Photooxidative Removal of p-Nitrophenol by UV/H2O2 Process in a Spinning Disk Photoreactor: Influence of Operating Parameters

In this paper, spinning disk photoreactor (SDP) has been used for the removal of a refractory pollutant, namely p-nitrophenol (PNP), in UV/H2O2 process. The effect of various parameters such as the plate type in the SDP, concentration of oxidant (H2O2), fluid volume, initial concentration of PNP, distance of the lamps from the spinning disk, distance of the lamps from each other, pH, and rotation speed of the spinning disk in the removal efficiency has been investigated. The results indicated that the use of scrobiculate disc instead of flat disc significantly increased the removal percentage of PNP from 46 to 100 % for the irradiation time of 20 min; it also increased with increasing H2O2 concentration, but the increase in fluid volume and the initial concentration of PNP reduced the removal percentage of PNP in the SDP. The increase in the distance of UV lamps from each other and from disc surface in the SDP reduced the removal percentage of PNP. However, the increase in pH to 5.5 increased removal efficiency while increasing pH above 5.5 reduced PNP removal efficiency. The disk rotation speed from 0 to 90 rpm increased the removal percentage from 49 to 70 % for the irradiation time of 5 min, but increasing the rotation speed to more than 90 rpm reduced the removal efficiency. This work is licensed under a Creative Commons Attribution 4.0 International License

Mathematical Kinetic Modelling and Representing Design Equation for a Packed Photoreactor with Immobilised TiO2-P25 Nanoparticles on Glass Beads in the Removal of C.I. Acid Orange 7

In this work, a design equation was presented for a batch-recirculated photoreactor composed of a packed bed reactor (PBR) with immobilised TiO2-P25 nanoparticle thin films on glass beads, and a continuous-flow stirred tank (CFST). The photoreactor was studied in order to remove C.I. Acid Orange 7 (AO7), a monoazo anionic dye from textile industry, by means of UV/TiO2 process. The effect of different operational parameters such as the initial concentration of contaminant, the volume of solution in CFST, the volumetric flow rate of liquid, and the power of light source in the removal efficiency were examined. A rate equation for the removal of AO7 is obtained by mathematical kinetic modelling. The results of reaction kinetic analysis indicate the conformity of removal kinetics with Langmuir-Hinshelwood model (kL-H = 0.74 mg L-1 min-1, Kads = 0.081 mg-1 L). The represented design equation obtained from mathematical kinetic modelling can properly predict the removal rate constant of the contaminant under different operational conditions (R2 = 0.963). Thus the calculated and experimental results are in good agreement with each other

Investigation of the effect of heat treatment process on characteristics and photocatalytic activity of TiO2-UV100 nanoparticles

The effect of heat treatment process on crystallite size, phase content, surface area, band gap energy and photocatalytic activity of TiO 2-UV100 nanoparticles were investigated. Heat treated TiO2 nanoparticles were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) isotherm and diffuse reflectance spectroscopy (DRS) techniques, and its photocatalytic activity was investigated in the removal of C.I. Acid Red 88 (AR88), an anionic monoazo dye of acid class, as a model contaminant. Heat treatment process at 600 °C causes an increase in crystallite size and band gap energy of TiO2-UV100 nanoparticles. The results indicate that the nanoparticles treated for 1 h at 600 °C show the highest photocatalytic activity which can effectively degrade AR88 under UV-irradiation. Increasing heat treatment temperature above 600 °C led to reduction in TiO2 photoactivity which may be related to the anatase-rutile phase transformation, increasing particle size and decreasing specific surface area. Removal efficiency of AR88 with heat treated TiO 2-UV100 nanoparticles was sensitive to the operational parameters such as catalyst dosage, pollutant concentration and light intensity