Journal articles: 'Photocatalytic oxidation process'

1

Witkowski, Hubert, Wioletta Jackiewicz-Rek, Janusz Jarosławski, Karol Chilmon, and Artur Szkop. "Ozone Formation during Photocatalytic Oxidation of Nitric Oxides under UV Irradiation with the Use of Commercial TiO2 Photocatalytic Powders." Materials 15, no. 17 (August 26, 2022): 5905. http://dx.doi.org/10.3390/ma15175905.

Full text

Abstract:

The application of photocatalytic materials has been intensively researched in recent decades. The process of nitric oxide (NO) oxidation during photocatalysis has been observed to result in the formation of nitric dioxide (NO2). This is a significant factor of the photocatalysis process, as NO2 is more toxic than NO. However, it has been reported that ozone (O3) is also formed during the photocatalytic reaction. This study analyzed the formation and oxidationof O3 during the photocatalytic oxidation of NO under ultraviolet irradiation using commercial photocatalytic powders: AEROXIDE® TiO2 P25 by Evonik, KRONOClean® 7050 by KRONOS®, and KRONOClean® 7000 by KRONOS®. An NO concentration of 100 ppb was assumed in laboratory tests based on the average nitric oxide concentrations recorded by the monitoring station in Warsaw. A mix flow-type reactor was applied in the study, and the appropriateness of its application was verified using a numerical model. The developed model assumed an empty reactor without a photocatalytic material, as well as a reactor with a photocatalytic material at its bottom to verify the gas flow in the chamber. The analysis of the air purification performance of photocatalytic powders indicated a significant reduction of NO and NOx and typical NO2 formation. However, no significant formation of O3 was observed. This observation was verified by the oxidation of pure ozone in the process of photocatalysis. The results indicated the oxidation of ozone concentration during the photocatalytic reaction, but self-decomposition of a significant amount of the gas.

APA, Harvard, Vancouver, ISO, and other styles

2

Khuzwayo, Z., and E. M. N. Chirwa. "Evaluation of flow-rate dynamics in the simultaneous photocatalytic treatment of multichlorinated substituted phenols in continuous-flow systems." Water Science and Technology 74, no. 9 (August 30, 2016): 2211–24. http://dx.doi.org/10.2166/wst.2016.411.

Full text

Abstract:

The project investigated the simultaneous degradation of chlorophenols dissolved in aqueous systems. The photocatalysis advanced oxidation process was the technology applied to achieve treatment. Chemical behavioural tracking was performed using the chloride dehalogenation sequence dynamics. The study recorded reductive dehalogenation chemical transformation kinetics of multi-substituted chlorinated phenolics in continuous flow reactor systems. This was performed by manipulation of liquid flow-rates in the photocatalytic oxidations process using suspended and immobilised catalyst applications. A modified Langmuir-Hinshelwood kinetic model was proposed that explained the oxidation transformational behaviour of the dehalogenation process derived intermediates. Complementary photocatalytic performance matrices were established for each flow regime; model parameters were calculated and estimated for behavioural profiles of all compounds under scrutiny.

APA, Harvard, Vancouver, ISO, and other styles

3

Kuliesiene, Neringa, Sandra Sakalauskaite, Simona Tuckute, Marius Urbonavicius, Sarunas Varnagiris, Rimantas Daugelavicius, and Martynas Lelis. "TiO2 Application for the Photocatalytical Inactivation of S. enterica, E. coli and M. luteus Bacteria Mixtures." Environmental and Climate Technologies 24, no. 3 (November 1, 2020): 418–29. http://dx.doi.org/10.2478/rtuect-2020-0113.

Full text

Abstract:

Abstract Water contamination by various bacteria, viruses and other pathogens is a great threat to human health. Amongst other Advanced Oxidation Processes TiO2 photocatalysis is considered as one of the most efficient treatment for the polluted wastewater disinfection. Usually, the wastewater produced by higher risk objects, such as hospitals, implicates diverse contaminants, but efficiency of most of the Advanced Oxidation Processes is tested by using only single pathogens and information on inactivation of bacteria mixtures is still limited. In this study, photocatalytical inactivation of three commonly found bacterial pathogens (gram-positive (Micrococcus luteus) and gram-negative (Salmonella enterica, Escherichia coli)) was investigated. Efficiency of traditional photocatalytic disinfection process using single bacterial pathogens was compared to the one observed for their mixtures. The impact of photocatalytical process parameters and treatment time on bacteria disinfection efficiency was studied. Photocatalytic disinfection efficiency testing with bacteria mixtures revealed, that in the presence of TiO2 photocatalyst and UV irradiation tested gram-positive cells were inactivated slower than gram-negative cells. Another important finding was that an overall photocatalytic disinfection efficiency of bacteria mixtures is not a straight forward sum of inactivation rates of individually tested pathogens but has a strong relationship to the properties of their competitive growth.

APA, Harvard, Vancouver, ISO, and other styles

4

Kuliesiene, Neringa, Sandra Sakalauskaite, Simona Tuckute, Marius Urbonavicius, Sarunas Varnagiris, Rimantas Daugelavicius, and Martynas Lelis. "TiO2 Application for the Photocatalytical Inactivation of S. enterica, E. coli and M. luteus Bacteria Mixtures." Environmental and Climate Technologies 24, no. 3 (November 1, 2020): 418–29. http://dx.doi.org/10.2478/rtuect-2020-0113.

Full text

Abstract:

AbstractWater contamination by various bacteria, viruses and other pathogens is a great threat to human health. Amongst other Advanced Oxidation Processes TiO2 photocatalysis is considered as one of the most efficient treatment for the polluted wastewater disinfection. Usually, the wastewater produced by higher risk objects, such as hospitals, implicates diverse contaminants, but efficiency of most of the Advanced Oxidation Processes is tested by using only single pathogens and information on inactivation of bacteria mixtures is still limited. In this study, photocatalytical inactivation of three commonly found bacterial pathogens (gram-positive (Micrococcus luteus) and gram-negative (Salmonella enterica, Escherichia coli)) was investigated. Efficiency of traditional photocatalytic disinfection process using single bacterial pathogens was compared to the one observed for their mixtures. The impact of photocatalytical process parameters and treatment time on bacteria disinfection efficiency was studied. Photocatalytic disinfection efficiency testing with bacteria mixtures revealed, that in the presence of TiO2 photocatalyst and UV irradiation tested gram-positive cells were inactivated slower than gram-negative cells. Another important finding was that an overall photocatalytic disinfection efficiency of bacteria mixtures is not a straight forward sum of inactivation rates of individually tested pathogens but has a strong relationship to the properties of their competitive growth.

APA, Harvard, Vancouver, ISO, and other styles

5

Tytgat, Tom, Birger Hauchecorne, Artem M. Abakumov, Marianne Smits, Sammy W. Verbruggen, and Silvia Lenaerts. "Photocatalytic process optimisation for ethylene oxidation." Chemical Engineering Journal 209 (October 2012): 494–500. http://dx.doi.org/10.1016/j.cej.2012.08.032.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Nikolenko, Anastasiya, and Boris Melnykov. "Photocatalytic Oxidation of Formaldehyde Vapour Using Amorphous Titanium Dioxide." Chemistry & Chemical Technology 4, no. 4 (December 15, 2010): 311–15. http://dx.doi.org/10.23939/chcht04.04.311.

Full text

Abstract:

The gas-phase photocatalytic oxidation of formaldehyde over illuminated amorphous titanium dioxide was investigated using a model flow reactor with the following experimental conditions: 0.1–0.5 l/min flow rate and an organic compound concentration range of 0.006–0.082 mol/m3. Mathematical model of the process which includes two sequential stages: formation of formic acid and its subsequent oxidation to CO2 was offered. It was found that when the amount of TiO2 on carrying agent (anodized titanium) is 3.6 mg/cm2, the intensity of UV lamp is 18 W and the catalyst temperature is 293 K, values of observed rate constants are equal to 6.5.10−3 s−1 for the first stage and 1.10−2 s−1 for the second stage of oxidation. The apparent activation energy of photocatalytic oxidation process of formaldehyde vapour for temperature interval 293 – 323 K is 20.2 kJ/mol.

APA, Harvard, Vancouver, ISO, and other styles

7

Quan, Yu Lian, Bi Qing Shi, Li Jing Yang, and Ren Zhi Zhang. "Pretreatment of Seawater by PAC/PAM Coagulation-Photocatalytic Oxidation Process." Advanced Materials Research 779-780 (September 2013): 1518–21. http://dx.doi.org/10.4028/www.scientific.net/amr.779-780.1518.

Full text

Abstract:

Coagulation-photocatalytic oxidation process was used for pretreatment of simulated seawater, which had moderate turbidity and more organics. The optimal conditions of PAC/PAM coagulation and TiO2 photocatalytic oxidation were investigated by simple variable method, coagulation and photocatalytic oxidation were combinated under optimal conditions finally. Results showed that when the dosage of polyacrylamide (PAM) and polyaluminium chloride (PAC) was 20mg/L and 0.5 mg/L respectively, the pH of simulated seawater was 8.0, the amount of TiO2 photocatalyst was 1.8g/L and UV radiation time was 1h, the removal ratio of the turbidity and CODMn in simulated seawater was 97.5% and 72% respectively. Synergistic effect between coagulation and photocatalytic oxidation eventually made turbidity and organics in the effluent water meet the requirements of reverse osmosis system.

APA, Harvard, Vancouver, ISO, and other styles

8

Coronel, Stalin, Diana Endara, Ana Belén Lozada, Lucía E. Manangón-Perugachi, and Ernesto de la Torre. "Photocatalytic Study of Cyanide Oxidation Using Titanium Dioxide (TiO2)-Activated Carbon Composites in a Continuous Flow Photo-Reactor." Catalysts 11, no. 8 (July 30, 2021): 924. http://dx.doi.org/10.3390/catal11080924.

Full text

Abstract:

The photocatalytic oxidation of cyanide by titanium dioxide (TiO2) supported on activated carbon (AC) was evaluated in a continuous flow UV photo-reactor. The continuous photo-reactor was made of glass and covered with a wood box to isolate the fluid of external conditions. The TiO2-AC synthesized by the impregnation of TiO2 on granular AC composites was characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), Scanning Electron Microscopy (SEM), and nitrogen adsorption-desorption isotherms. Photocatalytic and adsorption tests were conducted separately and simultaneously. The results showed that 97% of CN− was degraded within 24 h due to combined photocatalytic oxidation and adsorption. To estimate the contribution of only adsorption, two-stage tests were performed. First, 74% cyanide ion degradation was reached in 24 h under dark conditions. This result was attributed to CN− adsorption and oxidation due to the generation of H2O2 on the surface of AC. Then, 99% degradation of cyanide ion was obtained through photocatalysis during 24 h. These results showed that photocatalysis and the continuous photo-reactor’s design enhanced the photocatalytic cyanide oxidation performance compared to an agitated batch system. Therefore, the use of TiO2-AC composites in a continuous flow photo-reactor is a promising process for the photocatalytic degradation of cyanide in aqueous solutions.

APA, Harvard, Vancouver, ISO, and other styles

9

Shi, Laishun, Xiaomei Wang, Na Li, Chunlei Huai, and Jie Liu. "UV Irradiation Chlorine Dioxide Photocatalytic Oxidation of Simulated Fuchsine Wastewater by UV-Vis and Online FTIR Spectrophotometric Method." ISRN Analytical Chemistry 2012 (April 11, 2012): 1–7. http://dx.doi.org/10.5402/2012/951465.

Full text

Abstract:

The photocatalyst TiO2/SiO2 was prepared and used for chlorine dioxide photocatalytic oxidation of simulated fuchsine wastewater under UV irradiation. The removal efficiency of fuchsine treated by photocatalytic oxidation process is higher than that of chemical oxidation process. By using UV-Vis and online FTIR analysis technique, the intermediates during the degradation process were obtained. The benzene ring in fuchsine was degraded into quinone and carboxylic acid and finally changed into carbon dioxide and water during the photocatalytic oxidation. The degradation reaction mechanism of fuchsine by UV irradiation chlorine dioxide photocatalytic oxidation was proposed based upon the experiment evidence.

APA, Harvard, Vancouver, ISO, and other styles

10

Lu, Ming-Chun, and Jong-Nan Chen. "Pretreatment of pesticide wastewater by photocatalytic oxidation." Water Science and Technology 36, no. 2-3 (July 1, 1997): 117–22. http://dx.doi.org/10.2166/wst.1997.0497.

Full text

Abstract:

The toxic chemicals, 2,4-D (a herbicide) and propoxur (an insecticide), were used as the model compounds in these experiments. Total organic carbon analyzer was used to assess the efficiency of photocatalytic mineralization. Microtox bioassay was employed in evaluating the toxicity of solutions treated by photocatalysis. Ultraviolet absorption spectra were also used for showing the different characteristics of the compounds undergoing photocatalytic oxidation. Results show that propoxur is less degradable than 2,4-D, and the photomineralization of these pesticides follows a behavior of first-order reaction. Products of 2,4-D and propoxur are more toxic than the parent compound after partial photodegradation. This shows that complete mineralization is necessary for total detoxification of these pesticides. In other words, toxicity is an important criteria in assessing the pretreatment process.

APA, Harvard, Vancouver, ISO, and other styles

11

Salvadores, Federico, Orlando Mario Alfano, and María de los Milagros Ballari. "ASSESSMENT OF THE INDOOR AIR PURIFICATION BY PHOTOCATALYTIC PAINTS." Latin American Applied Research - An international journal 50, no. 2 (February 21, 2020): 71–76. http://dx.doi.org/10.52292/j.laar.2020.352.

Full text

Abstract:

Photocatalytic building materials containing TiO2 were extensively studied for outdoor applications using solar radiation. Nowadays, the market offers a wide variety of these materials with self-cleaning and air purification functionalities. However, heterogeneous photocatalysis applied in indoor construction materials was less developed. The objective of this work is to investigate the photocatalytic performance of carbon doped TiO2 in replacement of the normal pigments in indoor wall paint formulations. To achieve this goal, the photocatalytic oxidation of acetaldehyde in gas phase was carried out. The air decontamination process was conducted using regular indoor light in a bench scale chamber photoreactor simulating a room. The main environmental conditions that affect the photocatalytic process were varied: air flow rate, irradiance, relative humidity and acetaldehyde concentration. The results were analyzed through the response surface methodology and revealed the air purifying power of photocatalytic paints under indoor conditions.

APA, Harvard, Vancouver, ISO, and other styles

12

Xiaoju, Yan, Bao Ruiling, Yu Shuili, Li Qiongfang, and Chen Wei. "Photocatalytic oxidation of humic acid and its effect on haloacetic acid formation potential: a fluorescence spectrometry study." Water Science and Technology 65, no. 9 (May 1, 2012): 1548–56. http://dx.doi.org/10.2166/wst.2012.046.

Full text

Abstract:

By fluorescence spectrometry method, molecular conformation changes of humic acid (HA) during the photocatalytic oxidation process were studied. Haloacetic acids formation potential (HAAFP) changes during the oxidation process were also measured. The results indicated that aromatic rings of HA decreased and conjugated double bonds were destroyed at the beginning of the process. Meanwhile, organic matter with large molecular weight decomposed into intermediates with smaller molecular weight, such as tryptophan and tyrosine. HA can be degraded almost completely, but not be mineralized thoroughly. Structures of the intermediates were changing during the oxidation process. Molecular structure transformation of HA led to the fluctuation tendency of the HAAFP changes during the photocatalytic oxidation process. HAAFP increased to 1.22 times that in raw water after 30 min of ultraviolet (UV) radiation, and decreased to 0.66 times that in raw water after 60 min of photocatalytic oxidation.

APA, Harvard, Vancouver, ISO, and other styles

13

Bobirică, Liliana, Constantin Bobirică, Giovanina Iuliana Lupu, and Cristina Orbeci. "Influence of Operating Parameters on Photocatalytic Oxidation of 2,4-Dichlorofenol in Aqueous Solution by TiO2/Stainless Steel Photocatalytic Membrane." Applied Sciences 11, no. 24 (December 9, 2021): 11664. http://dx.doi.org/10.3390/app112411664.

Full text

Abstract:

The influence of some operating parameters of an UV photocatalytic reactor with TiO2/stainless steel photocatalytic membrane on the photocatalytic oxidation of 2,4-dichlorophenol from aqueous solutions was studied in this paper. It was shown that the pH of the working solution substantially influences the photocatalytic degradation of the organic substrate, with the degradation efficiency increasing with decreasing the pH of the working solution by a maximum corresponding to pH 3. The rate constant of the photocatalytic oxidation process is about twice as high at pH 3 comparative with pH 7 for the same initial concentration of the organic substrate. The molar ratio of hydrogen peroxide/organic substrate also influences the photocatalytic oxidation process of the organic substrate. The results obtained in this paper highlight the fact that a stoichiometric molar ratio is favorable for the photocatalytic degradation of 2,4-dichlorophenol. It has also been shown that the initial concentration of the organic substrate influences the rate of photocatalytic degradation. It appears that the rate of photocatalytic degradation decreases with the increasing of initial concentration of 2,4-dichlorophenol.

APA, Harvard, Vancouver, ISO, and other styles

14

Chen, Sheng Wen, Wen Chao Li, Zhi Guo Sun, and Hong Yong Xie. "Degradation of Artificial Sweetener Saccharin Sodium by Advanced Oxidation Technology." Applied Mechanics and Materials 448-453 (October 2013): 7–10. http://dx.doi.org/10.4028/www.scientific.net/amm.448-453.7.

Full text

Abstract:

In this paper, the advanced oxidation processes of photocatalytic oxidation and Photo-Fenton oxidation were used in degradation of emerging pollutants saccharin sodium. The concentration of saccharin sodium was determined by HPLC. The results showed both photocatalytic oxidation and Photo-Fenton oxidation had an effective degradation of saccharin sodium. The degradation process was followed the first-order reaction. The best conditions of photocatalytic oxidation system: 500W mercury lamp, 0.04 g TiO2, pH=7 and the best ratio of photo-Fenton was SAC:H2O2:Fe2+=5:60:1. The total organic carbon (TOC) of sample has significantly reduced to about 93% by the two systems.

APA, Harvard, Vancouver, ISO, and other styles

15

Wahyuni, Endang Tri, Titi Rahmaniati, Aulia Rizky Hafidzah, Suherman Suherman, and Adhitasari Suratman. "Photocatalysis over N-Doped TiO2 Driven by Visible Light for Pb(II) Removal from Aqueous Media." Catalysts 11, no. 8 (August 5, 2021): 945. http://dx.doi.org/10.3390/catal11080945.

Full text

Abstract:

The photocatalysis process over N-doped TiO2 under visible light is examined for Pb(II) removal. The doping TiO2 with N element was conducted by simple hydrothermal technique and using urea as the N source. The doped photocatalysts were characterized by DRUVS, XRD, FTIR and SEM-EDX instruments. Photocatalysis of Pb(II) through a batch experiment was performed for evaluation of the doped TiO2 activity under visible light, with applying various fractions of N-doped, photocatalyst mass, irradiation time, and solution pH. The research results attributed that N doping has been successfully performed, which shifted TiO2 absorption into visible region, allowing it to be active under visible irradiation. The photocatalytic removal of Pb(II) proceeded through photo-oxidation to form PbO2. Doping N into TiO2 noticeably enhanced the photo-catalytic oxidation of Pb(II) under visible light irradiation. The highest photocatalytic oxidation of 15 mg/L Pb(II) in 25 mL of the solution could be reached by employing TiO2 doped with 10%w of N content 15 mg, 30 min of time and at pH 8. The doped-photocatalyst that was three times repeatedly used demonstrated significant activity. The most effective process of Pb(II) photo-oxidation under beneficial condition, producing less toxic and handleable PbO2 and good repeatable photocatalyst, suggest a feasible method for Pb(II) remediation on an industrial scale.

APA, Harvard, Vancouver, ISO, and other styles

16

Qi, Yifei, Xiaoyue Zhou, Zhenjie Li, Renli Yin, Junhao Qin, Huashou Li, Wanqian Guo, Adela Jing Li, and Rongliang Qiu. "Photo-Induced Holes Initiating Peroxymonosulfate Oxidation for Carbamazepine Degradation via Singlet Oxygen." Catalysts 12, no. 11 (October 28, 2022): 1327. http://dx.doi.org/10.3390/catal12111327.

Full text

Abstract:

Peroxymonosulfate (PMS) has been intensively used to enhance the photocatalytic activity of catalysts, which is adopted as an electron acceptor to inhibit the recombination of electrons and holes. However, the effect of holes generated by visible light (VL) on PMS activation is always overlooked. Herein, the VL/Bi2WO6/PMS process was constructed for the efficient removal of organics, in which the degradation rate of carbamazepine (CBZ) increased by over 33.0 times by the introduction of PMS into Bi2WO6 under visible light. The radical quenching and determination experiments confirmed that the photogenerated holes could firstly oxidize PMS to form SO5•− and react with HSO5− to produce 1O2, then inducing the formation of other reactive species to greatly enhance the performance of pollutant removal by the VL/Bi2WO6/PMS process. Density functional theory (DFT) predicted that sites with high Fukui index (f0) on CBZ were more susceptible to being attacked, resulting in hydroxylation, ring closure, and C=C bond cleavage of CBZ. Toxicity estimation indicated that photocatalysis degradation products from CBZ were less toxic compared to the parent compound. This study provides a potential avenue for improving photocatalytic efficiency and widening the application of photocatalytic technology in wastewater purification.

APA, Harvard, Vancouver, ISO, and other styles

17

Lolli, Alice, Valeriia Maslova, Danilo Bonincontro, Francesco Basile, Simona Ortelli, and Stefania Albonetti. "Selective Oxidation of HMF via Catalytic and Photocatalytic Processes Using Metal-Supported Catalysts." Molecules 23, no. 11 (October 27, 2018): 2792. http://dx.doi.org/10.3390/molecules23112792.

Full text

Abstract:

In this study, 5-hydroxymethylfurfural (HMF) oxidation was carried out via both the catalytic and the photocatalytic approach. Special attention was devoted to the preparation of the TiO2-based catalysts, since this oxide has been widely used for catalytic and photocatalytic application in alcohol oxidation reactions. Thus, in the catalytic process, the colloidal heterocoagulation of very stable sols, followed by the spray-freeze-drying (SFD) approach, was successfully applied for the preparation of nanostructured porous TiO2-SiO2 mixed-oxides with high surface areas. The versatility of the process made it possible to encapsulate Pt particles and use this material in the liquid-phase oxidation of HMF. The photocatalytic activity of a commercial titania and a homemade oxide prepared with the microemulsion technique was then compared. The influence of gold, base addition, and oxygen content on product distribution in the photocatalytic process was evaluated.

APA, Harvard, Vancouver, ISO, and other styles

18

KARTAL TEMEL, Nuket, and Esra BAĞDA. "Decolourization of Methylene Blue in Aqueous Solution by Photocatalytic Oxidation, Fenton Oxidation and Biosorption." Cumhuriyet Science Journal 43, no. 4 (December 27, 2022): 638–44. http://dx.doi.org/10.17776/csj.1116265.

Full text

Abstract:

The aim of the study was to investigate decolourization of Methylene Blue (MB) in aqueous solution using advanced oxidation processes (AOPs) and biosorption comparatively. Photocatalytic decolourization of MB was studied using TiO2 as catalyst. The photocatalytic decolourization of MB by direct UV irradiation alone, only TiO2 and TiO2/UV processes was investigated. It was found that decolourization by photocatalytic process of MB increased with decreasing pH, and decolourization rate also increased in the presence of TiO2/UV when compared to UV irradiation alone. Decolourization of MB was also studied with using the Fenton process (Fe(II)/H2O2). Concentrations of Fe(II) and H2O2 on decolourization ratio were investigated. The optimum catalyst to H2O2 ratio was found 1:3 at pH 4.0. In the second part of the study, the biosorption process was conducted with using plant gall immobilised alumina. The removal percentages were calculated with both plant gall immobilised alumina and alumina alone. The immobilisation of plant gall increased the removal percentages from 60-70% to 90-95%. The proposed methods (AOPs and biosorption) have both advantages and disadvantages compared to each other.

APA, Harvard, Vancouver, ISO, and other styles

19

Betancourt-Buitrago, Luis Andrés, Aracely Hernandez-Ramirez, Jose Angel Colina-Marquez, Ciro Fernando Bustillo-Lecompte, Lars Rehmann, and Fiderman Machuca-Martinez. "Recent Developments in the Photocatalytic Treatment of Cyanide Wastewater: An Approach to Remediation and Recovery of Metals." Processes 7, no. 4 (April 20, 2019): 225. http://dx.doi.org/10.3390/pr7040225.

Full text

Abstract:

For gold extraction, the most used extraction technique is the Merrill-Crow process, which uses lixiviants as sodium or potassium cyanide for gold leaching at alkaline conditions. The cyanide ion has an affinity not only for gold and silver, but for other metals in the ores, such as Al, Fe, Cu, Ni, Zn, and other toxic metals like Hg, As, Cr, Co, Pb, Sn, and Mn. After the extraction stage, the resulting wastewater is concentrated at alkaline conditions with concentrations up to 1000 ppm of metals. Photocatalysis is an advanced oxidation process (AOP) able to generate a photoreaction in the solid surface of a semiconductor activated by light. Although it is well known that photocatalytic processes can remove metals in solution, there are no compilations about the researches on photocatalytic removal of metals in wastewater with cyanide. Hence, this review comprises the existing applications of photocatalytic processes to remove metal and in some cases recover cyanide from recalcitrant wastewater from gold extraction. The use of this process, in general, requires the addition of several scavengers in order to force the mechanism to a pathway where the electrons can be transferred to the metal-cyanide matrices, or elsewhere the entire metallic cyanocomplex can be degraded by an oxidative pathway.

APA, Harvard, Vancouver, ISO, and other styles

20

Pucher, Peter, Rabah Azouani, Andrei Kanaev, and Gernot Krammer. "A Photocatalytic Active Adsorbent for Gas Cleaning in a Fixed Bed Reactor." International Journal of Photoenergy 2008 (2008): 1–7. http://dx.doi.org/10.1155/2008/759736.

Full text

Abstract:

Efficient photocatalysis for gas cleaning purposes requires a large accessible, illuminated active surface in a simple and compact reactor. Conventional concepts use powdered catalysts, which are nontransparent. Hence a uniform distribution of light is difficult to be attained. Our approach is based on a coarse granular, UV-A light transparent, and highly porous adsorbent that can be used in a simple fixed bed reactor. A novel sol-gel process with rapid micro mixing is used to coat a porous silica substrate withTiO2-based nanoparticles. The resulting material posses a high adsorption capacity and a photocatalytic activity under UV-A illumination (PCAA = photocatalytic active adsorbent). Its photocatalytic performance was studied on the oxidation of trichloroethylene (TCE) in a fixed bed reactor setup in continuous and discontinuous operation modes. Continuous operation resulted in a higher conversion rate due to less slip while discontinuous operation is superior for a total oxidation toCO2due to a user-defined longer residence time.

APA, Harvard, Vancouver, ISO, and other styles

21

Muthukumaran, Shobha, Lili Song, Bo Zhu, Darli Myat, Jin-Yuan Chen, Stephen Gray, and Mikel Duke. "UV/TiO2 photocatalytic oxidation of recalcitrant organic matter: effect of salinity and pH." Water Science and Technology 70, no. 3 (May 27, 2014): 437–43. http://dx.doi.org/10.2166/wst.2014.221.

Full text

Abstract:

Photocatalytic oxidation processes have interest for water treatment since these processes can remove recalcitrant organic compounds and operate at mild conditions of temperature and pressure. However, performance under saline conditions present in many water resources is not well known. This study aims to explore the basic effects of photocatalysis on the removal of organic matter in the presence of salt. A laboratory-scale photocatalytic reactor system, employing ultraviolet (UV)/titanium dioxide (TiO2) photocatalysis was evaluated for its ability to remove the humic acid (HA) from saline water. The particle size and zeta potential of TiO2 under different conditions including solution pH and sodium chloride (NaCl) concentrations were characterized. The overall degradation of organics over the NaCl concentration range of 500–2,000 mg/L was found to be 80% of the non-saline equivalent after 180 min of the treatment. The results demonstrated that the adsorption of HA onto the TiO2 particles was dependent on both the pH and salinity due to electrostatic interaction and highly unstable agglomerated dispersion. This result supports UV/TiO2 as a viable means to remove organic compounds, but the presence of salt in waters to be treated will influence the performance of the photocatalytic oxidation process.

APA, Harvard, Vancouver, ISO, and other styles

22

Sakhnenko, Mykola, Serhii Indykov, and Hanna Karakurkchi. "APPLICATION OF PLASMA-ELECTROLYTE COATINGS ON TITANIUM WITH REFRACTORY METALS FOR DETOXIFICATION OF ENVIRONMENTS FROM POLLUTING SUBSTANCES." Bulletin of the National Technical University «KhPI» Series: New solutions in modern technologies, no. 1(7) (April 23, 2021): 96–102. http://dx.doi.org/10.20998/2413-4295.2021.01.14.

Full text

Abstract:

Based on the review of the peculiarities of the photocatalytic processes, the peculiarities of the catalytic action of oxide systems based on titanium dioxide are determined. It is shown that TiO2 is one of the most chemically and thermally stable and non-toxic inorganic oxides of semiconductors, whose photocatalytic activity is manifested by irradiation with ultraviolet part of the spectrum (λ 320–400 nm) and allows the oxidation of a significant amount of toxic agents to water and carbon dioxide. The essence of the photocatalytic process of oxidation of toxicants under the action of UV radiation on the TiO2 surface is considered. The proposed technology of photocatalytic detoxification of contaminants is economically available, environmentally friendly and allows its widespread use, in particular for autonomous systems, including dual purpose. It is established that the main requirements for materials for photocatalysis are their chemical and biological inertness, photocatalytic stability and activity, low cost. It is shown that the most rational technological form of the photocatalyst is the application (synthesis) of the catalytic layer on structured metal substrates, in particular titanium alloys. It is proved that these catalytic oxide systems can be effectively formed by the method of plasma-electrolyte oxidation in aqueous electrolytes with the addition of dopant metal compounds that increase the photocatalytic activity of the obtained heterooxide systems. It is proposed to use tungsten oxides of variable valence as the target additive. The kinetic regularities of the process of plasma-electrolytic oxidation of titanium VT1-0 in a diphosphate-borate electrolyte with the addition of tungstates have been studied. It is shown that in an electrolyte of this type at a current density of 1.0 A/dm2 in the galvanostatic mode for 30 min a uniform coating of TiO2·WxOy with a tubular torus-like structure and tungsten content of 2.5–7.5 wt.% is formed. The predicted quantitative composition of the heteroxide layer in combination with the surface morphology creates the preconditions for high catalytic activity of the synthesized coating for detoxification of media from anthropogenic pollutants.

APA, Harvard, Vancouver, ISO, and other styles

23

Ma, Chih-Ming, and Young Ku. "Photocatalytic oxidation of gaseous trichloroethylene by UV/TiO2 process." Reaction Kinetics and Catalysis Letters 89, no. 2 (August 2006): 293–301. http://dx.doi.org/10.1007/s11144-006-0140-1.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Henríquez, Adolfo, Victoria Melin, Nataly Moreno, Héctor D. Mansilla, and David Contreras. "Optimization of Cyclohexanol and Cyclohexanone Yield in the Photocatalytic Oxofunctionalization of Cyclohexane over Degussa P-25 under Visible Light." Molecules 24, no. 12 (June 15, 2019): 2244. http://dx.doi.org/10.3390/molecules24122244.

Full text

Abstract:

The sustainable transformation of basic chemicals into organic compounds of industrial interest using mild oxidation processes has proved to be challenging. The production of cyclohexanol and cyclohexanone from cyclohexane is of interest to the nylon manufacturing industry. However, the industrial oxidation of cyclohexane is inefficient. Heterogeneous photocatalysis represents an alternative way to synthesize these products, but the optimization of this process is difficult. In this work, the yields of photocatalytic cyclohexane conversion using Degussa P-25 under visible light were optimized. To improve cyclohexanol production, acetonitrile was used as an inert photocatalytic solvent. Experiments showed that the use of the optimized conditions under solar light radiation did not affect the cyclohexanol/cyclohexanone ratio. In addition, the main radical intermediary produced in the reaction was detected by the electronic paramagnetic resonance technique.

APA, Harvard, Vancouver, ISO, and other styles

25

Journal, Baghdad Science. "Toxicity Reduction of Reactive Red Dye-238 Using Advanced Oxidation Process by Solar Energy." Baghdad Science Journal 14, no. 3 (September 3, 2017): 516–23. http://dx.doi.org/10.21123/bsj.14.3.516-523.

Full text

Abstract:

Decolorization of red azo dye (Cibacron Red FN-R) from synthetic wastewater has been investigated as a function of solar advanced oxidation process. The photocatalytic activity using ZnO as a photocatalysis has been estimated. Different parameters affected the removal efficiency, including pH of the solution, initial dye concentration and H2O2 concentration were evaluated to find out the optimum value of these parameters. The results proved that the optimal pH value was 8 and the most efficient H2O2 concentration was 100mg/L. Toxicity reduction percent for effluent solution was also monitored to assess the degradation process. This treatment method was able to strongly reduce the color and toxicity of reactive red dye-238 to about (99 and 80) % respectively. It can be concluded, from these experiments, that the using of ZnO as a photocatalysis was exhibited as economical and efficient treatment method to remove reactive red dye-238 from aqueous solution.

APA, Harvard, Vancouver, ISO, and other styles

26

Bodzek, Michał, and Mariola Rajca. "Photocatalysis in the treatment and disinfection of water. Part I. Theoretical backgrounds / Fotokataliza w oczyszczaniu i dezynfekcji wody część i. podstawy teoretyczne." Ecological Chemistry and Engineering S 19, no. 4 (November 1, 2012): 489–512. http://dx.doi.org/10.2478/v10216-011-0036-5.

Full text

Abstract:

Abstract Photocatalysis process belongs to an advanced oxidation technology for the removal of persistent organic compounds and microorganisms from water. It is the technology with a great potential, a low-cost, environmental friendly and sustainable treatment technology to align with the “zero” waste scheme in the water/wastewater industry. At present, the main technical barriers that impede its full commercialization remained on the post-recovery of the catalyst particles after water treatment. This paper reviews the background of the process and photooxidation mechanisms of the organic pollutants and microorganisms. The review of the latest progresses of engineered-photocatalysts, photo-reactor systems, and the kinetics and modeling associated with the photocatalytic and photodisinfection water and wastewater treatment process, has been presented. A number of potential and commercial photocatalytic reactor configurations are discussed, in particular the photocatalytic membrane reactors. The effects of key photo-reactor operation parameters and water quality on the photoprocess performances in terms of the mineralization and disinfection are assessed.

APA, Harvard, Vancouver, ISO, and other styles

27

Ivantsova, Natalya A., Evgeniy N. Kuzin, and Alina A. Churina. "Photocatalytic water purification from phenol and formaldehyde." Izvestiya of Saratov University. Chemistry. Biology. Ecology 22, no. 3 (September 22, 2022): 275–81. http://dx.doi.org/10.18500/1816-9775-2022-22-3-275-281.

Full text

Abstract:

Industrial development leads to an increasing number of persistent and highly toxic organic compounds such as phenol and formaldehyde. Chemical oxidation processes (in particular, photooxidation) are widely used for water treatment and wastewater and groundwater treatment. As part of the work done, an assessment of the possibility of using photocatalysis for post-treatment of wastewater from phenol, formaldehyde, and their mixtures has been carried out. The processes of photooxidation of formaldehyde, phenol and their mixtures in an aqueous medium under the individual and combined effects of ultraviolet radiation and titanyl sulfate have been studied. The high efficiency (up to 90%) of photocatalytic post-treatment of wastewater containing phenol and formaldehyde has been determined. It has been established that ultraviolet water treatment under static conditions can significantly reduce the concentrations of phenol and formaldehyde to the values of the discharge standard into the city water canal. It has been proven that the introduction of titanyl sulfate microadditives (homogeneous photocatalytic process) makes it possible to intensify the oxidation process, while the addition of titanium(IV) compounds, due to its chemical inertness, will not have a toxic effect on the activated sludge biocenosis. Possible intermediate products of photooxidative degradation of phenol and formaldehyde are qualitatively determined. The kinetic dependences of the oxidation of phenol, formaldehyde and their mixtures are obtained, which allow further scaling up the process of photodegradation with the introduction of homogeneous catalysts for industrial facilities into the system. The proposed post-treatment method is included in the Best Available Techniques directory and will improve environmental and industrial safety.

APA, Harvard, Vancouver, ISO, and other styles

28

Gandhi, Vimal, Manish Mishra, and P. A. Joshi. "Titanium Dioxide Catalyzed Photocatalytic Degradation of Carboxylic Acids from Waste Water: A Review." Materials Science Forum 712 (February 2012): 175–89. http://dx.doi.org/10.4028/www.scientific.net/msf.712.175.

Full text

Abstract:

Among the new oxidation methods in advanced oxidation processes, heterogeneous photocatalysis based on UV/ titanium dioxide is one of the emerging technologies for degrading and totally mineralizing toxic and highly stable carboxylic acids from waste water has attracted great attention in last decade. The aliphatic and aromatic carboxylic acids are widely used as reactants or produced as main products or byproducts in various chemical process industries. These chemical process industries generates waste water containing significant amount of carboxylic acids, which need to be removed from waste water before disposal to natural water bodies due to the environmental restrictions and their hazardous effects on flora and fauna. This paper reviews photocatalytic degradation (PCD) process for various carboxylic acids in detail, including basic mechanism of titanium dioxide, effect of carboxylic acid structure and various reaction parameters like effect of initial concentration and kinetic study, catalyst loading, pH, adsorption and deactivation of the photocatalyst. A critical analysis of the available literature has been made and some general conclusions have been drawn related to the above mentioned parameters. The photocatalytic degradation pathways for carboxylic acids are also discussed to understand this process thoroughly.

APA, Harvard, Vancouver, ISO, and other styles

29

Hot, J., J. Topalov, E. Ringot, and A. Bertron. "Investigation on Parameters Affecting the Effectiveness of Photocatalytic Functional Coatings to Degrade NO: TiO2 Amount on Surface, Illumination, and Substrate Roughness." International Journal of Photoenergy 2017 (2017): 1–14. http://dx.doi.org/10.1155/2017/6241615.

Full text

Abstract:

This paper deals with the degradation of NO by photocatalytic oxidation using TiO2-based coatings. Tests are conducted at a laboratory scale through an experimental setup inspired from ISO 22197-1 standard. Various parameters are explored to evaluate their influence on photocatalysis efficiency: TiO2 dry matter content applied to the surface, nature of the substrate, and illumination conditions (UV and visible light). This article points out the different behaviors between three kinds of substrates which are common building materials: normalized mortar, denser mortar, and commercial wood. The illumination conditions are of great importance in the photocatalytic process with experiments under UV light showing the best results. However, a significant decrease in NO concentration under visible light is also observed provided that the TiO2 dry matter content on the surface is high enough. The nature of the substrate plays an important role in the photocatalytic activity with rougher substrates being more efficient to degrade NO. However, limiting the roughness of the substrate seems to be of utmost interest to obtain the highest exposed surface area and thus the optimal photocatalytic efficiency. A higher roughness promotes the surface contact between TiO2 and NO but does not necessarily increase the photochemical oxidation.

APA, Harvard, Vancouver, ISO, and other styles

30

Davis, A. P., and C. P. Huang. "Removal of Phenols from Water by a Photocatalytic Oxidation Process." Water Science and Technology 21, no. 6-7 (June 1, 1989): 455–64. http://dx.doi.org/10.2166/wst.1989.0248.

Full text

Abstract:

Photocatalyst, CdS, upon irradiation by bandgap energy produces electrons and positive holes. The positive holes are strong oxidizing agents that can render organic compounds such as phenol oxidized. The rate of phenol oxidation depends upon factors such as pH, phenol concentration, photointensity, oxygen concentration and temperature. An increase in the degree of chlorination appears to render phenols more oxidizable. Among the chlorinated phenols studied, the ease in oxidation increases in the order: 2,4,6-trichlorophenol > 2,4-dichlorophenol > 2-chlorophenol > phenol.

APA, Harvard, Vancouver, ISO, and other styles

31

Mounteer, A. H., R. O. Pereira, A. A. Morais, D. B. Ruas, D. S. A. Silveira, D. B. Viana, and R. C. Medeiros. "Advanced oxidation of bleached eucalypt kraft pulp mill effluent." Water Science and Technology 55, no. 6 (March 1, 2007): 109–16. http://dx.doi.org/10.2166/wst.2007.218.

Full text

Abstract:

In this study a poorly biodegradable (BOD/COD = 0.3) industrial alkaline ECF bleaching filtrate was treated using different advanced oxidation processes to evaluate their use in combined chemical–biological treatment aimed at increasing recalcitrant COD removal and improving final effluent quality. Oxidative treatments included ozonation combined with hydrogen peroxide (2, 5, 10, 20 mmol L−1 O3/0.7, 2, 5, 10 mmol L−1 H2O2) and photocatalysis with hydrogen peroxide (UV/2, 4 and 8 mmol L−1 H2O2) and with TiO2 (UV/TiO2/0.7 and 4 mmol L−1 H2O2). The O3/H2O2 process increased effluent biodegradability by up to 68% as a result of increasing BOD and decreasing COD. Increasing the O3 dose had a greater effect on biodegradability improvement and lignin and colour removal efficiencies than increasing the H2O2 dose. A combined oxidant dose of 5 mmol L−1 O3 and 2 mmol L−1 H2O2 resulted in 75% lignin removal, 40% colour removal and 6% carbohydrate loss without mineralizing the organic carbon. The photocatalytic processes led to a decrease in effluent biodegradability through combined decrease in BOD and increase in COD and did not result in efficient lignin or colour removal. Photocatalytic oxidation was apparently inhibited by the high chloride and COD levels in the alkaline filtrate, and may be more efficient in recalcitrant COD removal if performed after biological.

APA, Harvard, Vancouver, ISO, and other styles

32

Hassan, Ahmed K., Adnan F. Hassan, Alaa Jasim, and Salam Naser Owaiyd. "Treatment of Contaminated Textile Factories’ Wastewater by Photocatalyst Degradation." Iraqi Journal of Industrial Research 9, no. 2 (October 20, 2022): 132–40. http://dx.doi.org/10.53523/ijoirvol9i2id162.

Full text

Abstract:

The aim of this work is remove the textile factories’ wastewater such as dyes via the Advanced Oxidation Processes (AOPs) that on using the nano titanium dioxide photocatalytic degradation. The degradation of C. I. Reactive black 45 (RB 45) in aqueous medium by the photocatalysis process has been studied. The effects of several parameters such as pH, the concentration of TiO2, irradiation time, and dye concentration have been examined. The optimal parameters were found to be [TiO2] = 0.75 g/L, irradiation time 480 min and pH=3.0. The results shown that the photocatalytic degradation could be enhanced by adding hydrogen peroxide H2O2 or potassium persulfate K2S2O8, for example, the efficiency increased from 68.9% to 88.7% and 95.4% when added 0.027 M or 1.5 g/L of H2O2 and K2S2O8 respectively. Also, the effects of inorganic salts Na2SO4, Na2CO3, and NaCl on the degradation efficiency of the photocatalysis process were investigated.

APA, Harvard, Vancouver, ISO, and other styles

33

Que, Vo Nguyen Xuan, Tran Tien Khoi, Nguyen Thi Thuy, Ta Thi Minh Dung, Dao Thi Thanh Binh, and Nguyen Nhat Huy. "Factors Determining the Removal Efficiency of Procion MX in Waters Using Titanate Nanotubes Catalyzed by UV Irradiation." Journal of Nanotechnology 2021 (May 18, 2021): 1–10. http://dx.doi.org/10.1155/2021/8870453.

Full text

Abstract:

The treatment of wastewater from the textile industry containing organic dyes faces many challenges since these compounds resist the biodegradation process in conventional treatment units. Among the physicochemical processes, photocatalysis is considered a facile, cheap, and environmental-friendly technology for treating persistent organic pollutants in waters at low concentrations. This study investigated several physicochemical factors determining the photocatalytic activity of titanate nanotubes (TNTs) to remove Procion MX 032 (PMX), an azo dye, in waters. Degradation of PMX by photocatalytic oxidation process at room temperature (30°C) was set up with the UV irradiation in the presence of different types of photocatalyst such as ST-01 (100% anatase), industrial TiO2, TNTs calcined at 120°C and 500°C. Effect of reaction time, catalyst amount, pH, light wavelength and intensity, and oxidants was investigated. Consequently, TNTs calcined at 500°C provided the highest removal efficiency. The photocatalytic oxidation of PMX by TNT calcined at 500°C was affected by pH variation, getting the highest removal at pH of 8, and inhibited with the presence of H2O2 and O2. Particularly, the PMX degradation using titanate nanotubes was optimized under the UV-A intensity of 100 W/m2. The dye was degraded by more than 95% at the TNTs concentration of 75 mg/L and pH 8.0 after 90 min. The results suggest that photocatalysis using TNTs can be a simple but efficient treatment method to remove PMX and potentially be applied for the treatment of wastewaters containing dyes.

APA, Harvard, Vancouver, ISO, and other styles

34

Li, Z., H. Gulyas, M. Jahn, D. R. Gajurel, and R. Otterpohl. "Greywater treatment by constructed wetlands in combination with TiO2-based photocatalytic oxidation for suburban and rural areas without sewer system." Water Science and Technology 48, no. 11-12 (December 1, 2004): 101–6. http://dx.doi.org/10.2166/wst.2004.0815.

Full text

Abstract:

In this study greywater treatment through constructed wetlands and subsequently through TiO2-based photocatalytic oxidation was investigated. Through constructed wetlands treatment the organic substances have been reduced greatly. For further removal of organic substances and pathogens, a TiO2-based photocatalytic oxidation process was used subsequently. The results showed that the treated greywater through constructed wetlands and subsequent through TiO2-based photocatalytic oxidation with short irradiation time (3 hours irradiation time) met the requirements of European bathing water quality easily. Therefore, the greywater treated with the processes combination can directly be reused for non-potable purposes. Moreover, since residual organic substances through TiO2-based photocatalytic oxidation with long irradiation time can be eliminated almost totally, it is also possible that treated greywater is used for groundwater recharge as a drinking water resource.

APA, Harvard, Vancouver, ISO, and other styles

35

Selvabharathi, G., S. Adishkumar, S. Jenefa, G. Ginni, J. Rajesh Banu, and Ick Tae Yeom. "Combined homogeneous and heterogeneous advanced oxidation process for the treatment of tannery wastewaters." Journal of Water Reuse and Desalination 6, no. 1 (June 22, 2015): 59–71. http://dx.doi.org/10.2166/wrd.2015.139.

Full text

Abstract:

This study investigated the practical application of combined advanced oxidation processes (AOPs), such as homogeneous TiO2 photocatalysis and heterogeneous photo-Fenton, for the treatment of tannery wastewaters. An optimization study was conducted on the photocatalytic degradation of tannery wastewaters, in order to understand the effects of different operating parameters on the degradation kinetics. The chemical oxygen demand of tannery wastewater decreased from an initial level of 3,400 mg/L in raw wastewater to 140 mg/L (96% removal) in wastewater treated by the combined advanced oxidation process at optimum pH 7, TiO2 dosage of 0.2 g/L, Fe2+ dosage of 0.5 g/L, H2O2 dosage of 1.8 g/L and a treatment time of 4 hours. The biodegradability of wastewater increased from an initial level of 0.4 to 0.7 after treatment under optimum experimental conditions at a treatment time of 60 min. An annual treatment cost of US$21.34/m3 of treated water was obtained. The combined advanced oxidation process proved to be an efficient and appropriate technique for the effective removal of complex organic compounds in industrial wastewater.

APA, Harvard, Vancouver, ISO, and other styles

36

Huang, Zhuquan, Jiaqi Wang, Min-Quan Yang, Qingrong Qian, Xin-Ping Liu, Liren Xiao, and Hun Xue. "Construction of TiO2-Eggshell for Efficient Degradation of Tetracycline Hydrochloride: Sunlight Induced In-Situ Formation of Carbonate Radical." Materials 14, no. 7 (March 25, 2021): 1598. http://dx.doi.org/10.3390/ma14071598.

Full text

Abstract:

Photocatalytic degradation of an antibiotic by utilizing inexhaustible solar energy represents an ideal solution for tackling global environment issues. The target generation of active oxidative species is highly desirable for the photocatalytic pollutants degradation. Herein, aiming at the molecular structure of tetracycline hydrochloride (TC), we construct sunlight-activated high-efficient catalysts of TiO2-eggshell (TE). The composite ingeniously utilizes the photoactive function of TiO2 and the composition of eggshell, which can produce oxidative ·CO3− species that are especially active for the degradation of aromatic compounds containing phenol or aniline structures. Through the synergistic oxidation of the··CO3− with the traditional holes (h+), superoxide radicals (·O2−) and hydroxyl radicals (·OH) involved in the photocatalytic process, the optimal TE photocatalyst degrades 92.0% TC in 30 min under solar light, which is higher than TiO2 and eggshell. The photocatalytic degradation pathway of TC over TE has been proposed. The response surface methodology is processed by varying four independent parameters (TC concentration, pH, catalyst dosage and reaction time) on a Box–Behnken design (BBD) to optimize the experimental conditions. It is anticipated that the present work can facilitate the development of novel photocatalysts for selective oxidation based on ·CO3−.

APA, Harvard, Vancouver, ISO, and other styles

37

Vargas, Ronald, and Oswaldo Núñez. "The photocatalytic oxidation of dibenzothiophene (DBT)." Journal of Molecular Catalysis A: Chemical 294, no. 1-2 (October 2008): 74–81. http://dx.doi.org/10.1016/j.molcata.2008.08.001.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Xu, Difa, Shaowen Cao, Jinfeng Zhang, Bei Cheng, and Jiaguo Yu. "Effects of the preparation method on the structure and the visible-light photocatalytic activity of Ag2CrO4." Beilstein Journal of Nanotechnology 5 (May 19, 2014): 658–66. http://dx.doi.org/10.3762/bjnano.5.77.

Full text

Abstract:

Silver chromate (Ag2CrO4) photocatalysts are prepared by microemulsion, precipitation, and hydrothermal methods, in order to investigate the effect of preparation methods on the structure and the visible-light photocatalytic activity. It is found that the photocatalytic activity of the prepared Ag2CrO4was highly dependent on the preparation methods. The sample prepared by microemulsion method exhibits the highest photocatalytic efficiency on the degradation of methylene blue (MB) under visible-light irradiation. The enhanced photocatalytic activity could be ascribed to the smaller particle size, higher surface area, relatively stronger light absorption, and blue-shift absorption edge, which result in the adsorption of more MB molecules, a shorter diffusion process of more photogenerated excitons, and a stronger oxidation ability of the photogenerated holes. Considering the universalities of microemulsion, precipitation, and hydrothermal methods, this work may also provide a prototype for the comparative study of semiconductor based photocatalysis for water purification and environmental remediation.

APA, Harvard, Vancouver, ISO, and other styles

39

Pichat, Pierre. "Photocatalytic degradation of aromatic and alicyclic pollutants in water: by-products, pathways and mechanisms." Water Science and Technology 35, no. 4 (February 1, 1997): 73–78. http://dx.doi.org/10.2166/wst.1997.0089.

Full text

Abstract:

Pyridine, 1-2-dimethoxybenzene, morpholine and lindane are mineralized by the TiO2-UV process. In the studies briefly reviewed here, their intermediate products, in particular the aliphatics, were identified both to determine what are the compounds that may be left in the treated water and to increase our understanding of the photocatalytic pathways. In addition to the oxidation and cleavage of the bonds, H(Cl) atom addition (or transfer) and coupling reactions were found to occur, which illustrates the complexity of photocatalytic degradations. Moreover, a comparison of the primary products of quinoline degraded either by photocatalysis or by the photo-Fenton process (Fe ions-H2O2-UV) showed that OH° radicals are not the only active species involved in photocatalytic degradations. From the effects of adding superoxide dismutase, it was inferred thatin situ formed O2−o anion-radicals intervene chemically, possibly by reacting with quinoline cation-radicals generated via electron transfer from quinoline to TiO2.

APA, Harvard, Vancouver, ISO, and other styles

40

Bougarrani, Salma, Zakarya Baicha, Lahbib Latrach, Mohammed El Mahi, and Francisco José Hernandez Fernandez. "Improving the Imazapyr Degradation by Photocatalytic Ozonation: A Comparative Study with Different Oxidative Chemical Processes." Processes 8, no. 11 (November 11, 2020): 1446. http://dx.doi.org/10.3390/pr8111446.

Full text

Abstract:

The degradation of imazapyr (C13H15N3O3), an active element in the aqueous solution of commercial herbicide, was investigated. This study was the first to evaluate in a comprehensive manner the efficiency of advanced oxidation processes for imazapyr degradation. Results showed that Imazapyr degradation is significantly affected by operational conditions such as TiO2 concentration, ozone concentration, initial concentration of imazapyr and pH. The kinetics of Imazapyr consumption was the first order with respect to Imazapyr concentration and zero order with respect to ozone concentration with a constant rate of 0.247 min−1 and 0.128 min−1 for photocatalytic ozonation and heterogeneous photocatalysis, while it was the first order with respect to Imazapyr and the first order with respect to ozone concentrations when only ozone was used with a constant rate of 0.053 mol L−1 min−1 at pH 7. The results revealed that more than 90 percent of the removal efficiency representing the elimination of imazapyr was held up to 7 μM. Further increase in the concentration of imazapyr leads to a drop in the removal efficiency, however the total imazapyr degradation was reached in 20 min utilizing photocatalytic ozonation for 5 μM of Imazapyr in the presence of 100 mg L−1 of TiO2, 10 mg L−1 of ozone at pH 7. Photocatalytic ozonation and heterogeneous photocatalysis utilizing TiO2 as a semiconductor process appeared possible and well suited for the treatment of organic contaminants such as imazapyr herbicides, although at certain dosages of pH and common time for wastewater treatment, imazapyr was not degraded with ozonation on its own. The association of two oxidation processes, ozonation and photocatalysis, has improved oxidation efficiencies for water treatment under optimal conditions, leading to the development of non-selective hydroxyl and more reactive radicals in the oxidation medium, as well as the resulting synergistic effects between photocatalysis and ozonation that react more rapidly with imazapyr herbicide.

APA, Harvard, Vancouver, ISO, and other styles

41

Chen, Sudi, Xitong Ren, Shufang Tian, Jiajie Sun, and Feng Bai. "Controllable Synthesis of Cobalt Porphyrin Nanocrystals through Micelle Confinement Self-Assembly." MRS Advances 5, no. 42 (2020): 2147–55. http://dx.doi.org/10.1557/adv.2020.269.

Full text

Abstract:

AbstractThe self-assembly of optically active building blocks into functional nanocrystals as high-activity photocatalysts is a key in the field of photocatalysis. Cobalt porphyrin with abundant catalytic properties is extensively studied in photocatalytic water oxidation and CO2 reduction. Here, we present the fabrication of cobalt porphyrin nanocrystals through a surfactant-assisted interfacial self-assembly process using Co-tetra(4-pyridyl) porphyrin as building block. The self-assembly process relies on the combined noncovalent interactions such as π-π stacking and axial Co-N coordination between individual porphyrin molecules within surfactant micelles. Tuning different reaction conditions (temperature, the ratio of co-solvent DMF) and types of surfactant, various nanocrystals with well-defined 1D to 3D morphologies such as nanowires, nanorods and nano hexagonal prism were obtained. Due to the ordered accumulation of molecules, the nanocrystals exhibit the properties of the enhanced capability of visible light capture and can conduce to improve the transport and separation efficiency of the photogenerated carriers, which is important for photocatalysis. Further studies of photocatalytic CO2 reduction are being performed to address the relationship between the size and shape of the nanocrystals with the photocatalytic activity.

APA, Harvard, Vancouver, ISO, and other styles

42

Hawe, Philipp, Vitor R. R. Silveira, Robert Bericat Vadell, Erik Lewin, and Jacinto Sá. "Plasmon-Mediated Oxidation Reaction on Au/p-Cu2O: The Origin of Hot Holes." Physchem 1, no. 2 (July 27, 2021): 163–75. http://dx.doi.org/10.3390/physchem1020011.

Full text

Abstract:

More sustainable solutions are needed to produce chemicals and fuels, mainly to face rising demands and mitigate climate change. Light, as a reagent, has emerged as a route to activate small molecules, e.g., H2O, CO2, N2, and make complex chemicals in a process called photocatalysis. Several photosystems have been proposed, with plasmonic technology emerging as one the most promising technologies due to its high optical absorption and hot-carrier formation. However, the lifetime of hot carriers is unsuitable for direct use; therefore, they are normally coupled with suitable charge-accepting materials, such as semiconductors. Herein, a system is reported consisting of Au supported in p-Cu2O. The combination of p-Cu2O intrinsic photoactivity with the plasmonic properties of Au extended the system’s optical absorption range, increasing photocatalytic efficiency. More importantly, the system enabled us to study the underlying processes responsible for hot-hole transfer to p-Cu2O. Based on photocatalytic studies, it was concluded that most of the holes involved in aniline photo-oxidation come from hot-carrier injections, not from the PIRET process.

APA, Harvard, Vancouver, ISO, and other styles

43

Jiang, Liang, Lulu Xie, Jiao He, Juanxue Kang, Wei Wang, and Jiaqiang Wang. "Removal of As(III) from Water by Cellulase Templated TiO2: A Photocatalytic Oxidation Conjugated Adsorption Process." OBM Integrative and Complementary Medicine 7, no. 3 (July 16, 2022): 1. http://dx.doi.org/10.21926/cr.2203025.

Full text

Abstract:

TiO2 photocatalyst was prepared using cellulase as a biotemplate through a hydrothermal process. The as-prepared catalyst was characterized based on physicochemical techniques and was used to remove As(III) from contaminated water. The cellulase templated TiO2 photocatalyst (TiO2-cellulase) had a large specific surface area, which reached 166.6 m2·g–1. It also had a strong oxidation ability and, thus, behaved well in both photocatalytic oxidation of As(III) and dark adsorption. The pH of the solution had a negligible effect on the removal rate. TiO2-cellulase had a higher photocatalytic removal rate of As(III) than commercial Degussa P25 TiO2.

APA, Harvard, Vancouver, ISO, and other styles

44

Youssef, Carlos, Eric Puzenat, Samir Najm, Nicole Jaffrezic-Renault, and Chantal Guillard. "Effect of Oxygen and Water in the CO Photocatalytic Oxidation with TiO₂." Advanced Materials Research 324 (August 2011): 149–52. http://dx.doi.org/10.4028/www.scientific.net/amr.324.149.

Full text

Abstract:

TiO2P25 catalyst was used to study the photocatalytic oxidation of CO to CO2at 288K. Two parameters, O2and H2O were used to study its effect on the photocatalytic process. The dependency of the reaction rate on the CO concentration and water vapor was explained in terms of Langmuir-Hinshelwood mechanism. The presence of a high concentration of water vapor inhibits the CO photocatalytic oxidation at low oxygen concentration. We have noted an adsorption competition between CO and H2O on the TiO2active sites.

APA, Harvard, Vancouver, ISO, and other styles

45

Wang, Dejun, Hui Li, Xiren Jiang, Chaocheng Zhao, and Yuhui Zhao. "Comparison of Three Catalytic Processes in Degradation of HPAM by tBu-TPyzPzCo." Catalysts 11, no. 2 (January 29, 2021): 181. http://dx.doi.org/10.3390/catal11020181.

Full text

Abstract:

The present study describes a two-step synthesis process for the cobalt complex of tetra-2,3-(5,6-di-tert-butyl-pyrazino) porphyrazine (tBu-TPyzPzCo). The product was ultrasonically impregnated onto carbon black (CB) to prepare a supported catalyst (tBu-TPyzPzCo/CB). We built a split photoelectric catalytic device to test the performance of photocatalytic, electrocatalytic and photoelectrocatalytic degradation of partially hydrolyzed polyacrylamide (HPAM). The results confirm that HPAM exhibited more efficient degradation in the presence of a supporting catalyst using the photoelectrocatalytic process than by photocatalytic or electrocatalytic oxidation—or even the sum of the two in saline water. The photoelectrocatalytic reaction confirmed that the process conforms to quasi-first order reaction kinetics, while the reaction rate constants were 6.03 times that of photocatalysis and 3.97 times that of electrocatalysis. We also compared the energy consumption of the three processes and found that the photoelectrocatalytic process has the highest energy efficiency.

APA, Harvard, Vancouver, ISO, and other styles

46

Curteanu, Silvia, Ciprian George Piuleac, and Ioannis Poulios. "PHOTOCATALYTIC OXIDATION PROCESS OF SULFAMETHAZINE. MODELING BASED ON NEURAL NETWORKS." Environmental Engineering and Management Journal 8, no. 3 (2009): 439–45. http://dx.doi.org/10.30638/eemj.2009.059.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Khanahmadi, Maryam, Mohammad Hajaghazadeh, Fatemeh Nejatzadeh-Barandozi, and Fathollah Gholami-Borujeni. "Photocatalytic oxidation process (UV-Fe2O3) efficiency for degradation of hydroquinone." DESALINATION AND WATER TREATMENT 106 (2018): 305–11. http://dx.doi.org/10.5004/dwt.2018.22087.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Favier, Lidia, Lacramioara Rusu, Andrei Ionut Simion, Raluca Maria Hlihor, Mariana Liliana Pacala, and Adrian Augustyniak. "EFFICIENT DEGRADATION OF CLOFIBRIC ACID BY HETEROGENEOUS PHOTOCATALYTIC OXIDATION PROCESS." Environmental Engineering and Management Journal 18, no. 8 (2019): 1683–92. http://dx.doi.org/10.30638/eemj.2019.158.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Thiruvenkatachari, Ramesh, Saravanamuthu Vigneswaran, and Il Shik Moon. "A review on UV/TiO2 photocatalytic oxidation process (Journal Review)." Korean Journal of Chemical Engineering 25, no. 1 (January 2008): 64–72. http://dx.doi.org/10.1007/s11814-008-0011-8.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Tsoumachidou, Sophia, Maria Valari, and Ioannis Poulios. "Photocatalytic oxidation of psychoactive drug Duloxetine: Degradation kinetics, inorganic ions and phytotoxicity evaluation." Applied Chemical Engineering 3, no. 1 (June 9, 2020): 31. http://dx.doi.org/10.24294/ace.v3i1.509.

Full text

Abstract:

Pharmaceutically active compounds, emerging extensively in ecosystems as pollutants, have become an important environmental and public health issue, since they can contaminate drinking water and pose threat to wildlife and human health. Therefore, efforts should be made in order to establish proper methods for their inactivation or elimination in the environment. The photocatalytic oxidation of psychoactive drug Duloxetine (DLX) has been investigated. In the case of heterogeneous photocatalytic oxidation, the effect of TiO2 P25 concentration (0.1–1 g L-1), initial concentration of H2O2 (0.25–0.2 g L-1) and Fe3+ (0.00175–0.014 g L-1) and pH of the solution (3–10) on initial reaction rates were evaluated, while for homogeneous photocatalytic oxidation the effect of the amount of H2O2 (0.25–0.2 g L-1) and Fe3+ (0.00175–0.014 g L-1) were investigated. Additionally, the conversion of the heteroatoms in the molecule of DLX to inorganic ions (NO3-, NH4+, SO42-) during photocatalytic process has been observed, and phytotoxicity testing, using three plant species, was carried out in order to examine the effect of photocatalytic oxidation on the toxicity of DLX. According to the results presented in this study, both heterogeneous and homogeneous photocatalytic oxidation is an efficient methodology for DLX degradation.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Photocatalytic oxidation process'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles