Diffusion-Controlled Reactions in Micellar Systems

1994 ◽  
Vol 366 ◽  
Author(s):  
Masanori Tachiya ◽  
Alexander V. Barzykin
Keyword(s):  
Reaction Kinetics ◽  
Stochastic Theory ◽  
Micellar Solutions ◽  
Dynamic Information ◽  
Potential Approximation ◽  
Guest Molecules ◽  
Micellar Systems ◽  
Diffusion Controlled ◽  
Effective Potential Approximation ◽  
General Method

ABSTRACTReaction kinetics in micellar solutions are studied theoretically with an emphasis on diffusioncontrolled luminescence quenching. Different spatial arrangements of reactants within individual micelles are analyzed and a general method for treating diffusion-controlled reactions in a finite volume employing an effective potential approximation is developed. Several models are considered for the exchange of reactants between micelles including migration mediated by the bulk phase and successive multiparticle hopping through transient channels connecting micelles during their sticky collisions. These results are combined in a general stochastic theory of reaction kinetics in micellar solutions with exchange. The theory is further extended to reactions in clusters of micelles using a continuous time random walk approach. Once the principal features of micellar kinetics are understood, one can extract important structural and dynamic information on the aggregates and their guest molecules by analyzing suitably designed experiments.

Stochastic theory of diffusion-controlled reactions

2003 ◽  
Vol 327 (1-2) ◽  
pp. 99-104 ◽  
Author(s):  
M. Moreau ◽  
G. Oshanin ◽  
O. Bénichou ◽  
M. Coppey
Keyword(s):  
Stochastic Theory ◽  
Diffusion Controlled

Nonisothermal reaction kinetics and preparation of ferroelectric strontium bismuth niobate with a layered perovskite structure

2004 ◽  
Vol 19 (10) ◽  
pp. 2956-2963 ◽  
Author(s):  
Chung-Hsin Lu ◽  
Wei-Tse Hsu ◽  
Jiun-Ting Lee
Keyword(s):  
Reaction Kinetics ◽  
Formation Mechanism ◽  
Integral Method ◽  
Correlation Coefficients ◽  
Differential Method ◽  
Layered Perovskite ◽  
Heating Rates ◽  
Integral Methods ◽  
Diffusion Controlled ◽  
Layered Perovskite Structure

Ferroelectric layered perovskite SrBi2Nb2O9 has been successfully prepared through a new process using BiNbO4 as a precursor. The SrBi2Nb2O9 formation mechanism was investigated using a nonisothermal analysis method at constant heating rates. The weight loss recorded in thermal analysis under different heating rates was analogized to the reaction conversion. A combination of the differential and integral methods was introduced to solve the reaction mechanisms. Analysis using the differential method revealed that two kinds of diffusion-controlled models have higher linear correlation coefficients than other models. Based on the integral method principle, a new integral equation combining the Arrhenius equation and the Lobatto approximation was derived in this study. The established equation significantly simplified the conventional calculation process and improved the accuracy for predicting the reaction models. Analysis using the integral method corroborated that the SrBi2Nb2O9 formation mechanism is governed by Jander's diffusion controlled model, and the activation energy was calculated to be 192.1 kJ/mol. The proposed methods and the derived equations can be further applied to other solid-state-reaction systems to elucidate their reaction kinetics and estimate the related kinetic parameters.

Modulation spectroscopy. Kinetics for the self-reactions of some α-aminoalkyl radicals in solution

1982 ◽  
Vol 60 (3) ◽  
pp. 274-278 ◽  
Author(s):  
Paul R. Marriott ◽  
Arlindo L. Castelhano ◽  
David Griller
Keyword(s):  
Absorption Spectrum ◽  
Reaction Kinetics ◽  
Unpaired Electron ◽  
Rate Constants ◽  
Lone Pair ◽  
The Self ◽  
Modulation Spectroscopy ◽  
Alkyl Radicals ◽  
Diffusion Controlled ◽  
Kinetics Of

The optical spectra and reaction kinetics of some a-aminoalkyl radicals, RĊHN(CH2R)2; R≡H, Me, Ph, were measured in solution using the technique of modulation spectroscopy. These radicals undergo diffusion controlled self-reaction with rate constants [Formula: see text]. When R≡Ph, the absorption spectrum has a well defined maximum at 346 nm; ε = 3390 M−1 cm−1, while the spectra when R≡H or Me were less intense [Formula: see text] and tailed into the visible. These spectra are substantially red-shifted when compared with those of simple alkyl radicals, an effect which is thought to be due to the interaction between the unpaired electron and the lone pair of electrons on nitrogen.

Hydrodynamic studies on micellar solutions of styrene–butadiene block copolymers in selective solvents

1985 ◽  
Vol 63 (10) ◽  
pp. 2691-2696 ◽  
Author(s):  
Levent Oranli ◽  
Pratap Bahadur ◽  
Gérard Riess
Keyword(s):  
Block Copolymers ◽  
Molecular Mass ◽  
Photon Correlation Spectroscopy ◽  
Correlation Spectroscopy ◽  
Micellar Solutions ◽  
Photon Correlation ◽  
Influence Of Temperature ◽  
Selective Solvents ◽  
Micellar Systems ◽  
Influence Of Temperature On

Hydrodynamic radius of micelles of several block copolymers in different selective solvents (for both types of blocks) was determined from photon correlation spectroscopy. The boundaries of micellar solutions in heptane (good solvent for polybutadiene block) and dimethylformamide (good solvent for polystyrene block) were established for polymers in terms of their molecular mass and block composition. The photon correlation spectroscopy data in combination with intrinsic viscosities of block copolymers in selective solvents were used to determine micellar molecular mass and aggregation number. The influence of temperature on the micelle size was examined. The block copolymer micelles could solubilize a certain amount of insoluble homopolymer within their insoluble core. 1H nmr spectra were examined to study the influence of temperature on micellar systems.

Novel Kinetic Effects in Vkcoelasttc Surfactant Solutions Under Shear

1994 ◽  
Vol 376 ◽  
Author(s):  
P.D. Butler ◽  
L.J. Magid ◽  
P.J. Kreke ◽  
J.B. Hayter ◽  
W.A. Hamilton ◽  
...  
Keyword(s):  
Micellar Solutions ◽  
Micellar Systems ◽  
Surfactant Solutions ◽  
Order Of Magnitude ◽  
Kinetic Effects ◽  
The Individual ◽  
Two Stages ◽  
Aqueous Micellar Solutions ◽  
Transient Alignment ◽  
Threadlike Micelles

ABSTRACTUsing small-angle neutron scattering (SANS), we have investigated the transient alignment and relaxation under Couette shear of viscoelastic aqueous micellar solutions of cetyltrimethylarmmonium 3,5-dichlorobenzoate (CTA3,5C1) and CTA3,5C1/CTAB mixtures at concentrations well above ф* (but below 1.0 wt. %). Time constants of the order of ten's of minutes are reported for alignment and relaxation, orders of magnitude slower than any previously observed in similar micellar systems. The collective properties of the network of entangled, threadlike micelles, rather than the individual micellar segments, dominate the alignment and relaxation behavior. At low micellar surface charge density (σ) (e.g., in pure CTA3,5C1), the first observation of alignment proceeding in two stages has been made. Increasing a decreases by an order of magnitude the shear rate required to reach full alignment and provides a comparable decrease in the rate constant for relaxation after cessation of shear.

Modeling the Diffusion Mechanism and the Reaction Kinetics for the Photocatalytic Degradation of Acid Red 151 Aqueous Solutions by ZnO: Comparison of Linear and Non-Linear Methods

2007 ◽  
Vol 10 (2) ◽  
Author(s):  
K. Vasanth Kumar ◽  
K. Porkodi
Keyword(s):  
Aqueous Solution ◽  
Diffusion Coefficient ◽  
Aqueous Solutions ◽  
Photocatalytic Degradation ◽  
Reaction Kinetics ◽  
Diffusion Mechanism ◽  
Batch Processes ◽  
Average Diffusion Coefficient ◽  
Diffusion Controlled ◽  
Average Diffusion

AbstractBatch processes were carried out for the photocatalytic degradation of Acid Red 151 from its aqueous solution using ZnO catalyst at different initial dye concentrations. The process was found to be diffusion controlled for the first 15-20 minutes (before irradiation) with an average diffusion coefficient of 6.759 × 10

On the stochastic theory of continuous parametric systems and its application to electron cascades

1950 ◽  
Vol 202 (1070) ◽  
pp. 301-322 ◽  
Keyword(s):  
Stochastic Theory ◽  
Usual Method ◽  
Discrete State ◽  
The Mean ◽  
Electron Cascade ◽  
Definition Of ◽  
Reacting Systems ◽  
Parametric Systems ◽  
General Method ◽  
Number Of Particles

A mathematical definition of an assembly of continuous parametric systems is given and its theory developed which makes it correspond precisely to most of the continuous parametric assemblies known in nature. Certain general theorems (formulae (19) and (22)) are deduced which hold for all such assemblies. It is shown that the usual method of treating a continuous parametric assembly by dividing up the domain of the parameter into a number of small segments, treating each segment as belonging to a discrete state of the system and then passing to the limit of making the segments infinitely small does not lead to a continuous parametric assembly of the type described above, but one of much wider generality which does not correspond to any type of physical system met with in nature. The general method and the theorems are of immediate application in calculating the fluctuations of the number of particles in chain reacting systems, and not only for systems in thermodynamic equilibrium . The general theory is applied, as an illustration, to the stochastic treatment of an electron cascade to derive the differential equations which determine the functions from which the mean number of particles in any energy interval and the mean square deviation of this number can be calculated. It is shown in the appendix how the application of the usual method to this problem leads to the same results only if particular boundary conditions are imposed on the problem.

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