maandag 2 juni 2014

A separate post about separation

In relationships between people separation is often associated with pain, frustration, and aggression. But in the world of chemists separation is often a desirable outcome. Or, it’s at least worth serious research, and this blog post.

According to the Second Law of Thermodynamics the entropy increases in the course of time, i.e., the chaos in the universe increases if you let everything run its course. Apparently, it’s human to revolt against this regularity, by gathering what had been dispersed. Men wants to restore order, which already starts with separating household waste.

To separate
During the creation, as described in the book of Genesis, there is also talk of separation of matter:

Genesis 1: (4) …and God separated the light from the darkness. (5) God called the light “day,” and the darkness he called “night.” … (6) And God said: “Let there be a vault between the waters to separate water from water.” (7) And God made a vault to separate the water under the vault from the water above it.

Physical separation technology
At Chemelot Campus the Indian company Technoforce is located, a manufacturer of physical separation equipment. (1) In this equipment Technoforce applies techniques such as distillation, drying, stripping, crystallization, and extraction. And it applies extreme process values, such as a temperature of minus 20 up to plus 300 degrees Celsius and very deep vacuum up to 0,001 millibar (i.e., one millionth of a bar; normal air pressure is 1 bar).
Substances are separated based on their physical characteristics, such as differences in boiling point, density (which makes oil float on water), state (solids, liquids, and gases), and solubility (so some substance dissolves in water and others in oil).

Separation equipment is needed to make pharmaceutical products, food, oils and greases, polymers and chemicals. They’re used to purify process flows, concentrate fruit juices, recover dissolvent, and to process waste.

February 18, 2014, was the inauguration of Remco Tuinier, employed by DSM at Chemelot Campus, as Associate Professor Colloid-Polymer Mixtures at the Utrecht University. (2)

A colloidal dispersion consists of small particles (disperse phase), dispersed in a medium (continuous phase). These small particles measure from nanometers up to several micrometers. There are many examples of colloids.

A continuous gas phase with small particles we call an aerosol. Examples are mist with small drops and smoke with small solid particles. A liquid continuous phase with gas particles is foam, such as whipped cream. Small liquid particles in a fluid we call an emulsion, such as milk. Small solid particles in a fluid is called a sol, with paint as a typical example. Small particles can also be dispersed in solid substances. If this is a gas, we call it solid foam, for example pumice. If it is a liquid, it’s a solid emulsion or a gel, for example cheese. Finally, small solid particles in a solid substance is called a solid sol, such as ruby glass.

Paint is a colloidal dispersion, existing of various components: water, binding agents, pigment, and adjuvants; often polymers are added. The trick is to produce paint with the correct viscosity, that dries quickly enough and that forms a hard and durable layer.
To improve the art of paint making research on colloids is required. Part of this research concerns the depletion interaction.

Depletion interaction
The depletion interaction has to do with the fact that when extra components, for example polymers, are added to a colloidal dispersion, a disturbance is caused: the various components stand in each other’s way.
The word depletion is negatively derived from the Latin word ‘plere’, which mean ‘to fill’. So, depletion means ‘to de-fill’. The depletion interaction is scientifically explained by the interaction of physical forces, such as the vanderwaals forces, electrostatic forces, and sterical forces (spatial repulsion). Through these forces the smaller particles in the dispersion (the polymers) cannot get in areas around the larger particles (the other components). In these so-called depletion zones there is a lack of polymers and, as a result, the freedom of movement of the polymers is limited. The polymers can increase their freedom of movement by pushing the larger particles towards each other.

These ‘depletion forces’ lead to the separation of equal objects from the other objects. The larger particles attract each other indirectly: ‘attraction through repulsion’. If the depletion interaction gets stronger (for example, by adding more polymers to the dispersion), phase separation is the result. For example, the ‘smart addition’ of a polymer can result in gels, sometimes liquid-liquid segregation can result, and even crystals can be formed. Under specific circumstances, a dispersion can be separated into three components, with sharp interfaces. The phase transition from milk to cheese is desirable, the sifting of mayonnaise is not.

I end this blog post with a remark about the colloidal dispersion foam. The German philosopher Peter Sloterdijk uses foam to describe the world of today: foam as a metaphor for the extreme individualism of our time. (3) “During the formation of foam, the dense, continuous, massive is subject to an invasion of the hollow: air reaches unexpected places. However, as soon as the agitation of mixing, the insertion of air into liquid, settles, the reign of the foam collapses quickly. The foam air returns to the common atmosphere and the more solid substance collapses into drops.” According to Sloterdijk, the instability and volatility that characterize foam show the multiple ways in which the contemporary man experiences his life and the world.

Question: what is your metaphor for the way man nowadays experiences his life and the world?

(1) Click for more information about Technoforce.
(2) I quoted from Remco Tuinier’s oration, in which he makes a plea for broader technological knowledge. Click for more information about colloids.
(3) Peter Sloterdijk, “Sphären III. Schäume - Plurale Sphärologie” (2004, “Spheres, Volume III. Foam: Plural Spherology”).

This blog post is a repost of my (Dutch) April 14, 2014 post.
Read my May 20, 2013 blog post about the reason why of my English reposts.