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Degradation of methylene blue by natural manganese oxides: kinetics and transformation products.
R Soc Open Sci ; 6(7): 190351, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31417737
In this study, natural manganese oxides (MnO x ), an environmental material with high redox potential, were used as a promising low-cost oxidant to degrade the widely used dyestuff methylene blue (MB) in aqueous solution. Although the surface area of MnO x was only 7.17 m2 g-1, it performed well in the degradation of MB with a removal percentage of 85.6% at pH 4. It was found that MB was chemically degraded in a low-pH reaction system and the degradation efficiency correlated negatively with the pH value (4-8) and initial concentration of MB (10-50 mg l-1), but positively with the dosage of MnO x (1-5 g l-1). The degradation of MB fitted well with the second-order kinetics. Mathematical models were also built for the correlation of the kinetic constants with the pH value, the initial concentration of MB and the dosage of MnO x . Furthermore, several transformation products of MB were identified with HPLC-MS, which was linked with the bond energy theory to reveal that the degradation was initiated with demethylation.





Texto completo: Disponível Coleções: Bases de dados internacionais Base de dados: MEDLINE Idioma: Inglês Revista: R Soc Open Sci Ano de publicação: 2019 Tipo de documento: Artigo