Invited feature articleEvaluation and modeling of a spinning disc photoreactor for degradation of phenol: Impact of geometry modification

- Two new designs of spinning disc photoreactor were used to improve the performance of for degradation of phenol.
- Mass transfer limitation was eliminated within the new design applying a critical rotational speed.
- Residence time distribution (RTD) results show that modified reactors flow regime were seems to be closer to plug flow.
- Hydrodynamic and kinetic models were combined to predict the degradation of phenol for different designs of reactor.

A new spinning disc photoreactor with two different designs employing baffles in its structure for degradation of phenol was studied and compared with conventional ones. TiO2 was successfully immobilized on stainless steel disc and Teflon baffles. X-ray diffraction, scanning electron microscopy, field emission scanning electron microscopy and transmission electron microscopy analysis were performed in order to give information on the crystal phase and structure of both TiO2 coatings and size of particles. The wettability of the photocatalyst film on the disc surface was evaluated by contact angle test. The results have demonstrated that complete phenol removal was achieved using baffles after 180 and 150 min of reaction time, which was 60 and 90 min faster than the reactor with smooth disc under optimum condition of the reactor (rotational speed = 290 rpm, flow rate = 2000 mL/min, disc diameter = 22 cm). Influence of rotational speed for smooth and baffled discs was studied.Resultsindicated that there was no considerable mass transfer limitation for new designs above approximately 150 rpm. For description of flow regime in the reactor residence time distribution (RTD) measurements was performed experimentally. According to RTD data, reactor was accurately modeled using tanks-in-series model. The estimated equivalent number of tanks-in-series in baffled discs were 8 and 10 compared to 4 for smooth disc. The Langmuir-Hinshelwood (L-H) kinetic model was combined with hydrodynamic model for prediction of degradation of phenol and rate coefficients. Predicted results were in agreement with experimental data.

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