No abstract

Photocatalytic degradation of N-methyl-2-pyrrolidone (NMP) was investigated in an aerated UV/TiO2 batch system. The effects of TiO2 photocatalyst loading, temperature, pH, initial concentration, and the type of gas phase on the reaction rate were ascertained, and the optimum conditions for the maximum degradation rate were determined. The results showed that photocatalytic degradation of NMP is strongly influenced by these parameters. The optimum TiO2 loading, which provides enough surface area for reaction without irradiation loss due to scattering of UV light, was found to be 0.1 wt %. It was revealed that due to bilateral effect of temperature on the process, the maximum oxidation rate (0.22 min–1) is obtained at 45 °C. The highest photodegradation reaction rate is obtained in neutral or slightly acidic condition rather than in extreme acidic or alkaline range. The pseudo-first-order reaction rate expression based on Langmuir–Hinshelwood model can reasonably simulate the photocatalytic degradation process. The optimum values for TiO2 photocatalyst loading, temperature, and pH were confirmed by economic factor analysis based on electrical energy consumption.

N-methyl 2-pyrrolidone (NMP) is applied as a solvent in 1,3-butadiene (BD) extraction plants. The solvent, which is circulated through the unit, is regenerated in a solvent recovery unit. The wastes of solvent recovery unit contains at least 50 wt% NMP which is generally disposed. The recovery of NMP from this waste for reusing in the BD purification plant was studied in the present research by experimental methods such as dissolution, coagulation, and distillation. A purified NMP with the concentration of 99 wt% could be obtained. In addition, the process was scaled up for manufacturing and installing in the BD extraction plant.