LASER FLASH SPECTROSCOPY OF METHYLENE BLUE WITH NUCLEIC ACIDS. EFFECTS OF IONIC STRENGTH AND pH

1989 ◽  
Vol 49 (2) ◽  
pp. 145-151 ◽  
Author(s):  
WILHELM J. M. PUTTEN ◽  
JOHN M. KELLY
Keyword(s):  
Methylene Blue ◽  
Ionic Strength ◽  
Nucleic Acids ◽  
Laser Flash ◽  
Flash Spectroscopy

LASER FLASH SPECTROSCOPY OF METHYLENE BLUE WITH NUCLEIC ACIDS

1987 ◽  
Vol 45 (2) ◽  
pp. 167-175 ◽  
Author(s):  
John M. Kelly ◽  
Wilhelm J. M. Putten ◽  
David J. Mcconnell
Keyword(s):  
Methylene Blue ◽  
Nucleic Acids ◽  
Laser Flash ◽  
Flash Spectroscopy

Kinetics Studies of Methylene Blue Adsorption onto Spherical Chitosan Resin

2011 ◽  
Vol 233-235 ◽  
pp. 567-570
Author(s):  
Juan Qin Xue ◽  
Wei Bo Mao ◽  
Dan Dan Wen ◽  
Jing Xian Li ◽  
Yu Jie Wang
Keyword(s):  
Methylene Blue ◽  
Kinetic Equation ◽  
Ionic Strength ◽  
Adsorption Process ◽  
Sorption Kinetics ◽  
Methylene Blue Adsorption ◽  
Initial Concentration ◽  
Kinetics Studies ◽  
Kinetics Of ◽  
Chitosan Resin

Investigated the sorption kinetics of methylene blue on spherical chitosan resin. Studied the influences of ionic strength, pH， initial concentration on the adsorption process. The adsorption of methylene blue increases with the decreasing ionic strength and the increasing pH and the initial concentration of the system. Furthermore, the adsorption process correspondes with Lagergren pseudo-second kinetic equation and the finess (R2) of the model was above 0.99.

Formation and nucleophilic capture of N-nitrosiminium ions

1999 ◽  
Vol 77 (5-6) ◽  
pp. 1148-1161 ◽  
Author(s):  
Latifa Chahoua ◽  
Alain Vigroux ◽  
Yvonne Chiang ◽  
James C Fishbein
Keyword(s):  
Ionic Strength ◽  
Rate Constants ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Aqueous Media ◽  
Laser Flash ◽  
Azide Ion ◽  
Iminium Ions ◽  
Nucleophilic Trapping

A study of the solvolysis of a series of (N-nitrosomethylamino)arylmethyl esters and azides and the products of nucleophilic trapping of the corresponding N-nitrosiminium ion intermediates in aqueous media, 25°C, ionic strength 1 M is reported. Structure-reactivity data for the forward and reverse reactions have been obtained. In three cases, the rate constants for reactions of the cations with nucleophiles have been measured directly by laser flash photolysis. The data allow a comparison of the degree to which the N-methyl-N-nitroso functionality enhances cation stability from a thermodynamic and kinetic perspective. It has been possible to deduce that the carbon basicity of azide ion is less than 1 kcal/mol greater than that of acetate ion.Key words: nitrosiminium ions, α-acetoxynitrosamines, carbocations, iminium ions, nucleophilicity.

Photochemical Electron Transfer in the System Polypyrrole-Methylene Blue

1994 ◽  
Vol 47 (6) ◽  
pp. 1163 ◽  
Author(s):  
D Matthews ◽  
A Altus ◽  
A Hope
Keyword(s):  
Methylene Blue ◽  
Electron Transfer ◽  
Absorption Spectrum ◽  
Absorption Spectra ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Vitamin K1 ◽  
Photochemical Reduction ◽  
Long Chain

Methylene Blue incorporated into colloidal oxidized polypyrrole was investigated by absorption spectroscopy and laser flash photolysis. The absorption spectra of Methylene Blue and polypyrrole were unaffected by incorporation. Flash photolysis transients of Methylene Blue and triplet Methylene Blue in ethanol were affected by 1,4-benzoquinone and 1,4-benzoquinol but not by the long-chain naphthoquinone Vitamin K1. Incorporation of Methylene Blue in polypyrrole produced distinct changes in the flash photolysis transients of Methylene Blue and triplet Methylene Blue. Very long-lived transients, with lifetimes of the order of 10 ms, were observed. These effects were accompanied by long-lived changes in the absorption spectrum of Methylene Blue. The transients were modified by the addition of 1,4-benzoquinone but not 1,4-benzoquinol. The results indicate photochemical reduction of oxidized polypyrrole by triplet Methylene Blue with the production of stable long-lived species capable of reducing 1,4-benzoquinone.

scholarly journals Tea Stem as a Sorbent for Removal of Methylene Blue from Aqueous Phase

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Tzan-Chain Lee ◽  
Shumao Wang ◽  
Zonggui Huang ◽  
Zhongxing Mo ◽  
Gangxing Wang ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Ionic Strength ◽  
Aqueous Phase ◽  
Removal Efficiency ◽  
Adsorption Mechanism ◽  
Second Order ◽  
Isotherm Models ◽  
Order Model ◽  
Pseudo Second Order ◽  
Second Order Model

The potentiality of tea stem for the adsorption of methylene blue (MB) from aqueous phase was investigated. A series of operating factors, including the initial MB concentration, contact time, pH of solution, dose of tea stem, and ionic strength of solution, were conducted to understand the effect of adsorption of MB onto tea stem. Adsorption isotherm, kinetic models, thermodynamic investigation, and regenerability of tea stem were systematically investigated in this study. The experiment results revealed that the removal efficiency decreased with MB concentration and the equilibrium time of adsorption at different initial MB concentrations was approximately at 60 min. The appropriate dose of tea stem powder was found to be 4 g/L. The pHzpc of tea stem was evaluated and was observed to be 6.0 ± 0.2. The removal efficiency increased with pH ranging from 3.0 to 5.0 and remained constantly at the pH range of 5.0–11.0. The pH affected the adsorption because of the repellent power between H+ and dye cation. The ionic strength was found to have a negligible effect on the adsorption. The Langmuir and Temkin isotherm models were found to be the best isotherm models to elucidate the adsorption mechanism between MB and tea stem powder. The maximum adsorption capacity of 103.09 mg/g derived from the Langmuir model was much close to the experimental result. From the kinetic analysis, the pseudo-second-order model was found to be the suitable model to describe the adsorption behavior. The calculated adsorption capacities at different temperatures derived from the pseudo-second-order model ranging from 68.91 to 69.8 mg/g were well close to the experimental data. The intraparticle diffusion of MB molecules into pore structures of tea stem powder is the rate-limiting step for the adsorption process in this study. Evaluation of thermodynamic parameters including changes in enthalpy, entropy, and Gibb’s free energy indicated the adsorption mechanism between MB and tea stem powder was a spontaneous and exothermic process. The regeneration/adsorption experiments indicated that the tea stem powder efficiently remained more than 97% after five cycles using NaOH as a desorbing agent and thus be used for many times. On the basis of experimental results obtained, it is concluded that the tea stem has a considerable potential as a low-cost sorbent for removing MB from the aqueous phase.

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