Investigation of the efficiency of a tubular continuous-flow photoreactor with supported titanium dioxide nanoparticles in the removal of 4-nitrophenol: operational parameters, kinetics analysis and mineralization studies

摘要

In this study, to investigate the application of heterogeneous photocatalysis in the removal of organicncontaminants from aqueous media a novel tubular continuous-flow photoreactor with supportednTiO2-P25 on glass plates was designed and constructed. The photoreactor comprises six quartz tubesnand a UV lamp which was placed in the center of the quartz tubes. 4-nitrophenol (4-NP) as a mostnrefractory pollutant was chosen as a probe pollutant to examine the photoreactor efficiency fornenvironmental cleaning applications. Results of experiments show that the removal efficiency ofn4-NP in this photoreactor is a function of photoreactor length, gas and liquid flow rates and 4-NPninitial concentration. Kinetics analysis indicates that degradation of 4-NP in continuous-mode can benmodeled with the Langmuir–Hinshelwood (L–H) model (kL–H ¼ 1.5 mg Lu00021nminu00021n, Kads ¼ 0.11 mgu00021nL).nA design equation was obtained with a combination of L–H modified equation and tubular reactorndesign equation. This equation can be used for estimation of 4-NP concentration in differentnphotoreactor lengths under various operational parameters. Mineralization study was followednthrough total organic carbon (TOC) analysis and measurement of nitrite and nitrate as finalndegradation products.