Photocatalytic Mineralization of MAPO with Nano Titania Particles and the Process Optimum Conditions

Tris (2-methyl-1-aziridinyl) phosphine oxide (MAPO) in aqueous media was mineralized, using photocatalytic UV/nanoTiO2 process by means of a tubular falling film photo-reactor. MAPO is extremely poisonous and resistive against oxidants. Response surface methodology (RSM) was employed for experimental design, modeling and parameter optimization. Accordingly, a reduced quadratic model was developed to give the substrate mineralization efficiency percentage (%ME). Analysis of variance (ANOVA) for individual variables and their interactions was performed. The order of operational parameters relative importance is: temperature > pH > [MAPO]0 > [TiO2], within the used ranges. Maximum mineralization efficiency was achieved at the obtained conditions of: T = 30 ˚C, pH = 8.5, [MAPO]0 = 60 mg L-1 and [TiO2] =110 mg L-1, and the predicted maximum efficiency was experimentally tested. A power law model, with an order of 2.66 for chemical oxygen demand, describes the mineralization kinetic until 150 min of process progress.