Rapid mineralization rate of acetylsalicylic acid in a tubular photochemical reactor: the role of the optimized excess of H2O2

• Autor(a) principal: Silva, Douglas do Nascimento
• Data de Publicação: 2019
• Outros Autores: Cunha Filho, Fernando José Vieira da, Lima, Andressa Mota, Ratkievicius, Luciana Avelino, Silva, Danielle Jaiane, Chiavone Filho, Osvaldo, Nascimento, Claudio Augusto Oller do
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRN
• Texto Completo: https://repositorio.ufrn.br/handle/123456789/30977
• topic: Pharmaceutical pollutants; Emerging pollutants; Experimental design; Photo-Fenton; Photocatalysis

Acetylsalicylic acid (ASA) is a model pollutant and a representative of the emerging pharmaceutical micro- pollutants whose mineralization across several advanced oxidative processes takes hours to complete. This work devotes to optimize and understand the kinetic conditions to mineralize ASA using Photo-Fenton process with UVA radiation in a tubular photochemical reactor. The optimization employs a statistical tool termed factorial design (FD) that studies how the concentrations of ASA, Fe2+ and H2O2 affects the mineralization over a larger interval of concentrations. The factorial design indicates that the initial concentration of H2O2 is a crucial variable to achieve a fast rate of ASA mineralization. Using optimized contents of both H2O2 and Fe2+ (45 Mm and 1.5 mM, respectively) in the Photo-Fenton process (H2O2/Fe2+/UVA), mineralization around 90% is reached in about 10 min, the fastest rate ever observed, enabling to treat 0.012 m3 h−1 per tubular reactor. The underlying reason for such outstanding performance is attributed to the optimized 4.5-folds excess of [H2O2], i.e.the ratio of H2O2 concentration used at the initial time to that required for complete mineralization of the theoretic TOC. Measurements of the remaining concentration of H2O2 strongly indicates that excess of [H2O2] optimizes the instantaneous concentration of radical % OH. As a conclusion, the stoichiometric excess of [H2O2] is an important parameter to be optimized for achieving the highest degree of mineralization at the shortest time when using the photochemical reactor, in turn, decreasing costs related to the total energy consumed both by the lamp and by the recirculation pump