Special needs and characteristic features of (photo)catalytic reactors with a review of the proposed Solutions
Abstract In the present chapter, the analogies between photocatalytic systems and the systems where the more common thermally activated reactions take place are highlighted. The objective is to propose a unified approach for the analysis and the design, which, however, must take into account how and why photocatalytic reactors differ from reactors with thermal reactions. The necessity of absorbing photons to activate the photocatalytic process adds complexity to the system, but some approaches are presented to simplify the problems and make easier their solution.
Water Depollution by Advanced Oxidation Technologies
This chapter deals with water treatments by advanced oxidation processes (AOPs) based on chemical and photochemical reactions. The most used processes are described, and for each of them, the main reaction mechanisms, principles, advantages, drawbacks, performances and formation of by-products, coupled with technologies and their applications to waters and wastewater depollution, have been analysed, supporting the main results of studies published in the pertinent literature.
ChemInform Abstract: Elemental Bromine Production by TiO2Photocatalysis and/or Ozonation.
Significant production of elemental bromine (Br2 ) was observed for the first time when treating bromide containing solutions at acidic pH, with TiO2 photocatalyst, ozone, or a combination thereof. Br2 selectivities up to approximately 85 % were obtained and the corresponding bromine mass balance values satisfied. The process is general and may be applied at a laboratory scale for green bromination reactions, or industrially as a cheap, safe, and environmentally sustainable alternative to the currently applied bromine production methods.
Heat transfer by using TiO2 nanofluids
Abstract In the last decades, nanofluids have been proposed as thermo-vector fluids thanks to their interesting properties of thermal conduction and stability, which allow interesting performance in heat transfer applications. Consequently, different studies on the thermal properties, the potential benefits, and the possible applications of nanofluids appeared in the scientific literature. This chapter deals with heat transfer characteristics of TiO2 nanofluids, which nowadays appear to be almost ready for practical applications. Particular attention has been given to the preparation, the characterization, and the effects of different parameters on heat transfer. Moreover, challenges and op…
Validation of a two-dimensional modeling of an externally irradiated slurry photoreactor
Abstract A two-dimensional model describing the behavior of a batch cylindrical photoreactor has been validated through a series of photocatalytic reactivity runs. The light intensity radiation field produced by 1–6 external UV fluorescent lamps was modeled together with Langmuir–Hinshelwood kinetics and 4-nitrophenol (NP) and Degussa P25 TiO 2 were used as the probe molecule and the catalyst, respectively. The experiments were carried out under different conditions of light intensity, photocatalyst amount and substrate concentration. The model parameters were the kinetic constant of substrate adsorption, desorption and degradation and the exponent of the power law expressing the kinetics d…
Elemental Bromine Production by TiO2 Photocatalysis and/or Ozonation
Significant production of elemental bromine (Br2 ) was observed for the first time when treating bromide containing solutions at acidic pH, with TiO2 photocatalyst, ozone, or a combination thereof. Br2 selectivities up to approximately 85 % were obtained and the corresponding bromine mass balance values satisfied. The process is general and may be applied at a laboratory scale for green bromination reactions, or industrially as a cheap, safe, and environmentally sustainable alternative to the currently applied bromine production methods.
Heterogeneous Photocatalysis: a Promising Tool for Green Organic Syntheses
The present work deals with a short review of some applications of photocatalysis to green organic synthesis of valuable products in mild experimental conditions and in the presence of water as solvent.
Kinetic Aspects of Heterogeneous Catalytic Versus Photocatalytic Reactions
Abstract Kinetics aspects of heterogeneous catalysis and photocatalysis are reported together with the most used models developed for both fields. The chapter describes the main mechanisms involved in the different processes and the parameters used to determine their performances. A comparison of the behaviors and kinetics features of heterogeneous catalysis and photocatalysis is presented.