Psm Dunlop

Bio: Psm Dunlop is an academic researcher from Ulster University. The author has contributed to research in topics: Photocatalysis & Titanium dioxide. The author has an hindex of 11, co-authored 22 publications receiving 3370 citations.

A review on the visible light active titanium dioxide photocatalysts for environmental applications

Abstract: Fujishima and Honda (1972) demonstrated the potential of titanium dioxide (TiO2) semiconductor materials to split water into hydrogen and oxygen in a photo-electrochemical cell. Their work triggered the development of semiconductor photocatalysis for a wide range of environmental and energy applications. One of the most significant scientific and commercial advances to date has been the development of visible light active (VLA) TiO2 photocatalytic materials. In this review, a background on TiO2 structure, properties and electronic properties in photocatalysis is presented. The development of different strategies to modify TiO2 for the utilization of visible light, including non metal and/or metal doping, dye sensitization and coupling semiconductors are discussed. Emphasis is given to the origin of visible light absorption and the reactive oxygen species generated, deduced by physicochemical and photoelectrochemical methods. Various applications of VLA TiO2, in terms of environmental remediation and in particular water treatment, disinfection and air purification, are illustrated. Comprehensive studies on the photocatalytic degradation of contaminants of emerging concern, including endocrine disrupting compounds, pharmaceuticals, pesticides, cyanotoxins and volatile organic compounds, with VLA TiO2 are discussed and compared to conventional UV-activated TiO2 nanomaterials. Recent advances in bacterial disinfection using VLA TiO2 are also reviewed. Issues concerning test protocols for real visible light activity and photocatalytic efficiencies with different light sources have been highlighted.

Photocatalytic inactivation of Clostridium perfringens spores on TiO2 electrodes

Abstract: Disinfection of drinking water is commonly carried out by chlorination, however research has shown this method to be ineffective against certain protozoan, viral and biofilm forming microorganisms. Furthermore, chlorination can result in the formation of mutagenic disinfection by-products. Semiconductor photocatalysis may be a possible alternative to chlorination for point-of-use drinking water disinfection. In this work TiO 2 electrodes were fabricated using electrophoretic immobilisation of commercially available TiO 2 powders onto conducting supports, i.e. indium-doped tin oxide-coated glass, titanium metal and titanium alloy. Photocatalytic inactivation of Escherichia coli and Clostridium perfringens spores in water was demonstrated on all immobilised TiO 2 films. The rate of photocatalytic inactivation of E. coli was one order of magnitude greater than that of C. perfringens spores. The application of an external electrical bias significantly increased the rate of photocatalytic disinfection of C. perfringens spores. The effect of incident light intensity and initial spore loading were investigated and disinfection kinetics determined as pseudo-first order.

A comparative study on the removal of cylindrospermopsin and microcystins from water with NF-TiO2-P25 composite films with visible and UV–vis light photocatalytic activity

Abstract: In this investigation, in order to develop photocatalyst materials with improved photo-efficiency and visible light response compared to the state of the art materials, the role of Evonik Aeroxide® P25-TiO2(P25) nanoparticles incorporated in a modified sol–gel process to yield composite nitrogen and fluorinedoped TiO2-P25 (NF-TiO2-P25) films was investigated. The addition of P25 nanoparticles in the solleads to higher BET surface area, pore volume, porosity and total TiO2 mass, as well as larger thickness and roughness of the films after heat treatment. Microscopy techniques confirmed partial sintering of NF-TiO2 sol–gel formed and P25 nanoparticles having different average size. The existence of well defined regions of only anatase from NF-TiO2 and anatase–rutile mix from P25 was verified in the micro-Raman spectra. The photocatalytic degradation of four microcystins (microcystin-LR, -RR, -LA and -YR) and cylindrospermopsin was evaluated with NF-TiO2 and NF-TiO2-P25 films under visible and UV–vis light. The general reactivity for the microcystins under acidic conditions (pH 3.0) was: MC-LA > MC-LR ≥ MC-YR > MC-RR where the highest initial degradation rate was achieved with the NF-TiO2-P25 films (5 g L−1 of P25 in sol when irradiated with visible light and 15 g L−1 of P25 in sol when irradiated with UV–vis light). Cylindrospermopsin showed negligible adsorption at pH 3.0 for all films. Nevertheless, significant photocatalytic removal was found under UV–vis light with maximum P25 loaded films indicating that the degradation was mediated by the involvement of photogenerated reactive oxygen species and not by the trapping reaction of the positive hole., (2012) Applied Catalysis B: Environmental, 121/122, 30-39.

Anion-Doped TiO2Nanocatalysts for Water Purification under Visible Light

Abstract: Innovative sol–gel synthesis based on the self-assembling template method has been applied to synthesize mesoporous anion-doped TiO2 with N–F, S and C atoms using suitable surfactants and reagents, to improve simultaneously the structural, morphological, and electronic properties of TiO2 nanomaterials and achieve anion doping of titania with high visible light photoinduced reactivity. The incorporation of anion species in the titania structure resulted in the effective extension of TiO2 optical absorption in the visible range through the formation of intragap energy states. The anion-doped titania materials immobilized in the form of nanostructured thin films on glass substrates exhibited high photocatalytic efficiency for the degradation of the microcystin-LR (MC-LR) cyanotoxin, a hazardous water pollutant of emerging concern, under visible light irradiation. The development of these visible light-activated nanocatalysts has the potential of providing environmentally benign routes for water treatment.

A review on the visible light active titanium dioxide photocatalysts for environmental applications

Abstract: Fujishima and Honda (1972) demonstrated the potential of titanium dioxide (TiO2) semiconductor materials to split water into hydrogen and oxygen in a photo-electrochemical cell. Their work triggered the development of semiconductor photocatalysis for a wide range of environmental and energy applications. One of the most significant scientific and commercial advances to date has been the development of visible light active (VLA) TiO2 photocatalytic materials. In this review, a background on TiO2 structure, properties and electronic properties in photocatalysis is presented. The development of different strategies to modify TiO2 for the utilization of visible light, including non metal and/or metal doping, dye sensitization and coupling semiconductors are discussed. Emphasis is given to the origin of visible light absorption and the reactive oxygen species generated, deduced by physicochemical and photoelectrochemical methods. Various applications of VLA TiO2, in terms of environmental remediation and in particular water treatment, disinfection and air purification, are illustrated. Comprehensive studies on the photocatalytic degradation of contaminants of emerging concern, including endocrine disrupting compounds, pharmaceuticals, pesticides, cyanotoxins and volatile organic compounds, with VLA TiO2 are discussed and compared to conventional UV-activated TiO2 nanomaterials. Recent advances in bacterial disinfection using VLA TiO2 are also reviewed. Issues concerning test protocols for real visible light activity and photocatalytic efficiencies with different light sources have been highlighted.

Advanced Oxidation Processes in Water/Wastewater Treatment: Principles and Applications. A Review

Abstract: Advanced oxidation processes (AOPs) constitute important, promising, efficient, and environmental-friendly methods developed to principally remove persistent organic pollutants (POPs) from waters and wastewaters. Generally, AOPs are based on the in situ generation of a powerful oxidizing agent, such as hydroxyl radicals (•OH), obtained at a sufficient concentration to effectively decontaminate waters. This critical review presents a precise and overall description of the recent literature (period 1990–2012) concerning the main types of AOPs, based on chemical, photochemical, sonochemical, and electrochemical reactions. The principles, performances, advantages, drawbacks, and applications of these AOPs to the degradation and destruction of POPs in aquatic media and to the treatment of waters and waste waters have been reported and compared.

Black titanium dioxide (TiO2) nanomaterials

Abstract: In the past few decades, there has been a wide research interest in titanium dioxide (TiO2) nanomaterials due to their applications in photocatalytic hydrogen generation and environmental pollution removal. Improving the optical absorption properties of TiO2 nanomaterials has been successfully demonstrated to enhance their photocatalytic activities, especially in the report of black TiO2 nanoparticles. The recent progress in the investigation of black TiO2 nanomaterials has been reviewed here, and special emphasis has been given on their fabrication methods along with their various chemical/physical properties and applications.