Kinetics of bacteria disinfection with UV radiation in an absorbing and nutritious medium

2005 ◽  
Vol 114 (1-3) ◽  
pp. 87-97 ◽  
Author(s):  
Marisol D. Labas ◽  
Carlos A. Martín ◽  
Alberto E. Cassano
Keyword(s):  
Uv Radiation ◽  
Kinetics Of

Water decolorization using UV radiation and hydrogen peroxide: A kinetic study

2001 ◽  
Vol 44 (5) ◽  
pp. 53-60 ◽  
Author(s):  
C.A. Martín ◽  
O.M. Alfano ◽  
A.E. Cassano
Keyword(s):  
Hydrogen Peroxide ◽  
Uv Radiation ◽  
Absorption Rate ◽  
Fulvic Acids ◽  
Photon Absorption ◽  
Contaminant Concentration ◽  
Organic Substances ◽  
Mechanistic Approach ◽  
Natural Contamination ◽  
Kinetics Of

Sometimes, provision of water for domiciliary consumption faces the problem of natural contamination originated by the presence of organic substances such as humic or fulvic acids. Very often, after conventional sanitary treatments this water exhibits a persistent yellowish coloration that affects its use. Moreover, these substances may act as precursors of tri-halomethanes formation during pre-desinfection with chlorine. This paper presents, with a simplified mechanistic approach, the intrinsic reaction kinetics of natural water decolorization employing UV radiation and hydrogen peroxide. The main variables for the model are: contaminant concentration expressed as TOC, hydrogen peroxide concentration and the photon absorption rate.

Molecular analysis of enhanced replication of UV-damaged simian virus 40 DNA in UV-treated mammalian cells

1988 ◽  
Vol 8 (6) ◽  
pp. 2428-2434
Author(s):  
J M Treger ◽  
J Hauser ◽  
K Dixon
Keyword(s):  
Uv Radiation ◽  
Uv Irradiation ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Viral Dna ◽  
Repair Capacity ◽  
Pyrimidine Dimers ◽  
Infected Cells ◽  
Replicative Intermediates ◽  
Kinetics Of

Irradiation of simian virus 40 (SV40)-infected cells with low fluences of UV light (20 to 60 J/m2, inducing one to three pyrimidine dimers per SV40 genome) causes a dramatic inhibition of viral DNA replication. However, treatment of cells with UV radiation (20 J/m2) before infection with SV40 virus enhances the replication of UV-damaged viral DNA. To investigate the mechanism of this enhancement of replication, we analyzed the kinetics of synthesis and interconversion of viral replicative intermediates synthesized after UV irradiation of SV40-infected cells that had been pretreated with UV radiation. This enhancement did not appear to be due to an expansion of the size of the pool of replicative intermediates after irradiation of pretreated infected cells; the kinetics of incorporation of labeled thymidine into replicative intermediates were very similar after irradiation of infected control and pretreated cells. The major products of replication of SV40 DNA after UV irradiation at the low UV fluences used here were form II molecules with single-stranded gaps (relaxed circular intermediates). There did not appear to be a change in the proportion of these molecules synthesized when cells were pretreated with UV radiation. Thus, it is unlikely that a substantial amount of DNA synthesis occurs past pyrimidine dimers without leaving gaps. This conclusion is supported by the observation that the proportion of newly synthesized SV40 form I molecules that contain pyrimidine dimers was not increased in pretreated cells. Pulse-chase experiments suggested that there is a more efficient conversion of replicative intermediates into form I molecules in pretreated cells. This could be due to more efficient gap filling in relaxed circular intermediate molecules or to the release of blocked replication forks. Alternatively, the enhanced replication observed here may be due to an increase in the excision repair capacity of the pretreated cells.

Kinetics of bacteria inactivation employing UV radiation under clear water conditions

2006 ◽  
Vol 121 (2-3) ◽  
pp. 135-145 ◽  
Author(s):  
M LABAS ◽  
R BRANDI ◽  
C MARTIN ◽  
A CASSANO
Keyword(s):  
Uv Radiation ◽  
Clear Water ◽  
Bacteria Inactivation ◽  
Water Conditions ◽  
Kinetics Of

KINETICS OF ATRAZINE OXIDATION BY UV RADIATION AND OXALATE ASSISTED H2O2/UV PROCESSES

2006 ◽  
Vol 11 (1) ◽  
pp. 28-32
Author(s):  
Hyun-Jin Choi ◽  
Jong-Duck Choi ◽  
Hyun-Kab Kim ◽  
Tae-Jin Lee
Keyword(s):  
Uv Radiation ◽  
Kinetics Of

The photochemical stabilization of block copolymer micelles

1989 ◽  
Vol 54 (6) ◽  
pp. 1648-1660 ◽  
Author(s):  
Karel Procházka ◽  
Kateřina Kupková ◽  
Jaroslav Burda ◽  
Zdeněk Tuzar ◽  
Bohumil Bednář
Keyword(s):  
Block Copolymer ◽  
Uv Radiation ◽  
Binary Solvent ◽  
Ethanol Mixture ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles ◽  
Kinetics Of

Conditions of the polymolecular micellization of a linear three-block copolymer-polystyrene-block-polybutadiene-block-polystyrene in a binary solvent tetrahydrofuran-ethanol were determined. Photochemical stabilization of micelles by the crosslinking of polybutadiene chains in the cores induced by intense UV radiation was carried out in a tetrahydrofuran-ethanol mixture (34.5 vol. %), in which compact micelles with the polybutadiene core are formed and, at 25 °C, the micellization equilibrium is markedly shifted in favour of micelles containing a large number of associated copolymer chains. The kinetics of crosslinking of the micellar cores and the behaviour of stabilized micelles in solution were investigated.

Tertiary treatment of slaughterhouse effluent: degradation kinetics applying UV radiation or H2O2/UV

2009 ◽  
Vol 60 (7) ◽  
pp. 1869-1874 ◽  
Author(s):  
D. B. Luiz ◽  
A. K. Genena ◽  
H. J. José ◽  
R. F. P. M. Moreira ◽  
H. Fr. Schröder
Keyword(s):  
Uv Radiation ◽  
Aromatic Compounds ◽  
Water Reuse ◽  
Degradation Kinetics ◽  
Water Source ◽  
Tertiary Treatment ◽  
First Order ◽  
Pseudo First Order ◽  
Over Exploitation ◽  
Kinetics Of

In some Brazilian regions, surface water has become scarce, e.g. semi arid climate areas and densely populated and industrial areas, where water over-exploitation and/or fluvial pollution has been more common. Advanced oxidative processes (AOP) provide treated water as a source of reuse water even with the characteristics of drinking water enabling water reuse practices also in food industries. The secondary wastewater of a slaughterhouse was the water source for a tertiary treatment study evaluating the kinetics of the photo-induced degradation of color and UV254 under UV radiation with and without the addition of H2O2. The proximity of the k′ values of color and UV254 degradation by UV indicates that the compounds responsible for color may be the same content measured by UV254. The H2O2/UV treatment was 5.2 times faster than simple UV in removing aromatic compounds. The degradation kinetics of aromatic compounds in both treatments followed a pseudo-first order law. The pseudo-first order constant for H2O2/UV and UV treatments were kUV254′=0.0306 min−1 and kUV254′=0.0056 min−1, respectively.

scholarly journals Degradation of Tannic Acid Using TiO2 Nanotubes as Electrocatalyst

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
N. Lakshmi Kruthika ◽  
G. Bhaskar Raju ◽  
S. Prabhakar
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Uv Radiation ◽  
Tannic Acid ◽  
Tio2 Nanotubes ◽  
Zero Order ◽  
Titanium Sheet ◽  
Kinetics Of ◽  
Scanning Electron ◽  
Tannic Acid Solution

Structured TiO2 nanotubes were grown on 2 mm thick titanium sheet by anodization of titanium in ethylene glycol medium containing 0.025 M NaF. The morphology of TiO2 nanotubes (TNT) was characterized using field emission scanning electron microscope. The potential of TNT as anode and also as photocatalyst for the degradation of tannic acid was studied. The mineralization of tannic acid was measured in terms Total Organic Carbon (TOC). Only 50% of TOC could be removed by exposing the tannic acid solution to UV-radiation (photolysis), whereas it was improved to 70% by electrooxidation (EO) using TNT as anode. Maximum degradation of 83% was achieved when electrooxidation was conducted under the influence of UV-radiation (photoelectrocatalytic process (PEC)). Among the electrolytes tried, Na2SO4 was observed to be very effective for the degradation of tannic acid. The kinetics of tannic acid degradation by photoelectrocatalytic process was found to follow zero-order rate expression.

The impact of UV radiation on the decomposition kinetics of cationic SAS with ozone in an aqueous medium

2007 ◽  
Vol 29 (2) ◽  
pp. 59-64 ◽  
Author(s):  
V. V. Goncharuk ◽  
V. F. Vakulenko ◽  
Yu. O. Shvadchina ◽  
A. N. Sova
Keyword(s):  
Aqueous Medium ◽  
Uv Radiation ◽  
Decomposition Kinetics ◽  
The Impact ◽  
Kinetics Of
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