Surfactants and interfacial phenomena pdf


Rosen, Milton J. Surfactants and interfacial phenomena / Milton J. Rosen. – 3rd ed. p. cm. Includes bibliographical references and index. ISBN 1. Now in its fourth edition, Surfactants and Interfacial Phenomena explains why and how surfactants operate in interfacial processes (such as. This book is the premier text on the properties and applications of surfactants. The third edition is completely updated and revised, including.

Language:English, Spanish, Hindi
Published (Last):12.07.2016
Distribution:Free* [*Registration Required]
Uploaded by: VALERIE

54724 downloads 181314 Views 39.83MB PDF Size Report

Surfactants And Interfacial Phenomena Pdf

Interfacial Phenomena. ESS Lecture. Fall Surfactant Structures. • Surfactants possess a characteristic chemical structure that consists of. – Molecular. SURFACTANTS AND. INTERFACIAL PHENOMENA. THIRD EDITION. Milton J. Rosen. Surfactant Research Institute. Brooklyn College. The City University of. Surfactants and Interfacial Phenomena, 2nd ed. M. J. Rosen. Wiley-Interscience. New York. , pp. xv + , $ As the title suggests, the emphasis in this.

For this reason, interfacial phenomena are almost always associated with disperse systems. Recall from Chapter 3 that disperse systems consist of discrete particle phases surrounded by a continuous phase medium. The particles can be in the solid, liquid or gaseous phase; and the continuous phase medium can also be solid, liquid or gas. Thus, disperse systems can exist in any one of nine different combinations of particle phase and continuous phase. Some examples of cases where interfaces can be formed are given in Table 5. This is a preview of subscription content, log in to check access. Preview Unable to display preview. Download preview PDF. Goff HD The role of chemical emulsifiers and dairy proteins in fat destabilization during the manufacture of ice cream. Rohenkohl H Influence of recipe parameters on fat-and gas-phase-structure in ice cream.

Safety and environmental risks[ edit ] Most anionic and nonionic surfactants are nontoxic, having LD50 comparable to sodium chloride. The toxicity of quaternary ammonium compounds , which are antibacterial and antifungal , varies. Prolonged exposure to surfactants can irritate and damage the skin because surfactants disrupt the lipid membrane that protects skin and other cells.

Skin irritancy generally increases in the series nonionic, amphoteric, anionic, cationic surfactants. Biosurfactants and Deepwater Horizon[ edit ] The use of biosurfactants as a way to remove petroleum from contaminated sites has been studied and found to be safe and effective in the removal of petroleum products from soil. Other studies found that surfactants are often more toxic than the oil that is being dispersed, and the combination of the oil and the surfactant can be more toxic than either alone.

Biosurfactants were not used by BP after the Deepwater Horizon oil spill. However, unprecedented amounts of Corexit active ingredient: dioctyl sodium sulfosuccinate DOSS , sorbitan monooleate Span 80 , and polyoxyethylenated sorbitan monooleate Tween , [33] [34] were sprayed directly into the ocean at the leak and on the sea-water's surface, the theory being that the surfactants isolate droplets of oil, making it easier for petroleum-consuming microbes to digest the oil.

Biosurfactants produced by microbe or bacteria can be used to enhance oil production by microbial enhanced oil recovery method MEOR.

Interfacial Phenomena - 2nd Edition

Also agrochemical formulations such as Herbicides some , insecticides , biocides sanitizers , and spermicides nonoxynol Depending on the number and nature of the polar and nonpolar groups present.

Surfactant Molecules and ions that are adsorbed at interfaces are termed surface active agents. At water-air interface Surface active molecules will be adsorbed at water-air interfaces and oriented so that the hydrocarbon chains of are pushed out of the water and rest on the surface.

At oil-water interface Surface active molecules will be oriented so that the hydrophobic portion is inside the oil phase and the hydrophilic portion inside the water phase. Perhaps the polar groups pull the hydrocarbon chains partly into the water. Oriented adsorption of surfactant at interfaces As a Surface active substance contains a hydrophilic and a hydrophobic portions.

Micelle Formation When the surfactant molecules adsorbed as a monolayer in the water-air interface have become so closely packed that additional molecules cannot be accommodated with ease.

Basic Theory of Interfacial Phenomena and Colloid Stability

Micelles Excess surfactants add will begin to agglomerate in the bulk of the solution forming aggregates called micelles and the free energy of the system is reduced. At certain concentration the interface and the bulk phase become saturated with monomers. The lowest concentration at which micelles first appear is called the critical concentration for micelle formation [CMC ].

Because of their ability to form aggregates of colloidal size. They form and disperse continually. For different surfactants in dilute aqueous solutions. Tweens with high HLB are hydrophilic.

Hydrophilic Lipophilic Balance A scale showing classification of surfactant function on the basis of HLB values of surfactants. The higher the HLB of a surfactant the more hydrophilic it is. Spans with low HLB are lipophilic. Classification of Surface active agent Functional Classification According to their pharmaceutical use. Surface and interfacial phenomena Wetting agents: The resulting viscous liquid was cooled to room temperature, and then washed by diethyl ether.

After 3.

The obtained results Figure 3 revealed 2. A detailed description of the used spinning drop has been brought elsewhere.

Afterward, this system was about This observed trend can be ted with the observation of increased interfacial convection. Surfactants are composed of According to these facts, it seems that in the investigated two different pairs including one hydrophobic and one system involved to IL as a surfactant, effect of interfacial hydrophilic part. Due to this nature, surfactant molecules convection is more dominant compared with the role of are able to oriented monolayer at the interface of polar surfactant as barrier.

Furthermore, a detailed investigation and nonpolar surfaces, and consequently reduce the IFT. If the kinetic variables are of Marangoni convection may be obtained from plots or the neglected, the maximum permissible change in IFT that equilibrium IFT versus the bulk surfactant concentration a surfactant may cause is only a function of its bulk concen- see Figure 4. In details, when a continuous relation tration.

So, as the concentration of surfactant molecules in between the increase of concentration and IFT reduction the bulk phase increases, a denser monolayer layer of the exist in a wide range of concentration variation, it is more surfactants will be formed in the interfaces and leads to possible that the system experiences Marangoni effect.

This concentration observed can be considered as a reason for trend can be related to this fact that as the bulk phase concen- the existence of Marangoni effect in the under studied system. So, the rate investigation for [C18mim] [Cl] and those obtained for of mass transfer in the interface increases and the lower time for equilibrium of DIFT is needed.

On the other hand, it has been accepted that the presence of surfactants at liquid—liquid interfaces prevent mass transfer by suppressing interfacial convection[49] or by caus- ing a barrier effect.


In general, it is believed that the DIFT reaches a minimum when the adsorbed surface-active species including the added surfactant and the crude oil FIG. One of the known as the phase inversion temperature PIT. In more reasons for such behavior may be related to the structure details, when the temperature is below PIT, the adsorption and size of the surfactant concerned. Longer chain surfac- of surfactant molecules onto the interface increases by tants are generally more effective at reducing the IFT, since increasing temperature, which reduces the IFT; thus, the they cause greater interaction between phase molecules at IFT decreases by increasing the temperature.

While the the interface on account of their longer chains , and they solution temperature reaches PIT, the adsorption of also adsorb strongly at the interface on account of their surfactant onto the interface achieves its maximum value, greater hydrophobic tendency.

As a consequence, a very and leads to the minimum IFT. It is proved for the tempera- small amount of surfactant arriving at the interface will ture higher than PIT, the surfactant adsorbed onto the cause a large decrease in the IFT, and further increases in interface diffuses into the oil phase, which may lead to the the surfactant concentration at the interface will produce inversion of emulsion as the content of surfactant in oil only small changes in the IFT.

This can be attributed to the fact — K on the IFT of IL solution and crude oil was inves- that in imidazole, nitrogen atoms are in aromatic ring with tigated. In this direction, an IL solution with concentration sp2 hybridization , and the positive charge is in resonance. The point is worthy to be the oil phase increases, which results in emulsion inversion noted is that IL solution with concentration ppm was as the content of IL in oil phase accumulated to some used to clearly observe the dynamic behavior of IFT extent.

Lecture - 3 Surface and Interfacial Phenomena

This would be considered as a probable reason variation while the other high concentrations show no wide for increase in IFT by increasing the temperature.

The obtained results In addition, a detailed investigation in Figure 3 revealed demonstrated in Figure 5 revealed that as the temperature that as the temperature increases, the required time to reach increases from to K, the IFT of IL solution and the equilibrium IFT decreases. This observed trend can crude oil increases from 2.

So, as the temperature increases, the reduction of IFT and increase of diffusion mass transfer in these layers lead to the easier migration of surfactants from bulk phase continues phase to the oil drop phase dispersed phase. So, the rate of mass transfer between bulk phase and oil drop phase increases, consequently less time will be required for reaching the equilibrium IFT. In addition, when the oil drop is injected through the rotating bulk phase in the spinning drop instru- ment, due to the temperature difference between the bulk phase and oil drop, a temperature gradient will be introduced, which leads to the convective mass transfer.

On the other hand, since, as aforementioned, one of the possible effective parameters on the occurrence of the Marangoni effect is the temperature gradient in the system. It is possible to consider the Marangoni effect as an effective mechanism accelerates the equilibrium in the system, consequently the DIFT becomes rapidly constant as the temperature increases.

Similar to the previous section, the IL solution with concentration of ppm was used to exam- ine the effect of the rotational speed on the IFT of the used IL.

In other words, low concentration of surfactant may lead to lack of concentration for mass transfer between the bulk phase and oil drop phase.

In this direction, four different IFT measurements at different rotational speed of , , , and rpm, while the temperature was kept constant at temperature of K, were performed. A close examination on the results in Figure 6 clearly illustrated that the higher rotational speed leads to faster equilibrium of IFT under the studied system. This observed trend can be related to the fact that as the rotational speed increases, the convective mass transfer FIG.

Effect of rotation on the equilibrium IFT of IL solution helps to the mass transfer through the diffusion mechanism; and crude oil system. In other words, in general there are two different mechanisms during the mass transfer of surfactants from the bulk phase measure the IFT of IL solution with concentration of into the oil drop phase, namely, diffusion and interfacial ppm while the temperature was held constant at convection.

Related articles:

Copyright © 2019 All rights reserved.
DMCA |Contact Us