Demulsifier
A demulsifier (also emulsion breaker , organic breaker , emulsion separating agent ) is a surfactant compound or a mixture of surfactant compounds in a suitable solvent system to separate an emulsion into its components. It works by destabilizing the emulsion system by displacing the surfactants that have already been absorbed and stabilizing the system, the emulsifiers .
Demulsifiers are used in crude oil and waste water conditioning , for example in emulsion splitting plants .
Demulsifiers for breaking emulsions and for oil recovery
In many technical petrochemical processes, the formation of stable w / o emulsions is undesirable, for example in the desalination (removal of electrolytes by washing with water) of oils in the context of waste oil treatment, processing of oil residues or crude oil treatment. In the chemical industry in particular, there are many examples of undesired emulsion formation or the interest in a rapid “destruction” of the emulsion, called emulsion breaking or emulsion splitting, for example when water is to be separated from an organic phase.
In emulsions of the w / o type, finely distributed water droplets are present as a homogeneous mixture in the organic phase. This energetically quasi-stable state can be caused by the input of mechanical energy (for example emulsification by rapid stirring) or by the action of surface-active / interface-active substances, i.e. surfactants / emulsifiers. Even additives used for completely different purposes, for example corrosion inhibitors, biocides, can have an emulsifying effect. Emulsions can also be stabilized by electrical charges (polarizations) (polar organic phase or changes in the pH value in the production / process process as a result of the addition of acids / bases).
Emulsion stability is relative. A separation of water and organic phase after months is of no interest for continuous production processes because it is much too slow. Such emulsions are therefore referred to as stable. Emulsions that can only be partially separated and that have a mixed phase between water and organic phase that is difficult or impossible to separate (no clear phase boundary / "interface") cause particular problems.
For targeted emulsion splitting (that is, emulsion separation or water separation), attempts are made to accelerate the phase separation considerably or to prevent emulsion formation. This can be achieved by adding chemical substances (called demulsifiers, emulsion separators, emulsion splitting agents) or by avoiding the input of energy or surface-active additives. According to the state of the art, the following methods are in principle suitable for destabilization and emulsion separation and, if necessary, can also be combined with electrostatic processes such as electroflotation:
- Addition of demulsifiers to change micro-energetic conditions (charges, polarizations at the interface), that is, to reduce the repulsive forces of the finely distributed water droplets.
- Modification of surface-active substances (emulsifiers) in order to block their effect (e.g. acid treatment if anionic surfactants are the cause of the emulsion formation).
The addition of demulsifiers is typical for the treatment of w / o emulsions or the avoidance of their formation, while the reduction of the emulsifying effect of existing surfactants is more likely to be used for o / w emulsions (e.g. waste water treatment, deoiling) and with further process steps (addition of Primary flocculants / flocculants) is combined. One of the most important examples of the “suppression” of emulsification is the addition of appropriate “non-emulsifiers” to aqueous liquids, which are pumped into the oil field for more effective oil extraction and to make the rock more permeable to the crude oil by creating cracks (fracturing process). In principle, all surface-active substances are conceivable as demulsifiers which are suitable in an emulsion to influence the surface energies at the interfaces in such a way that the finely distributed water droplets can combine to form larger drops. These larger drops can then separate out much better (phase separation). Accordingly, chemicals of various substance classes are offered under the names of emulsion breakers, emulsion release agents, desalinators or demulsifiers.
Examples
- w / o emulsion: water in oil (water in organic phase)
- o / w emulsion: oil in water (organic phase in water)
Individual evidence
- ↑ Patent: Demulsifier for oil-in-water emulsions and process for its application . patent-de 69530032. Retrieved November 19, 2010.
- ↑ Helmar Schubert: Emulsification technology . B. Behr's publishing house . 79. 2005. Retrieved November 19, 2010.
- ↑ Demulsifiers for splitting emulsions and for oil recovery . GS INTECH. Accessed April 2017.