Introduction to the use of HLB in surfactant selection for emulsification.
In developing emulsifier systems, it is important to select a surfactant/emulsifier system with the correct characteristics to match the requirements of the oil phase plus other factors, such as the temperature the emulsion, will be exposed to the presence of electrolyte etc. The use of the HLB system can help in quickly identifying the optimum surfactant system.
HLB = Hydrophile - Lipophile Balance
It provides the starting point for matching the HLB of the surfactant with the “required HLB” of the oil to form stable emulsions.
The HLB of a surfactant effects it’s characteristics in aqueous solutions and dictates their characteristics and the typical applications where they will be used.
An emulsion is most accurately defined as a dispersion of liquid droplets in a second immiscible liquid. Temporary emulsions may be formed by mixing/agitating the two normally immiscible liquids, however, the stability of temporary emulsions produced in this way is poor. Emulsifiers are surface active materials (surfactants) that are used to assist in the formation and stabilisation of an emulsion.
When determining the optimum HLB the nature of the oil phase and the emulsion type (oil in water or water in oil) are the starting point, there are literature values available for several materials:
Where data is not available an approximate value can be determined by preparing surfactant blends with a range of HLB values, this can be carried out using several emulsifier classes. The following table shows a range based on sorbitan esters and their ethoxylates:
Preparing emulsions based on these samples will provide an initial indication of the optimum HLB. This can be followed up by the evaluation of alternative surfactant classes, fine-tuning of the emulsifier system can be achieved by preparing further blends close to the target HLB.
In many applications blending emulsifiers so that a broader range of emulsifier HLB’s are present in the system can be beneficial, the optimum HLB’s to blend will vary from system to system.
There are a few factors that will influence the optimum emulsifier HLB in addition to the oil type these include:
· Ratio Emulsifier to oil
· Emulsifier type/chemistry
Therefore, when any of these parameters change further optimisation of the HLB may be necessary.
Lankem Range in order of HLB
Product Description HLB
Lansurf STO Sorbitan tri-oleate 1.8
Lansurf SMO Sorbitan mono-oleate 4.3
Lansurf SMS Sorbitan mono-stearate 4.7
Lansurf AE73 Cetyl oleyl + 3EO 6.8
Lansurf CO12 Castor oil + 12EO 7.0
Lansurf AE103 C10 Alcohol + 3EO 8.0
Lansurf SML Sorbitan mono-laurate 8.0
Lansurf AE33 C13 Alcohol + 3EO 9.0
Lansurf AE105 C10 Alcohol + 5EO 10.0
Lansurf SMO81 Sorbitan mono-oleate + 5EO 10.0
Lansurf OA7 Oleic acid + 7EO 10.4
Lansurf AE35 C13 Alcohol + 5EO 10.5
Lansurf STO85 Sorbitan tri-oleate + 20EO 11.0
Lansurf OA10 Oleic acid + 10EO 11.8
Lansurf AE107 C10 Alcohol + 7EO 12.0
Lansurf AE37 C13 Alcohol + 7EO 12.0
BioLoop 68L 100% Bio-based BioLoop 12.5
BioLoop T25 BioLoop with hydrophilic tails 12.9
Lansurf AE310W C13 Alcohol + 10EO 13.5
Lansurf CO40 Castor oil + 40EO 13.5
Lansurf OA14 Oleic acid + 14EO 13.6
Lansurf AE109W C10 Alcohol + 9EO 14.0
BioLoop T45 BioLoop with hydrophilic tails 14.1
BioLoop 84L 100% Bio-based BioLoop 14.2
Lansurf TA15 Tallow amine + 15EO 14.2
Lansurf AE108W C10 Alcohol + 8EO 14.5
Lansurf AE312W C13 Alcohol + 12EO 14.5
BioLoop T65 BioLoop with hydrophilic tails 14.7
Lansurf SMO80 Sorbitan mono-oleate + 20EO 15.0
Lansurf SMS60 Sorbitan mono-stearate + 20EO 15.0
BioLoop T27 BioLoop with hydrophilic tails 15.4
Lansurf AE315W C13 Alcohol + 15EO 15.5
BioLoop T103 BioLoop with hydrophilic tails 15.7
BioLoop T46 BioLoop with hydrophilic tails 16.0
BioLoop T66 BioLoop with hydrophilic tails 16.3
BioLoop T153 BioLoop with hydrophilic tails 16.4
Lansurf AE320W C13 Alcohol + 20EO 16.5
Lansurf SML20 Sorbitan mono-laurate + 20EO 16.5
Lansurf TH30W Tallow amine + 30EO 16.6
BioLoop T105 BioLoop with hydrophilic tails 16.8
Lansurf AE735 Cetyl oleyl + 35EO 17.0
BioLoop T155 BioLoop with hydrophilic tails 17.2