Types Of Photocatalytic Reactors Research Articles

Photocatalytic Hydrogen Production Using TiO2‐based Catalysts: A Review

AbstractPhotocatalytic water splitting is an environmentally friendly hydrogen production method that uses abundant renewable resources such as water and sunlight. While Titanium dioxide (TiO2) photocatalyst exhibits excellent properties, its high band gap limits absorption to ultraviolet (UV) irradiation, resulting in low photo conversion efficiency. This review explores various modification techniques aimed at enhancing the efficiency of TiO2 under visible light irradiation. Factors influencing the photocatalytic water splitting reaction, such as catalyst structure, morphology, band gap, sacrificial reagents, light intensity, temperature, and potential of Hydrogen (pH) are examined. This review also summarizes different catalyst synthesis methods, and types of photocatalytic reactors, and provides insights into quantum yield. Finally, the review addresses the challenges and future outlook of photocatalytic water splitting.

Solar-powered photocatalysis in water purification: applications and commercialization challenges

Although heterogeneous photocatalysis has been recognized as a promising technology for decontaminating and disinfecting municipal and industrial wastewater over the last few decades, it has not yet successfully transitioned from laboratory-scale research to real-world applications. This limited progress is attributed to inherent physicochemical properties of most photocatalytic materials available, which exhibit reduced photoefficiency under visible light irradiation, along with multiple engineering considerations. This comprehensive review delves into the intricate dynamics of photocatalytic reactions kinetics, exploring several types of photocatalytic reactors and elucidating the significance of materials employed in photocatalytic wastewater treatment. This critical survey systematically examines the effectiveness of different materials such as titania, zinc oxide and graphitic carbon nitride which are commercially applied for different reactor systems. Understanding the role of these materials for photocatalytic reactions is essential to address the challenges associated with wastewater treatment. Furthermore, the discussion extends beyond the technical aspects to encompass the broader landscape of challenges hindering the commercialization and widespread adoption of photocatalytic technologies. By critically evaluating these challenges, the minireview aims to provide valuable insights for researchers, engineers, and policymakers seeking to advance and implement photocatalytic wastewater treatment on a broader scale. This synthesis of knowledge consolidates the current state of the field and outlines future prospects for overcoming barriers and optimizing the potential of photocatalytic processes in environmental remediation.

Role of Physics for Development of Different Techniques for Photocatalytic Degradation of Heavy Metals and Effluents in Water

Several factors contributed to the elevated levels of water pollution in the earth surface increasing the risk of wastewater pollution. Inorganic metal irons and suspended liquid metals are also leads cause of water pollution. Physical treatments for water treatment include the use of effective membrane filters in two ways. Small membrane filter and large membrane filters also used for commercial applications. Different types of nanoparticles are used for the treatment of organic contaminants suspended in the wastewater. The adsorption of a reactive dye through the hydroxyapatite (HAP) leads the excellent filtration of ions in the wastewater. Different types of photocatalytic reactors are used for the treating the large amount of wastewater in effective ways. These included the titanium based photocatalytic reactors that employed the sub-micron TiO2 particles from the treated water which accompany the treatment process. Polymer composites are used for removal of wastewater due to their low operating temperat Nanofiltration also used for removal of wastewater due to the formation of utilizing of the semipermeable membrane allows the fine removal of the different ions and different types of pollutants ure and susceptibility to environmental degradation as compared to other operations.

Numerical analysis of solar chimney power plant integrated with CH4 photocatalytic reactors for fighting global warming under ambient crosswind

Methane's global warming potential (GWP) is much larger than carbon dioxide and contributes significantly to global warming. Solar chimney power plant (SCPP) integrated with photocatalytic reactors can capture and remove atmospheric methane, and generate electrical power without fossil energy consumption simultaneously. In this paper, the performance of the flow characteristics, the CH4 removal, the CO2 emission reduction, and the power generation were analyzed for the SCPP integrated with different types of photocatalytic reactors under ambient crosswind (ACW). The results revealed that the SCPP integrated with a honeycomb reactor was more stable for the degradation of CH4 than that with a plate reactor. With an increase in ACW, the removal rate of atmospheric CH4 was reduced to a constant value of 0.41 g/s for the honeycomb reactor and 0.11 g/s for the plate reactor. The SCPP integrated with a honeycomb reactor achieved a maximum power generation of 88.31 kW, which was 1.63 times than that of the conventional SCPP when G = 857 W/m2 and ACW = 0 m/s. In addition, the improved SCPP could reduce CO2 emissions by 85.04 kg/h when G = 857 W/m2, ACW = 0 m/s, and △P = 320 Pa.

Strategies for the intensification of photocatalytic oxidation processes towards air streams decontamination: A review

• The state-of-the-art on strategies for gas-phase PCO process intensification. • Advances and challenges on mass and photon-transfer. • Disruptive reactors designs with a high illuminated catalyst surface area. • Reports on LEDs and optical fibers as “customized” efficient light sources. • Overview on hybrid photocatalytic oxidation systems. This review reports different approaches for the intensification of photocatalytic oxidation (PCO) processes towards air streams decontamination. From reactor design to the combination of different oxidative processes, many approaches have been exploited in order to reach higher photocatalytic reaction rates. When it comes to reactor design, enhancing photon transfer is still the biggest challenge to be overcome. Several types of photocatalytic reactors can provide a large surface-to-volume ratio, exhibiting satisfactory mass transfer; however, the irradiation of the entire catalytic coated surface has shown to be quite difficult for some particular reactor geometries. In this context, the use of miniaturized light sources e.g. LEDs has shown to be a promising alternative for a more “customized” irradiation profile, resulting in a more efficient catalytic surface illumination. Coupling PCO with other oxidative processes has been reported to enhance substantially the reaction rates. In fact, synergistic effects have been reported for both ozone and plasma-enhanced photocatalytic systems. The use of vacuum ultraviolet radiation (VUV, λ < 200 nm) in PCO processes is another commonly used strategy for the intensification of PCO processes. The improved photocatalytic activity for VUV-PCO process is usually related to the ability of VUV light to break most chemical bonds and generate strong oxidants, such as hydroxyl radicals and ozone, through the photolysis of H 2 O and O 2 , respectively.

New Generation Energy-Efficient Light Source for Photocatalysis: LEDs for Environmental Applications

In this review, current progress in the area of photocatalysis using energy efficient Light Emitting Diodes (LEDs) as an irradiation source is discussed. LEDs are small in size, robust, do not contain mercury, have a longer life span than conventional light sources, and can operate on a direct current. These properties of LEDs offer a new alternative to traditional ultraviolet sources and open new possibilities for photocatalytic degradation with reduced power consumption, along with greater freedom in the design of various types of photocatalytic reactors. The present review mainly focuses on the photocatalytic degradation of organic compounds and dyes as well as the sterilization of microrganisms which are present in water and air, using irradiation by various types of LEDs, photocatalytic reactors, and catalysts. In addition, future prospects and challenges for the application of LEDs for to photocatalytic environmental pollutant degradation have been highlighted.

A novel photocatalytic microreactor bundle that does not require an electric power source

A new type of photocatalytic reactor was developed. Capillaries coated on the inside with photocatalytic materials induced an effective photocatalytic reaction by pulling up a solution under the action of capillary forces; no electric pump was required for the replacement of the chemicals, due to the concentration gradient generated in the capillaries.

The Degradtion of Humic Substance using Continuous Photocatalysis Systems

Photocatalytic oxidation is an emerging technology in water and wastewater treatment. Photocatalysis often leads to complete degradation of organic pollutants without the need for chemicals. This study investigated the degradation of humic substances in water using photocatalysis systems coupled with physio‐chemical processes such as adsorption and/or flocculation. Dissolved Organic Carbon (DOC) removal of PAC‐TiO2 was improved by a factor of two to three times compared with TiO2 alone. Solid Phase Micro Extraction (SPME)/Gas Chromatograph (GC) flame ionisation detector (FID) was used to investigate intermediates of photocatalytic oxidation in a batch reactor with TiO2 alone and with powder activated carbon (PAC) with TiO2. GC peaks showed that PAC‐TiO2 adsorbed some by‐products which were photo‐resistant and prevented the reverse reaction that occurred when TiO2 was used alone. The two other types of photocatalytic reactors used were the continuous photocatalytic reactor and recirculated photocatalytic reactor. The results show that the recirculated reactor had the highest efficiency in removing organic matter in a short photo‐oxidation (detention) time of less than 10 min. The use of PAC‐TiO2 in recirculated continuous reactor resulted in 80% removal of organic matter even when it was operated for a short detention time and allowed the use of a smaller dose of TiO2.

Decompositions of Formic Acid in Two Types of Photocatalytic Reactors

Decompositions of Formic Acid in Two Types of Photocatalytic Reactors

The spinning disc reactor – studies on a novel TiO 2 photocatalytic reactor

A new type of photocatalytic reactor, the spinning disc reactor (SDR), was used to degrade aqueous solutions of 4-chlorophenol and salicylic acid. The efficiency of the photocatalytic process depends on the type of UV source used. Lamps supplying shorter wavelength UV radiation are more efficient than those whose emissions lay mainly in the near UV region. The method used to coat the disc of the SDR does not meet its operational requirements. The characteristics of the turbulent liquid films produced in the SDR reduce the influence of mass transfer over the overall photocatalytic process.

Degradation of Phenol in Aqueous Solution by TiO2 Photocatalyst Coated Rotating-Drum Reactor.

In order to commercialize a photochemical reactor for treatment of biohazard organic compounds in aqueous solution, a film-shaped photocatalyst composed of platinum-loaded TiO2/water glass/substrate was fabricated, immobilizing pretreated TiO2 powders on a substrate plate by a double spread method. A new type of photocatalytic reactor, called a TiO2 photocatalyst coated rotating-drum reactor, was proposed, in which the surface of the drum is the reaction site so that the photocatalyst can effectively contact aqueous solution and receive light. A experiment in decomposing phenol in an aqueous solution using this reactor was carried out. In consequence, it is shown that phenol can be decomposed in a relatively short time, not only under artificial ultraviolet light, but also under solar light.

Heterogeneous Photocatalysis in Environmental Remediation

AbstractSemiconductor‐based photocatalytic processes have been studied for nearly 15 years due to their many intriguing advantages in environmental remediation and other areas. In this paper, underlying principles and mechanism of the photocatalytic degradation process were discussed, followed by thermodynamics, kinetics, mass transfer effects were discussed. The kinetics of photocatalytic degradation was analysed with the aim of determining the favourable conditions to obtain high quantum yield. Primary parameters that influence the process such as catalyst loading, dissolved oxygen, pH, temperature, light intensity, crystalline structure, etc. have been discussed in detail. Different types of photocatalytic reactors, process efficiencies and applications in environmental engineering as well as in other areas have also been mentioned. The main barrier to the commercialization of the processes is the low quantum yield. However, it is expected that large‐scale applications could be achieved with significant progress by improvement of process performance.

Photocatalytic conversion of methane

Methane's global warming potential (GWP) is much larger than carbon dioxide and contributes significantly to global warming. Solar chimney power plant (SCPP) integrated with photocatalytic reactors can capture and remove atmospheric methane, and generate electrical power without fossil energy consumption simultaneously. In this paper, the performance of the flow characteristics, the CH4 removal, the CO2 emission reduction, and the power generation were analyzed for the SCPP integrated with different types of photocatalytic reactors under ambient crosswind (ACW). The results revealed that the SCPP integrated with a honeycomb reactor was more stable for the degradation of CH4 than that with a plate reactor. With an increase in ACW, the removal rate of atmospheric CH4 was reduced to a constant value of 0.41 g/s for the honeycomb reactor and 0.11 g/s for the plate reactor. The SCPP integrated with a honeycomb reactor achieved a maximum power generation of 88.31 kW, which was 1.63 times than that of the conventional SCPP when G = 857 W/m2 and ACW = 0 m/s. In addition, the improved SCPP could reduce CO2 emissions by 85.04 kg/h when G = 857 W/m2, ACW = 0 m/s, and △P = 320 Pa.