; Ozonização; Oxidação; CNPQ::OUTROS::CIENCIAS

In the present work, two oxidative processes (ozonization and electro-Fenton (EF)) were applied aiming at the degradation and reduction of the toxicity of a commercial solution of cationic surfactant. After the EF experiments a final polishing was performed using reverse osmosis (RO) membranes, for rejection of iron and sodium ions and decrease of conductivity. Toxicity monitoring was performed using three species (Pseudokirchneriella subcapitata, Daphnia similis and Lactuca sativa). For ozonation, the influence of the pH, time, type of reactor and the use of an antifoam agent was investigated. In the EF process, we investigated the influence of time and type of support electrolyte during the reactions and in the RO system operated at a constant flow of 1 L min-1, the feed pressures of 1 MPa, 2 MPa and 3 MPa were varied. The higher efficiency of removal of the surfactant was obtained by ozonization in alkaline medium (73%), in the time of 120 min, while for the electro-Fenton, the maximum efficiency was 67%, in the time of 60 min. A comparative analysis of the treatments evidences the potential application of these techniques in the degradation of cationic surfactants. It has been found that the use of antifoam in the ozonation tests does not interfere with removal of TOC and that the response of the EF technique is faster than ozonation. In the best experimental condition, the EF+RO treatment showed removal efficiency of 83% of conductivity, 85% for sodium and 99% for iron. Ecotoxicological analyzes showed that the untreated surfactant was detrimental to the three species used. The two oxidative processes decreased the toxicity of the surfactant and did not generate more toxic byproducts, but the ozonization presented better results, since a higher value of the IC50 for microalgae was obtained, did not present significant effect on the relative growth index of lettuce seeds and not presented a toxic effect for microcrustaceans. The types of ions present after EF impaired the development of the species, and the use of the combined treatment EF + RO is of paramount importance. After the treatment EF + RO the same results were obtained in the ozonation, except for the microcrustacean, since it is a more sensitive organism.