scholarly journals Degradation of chlorinated benzaldehydes in aqueous solutions by UV-irradiation

2002 ◽  
Vol 4 (4) ◽  
pp. 133-139 ◽  
Author(s):  
Miray Bekbölet ◽  
Nikola Getoff
Keyword(s):  
Aqueous Solutions ◽  
Hplc Analysis ◽  
Degradation Rate ◽  
Uv Light ◽  
Order Reaction ◽  
Quantum Yields ◽  
Homolytic Cleavage ◽  
First Order ◽  
Probable Reaction Mechanism ◽  
Probable Reaction

Photoinduced degradation of chlorinated benzaldehydes was investigated using UV light with λ = 253.7 nm in aerated aqueous solutions. Substrate degradation rate as expressed by first order reaction kinetics revealed rate constants, k;7.45×10−3min-1,3.90×10−3min-1and3.90×11−2min-1for 2- chlorobenzaldehyde, 3-chlorobenzaldehyde and 4-chlorobenzaldehyde respectively. The decomposition of the substrates was related to the formation of chloride and formaldehyde by homolytic cleavage processes. initial quantum yields and photochemical “GiPH-values” are reported for the degradation of the substrates. Based on the qualitative HPLC analysis, a probable reaction mechanism for the photoinduced degradation of chlorinated benzaldehydes is also presented.

Effect of Cyclodextrins on Photodegradation of 4,4-Bis(4-Hydroxyphenyl)Pentanoic Acid under UV Irradiation

2014 ◽  
Vol 665 ◽  
pp. 455-458
Author(s):  
Li Guo ◽  
Jin Huang ◽  
Jun Wu ◽  
Lei Lei Luo
Keyword(s):  
Aqueous Solutions ◽  
Fluorescence Spectra ◽  
High Efficiency ◽  
Uv Light ◽  
Order Reaction ◽  
Pentanoic Acid ◽  
Pseudo First Order Reaction ◽  
First Order ◽  
Inclusion Interaction ◽  
Pseudo First Order

The photodegradation of 4,4-bis (4-hydroxyphenyl) pentanoic acid (DPA) with two cyclodextrins (α-CD and β-CD ) in aqueous solutions induced by UV-light was studied in this paper by means of fluorescence spectra and high efficiency liquid chromatography. The result suggested that DPA with α-CD or β-CD formed inclusion compound in aqueous solutions. The photodegradation of DPA with two cyclodextrins or without cyclodextrin was pseudo-first order reaction. The photodegradation of DPA was accelerated by the addition of β-CD in aqueous solutions, but the that of DPA was inhibited in case of adding α-CD. These differences were due to the differences in inclusion interaction of DPA with α-CD or β-CD.

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.

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.

Synthesis, Properties and Application in Optical Memory of a Photochromic Diarylethene Bearing Pyrimidine and Pyridine Ring

2012 ◽  
Vol 490-495 ◽  
pp. 3733-3737
Author(s):  
Shu Hong Jing ◽  
Shou Zhi Pu ◽  
Shi Qiang Cui
Keyword(s):  
Uv Light ◽  
Optical Memory ◽  
Order Reaction ◽  
Pmma Film ◽  
Zeroth Order ◽  
First Order ◽  
Synthesis Properties ◽  
Fluorescence Switching ◽  
Photochromic Reaction ◽  
Hexane Solution

A new photochromic diarylethene compound, 1-(2,4-dimethoxy-5-pyrimidine)-2-[2-methyl-5-(3-pyridine)-3-thienyl]perfluorocyclopentene(1a), was synthesized, and its photochromic reactivity, fluorescent and electrochemical property were also investigated. Diarylethene 1a changed the color from colorless to pink upon irradiation with UV light, in which absorption maxima were observed at 520 and 519 nm in hexane and PMMA film, respectively. The the photochromic reaction kinetics indicated that the cyclization processes of 1 belong to the zeroth order reaction and the cycloreversion process belong to the first order reaction. This new photochromic system also exhibited remarkable fluorescence switching in hexane solution and this new photochromic system also exhibited remarkable optical storage character.

scholarly journals Photoinduced Transformation of Carbon Monoxide in Aqueous Solution

1988 ◽  
Vol 43 (5) ◽  
pp. 430-434
Author(s):  
Hyoung Ryun Park ◽  
Nikola Getoff
Keyword(s):  
Aqueous Solution ◽  
Carbon Monoxide ◽  
Product Formation ◽  
Quantum Yields ◽  
Ph Values ◽  
Probable Reaction Mechanism ◽  
Probable Reaction ◽  
Photoinduced Transformation ◽  
Vacuum Uv Radiation ◽  
Vacuum Uv

Abstract The photoinduced conversion of CO in aqueous solution under the influence of vacuum-uv radiation at λ = 185 nm has been investigated at pH values ranging from 2 to 13. Formaldehyde, glyoxal, carboxylic acids and small amounts of glycol were determined as final products. Initial quantum yields for product formation have been determined. A probable reaction mechanism is presented.

Studies on the Interaction Mechanism between Lithium Chloride and Amorphous Al(OH)3

2013 ◽  
Vol 634-638 ◽  
pp. 126-129 ◽  
Author(s):  
Hong Jun Yang ◽  
Bing Li ◽  
Xiao Li Chai ◽  
Wu Li
Keyword(s):  
Aqueous Solutions ◽  
Chemical Reaction ◽  
Lithium Chloride ◽  
Dynamic Equation ◽  
Interaction Mechanism ◽  
Lithium Ion ◽  
Order Reaction ◽  
Dynamic Equations ◽  
First Order ◽  
Xrd Patterns

Experiments on the interaction mechanism between lithium chloride and amorphous Al(OH)3 were designed and conducted applying simulated brines and aqueous solutions, respectively. The concentrations of lithium ion in the different solutions were determined and XRD patterns of solids formed between lithium chloride and amorphous Al(OH)3 were obtained. The data were fitted according to related dynamic equations. The results show that the variation of the concentration of lithium ion with time obeys the first order reaction dynamic equation, and the mechanism of the interaction should be chemical reaction between lithium chloride and amorphous Al(OH)3. Li/Al ratio should be 1:2 in the formula of the solid products.

Synthesis and Properties of 1-(2-Methyl-3-benzothiophene)-2-[2-methyl-5-(3-fluoro-4-chloro)phenyl-3-thienyl]perfluorocyclopentene

2014 ◽  
Vol 1078 ◽  
pp. 98-101
Author(s):  
Guan Ming Liao ◽  
Chun Hong Zheng ◽  
Shou Zhi Pu
Keyword(s):  
Absorption Band ◽  
Emission Intensity ◽  
Uv Light ◽  
Order Reaction ◽  
First Order Reaction ◽  
Fluorescent Properties ◽  
Visible Absorption ◽  
First Order ◽  
Photostationary State ◽  
Closed Ring

An asymmetrical photochromic diarylethene1-(2-Methyl-3-benzothiophene)-2-[2-methyl-5-(3-fluoro-4-chloro) phenyl-3-thienyl] perfluorocyclopentene (1o) was synthesized and its phtochromic, fluorescent properties were investigated in detail. This compound exhibited remarkable photochromism, upon irradiation with 297 nm UV light, the colorless solution of 1o turned to violetred with a new visible absorption band centered at 538 nm (ε = 1.17 × 104 L mol-1 cm-1) attributable to the closed-ring isomer 1c. The kinetic experiments showed that the cyclization and cycloreversion processes were zeroth and first order reaction, respectively. Moreover, diarylethene 1o also exhibited obviously fluorescence switches along with the photochromism.The emission intensity of diarylethene 1o in a photostationary state was quenched to ca. 27% in hexane.

Synthesis and Photochromism Studies of 1-(2-methyl-3-benzofuran)-2-[2-methyl-5-naphthyl-3-thienyl]perfluorocyclopentene

2014 ◽  
Vol 1078 ◽  
pp. 86-89
Author(s):  
Xiao Rong Dong ◽  
Hong Yan Xu ◽  
Shou Zhi Pu
Keyword(s):  
Absorption Band ◽  
Uv Light ◽  
Amorphous Film ◽  
Order Reaction ◽  
Pmma Film ◽  
Zeroth Order ◽  
Fluorescent Properties ◽  
Visible Absorption ◽  
First Order ◽  
Photochromic Reaction

A novel photochromic diarylethene was synthesized and its photochromic and fluorescent properties were investigated. The results showed that this compound exhibited reversible photochromism, changing from colorless to amaranth after irradiation with UV light both in solution and PMMA amorphous film. In hexane, compound 1a exhibited an absorption peak at 266 nm, upon irradiation with 297 nm light, a new visible absorption band centered at 530 nm emerged while the original peak at 266 nm decreased. In PMMA amorphous film, diarylethene 1a also showed good photochromism as similar to that in solution. The photochromic reaction kinetics indicated that the cyclization processes of 1a belong to the zeroth order reaction and the cycloreversion process belong to the first order reaction. Diarylethene 1a also exhibited good fluorescent switching both in solution and in PMMA film upon alternating irradiation with UV and visible light.

scholarly journals Estudios fotoquímicos y electroquímicos de complejos lantánidos de 6-(hidroximetil)piridin- 2-carboxaldehído[2- metilpirimidina-4,6-diil] bishidrazona

2015 ◽  
Vol 43 (1) ◽  
pp. 5-11 ◽  
Author(s):  
María Alejandra Fernandez ◽  
Juan Camilo Barona ◽  
Dorian Polo-Cerón ◽  
Manuel N. Chaur
Keyword(s):  
Uv Light ◽  
Condensation Reaction ◽  
Quantum Yields ◽  
Consecutive Reaction ◽  
Metal Centers ◽  
First Order ◽  
Fluorescence Quantum Yields ◽  
H Nmr ◽  
First Order Kinetics ◽  
Uv Light Irradiation

<p>Herein we report the synthesis of the 6-(hydroxymethyl)pyridine-2- carboxaldehyde[2-methyl-pyrimidine- 4,6-diyl]bis-hydrazone by a condensation reaction between 6-(hydroxymethyl) picolinaldehyde with 4,6-(bis-hydrazino)-2- methylpyrimidine. This bis-hydrazone can be visualized as a two-arm system which exhibits photochemical induced [E,E]/[E,Z]/[Z,Z’] isomerizations and double coordination to metal centers. Configurational changes, upon UV light irradiation, were followed over time by 1 H NMR, establishing that isomerization, in both arms, is a consecutive reaction that follows first-order kinetics (k1 = 4.06 x 10-4 s-1 and k2 = 2.80 x 10-4 s-1). Furthermore, the synthesis of bis-hydrazone metal complexes with La (III) and Sm (III) ions was achieved; subsequently, the absorption and emission properties of these complexes were studied, determining the fluorescence quantum yields, 𝟇La= 0.2024 and 𝟇Sm= 0.1413. Electrochemical studies of the complexes were conducted by square wave voltammetry, demonstrating that the bis-hydrazone and its complexes are electroactive species between +1.5 and -2.5 V.</p>

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