Surfactants - Science topic

Many surfactants will self-assemble. At low concentrations, these self-assemblies may be simple, small micelles. Their small size means that they won't scatter light very much. However, as the concentration of the surfactant is increased, other larger structures may form, such as lamellae. Because scattering of light scales with the sixth power of the scattering object's size, significant turbidity may occur.

Hello Adam,

You may buy it online. You may make an inquiry at Alfa Chemistry, they offer kinds of good-quality surfactants.

Extraction liquid needs good contact with surface. E.g., water shows poor contact on fatty surface.

For the spectrophotometric determination of sodium dodecyl sulfate, many cationic dyes have been proposed that form ion pairs with it, extractable with chloroform or benzene. Examples of such dyes are methylene blue (standard method), azure A, crystal violet, methyl green, and others. Methods of determination are easy to find in the literature by keywords.

1. If you place the wax + TW 80 system and disperse it well, then TW 80 will dissolve in water and TW 80 reverse micelles will be converted into straight micelles.

HLB is used to predict emulsions, wetting agents, detergents, solubilisates. To predict the structure of micelles,

So, to obtain stable direct emulsions (oil in water), surfactants with HLB numbers from 10 to 16 (depending on the nature of the oil) are used, to obtain reverse emulsions (water in oil) - from 3 to 5; at HLB 7-8, a transition of emulsions from direct to reverse is observed; HLB numbers are 7-9 for wetting agents, 13-15 for detergents, and 15-16 for solubilizers in aqueous solutions.

In addition to the HLB numbers and the CMC values, there is one more quantity that characterizes the state of the surfactant in the liquid phase. This quantity is called the packing parameter and is denoted Ns in most literature sources. The packing parameter is a dimensionless value of the ratio of the volume of the hydrophobic part of the surfactant (v) to the length of the hydrophobic part of the surfactant (l) and the area of the terminal polar group (s). Thus:

Ns = v/lхs.

If Ns<1/3, then spherical or ellipsoidal micelles are formed

OP-10 (Octylphenol Ethoxylates)

Dorian Foster The stages in making a stable dispersion (as well-known by paints and ceramic experts) are:

If your iron oxide (powder) particles do not wet in the liquid you're intending them to be dispersed in then this is the function of a surfactant (wetting agent). If your particles wet then you don't need a surfactant generally. Separation is achieved with input of energy, typically ultrasound in the wet. If the particles aggregate or agglomerate after separation then a stabilizer (charge/electrostatic or steric) is needed. IMHO, this is where your issues lie. I'd try sonicating in a 0.05wt% sodium hexametaphosphate solution as the phosphates are classic inorganic oxide stabilizers. Take a look at the following webinar (free registration required) for more details:

An acronym approach to laser diffraction method development: https://www.malvernpanalytical.com/en/learn/events-and-training/webinars/W190815PST

I agree with John Francis Miller . If your particles are in the dry form it's going to be very difficult to disperse them. Try measuring the specific surface area of the powder by BET. It should be greater than 60 m²/cm³ for the particles to be considered less than 100 nm. Also see plenty of discussions on Research Gate on this topic.

2 quotes from those much greater than I:

'I think dry nanotechnology is probably a dead-end' Rudy Rucker Transhumanity Magazine (August 2002)

‘If the particles are agglomerated and sub-micron it may be impossible to adequately disperse the particle… ‘The energy barrier to redispersion is greater if the particles have been dried. Therefore, the primary particles must remain dispersed in water...’ J H Adair, E. Suvaci, J Sindel, “Surface and Colloid Chemistry” Encyclopedia of materials: Science and Technology pp 8996 - 9006 Elsevier Science Ltd. 2001 ISBN 0-08-0431526

See also a recent question:

Sarmad Alrekabi

Your results are similar to our experiments with dodecyl sulfate solution

Pratyush Gupta

Polyethylene is hydrophobic so it can only be combined with hydrophobic solvents mineral oil i.e. hydrocarbons. The term "homogeneous suspension" is not correct. A suspension is a heterogeneous system consisting of solid particles distributed in a liquid medium. Apparently, by the term "homogeneous suspension" you mean a thermodynamically and kinetically stable suspension. Without surfactants, the suspension of polyethylene in mineral oil can be improved by adding polyethylene oligomers. The more viscous the suspension, the more stable it is.

Alan Lo

The glass transition temperature (like the melting temperature of anisotropic) characterizes the properties of isotropic bodies. When the solid components of the cleaning composition are dissolved in water, this parameter has no effect on the cleaning action.

You are facing a very difficult problem! In a multicomponent (polygenic) rock (without destruction), only physical and hydrophysical parameters can be studied. To study physical and chemical processes, it is necessary to decompose the rock into separate mineral and organomineral formations and study each separately, and then, most likely, model. But I foresee that the model will not give high accuracy.

totally depends on method of size determination to be used

Thank you and can you please provide method parameters if possible for the method developed . Can I use C18 column with your method parameters?.

Noor Tayyaba

Cysteine is not a surfactant and therefore you will not find it in CMC. This amino acid, which can be attributed to hydrotropes. At high concentrations, they form mesophases with water, but not micelles. If you imagine that you have synthesized an alkyl derivative of cysteine, then starting from the chain length of the alkyl residue with a chain length of С=7, the typical properties of a colloidal surfactant will appear.

Konnor K Jones

Indeed, the area of the hydrophilic group does not change. It has a certain structure. When surfactant molecules are arranged over a large area, they lie almost horizontally at the interface. Such a monomolecular layer has the properties of a gas. Then, with an increase in surface pressure, the surfactant molecules approach and the film becomes liquid, and finally, when the area per molecule is equal to the area of the hydrophilic group, the monolayer will have the properties of a crystalline body with close packing of molecules.

Dear all, another possibiity is through the 'salting-out' following the Hofmeister series. Increasing salt concentration and decreasing temperature reduce CMC and favor shape transitions. Please have a look at the following free access paper. My Regards

10.1039/D0SM00982B

Debanik Bhattacharjee

The equilibrium constants depend on the equilibrium process (chemical reaction). Equilibrium processes: chemical reaction, micellization, adsorption. To determine it, the concentrations of substances involved in the equilibrium are necessary. Look up the chemical equilibrium section in the Temins Dictionary for Students

Miguel Pereira-Silva Sir,

If you are taking ionic surfactant, then please read about "coacervation" of surfactant solution. That may be one of possibility. In coacervation there will be cloudiness of surfactant and two distinct phases can be observe.

If the whole solution is cloudy, then the answer given by Yuri Mirgorod sir possible.

Try one experiment by adding excess surfactant into solvent/ aqueous solution to check whether cloudiness of solution occurs.

Best wishes

Mona H. Ali Bnhmad

Wash with ethanol on a centrifuge or during dialysis.

Material Studio v.6.0.0 (Accelyres Software Inc., San Diego, CA) may work. This was used in a paper I co-authored recently:

Alaa Aldabet, John F. Miller, Somaieh Soltani, Salva Golgoun, Mohammad Haroun, Marouf Alkhayer, Wassim Abdelwahed,

Development of an ethanol-free salbutamol sulfate metered-dose inhaler: Application of molecular dynamic simulation-based prediction of intermolecular interaction,

European Journal of Pharmaceutics and Biopharmaceutics,

Volume 179,

2022,

Pages 118-125

100 ml nanofluid= 0.1 gram CuO+0.05 surfactant+ 99.85 ml water (add little extra to compensate for evaporation and spilling during sonication and mixing)

Dear Samridhi, if you do the streak plate method for pure culture formation then no any matter of contamination. After pure culture formation , you do the sub culturing of your sample only 2- 3 times, then preserve the culture at 4 degree celcius.

Dear Eduard Babulak ,

The simple difference is that human beings use their brain, ability to think, memory, while AI machines depend on the data given to them. As we all know that humans learn from past mistakes and intelligent ideas and intelligent attitudes lie at the basis of human intelligence.

While AI researchers are trying to replicate our mental functions, many people are scared that AI will replace them. Hundreds of jobs such as drivers, radiologists and cashiers are facing substitution with machines in the next 5 years. Who’s next? To get a better idea what is coming we need a better understanding in which domains AI is stronger than humans and vice-versa.

Regards,

Shafagat

Dear all, I think you need a co-solvent such as ethyl acetate, ethyl alcohol and water, and not a co-surfactant. Solvents mixtures are used for enhanced extraction of eugenol. My Regards

For micellization, betaines and sulfobetaines behave more like nonionic surfactants than ionic surfactants with added electrolyes, provided they are in the zwitterionic state. At low pH they will be cationic and far more susceptible to electrolyte effects...

See Weers et al. Effect of intramolecular charge separation distance on the solution properties of betaines and sulfobetaines. Langmuir 1991, 7:854-867.

interested

Yuri Mirgorod, we have finally succed in finishing this investiagtion and we have published it. If you are interested, I can share tthe publication with you.

Oliver Roe Hi Oliver! That mix of three solvents is a cleaning solution we used to use at a lab I previously worked at - the mixture did an excellent job of cleaning ppb-level analytes from microextractive devices like SPME. We'd do 1 hour sonication of the SPME devices in the cleaning solution and voila - clean as a whistle!

The Piroxicam molecule has practically no charge in water, therefore, the solubilization in L-81 (nonionic surfactant) and SDS (anionic surfactant) micelles is due, as Mirgorod pointed out, mainly due to hydrophobic interaction, which can be supplemented by the formation of an H-bond with oxygen included in surfactant molecules, especially L-81. Both types of interaction do not lead to significant changes in the electronic spectrum, which was observed by the author. I do not agree that the band with a maximum of 353 nm refers to the n-pi transition, this is a pi-pi transition, since the bands of the n-pi transition are 100-1000 times less intense. The methylene blue molecule has a cationic charge and, upon interaction with the SDS micelle, an electrostatic interaction will appear, which will lead to a change in the electronic spectrum of the dye both due to this effect and a shift in the dye monomer-dimer equilibrium.

I’m not entirely sure of the reason of your findings, although I’d like to help you with some insights. MB has some aggregate forms depending on its concentration and charge distribution (S+ or N+) on solution. For that reason, different absorption spectra can be seen. Take a look on this work for further details.

It can if the acid value of the Tween 80 and PEG 600 is on higher side

to add glycols are no surfactants, unfortunately, using the definition - surfactant = surface active compound - almost all chemical substances would be a surfactant.

Dear Ramil,

the appropriate choice of surfactant, particularly for materials with amine groups, can be highly dependent on the pH of the synthesis and also on the initiator. Depending on your choices on all the mentioned parameters, you may influence the particle size and morphology . I attached two publications, which deal with the influence of pH value on amine containing particles and the general influence of anionic, non-ionic and cationic surfactants on particle size and morphology of acrylamide microgels. I hope these are helpful.

cis- oleic acid can be used for oil-based ferrofluids as a surfactant that produces steric repulsions

Just to reiterate, the experimental size (for example by DLS) will strongly depend on the system (which ionic strength, counter ions, pH, etc.) and lead to, for example, more compact or more elongated ellipsoids as shown in https://www.sciencedirect.com/science/article/abs/pii/S0927775714003835

You may also find the general info on aggregation number of interest https://en.wikipedia.org/wiki/Cetrimonium_bromide

polystyrene beads naturally contain negative charges from polymerization reaction from the inbound initiator molecules.

Maryam Yousefi

Emulsion polymerization begins in surfactant micelles. Sodium deoxycholate is highly soluble in water. Its CMC begins at low concentrations. The only difference from SDS is that it hydrolyzes. An alkaline medium is formed, which can hydrolyze the monomer through the ether bond. All of this mixture can form a precipitate, or more specifically a latex, which is poorly stabilized in water. Latex with SDS is better stabilized.

You can read about emulsion polymerization in my book.

William Ewbank Thank you so much.

Best wishes,

Duncan

Dear Abu,

Ligand densities on NC surfaces typically fall in the range of a couple of ligands per nm2 surface (roughly 3 on average). While the order of magnitude of your calculation seems correct, 6.3 ligands/nm2 is likely an overestimation of the actual number (TGA will show both bound and free ligands). If your dispersions are stable, you could verify your results through quantitative NMR.

Iti Chauhan

Nanostructured lipid carriers (NLCs) are novel pharmaceutical formulations which are composed of physiological and biocompatible lipids, surfactants and co-surfactants. This is a complex mixture of substances that self-organizes with the help of water into a certain volumetric structure of different sizes. Moreover, in the chemical structure, proportions, sizes of molecules, the structure of the particle is already encrypted. So far, the theory has not been developed. There are too many parameters to consider for this.

Yes. You might A) drill holes to sample the various areas, B) place many fiber optic probes with reflective ends that respond to the chemical(s), or C) place broadcasting monitors that report the presence of the material you can follow the dispersion of the additive. Of course this may not be economically feasible, but if works, please donate the royalties to support young technical students.

Secondary alkane sulfonates are recommended for alkaline cleaners. The manufacturers probably have data on how stable they are in such extreme cases. 30% NaOH has a very high electrolyte concentration, so there may be solubility problems - if so, that might be solved by optimising the formulation.

Kabiru Adebayo

You should always do what the RG recommends. You need to click on "mention". I accidentally saw an appeal to me.

The method suggested earlier will not work for you.

You must definitely remove the soil, then extract the oil with a solvent from the soil. The kerosene fraction is best suited as a solvent.

Dear Noor Ul Ain, there are many studies where this couple of blend is prepared without any extra additives or further chemical modification of any of the two components forming the blend. Please have a look at the following sample document. My Regards

Wathsla Weerasinghe The stages in making a stable dispersion are wetting (for which a surfactant is required), separation (dispersion of agglomerates), and stabilization (prevention of recombination of particles). If you materials wet in water a surfactant is not needed but sometimes an ionic surfactant can be used in optimum concentration to aid stabilization. I agree with Yuri Mirgorod in this respect. Take a look at this webinar (registration needed) for further information:

Dispersion and nanotechnology

I have several comments on your statement 'I have to green synthesize the CU Fe ZN and Ag nano particles from selected plant materials'.

Wathsla Weerasinghe

Perhaps the concentration of substances in the extract was high. Try reducing your concentration.

density of polyethylene is mostly smaller than water, that is why your spheres are floating, not because of entrapped air.

before getting into it you should first read about fuel emulsions, where the goal is use oils difficult to burn by increasing the surface of contact to air. It is not for simply replacing part of fuel by water.

Buy and read a textbook on colloid science.

There's no way you are going to the answer to your question since you haven't said anything about what your are making and why you are making it. i.e., readers have no idea at all about your application, what you need to achieve and what you have to avoid.

And please ignore anyone who makes claims about minimum zeta potentials for stability - they are showing their ignorance of what is a complicated and well-understood scientific discipline. A good textbook (preferable with the word colloid and not nanoXXXX in the title!) will prove invaluable.

mildness mostly means minor interaction, which first of all is affected by general structural quality. If this is identical than adsorption (interaction) at fixed concentration increases with hydrophobicity (low cmc values).

B. S. Rawat

I theoretically predicted the formula by comparing the pK of dichloroacetic acid with the pK of carboxylic acids. I meant the effect on pK of the positive inductive effect of the alkyl group and the negative inductive effect of chlorine. So I don't know where to buy the reagent. Look for a reagent with any alkyl groups that suits you.

Dear Ramesh Oraon, for micellization there is always a hydrophobic/hydrophilic balance, which manifests in the CMC value. Please have a look at the following study and the references therein. My Regards

Dear Frederik,

Long sonication times (more than a few minutes) might break the crystals or even promote secondary nucleation (this might explain why you observe more agglomerates after sonication). I would try pulsed sonication instead.

However, I would first focus on the crystallisation conditions and crystallisation volume.

Good luck,

Joana

Hi,

My project is also related with IFT calculation in microemulsion (oil-water-surfactant solution). Did you could solve this problem later?

Ethanol as a surfactant.? Or solvent.

The immediate effect of tween 20 depends on the systems (e.g. https://www.sciencedirect.com/science/article/abs/pii/S0023643809000590).

Indirectly, Tween 20 hydrolysis (via target microorganisms esterases) offers C12 lauric acid/laurate that has direct antimicrobial potential. If you find this an issue, true Tween 80.

Dear Runcen Yin, once the CMC is reached, further incorporation of surfactant molecules depends on the structure balance between head and tail length of the surfactant molecules, with possible shifts from micelles to lamillar structures to accomodate further increase in concentration, so both changes in size and shape are involved. Please have a look at the attached files. My Regards

as pointed out by John Francis Miller you should first define the goal of dispersing the particles. Beside, primary particle size cannot be measured by light scattering or most other sizing techniques because it is impossible to discriminate primary particles and aggregates. Starting from dry powder it is almost impossible to achieve redispersion of aggregates. As mentioned (for dispersing agglomerates) adjustment of pH, addition of surfactants or phosphates may be useful. You may consider removal of larger aggregates/agglomerates by sedimentation, filtration or other means. Size selective flocculation may help in removing an oversized fraction (the smaller the size the larger dosis of flocculant is necessary).

generally ethoxylated products with alkyl chain length in range between about 10 to 14 and EO chain length between about 3 to 5 will work fine, however, viscosity will usually be relatively high.

Is it PVA solution? By dynamic viscosity you mean the absolute value of the dynamic viscosity? Could you share the G' and G" values too? Is the carbon dispersion stable?

Please try branched oxo alcohols C9+.

Food grade examples of Pickering emulsifiers mentioned by @Titus Sobisch include small granule starches like amaranth or quinoa starch (particle size 1.5 micrometer). An alternative is N-octenyl succinate starch (N-OSA-starch) which is allowed as a food grade emulsifying starch, prepared from regular starches and commercially available. In the literature you find these two approaches combined: N-OSA-quinoa and amaranth starch.

Long time ago we used it to open up cells (yeasts) in order to release ATP. As already said it is a hydrophobic interaction.

Dear all, please have a look at the following two free access patents, and the other RG documents. My Regards

John Francis Miller Thank you!

This was my first idea, however I was concerned that such approach will interfere with calculations.

Makayla Loey

Cationic dyes are used to detect SDS. SDS + dye in water forms a complex colored differently than the dye. In water, such complexes precipitate depending on the concentration. To avoid the appearance of a precipitate that interferes with photometry and analysis, formamide is used, in which the complex dissolves better than in water.

Dear Helena Mirzabeigi, in brief

- crosslinker is a polyfunctional compound responsible for interconnecting chains during polymerization so that a 3D network is formed.

- surfactant is used to controle cell size and to protect against collision and collapse.

- blowing agent is the chemical that generates a gas responsible for cells formation (foaming) during the polymerization reaction progress. Please have a look at the following links. My Regards

you have to control the pH. If it is neutral, concentration of oleic acid will be relatively high due to hydrolysis of the sodium salt of a weak acid. To have almost no free acid in solution and micelles higher pH, e.g., pH 10 is necessary.

If you want to disperse oil-stabilized nanoparticles in water, the procedure indicated below might help. However, Tween 80 is a nonionic surfactant, so that Zeta Potential values might not improve.

Stability by steric hindrance would be possible, so that electrostatic stabilization (indicated by Zeta Potential) would not be necessary.

The dialysis method you show is for removing the small molecules from the interior of the bag while retaining the large molecules. In the case of micelles, the small molecules (monomers) and the micelles are in equilibrium. If you reduce the concentration of the small molecules by dialysis, the micelles will dissociate into monomers once the monomer concentration falls below the critical micellar concentration.

To increase the concentration of micelles without changing the concentration of monomers, you can use ultrafiltration. In this method, the solution is forced through a porous membrane either by gas pressure or by centrifugation. The membrane has holes of a certain size that is smaller than the size of the micelles but larger than the monomers. The risk of this method is that the micelles may aggregate due to compression against the membrane.

Another approach, going back to the dialysis bag, is to immerse the bag in an absorbent material to draw out some of the water. This will also draw out some of the monomers, of course, but because the volume inside the bag also decreases, the monomer concentration should not change substantially. Some useful absorbent materials are carboxymethylcellulose and dry gel filtration resin, such as Sephadex G-100 or Bio-Gel.

You can read:

Dear Subhrajit Mohanty sorry to see that your very interesting technical question has not yet received any expert answers. Personally, I'm not an expert in this field enough to give you a qualified answer. My suggestion would be to search the "Publications" and "Questions" sections of RG for relevant literature refernces and for closely related questions which have been asked earlier on RG. Moreover, please have a look at the following potentially useful review article which might help you in your analysis:

This article has been posted by te authors as public full text on RG so that you can freely download it as pdf file.

I hope this helps. Good luck with your work!