Novel Technique to Characterize the Hydrodynamics and Analyze the Performance of a Fluidized-Bed Photocatalytic Reactor for Wastewater Treatment

Abstract

Heterogeneous photocatalysis, as a technology for wastewater treatment, is a very attractive approach for treating low-concentration, high-volume fluids. The design and development of an appropriate photocatalytic reactor for conducting photocatalysis requires a study of the hydrodynamics of the reactor coupled with the intrinsic rate kinetics to achieve higher quantum yields and optimum photocatalyst requirements. An annular dual-function photocatalytic reactor operating in absorption (fixed-bed) and regeneration (fluid-bed) modes was constructed for the purpose of this study. A technique using radioactive particle and two γ-ray cameras arranged perpendicularly to each other was used successfully to study the fluidized-bed behavior. This three-dimensional radioactive particle tracking (RPT) approach can enable the prediction of the amount of UV light a particle would receive during illumination, which decides the production rate of hydroxyl radicals and, in turn, the reaction rates. Also, CT scanning of the bed at various superficial velocities provides a tool for reliably and accurately predicting the bed voidage in a particular region of interest. Degradation experiments of model pollutant (phenol) were conducted with a pilot-scale reactor to evaluate its effectiveness. Adsorption of pollutant onto the catalyst and pollutant degradation with respect to various catalyst loadings were investigated. The economic viability of the reactor in comparison with other existing technologies is discussed in this paper.

Intenzifikacija fotokatalitičkih procesa za obradu voda i otpadnih voda

“…Detaljnije informacije o solarnoj fotokatalitičkoj dezinfekciji vode mogu se naći u literaturi. [50][51][52][53][54][55][56][57] Velik izazov u primjeni solarnih fotoreaktora predstavlja izrada solarnih fotoreaktora koji se znatno razlikuju od uobičajenih kemijskih reaktora. Naime, da bi se moglo iskoristiti Sunčevo zračenje koje će omogućiti uklanjanje onečišćenja, reaktor mora biti izrađen od transparentnog materijala što istodobno uzrokuje probleme vezane uz brtvljenje, rizik od loma, a ograničava i veličinu reaktora.…”

A fluidized bed photoreactor exploiting a supported photocatalyst with adsorption pre-concentration capacity

“…For liquid-solid systems and gas-solid systems, stirred tank or fluidized bed photo-reactors are to be preferred despite cost and operational delicacy. To test fluidization of IPCAs and the adsorption properties of the IPCA, a dual mode fixed bed-fluidized bed reactor with full recirculation was constructed [6]. The design is very similar to that of the lab reactor shown in Figure 2.…”

“…This is verified directly by the gamma tracking maps. Figure 3 [6] shows particle positioning in the prototype photoreactor at a superficial velocity of 0.66 cm s )1 . Thus, it was demonstrated that a uniform illumination of the IPCA is possible under reasonable conditions.…”

Advanced titanium dioxide fluidizable nanowire photocatalysts

“…16 Several researchers have successfully deposited TiO 2 photocatalysts onto porous, fluidizable particles to protect photocatalyst coatings from particle-to-particle and particle-to-wall collisions, which greatly reduced the mechanical ablation of the photocatalyst layer. 17–20 The research group of Langford and Kantzas 18–22 has aptly described the structure of the porous support particles as being “golf ball”-like, wherein the rough surface of the particles created many indentations (much like the “dimples” of a golf ball) in which the deposited TiO 2 photocatalyst coating could reside and remain protected from mechanical ablation during fluidization. Such porous, “golf ball”-like particles may provide sufficient protection to allow the use of 1-D nanostructured films on their surface.…”