BACKGROUND: Photocatalysis is one of the advanced oxidation processes that has gained in importance over recent years owing to its ability to decompose a wide range of organic and inorganic pollutants at ambient temperature and pressure. However, there are two essential issues regarding photocatalytic processes, i.e. limitations on photon transfer and on mass transfer. In the present study, a novel photo-impinging streams reactor, which can minimize such limitations, has been utilized in the photocatalytic degradation of phenol. The design and operating parameters such as type of nozzle, flow rate, catalyst loading, pH, initial phenol concentration and light intensity were found to have the expected impact on the efficiency of the process. The effects of two different co-oxidants, H2O2 and Na2S2O8 on the photocatalysis were also examined.



RESULTS: Results indicated that 100 mg L−1 of phenol in a 750 cm3 solution was completely degraded within 2.5 h reaction time in the presence of TiO2 without a co-oxidant present; and within 1 h in the presence of a co-oxidant.



CONCLUSION: A comparison between the current data and those available in the literature revealed higher efficiency and increased performance of the present reactor relative to conventional apparatus. Copyright © 2010 Society of Chemical Industry

Performance of a photo‐impinging streams reactor for the phenol degradation process

A new model was developed for the flow behavior of a counter-current liquid–liquid impinging streams reactor. As a modification of the well-known tanks-in-series model, the new model considers a cascade of descending-sized stirred tanks in series. This assumption is made because a distribution of the residence time exists for different liquid droplets depending on their initial elevation at the entrance to the system. The accuracy of this theoretical RTD model was analyzed through the comparison of the latter with that determined experimentally using the impulse tracer method. The results show that the presented model improves the predictions of the hydrodynamic behavior of impinging streams reactors. A comparison between the sum of the statistical parameter mean residual sum of squares (MRSS) for the new model with a number of previously presented models (the stirred tanks-in-series model, the gamma distribution with bypass (GDB) model, the Markov chains discrete time model, and the direct simulation Monte Carlo (DSMC) method) revealed that the proposed model is more capable of prediction of the hydrodynamic behavior of impinging stream reactors.

A new model for residence time distribution of impinging streams reactors using descending-sized stirred tanks in series

In the present study, the decomposition of phenol in aqueous solutions was investigated in both impinging system and batch reactor. In impinging reactor, catalyst particles with an average diameter of 1.5 × 103μm were confined in a wired cage located in the middle of the reaction vessel. The catalyst was synthesized by impregnation of iron on clinoptilolite zeolite as the support. The mean residence time of the solution in this reactor was 3 s. Therefore, the number of impingements required for the complete degradation of phenol was assessed to be 8 times. The advantage of performing the impinging reactor over a conventional reaction system has been demonstrated in this study. In the impinging reactor at 55 °C, time needed for degradation of phenol in aqueous media was measured to be as low as 24 s; however, phenol degraded completely in 10 min in batch stirred reactor. The optimum operating conditions for the impinging reactor were found as: catalyst containing 5 wt% iron, pH = 3.25, weight ratio of H2O2/phenol = 20, temperature = 55 °C. © 2017 Curtin University of Technology and John Wiley & Sons, Ltd.

Degradation of phenol by heterogeneous Fenton process in an impinging streams reactor with catalyst bed

Different configurations of impinging streams (IS) reactors are designed and widely applied in multiphase reactions. The great properties of IS reactors is to enhance the reaction kinetics by atten...

Applying a new approach to predict the residence time distribution in impinging streams reactors

In spite of the fact that the principles of impinging stream reactors have been developed for more than half a century, the performance analysis of such devices, from a viewpoint of the mathematical modeling, has not been investigated extensively. In this study two models are proposed to describe the drying performance of particulate materials in two-impinging stream dryers. The models are developed based on the Markov chain analysis and the tanks-in-series model. The required parameters for each model are determined by using RTD data obtained in a two-impinging stream dryer and the governing equations are solved numerically. Comparison of the results of the models with available experimental data shows that the stirred tanks-in-series model successfully explains the drying behavior in impinging stream dryers. Nevertheless, the results of the model that is developed based on the Markov chain analysis are not in exact agreement with corresponding experimental data because of the extremely short residence t...

Application of Markov Chain Analysis and Tanks-in-Series Model in Mathematical Modeling of Impinging Stream Dryers

A stochastic model for the residence time distribution in continuous two impinging streams reactors with spray nozzles (CISR) has been developed based on Markov chain processes The performance capability of the CISR in chemical absorption operations has been demonstrated by a typical example of reaction between carbon dioxide and monoethanolamine

Jamshidi Amir Masoud

Papers

Application of the continuous two impinging streams reactors in chemical absorption