Photocatalytic thin film cascade reactor for treatment of organic compounds in wastewater

2001 ◽  
Vol 44 (5) ◽  
pp. 187-195 ◽  
Author(s):  
A.H.C. Chan ◽  
J.F. Porter ◽  
J.P. Barford ◽  
C.K. Chan
Keyword(s):  
Benzoic Acid ◽  
Photocatalytic Oxidation ◽  
Uv Light ◽  
Degradation Process ◽  
Pilot Scale ◽  
Steel Plates ◽  
Solution Temperature ◽  
Photocatalytic Process ◽  
Photolytic Degradation ◽  
Uv Lamps

The photocatalytic oxidation of benzoic acid was investigated in a pilot scale-cascade photoreactor. The photoreactor consists of an array of UV lamps (40 W, 365 nm) illuminating a cascade of three inclined 316 stainless steel plates, on which titanium dioxide (TiO2) was immobilized by electrophoretic deposition. The percentage removal of total organic carbon (TOC) of liquid samples was determined. The photocatalytic process was affected by several operating parameters. Increasing the solution temperature was found to reduce the dissolved oxygen (DO) level and to decrease the rate of the degradation process. The Langmuir-Hinshelwood equation was found to be accurate for modeling the degradation of benzoic acid with initial concentrations of 50 ppm, 75 ppm and 100 ppm. The rate of removal of TOC was positively affected by UV light intensity, but appeared to be independent of solution flowrate in the range examined. Control experiments confirmed that the effects of adsorption of the solute onto the TiO2 catalysts and photolytic degradation were negligible.

Effect of Thermal Treatment on the Photocatalytic Activity of TiO2 Coatings for Photocatalytic Oxidation of Benzoic Acid

2002 ◽  
Vol 17 (7) ◽  
pp. 1758-1765 ◽  
Author(s):  
Alex H. C. Chan ◽  
John F. Porter ◽  
John P. Barford ◽  
Chak K. Chan
Keyword(s):  
Stainless Steel ◽  
Thermal Treatment ◽  
Benzoic Acid ◽  
Surface Area ◽  
Photocatalytic Oxidation ◽  
Steel Plates ◽  
X Ray Diffraction ◽  
X Ray ◽  
316 Stainless Steel ◽  
Unheated Sample

The effects of thermal treatment on the properties and photoactivities of TiO2 catalysts supported on 316 stainless steel plates were examined. Degussa P-25 was immobilized on 316 stainless steel plates by electrophoretic deposition. These TiO2-coated plates were heated at 473, 673, and 873 K for 1 h. The photoactivities of these TiO2 coatings were determined based on the removal of benzoic acid as the model pollutant. In particular, the photoactivity decreased by 52% in the sample heated at 873 K compared with the unheated sample. The results of x-ray diffraction showed that the crystallinity and the crystallite sizes of the catalysts supported on the plates did not significantly vary with increasing temperature over the range examined. Negligible change in the catalyst phase (the anatase-to-rutile ratio) was indicated from x-ray diffraction and micro-Raman spectroscopy. However, it was found that the Brunauer–Emmett–Teller surface area of the scraped catalysts heated at 873 K decreased by nearly 13% compared with the unheated sample. In addition, scanning electron microscopy/energy dispersive x-ray and x-ray photoelectron spectroscopy analyses also detected the presence of Fe3+ ions at the surface of the supported catalysts heated at 873 K. The drop in surface area and the presence of Fe3+ ions at the catalyst surface, which were considered to function as electron–hole recombination centers, were possible factors leading to the drop in the photoactivity exhibited by the sample. A lower temperature for thermal treatment such as 473 K was proposed to ensure the coating stability and the catalyst photoactivity.

scholarly journals Diatom Biosilica Doped with Palladium(II) Chloride Nanoparticles as New Efficient Photocatalysts for Methyl Orange Degradation

2021 ◽  
Vol 22 (13) ◽  
pp. 6734
Author(s):  
Myroslav Sprynskyy ◽  
Paulina Szczyglewska ◽  
Izabela Wojtczak ◽  
Izabela Nowak ◽  
Andrzej Witkowski ◽  
...  
Keyword(s):  
Methyl Orange ◽  
Photocatalytic Degradation ◽  
Dye Degradation ◽  
Uv Light ◽  
Irradiation Time ◽  
Water Solution ◽  
Degradation Process ◽  
Solution Temperature ◽  
Scattering Effect ◽  
Light Excitation

A new catalyst based on biosilica doped with palladium(II) chloride nanoparticles was prepared and tested for efficient degradation of methyl orange (MO) in water solution under UV light excitation. The obtained photocatalyst was characterized by X-ray diffraction, TEM and N2 adsorption/desorption isotherms. The photocatalytic degradation process was studied as a function of pH of the solution, temperature, UV irradiation time, and MO initial concentration. The possibilities of recycling and durability of the prepared photocatalysts were also tested. Products of photocatalytic degradation were identified by liquid chromatography–mass spectrometry analyses. The photocatalyst exhibited excellent photodegradation activity toward MO degradation under UV light irradiation. Rapid photocatalytic degradation was found to take place within one minute with an efficiency of 85% reaching over 98% after 75 min. The proposed mechanism of photodegradation is based on the assumption that both HO• and O2•− radicals, as strongly oxidizing species that can participate in the dye degradation reaction, are generated by the attacks of photons emitted from diatom biosilica (photonic scattering effect) under the influence of UV light excitation. The degradation efficiency significantly increases as the intensity of photons emitted from biosilica is enhanced by palladium(II) chloride nanoparticles immobilized on biosilica (synergetic photonic scattering effect).

Theoretical Investigation on Nano TiO2 Photocatalytic Oxidation of VOCs

2007 ◽  
Author(s):  
Huili Yu ◽  
Kaili Zhang ◽  
Carole Rossi
Keyword(s):  
Mathematical Model ◽  
Photocatalytic Oxidation ◽  
Uv Light ◽  
Light Attenuation ◽  
Degradation Process ◽  
Air Purification ◽  
Key Factors ◽  
Nano Tio2 ◽  
Plane Plate ◽  
Volatile Organic

Controlling mechanisms for photocatalytic degradation of volatile organic compounds by nano TiO2 catalyst are found to be mass transfer, diffusion, adsorption and photochemistry. A mathematical model for the degradation process is developed by incorporating these mechanisms in a plane plate air purification physical model. Finite difference method is employed to solve the governing equation and boundary conditions. The computation results are validated using the data from experiments. The model is then used to investigate the effects of some key factors on the degradation of formaldehyde including UV light intensity, UV light attenuation coefficient, adsorption, catalyst thickness, and flow rate.

Case Study of Particle-Related UV Shielding of Microorganisms When Disinfecting Unfiltered Surface Water

2010 ◽  
Vol 45 (3) ◽  
pp. 343-351 ◽  
Author(s):  
Raymond E. Cantwell ◽  
Ron Hofmann ◽  
Jennie L. Rand ◽  
Patrick M. Devine ◽  
Monique VanderMarck
Keyword(s):  
Surface Water ◽  
Uv Light ◽  
Pilot Scale ◽  
Uv Disinfection ◽  
Particle Count ◽  
Uv Reactor ◽  
Before And After ◽  
Log Linear ◽  
Uv Lamps

Abstract The goal of this case study was to provide pilot-scale information about the ability of ultraviolet (UV) light to disinfect unfiltered surface water. A pilot-scale (0.25 L/s) UV reactor with low-pressure UV lamps was installed on raw water entering an aqueduct from the Pardee Reservoir at the East Bay Municipal District, California. A pilot monitoring system also collected hourly particle count (2 to 100 m), turbidity, and ultraviolet transmittance (UVT) measurements for 14 months. Grab microbial samples were collected and analyzed for indigenous total coliforms and total aerobic spores (TAS) both before and after UV disinfection, to correlate survival of the organisms across the UV reactor to water quality characteristics. Concentrations of indigenous coliforms and TAS ranged up to 163 and 1,383 per 100 mL respectively, before UV exposure. The data showed that the ability of UV to disinfect coliforms was essentially unaffected by the presence of particles (up to 703>10 m per mL and 1.3 nephelometric turbidity unit [NTU]) in the unfiltered surface water. In 13 of 14 samples, no coliforms were detected in the UV treated water. Log-linear inactivation of TAS up to 2.5-log suggests that at least 99.6% of the TAS were not protected from UV disinfection by particles.

scholarly journals Visible Light-Induced Superior Photocatalytic Activity of Ag@Nd2WO6/ZnO Nanocomposite and its Biological Activity

2019 ◽  
Vol 9 (2S2) ◽  
pp. 232-236
Keyword(s):  
Antibacterial Activity ◽  
Visible Light ◽  
Uv Light ◽  
Uv Spectroscopy ◽  
Photocatalytic Process ◽  
Spectroscopy Technique ◽  
Phase Purity ◽  
X Ray ◽  
Uv Light Irradiation ◽  
Catalytic Material

In this work, degradation of Ciprofloxacin has been studied over the catalyst Ag@Nd2WO6/ZnO (ANWZ) synthesized via hydrothermal method. The catalysts are characterized with techniques such as X-ray diffractometer, Scanning electron microscope with EDX spectroscopy and DRS- UV spectroscopy respectively. For the results shows, the PXRD spectroscopy was confirmed a phase purity and crystalline structure of the as-synthesized catalyst. The SEM results are explained about the morphology structure of the material, the structure spherical with nanorod like clustered morphology structure was shown in SEM and the reacting elements in the catalytic material are confirmed by EDX spectroscopy. And the DRS-UV spectroscopy technique is telling about the band energy value for prepared materials and also select the suitable way (i.e: Visible or UV light irradiation) for the degradation. The photocatalytic process, Ciprofloxacin (CIP) drug are degraded under visible light within 140 minutes and the degradation efficiency are 95.54%. The reusability test explains the efficiency and stability of the ANWZ catalyst and its stable up to the fifth run. Further, the photodegradation process, the catalyst is tested antibacterial activity study against Bacillus cereus and Escherichia Coli bacterial organisms. From the result, Bacillus bacteria contain more efficient antibacterial activity than that of E.coli bacteria

scholarly journals Degradasi Tirosina Menggunakan Mangkinfoto Berasaskan TiO2

2012 ◽  
Author(s):  
Rusmidah Ali ◽  
Siti Salamah Maisoan @ Selamat
Keyword(s):  
Amino Acid ◽  
Metal Ions ◽  
Uv Light ◽  
Degradation Process ◽  
Aqueous System ◽  
Visible Spectroscopy ◽  
Photo Degradation ◽  
Efficient System ◽  
Catalyst Powder ◽  
Uv Visible

Asid amino merupakan bahan asas dalam tisu tumbuhan dan haiwan. Tirosina (Tr) salah satu jenis asid amino yang mengandungi gelang aromatik, telah dipilih sebagai sampel untuk proses degradasi dalam medium akueus. Ini bertujuan melihat kesan penggunaan mangkinfoto dalam sinaran ultralembayung (λ < 400 nm) atau cahaya matahari ke atas molekul tirosina. Kajian telah dijalankan menggunakan sistem cahaya, mangkin serbuk TiO2, hidrogen peroksida, H2O2 dan ion logam. Penambahan ion logam seperti Ni2+, Cu2+, Ag+, Mn2+, Co2+, Fe2+ dan Cd2+ dan agen pengoksidaan, iaitu hidrogen peroksida adalah untuk mendapatkan kaedah yang paling cekap. Keputusan menunjukkan penambahan H2O2 dan ion Fe2+ dan Ni2+ berjaya meningkatkan kecekapan proses degradasifoto tirosina. Ion Ni2+ memberikan keputusan terbaik berbanding ion-ion lain. Ion Cu2+, Ag+, Mn2+ dan Cd2+ merencat proses degradasi. Keputusan juga menunjukkan cahaya matahari adalah setanding dengan cahaya ultralembayung. Kepekatan H2O2 terbaik adalah 5.0 x 10-2M dan semakin banyak TiO2 digunakan semakin baik peratus degradasi tirosina. Oleh itu kaedah optimum untuk proses degradasifoto ialah Tr 2.5 x 10-4 M + TiO2 + H2O25.0 x 10-3 M + Mn+ 1.0 x 10-2 M. Proses degradasifoto dikaji menggunakan spektroskopi ultralembayung-nampak pada julat panjang gelombang 400-200 nm. Kata kunci: Tirosina; degradasifoto; serbuk TiO; akueus Amino acid is a basic component in plant or animal tissue. Tyrosine (Tr), an amino acid which contains aromatic ring, was chosen as a sample for a photodegradation process in an aqueous system. The purpose of the experiment is to study the effect of photocatalysis under UV (λ < 400 nm) or sunlight on tyrosine. The experiment was carried out by using UV light, catalyst powder (TiO2), hidrogen peroxide H2O2 and metal ions system. The addition of oxidising agent H2O2 and metal ions such as Ni2+, Cu2+, Ag+, Mn2+, Co2+, Fe2+ and Cd2+ were used in order to achieve the most efficient system. Results showed that the system with added H2O2 and metal ions such as Ni2+ and Fe2+ had successfully enhanced the process of the tyrosine photodegradation. Other metal ions system such as Cu2+, Ag+, Mn2+ and Cd2+ were found to inhibit the degradation process. The results also showed that sunlight was comparable to ultraviolet light. The best H2O2 concentration was 5.0 x 10-2 M and the percentage of tyrosine degradation increased with the addition of more TiO2) by mass. Therefore, the optimum condition for tyrosine photodegradation process was in Tr 2.5 x 10-4 M + TiO2 + H2O2 5.0 x 10-3 M + H2O2 1.0 x 10-2 M. The dissappearance of tyrosine in the photo degradation process was monitored by UV-visible spectroscopy between 400-200 nm. Key words: Tyrosine; photodegradation; TiO2 powder; akueus

scholarly journals Study of mosquito attractants for photo catalytic mosquito trap

2013 ◽  
Vol 3 (1) ◽  
pp. 14
Author(s):  
Dewi Tristantini ◽  
Slamet ◽  
Angela Jessica Stephanie
Keyword(s):  
Activated Carbon ◽  
Air Temperature ◽  
Heat Production ◽  
Uv Light ◽  
Performance Testing ◽  
Humid Air ◽  
Combination Process ◽  
Photo Catalyst ◽  
Mosquito Trap ◽  
Uv Lamps

Photo catalytic mosquito trap is made of TiO2-Activated Carbon (AC) with a certain composition of AC. Research concerns on the heat spectrum which is produced by combination process of existing CO2 and humid air. The purpose of performance testing is to observe capability of this device in trapping mosquitoes related to the air temperature profile for heat spectrum is play important role for attracting mosquitoes. Result shows photo catalytic mosquito trap is more effective than devices which only consist of UV light or stream of CO2 and the humid air. A number of mosquitoes trapped by the photo catalyst coated panel configuration and UV lamps were lit proved far more effective because the heat production from recombination process. A little difference in temperature can be detected by mosquito. Keywords: Photo Catalytic, Mosquito, Recombination.

Use of Experimental Designs to Establish a Kinetic Law for a Gas Phase Photocatalytic Process

2014 ◽  
Vol 12 (1) ◽  
pp. 113-122 ◽  
Author(s):  
Cécile Raillard ◽  
Audrey Maudhuit ◽  
Valérie Héquet ◽  
Laurence Le Coq ◽  
Jean Sablayrolles ◽  
...  
Keyword(s):  
Light Intensity ◽  
Photocatalytic Degradation ◽  
Gas Phase ◽  
Photocatalytic Oxidation ◽  
Experimental Designs ◽  
Photocatalytic Process ◽  
Air Velocity ◽  
Kinetic Rate ◽  
Initial Concentration ◽  
Designs Of Experiments

Abstract The photocatalytic degradation of three common indoor VOCs – acetone, toluene and heptane – is investigated in a dynamic photocatalytic oxidation loop using Box–Behnken designs of experiments. Thanks to the experimental results and the establishment of a kinetic rate law based on a simplified mechanism, a predictive model for the VOC degradation involving independent factors is developed. The parameters under investigation are initial concentration, light intensity and air velocity through the photocatalytic medium. The obtained model fits properly the experimental curves in the range of concentration, light intensity and air flow studied.

Photolytic degradation of 2,4-D onZea maysleaves

Weed Science ◽  
1999 ◽  
Vol 47 (3) ◽  
pp. 262-269 ◽  
Author(s):  
Ramarao Venkatesh ◽  
S. Kent Harrison
Keyword(s):  
Zea Mays ◽  
Time Course ◽  
Uv Light ◽  
Light Regime ◽  
Growth Chamber ◽  
Polychromatic Light ◽  
Photolytic Degradation ◽  
Microscope Slides ◽  
Glass Microscope

Growth chamber experiments were conducted to determine the effects of UV light and riboflavin on photolysis of 2,4-D applied toZea maysleaves. Droplets of 100 mg L−114C-2,4-D were applied toZ. maysleaves with and without 10 mg L−13H-riboflavin and exposed to either UV-enhanced or UV-attenuated polychromatic light in a time-course assay. Photolysis of nonabsorbed14C-2,4-D residues onZ. maysleaves was sensitized by riboflavin regardless of UV light regime, but a larger percentage of nonabsorbed herbicide was degraded under UV-enhanced light compared to UV-attenuated light. Riboflavin was almost completely photolyzed during the first 10 h of exposure; yet, photolysis of14C-2,4-D surface residues in treatments containing riboflavin increased from 59% at 10 h of exposure to 87% at 42 h of exposure. In corresponding treatments without riboflavin, photolysis of14C-2,4-D surface residues was 37% at 10 h of exposure and 84% at 42 h of exposure. In contrast, only 7% of the14C-2,4-D deposited on glass microscope slides was degraded after 42 h of exposure in the absence of riboflavin, whereas 59% was degraded in the presence of riboflavin. Photolysis of 2,4-D onZ. maysleaves in treatments without riboflavin suggests that certain epicuticular component(s) ofZ. maysacted as photosensitizers or catalytic agents that promoted photolysis of nonabsorbed 2,4-D residues.

Photocatalytic Treatment of Wastewater From 5–Fluorouracil Manufacturing

1996 ◽  
Vol 118 (1) ◽  
pp. 2-8 ◽  
Author(s):  
M. Anheden ◽  
D. Y. Goswami ◽  
G. Svedberg
Keyword(s):  
Hydrogen Peroxide ◽  
Photocatalytic Oxidation ◽  
Uv Light ◽  
Substantial Reduction ◽  
Reduction Rate ◽  
Reaction Rates ◽  
Batch Experiments ◽  
Cod Reduction ◽  
Potential Use ◽  
Percent Decrease

This paper presents some of the experimental results from a study conducted to demonstrate the potential use of photocatalytic oxidation for decolorization and COD reduction of wastewater from 5–fluorouracil manufacturing. A series of batch experiments, were carried out using diluted solutions of the wastewater with 0.1 percent w/v TiO2. Low pressure mercury lamps were used to simulate the UV part of sunlight. The experiments showed that a complete decolorization and a substantial reduction of COD was achieved within 20 hours with a 20 percent solution. During the reaction period, the pH was noted to decrease considerably, indicating formation of acids. Adding hydrogen peroxide to the solution was found to significantly increase the reaction rates. Adding 2400 ppm of H2O2 gave an 80 percent decrease in color in one hour and a 70-80 percent decrease in COD in 20 hours. The influence of UV-light intensity was also examined. This experiment showed that with a UV-intensity of 15 W/m2, i.e., a cloudy day, the decolorization rate was still considerable, while the COD reduction rate was very low.

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