Jian-Hai Mu

Effect of KBr on the micellar properties of CTAB

The effect of KBr on the size, shape and microviscosity of CTAB micelles has been investigated by means of laser light scattering (LLS),1H NMR measurements and fluorescence probe. The data obtained from the various techniques are quantitatively in agreement. The Rh of micelles in 0.01 rnol · L−1 CTAB solution increases from 3.5 nm to 43 nm andRg increases to 89 nm with addition of KBr salt. In this process, both the microviscosity and molecular weight of micelles Mw have noticeable increases, too. The rod-like micelles are formed at 0.1 rnol · L1 KBr and the worm-like micelles are formed at above 0.2 rnol · L-1 KBr.

Effect of benzyl alcohol on the rheological properties of CTAB/KBr micellar systems

Abstract The effect of benzyl alcohol on the rheological properties of cetyltrimethylammonium bromide (CTAB)/potassium bromide (KBr) micellar systems has been investigated. The addition of the alcohol induces the viscosity of 0.01 mol l−1 CTAB/KBr micellar system to go through a marked maximum. These results have been discussed in terms of 1H-NMR spectra of CTAB molecules in the aqueous systems included benzyl alcohol and KBr salt. It is argued that benzyl alcohol will be located in the interfacial region of CTAB/KBr micelles and promotes these micelles to be bigger with lower concentration of alcohol. This process makes the viscosity of the system rise. With increasing alcohol content continuously, it will be solubilized in the palisades of the micelles and induce these worm-like micelles to be transformed into rod and spherical ones.

Determination of the second CMCs of dodecyl polyoxyethylene polyoxypropylene ether by the methods of cloud point, fluorescence, and viscosity

Abstract The second critical micellar concentrations (CMCs) of nonionic surfactant dodecyl polyoxyethylene polyoxypropylene ether C12H25O(EO)m(PO)nH (LS54: m=5, n=4; LS45: m=4, n=5; LS36: m=3, n=6) were determined by three methods: cloud point, steady-state fluorescence and viscosity in paper. A comparison of the results obtained from different experiment shows that the cloud point method is easier than the steady-state fluorescence, and the viscosity method is not a good method for the second CMCs’ determination.

Design and Application of an Alkaline‐Surfactant‐Polymer Flooding System in Field Pilot Test

We have developed an inexpensive sort of flooding reagent whose major components are natural mixed carboxylates from proportionally mixed saponification residuals of cottonseed oil, tea oil, vegetable oil, and soybean oil. An orthogonal test design method was used to select one form of this flooding reagent (which is named SD) by measuring the phase behavior and another form of the flooding system: alkaline/surfactant/polymer (named SD‐ASP). The optimal composition was obtained by measuring the transient interfacial tension (IFT) at the crude oil/aqueous interface. Results of the tests show that the SD‐ASP flooding systems are tolerant to salt up to 1.5×105 mg/L and to Ca2+ and Mg2+ to 5.0×103 mg/L at 90°C, the IFTmin (the minimum of IFT) is 10−3 mN/m, and the oil recovery ratio reaches 22.77% by using the core flood experiment. The pilot tests, including a putting in and sending out in a single oil well, a group oil well and a larger well region, were all very successful, with an average input‐output ratio of 1∶4.15. All these results demonstrate that the SD‐ASP formulation is a new, very inexpensive, and highly effective flooding system.

What is the Criterion for Selecting Alkaline/Surfactaint/Polymer Flooding Formulation: Phase Behavior or Interfacial Tension

Abstract An experimental study on determination of alkaline, surfactant, polymer (ASP) flooding systems using natural mixed carboxylate was conducted to examine the decisive factor for ASP flooding, phase behavior or interfacial tension. The volume and color of middle phase liquid were observed, the transient interfacial tension at different salt and alkaline concentrations were measured and, finally, coreflood test in laboratory were made. The results showed the flooding system with larger volume and brown color of middle phase emulsion sometimes not to obtain better oil recovery efficiency. The primary and more important phenomenon affecting the oil recovery is a lower or ultralow minimum interfacial tension value at the crude oil/soluble phase interface.

A CIDEP study of photolyzed anthraquinone radicals in aqueous micellar solutions and microemulsions

Abstract A comparative study of CIDEP spectra was made, using a highly time-resolved ESR spectrometer, of photolyzed anthraquinone radicals in aqueous micellar solutions and O/W microemulsions to determine the influence of different surfactant microenvironments on the photolysis of anthraquinone. It is obtained that the difference in the mechanism of the photolysis reaction could be attributed to the different solubilization location of anthraquinone molecules in micelles and microemulsions, and the CIDEP spectrum of photolyzed anthraquinone radicals in microenvironments is not mainly affected by the structure of the micellar solutions or microemulsions, but the structure of the surfactant molecules.

A time-resolved electron spin resonance investigation of the photolysis of 1,4-naphthoquinone in aqueous micellar solutions and microemulsions

Abstract A comparative study of CIDEP spectra was made using a highly time-resolved ESR spectrometer of photolyzed 1,4-naphthoquinone radicals in aqueous micellar solutions and O/W microemulsions, to determine the influence of different surfactant microenvironments on the photolysis of 1,4-naphthoquinone. It is concluded that the difference in the mechanism of the photolysis reaction could be attributed to the different solubilization location of 1,4-naphthoquinone molecules in micelles and microemulsions.

Rheological Properties of Anionic Surfactant Solutions in the Presence of Al3+ Counterion

Aqueous solutions of ionic surfactants with strongly binding counterions exhibit wormlike or network properties. The properties of anionic micelles of sodium dodecyltrioxyethylene sulfate (AES) in the presence of multivalent counterion Al3+ were investigated by dynamic rheological methods. The steady-shear viscosity and stress, the zero-shear viscosity, the complex viscosity, and the dynamic shear modulus have been determined as a function of the surfactant and salt concentrations. Some interesting and noticeable results have been obtained, which can express the micellar growth and structure. The formation of wormlike micelles or network structure in surfactant solutions becomes much easier with increasing surfactant and salt concentrations. The Cox-Merz rule and the Cole-Cole plot are not applicable perfectly to the systems studied. The nonlinear viscoelasticity and non-Newtonian behavior can be found in all solutions according to the comparison with the simple Maxwell model. The technique of freeze-fracture transmission electron microscopy (FF-TEM) was also applied to confirm the formation of these interesting structures.

A time-resolved ESR study on the photolysis of benzaldehyde in homogeneous solvent, micelles and microemulsions

The time-resolved electron spin resonance (TRESR) spectra and chemically induced dynamic electron polarization (CIDEP) phenomena obtained from laser flash photolysis of benzaldehyde (BA) in homogeneous solvent, micellar solutions and microemulsions were investigated. The α-hydroxybenzyl radical generated from the hydrogen abstraction of the triplet state of BA from ethylene glycol (EG) or surfactant molecules was observed. The radical pair mechanism (RPM) and triplet mechanism (TM) and computer simulation were applied to express the photolysis. The intensity of CIDEP signals, the lifespan of the radicals and the polarization mechanism were different in EG, micelles or microemulsions because of their different microstructures.

THE INTERACTION BETWEEN DODECYL POLYOXYETH YLENE POLYOXYPROPYLENE ETHER NON1ONIC SURFACTANT AND POLYV1NYLPYRROLIDONE IN AQUEOUS SOLUTIONS

Abstract The changes of cloud points and surface tensions of a nonionic surfactant dodecyl polyoxycthylene(5) polyoxypropylene(4) ether (LS54) in aqueous solutions with added polyvinylpyrrolide (PVP-K90) were determined in order to evaluate polymer-surfactant interactions in the bulk solutions. A new model, corona-shaped intra-chain micelles, was applied lo these phenomena and the thermodynamic parameters of micellization were determined.