Photocatalytic Discolouration of Solutions of Reactive Dyes in the Presence of H2O2

1995 ◽  
Vol 30 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Deng Nansheng ◽  
Tian Shizhong ◽  
Xia Mei
Keyword(s):  
Photochemical Reaction ◽  
Uv Light ◽  
Reactive Dyes ◽  
Solar Light ◽  
Rate Equations ◽  
Oh Radical ◽  
Test Results ◽  
Dye Molecules ◽  
First Order ◽  
Dye Solutions

Abstract Tests for the photocatalytic degradation of solutions of three reactive dyes, Red M-5B, Procion Blue MX-R and Procion Black H-N, in the presence of H2O2 were carried out. When the solutions of the three reactive dyes were irradiated by UV or solar light, the colour of the solutions disappeared gradually. A statistical analysis of the test results indicated a linear relation between the concentration of dyes and the time of irradiation. The discolouration reaction of the solutions was of the first order. Rate equations for the discolouration reactions of dye solutions were developed. The dark reactions or the dye solutions containing H2O2 were very slow, illustrating that the photochemical reaction played a very important role. It was demonstrated that UV light and solar light (300 to 380 nm) photolyzes the HO and that the resulting OH radical reacts with the dye molecules and destroys the chromophore.

scholarly journals Systematically Exploring Molecular Aggregation and Its Impact on Surface Tension and Viscosity in High Concentration Solutions

Molecules ◽  
2020 ◽  
Vol 25 (7) ◽  
pp. 1588 ◽  
Author(s):  
Huan Wang ◽  
Han Kong ◽  
Jie Zheng ◽  
Hui Peng ◽  
Chuangui Cao ◽  
...  
Keyword(s):  
Surface Tension ◽  
Great Influence ◽  
Reactive Dyes ◽  
Side Chain ◽  
Molecular Aggregation ◽  
Dye Molecules ◽  
High Concentration ◽  
Hydrophilic Group ◽  
Aggregation Structure ◽  
Dye Solutions

The aggregation structure of dye molecules has a great influence on the properties of dye solutions, especially in high concentration. Here, the dye molecular aggregation structures were investigated systemically in aqueous solutions with high concentration using three reactive dyes (O-13, R-24:1 and R-218). O-13 showed stronger aggregation than R-24:1 and R-218. This is because of the small non-conjugate side chain and its β-linked position on the naphthalene of O-13. Compared with R-218, R-24:1 showed relatively weaker aggregation due to the good solution of R-24:1. The change of different aggregate distributions in the solutions were also investigated by splitting the absorption curves. Moreover, it is found that the surface tension of solutions can be modified by the combined effect of both aggregation and the position of the hydrophilic group, which, however, also have an effect on viscosity. This exploration will provide guidance for the study of high concentration solutions.

Disinfection effects on E. coli using TiO2/UV and solar light system

2002 ◽  
Vol 2 (1) ◽  
pp. 181-190 ◽  
Author(s):  
I.-H. Cho ◽  
I.-Y. Moon ◽  
M.-H. Chung ◽  
H.-K. Lee ◽  
K.-D. Zoh
Keyword(s):  
Light Intensity ◽  
Flow Rate ◽  
Alternative Energy ◽  
Advanced Oxidation Process ◽  
Uv Light ◽  
Solar Light ◽  
Survival Ratio ◽  
E Coli ◽  
First Order ◽  
First Order Kinetics

First, a continuous flow TiO2/UV reactor was designed and developed in order to examine E. coli disinfection effect using UV light. The optimum conditions for disinfection such as flow rate, light intensity, TiO2 concentration, initial E. coli concentration were examined. The results are as follow (i) The use of the quartz device and TiO2 (anatase) resulted in killing of E. coil within minutes. (ii) Photocatalytic disinfection with UV light in the presence of TiO2 more effectively killed E. coli than UV or TiO2 adsorption only. (iii) As flow rate increased, the survival ratio of E. coli decreased, but over 3 L/min of flow rate, the efficiency was limited. (iv) E. coli survival ratio decreased linearly with increasing UV light intensity. (v) The dosage of TiO2 affected the E. coli disinfection efficiency, and above 0.1 wt% TiO2 concentration, the disinfection was less effective because TiO2 particles may result in screening off the light. (ri) The disinfection reaction follows first-order kinetics. Secondly, outdoor experiments with natural sunlight instead of artificial UV light in TiO2 reactors were also conducted to investigate alternative energy source applicability on E. coli disinfection. It is found that the presence of clouds in the sky markedly increased the time required for killing E. coli and the bacteria cells also disappeared with a first-order kinetics. On the basis of these experimental observations, the disinfection of E. coli using TiO2 under solar light irradiation can be a feasible application of the advanced oxidation process.

Studies on photocatalytic activity of the synthesised TiO2 and Ag/TiO2 photocatalysts under UV and sunlight irradiations

2011 ◽  
Vol 63 (3) ◽  
pp. 377-384 ◽  
Author(s):  
R. Vaithiyanathan ◽  
T. Sivakumar
Keyword(s):  
Uv Light ◽  
Sol Gel ◽  
Solar Light ◽  
Light Sources ◽  
Tio2 Photocatalysts ◽  
First Order ◽  
First Order Kinetics ◽  
Radiation Sources ◽  
Silver Metal ◽  
Comprehensive Study

Photocatalytic decolorisation and degradation of Reactive Red 120 (RR 120) has been investigated under UV (365 nm) and solar light as radiation sources using synthesised nano titania catalyst prepared via sol-gel method. The study encompassed calcination of synthesised titania catalyst at a range of temperature up to 1,000°C. The effects of calcination temperature on titania catalyst have been evaluated on the decolorisation of RR 120. The analysis revealed complete decolorisation of dye solution in 100 min under UV light with the TiO2 catalyst calcined at 200°C. Only a maximum of 47% dye decolorisation was achieved under sunlight in 4 h with no improvement even after prolonged irradiation. In an endeavour to improve the catalytic activity, bare titania was modified with silver metal and a comprehensive study on the characteristics of silver modified catalyst was made. The result was an enhancement of the rate of decolorisation of dye under both UV and solar light sources. All the catalysts were characterised by XRD and BET analyses. Optimisation of the degradation of RR 120 has been carried out using the unmodified catalyst by varying the amount of catalyst, substrate concentration, pH of dye solution. Effects of addition of small amounts of various oxidants such as H2O2, KBrO3 and (NH4)2S2O8 have also been studied. Pseudo first order kinetics was observed in the photocatalytic decolorisation of dye. The mineralisation of RR 120 was monitored by TOC analysis.

The Structure and Photochromism of 2,4,4,6-Tetraphenyl-4H-thiopyran

1992 ◽  
Vol 57 (6) ◽  
pp. 1326-1334 ◽  
Author(s):  
Jaroslav Vojtěchovský ◽  
Jindřich Hašek ◽  
Stanislav Nešpůrek ◽  
Mojmír Adamec
Keyword(s):  
Solid State ◽  
Uv Light ◽  
Order Reaction ◽  
Boat Conformation ◽  
X Rays ◽  
Exponential Time ◽  
First Order ◽  
Double Plane ◽  
The Mean ◽  
Independent Molecules

2,4,4,6-Tetraphenyl-4H-thiopyran, C29H22S, orthorhombic, Pna21, a = 17.980(4), b = 6.956(2), c = 34.562(11) Å, V = 4323(2) Å3, Z = 8, Dx = 1.237 g cm-3, F(000) = 1696, λ(CuKα) = 1.54184 A, μ = 1.372 mm-2, T = 294 K. The final R was 0.050 for the unique set of 3103 observed reflections. The central 4H-thiopyran ring forms a boat conformation for both symmetrically independent molecules with average boat angles 4.4(3) and 6.8(3)° at S and C(sp3), respectively. The mean planes of phenyls at the position 2 and 6 are turned from the double plane of 4H-thiopyran by 42.5(5) and 35.8(3)°, respectively. The investigated material undergoes a photochromic change in the solid state after irradiation with UV light or X-rays. The maximum of the new absorption band is situated at 564 nm. The non-exponential time dependence of photochromic bleaching is analysed in terms of a dispersive first-order reaction.

Efficient Synthesis and Photochromic Properties of a New Diarylethene Bearing a Condensed Aromatics Moiety

2012 ◽  
Vol 455-456 ◽  
pp. 33-36
Author(s):  
Ren Jie Wang ◽  
Hong Ying Xia ◽  
Gang Liu ◽  
Shi Qiang Cui
Keyword(s):  
Uv Light ◽  
Optical Storage ◽  
Hybrid Structure ◽  
Order Reaction ◽  
Pmma Film ◽  
Efficient Synthesis ◽  
Photochromic Properties ◽  
First Order ◽  
New Class ◽  
Hexane Solution

A new class of diarylethenes based on a hybrid structure of thiophene and naphthalene has been developed and its properties including photochromism, kinetics and fluorescence were investigated in detail. The results showed that the compound exhibited obvious photochromism, changing from colorless to red after irradiation with 297 nm UV light both in solution and in PMMA film. The kinetic experiments indicated that the cyclization/cycloreversion process of the compound was determined to be the zeroth/first order reaction in hexane solution. At last, the results demonstrated that the diarylethene compound had attractive properties for potential application in optical storage.

Wavelength controlled production of SO4- radicals in the ultraviolet photolysis of ceric sulfate solutions

1984 ◽  
Vol 37 (3) ◽  
pp. 475 ◽  
Author(s):  
RW Matthews
Keyword(s):  
Rate Constants ◽  
Photochemical Reaction ◽  
Transfer Reaction ◽  
Quantum Yields ◽  
Oh Radical ◽  
Transfer Energy ◽  
Fluorescence Measurements ◽  
Sulfate Solutions ◽  
Ultraviolet Photolysis ◽  
Primary Photochemical Reaction

Solutions of cerium(III)/(IV) and formic acid in 0.4 M sulfuric acid have been photolysed under 254 nm and 365 nm light. Marked differences in the reaction kinetics and quantum yields are observed at the two different wavelengths. At 365 nm, the reactions leading to cerium(IV) reduction are caused almost exclusively by the SO4- radical. The ratio of rate constants, k(SO4- + CeIII)/ k(SO4- + HCOOH), is 116 � 11 and the quantum yield of sulfate radicals, ф(SO4-), is 0.023 � 0.002. At 254 nm, the reactions leading to cerium(IV) reduction are caused mainly by the OH radical, but approximately 35% of the oxidizing radicals formed in the primary photochemical reaction are SO4-. Cerium(III) species, excited at 254 nm, transfer energy to cerium(IV) and this results in an additional yield of OH and SO4- radicals. Fluorescence measurements confirmed the efficiency of the energy transfer reaction. The ratio of rate constants, k(OH+CeIII)/k(OH+HCOOH), is 2.22 � 0.18 and ф(CeIV*) and ф(CelIII*) giving oxidizing radicals are 0.116 � 0.010 and 0.0083 � 0.0008 respectively. Thus about 5 times more total oxidizing radicals are produced from excited cerium(IV) species at 254 nm than at 365 nm.

Fly Ash for Colour Removal from Synthetic Dye Solutions

1999 ◽  
Vol 34 (3) ◽  
pp. 505-518 ◽  
Author(s):  
T. Viraraghavan ◽  
K.R. Ramakrishna
Keyword(s):  
Activated Carbon ◽  
Fly Ash ◽  
Granular Activated Carbon ◽  
Particle Sizes ◽  
Colour Removal ◽  
First Order ◽  
Synthetic Dye ◽  
Removal Capacity ◽  
Acid Blue ◽  
Dye Solutions

Abstract Fly ash was investigated for its ability to adsorb dyes from aqueous solutions. Batch pH, kinetic and isotherm studies were performed on a laboratory scale with synthetic dye solutions made up of four different commercial grade dyes. Fly ash samples with differing compositions and particle sizes were employed to understand the effect of fly ash composition and particle size on their dye removal capacity. The first-order rate equation by Lagergren was tested on the kinetic data, and isotherm data was analyzed for possible agreement with the Langmuir and Freundlich adsorption isotherm equations. The removal capacity of fly ash for the different dyes was compared with that of granular activated carbon under identical conditions. Results showed that fly ash exhibited reasonably good dye removals for Basic Blue 9, Acid Blue 29 and Acid Red 91, while the removals by fly ash exceeded that of granular activated carbon for Disperse Red 1. Lime content in fly ash seemed to influence dye adsorption to a significant degree — better adsorption was observed at lower particle sizes because of the increased external surface area available for adsorption. Acid Blue 29 adsorption by fly ash provided the best fit for the Lagergren first-order plot. Because high pH and heavy metals (leached from fly ash) in the treated wastewater may exceed the limits set in municipal sewer-use bylaws, engineering and economic feasibility assessment should include these aspects when considering fly ash for colour removal.

UV Based Advanced Oxidation Process for Degradation of Ciprofloxacin: Reaction Kinetics, Effects of Interfering Substances and Degradation Product Identification

2021 ◽  
Author(s):  
Bijoli Mondal ◽  
Shib Sankar Basak ◽  
Arnab Das ◽  
Sananda Sarkar ◽  
Asok Adak
Keyword(s):  
Organic Compounds ◽  
Advanced Oxidation Process ◽  
Oxidation Process ◽  
Uv Light ◽  
Degradation Products ◽  
Irradiation Time ◽  
Advanced Oxidation ◽  
Quantum Yields ◽  
Photon Flux ◽  
First Order

Abstract In the photochemical UV-H2O2 advanced oxidation process, H2O2 absorbs UV light and is decomposed to form hydroxyl radicals (OH·), which are highly excited and reactive for electron-rich organic compounds and hence can degrade organic compounds. In the present work, the UV-H2O2 process was investigated to degrade ciprofloxacin (CIP), one of India's widely used antibiotics, from aqueous solutions using a batch type UV reactor having photon flux = 1.9 (± 0.1) ×10-4 Einstein L-1 min-1. The effects of UV irradiation time on CIP degradation were investigated for both UV and UV-H2O2 processes. It was found that about 75% degradation of CIP was achieved within 60 s with initial CIP concentration and peroxide concentration of 10 mg L-1 and 1 mol H2O2/ mol CIP, respectively, at pH of 7(±0.1) and fluence dose of 113 mJ cm-2. The experimental data were analyzed by the first-order kinetics model to find out the time- and fluence-based degradation rate constants. Under optimized experimental conditions (initial CIP concentration, pH and H2O2 dose of 10 mg L-1, 7(±0.1) and 1.0 mol H2O2 / mol CIP, respectively), the fluence-based pseudo-first-order rate constant for the UV and UV-H2O2 processes were determined to be 1.28(±0.0) ×10-4 and 1.20(±0.04) ×10-2 cm2 mJ-1 respectively. The quantum yields at various pH under direct UV were calculated. The impacts of different process parameters such as H2O2 concentration, solution pH, initial CIP concentration, and wastewater matrix on CIP degradation were also investigated in detail. CIP degradation was favorable in acidic conditions. Six degradation products of CIP were identified. Results clearly showed the potentiality of the UV-H2O2 process for the degradation of antibiotics in wastewater.

scholarly journals Simple models for the continuous aerobic biodegradation of phenol in a packed bed reactor

2006 ◽  
Vol 49 (4) ◽  
pp. 669-676 ◽  
Author(s):  
Andrew Mark Gerrard ◽  
Jan Páca Júnior ◽  
Alena Kostecková ◽  
Jan Páca ◽  
Marie Stiborová ◽  
...  
Keyword(s):  
Plug Flow ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Aerobic Biodegradation ◽  
Rate Equations ◽  
Phenol Removal ◽  
First Order ◽  
Peak Loads ◽  
Linear Graphs ◽  
Best Fit

This paper proposes the use of a preliminary, phenol removal step to reduce peak loads arriving at a conventional effluent plant. A packed bed reactor (PBR) using polyurethane foam, porous glass and also cocoa fibres as the inert support material was used. Experiments have been carried out where the flow-rates, plus inlet and outlet phenol concentrations were measured. A simple, plug-flow model is proposed to represent the results. Zero, first order, Monod and inhibited kinetics rate equations were evaluated. It was found that the Monod model gave the best fit to the experimental data and allowed linear graphs to be plotted. The Monod saturation constant, K, is approximately 50 g m-3, and ka is around 900 s-1.

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