Photodegradation of 4-nitrophenol using an impinging streams photoreactor coupled with a membrane

In the present work, degradation of 4-nitrophenol (4-NP) in a novel configuration of an axial radial impinging streams photoreactor coupled with a membrane microfiltration was proposed. The influences of initial 4-NP concentration, catalyst loading, slurry flow rate and pH were investigated as the most important operating parameters. Firstly, the performance of axial radial impinging streams photoreactor was evaluated in a batch recirculation mode and optimum conditions for pertinent parameters were determined. Complete decomposition of a 30 ppm batch solution of 4-NP was obtained within almost 180 min under optimal conditions and the decrease in COD and TOC were 71% and 62%, respectively. The experimental data of 4-NP degradation with an initial concentration in the range of 10-50 ppm accorded well with pseudo-first order model. Finally, the photoreactor was equipped with a membrane and applied in the continuous degradation of 4-NP. A combination of pH 4, 2 g/L TiO2 and 2.24 L/min flow rate were determined to be the optimized conditions for degradation of 30 ppm 4-NP in the continuous membrane impinging streams photoreactor. In this reactor, an increased performance capability, a less membrane fouling, a higher permeate flow rate and subsequently a higher efficiency compared to conventional processes can be seen.