Methylamine and dimethylamine photocatalytic degradation—Adsorption isotherms and kinetics Original Research Article

The photocatalytic degradation of two nitrogenous organic compounds, methylamine CH3NH2 and dimethylamine (CH3)2NH, used in pharmaceutical and chemical industries was investigated in the presence of UV-irradiated TiO2 aqueous suspensions. Different parameters were studied: adsorption under dark and UV-A conditions, photolysis, kinetics of degradation, and chemical pathway of methylamine (MA) and dimethylamine (DMA) degradation. The percentage of covered OH in the dark was equal for different concentrations of MA and DMA. The adsorption isotherms of these two amine compounds MA and DMA follow the Langmuir model. The photocatalytic oxidation kinetics of MA and DMA are described by the Langmuir–Hinshelwood model with a first order kinetics for concentrations below 0.5 mmol L−1, and then reach a plateau.