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Chengdu – Phun with Phase Diagrams

March 23, 2009

The institution of the day is again located in China (as the country that has been selected for the week) and is located in Chengdu, Sichaun (I always think of spicy chilli dishes when I see that name).  The university I am writing about today specialises in the areas of science (yay!) and engineering (yay again!) but also offers courses in business (economics and management), arts, philosopy and law.  It is:

Chengdu University of Technology.

Historically CDUT carried out a lot of work in geology and some of their research centres reflect that as the university houses both the National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (hmm not sure if that last word translated correctly)  as well as the National Specialty Laboratory of Geohazard Prevention and Geoenvironment Protection (interesting juxtaposition of research).

Today’s work actually falls inside my field, chemical engineering, so maybe I will have something lucid to say about this work (or not…):

Deng, T., Yin, H., Li, D., Metastable Phase Equilibrium in the Aqueous Ternary System (Li2SO4 + MgSO4+ H2O) at 348.15 K, Journal of Chemical and Engineering Data, 54(2), 498-501.

I am already loving this paper as it is only 4 pages long, when I looked closer the 4th page was made up of half a page of references.  EXCELLENT paper already.  Hopefully it means that it’s succinct and to the point.  The aim of this paper appears to be add to the general lexicon of physicochemical data by gathering information on the ternary phase diagram of the 2 salts and water in equilibrium, both stable and metastable (duh!) – this is of particular interest as the authors explore the possibility of ‘mining’ lithium and magnesium salts from  natural salt lakes.

This paper is a true to the spirit of chemical engineering paper – the authors built and used their own apparatus to investigate the phase equilibrium – genius!  I also like this paper because there is very little waffling or pontificating (I could learn something here).

The authors propose harnessing the power of natural effects (wind energy and solar techniques) to carry out the salt ‘mining’ but obviously first there is a need to know something about the equilibrium of the salt mixture in water.  The metastability provides the opportunity for harvesting of salts (I think) and the reactions can be exploited to promote this.  As well as getting phase equilibrium data, to help the process along, solubilities, densities and refractive indices were also determined.  There is a lot of quality info packed into this little paper and if you happen to be interested in this area it’s well worth a read.  If you are any type of physico-chemical  scientist it’s also well worth taking a look at how to write a nice, concise ‘meat and potatoes’ paper.

As an aside I must say looking at the phase diagrams takes me back to my halcyon undergraduate days….For those who aren’t familiar with ternary phase diagrams, basically it’s a way of combining data on the concentration of  elements in a 3-phase system and then determining how much of each resides in a particular ‘form’ (e.g. solid, liquid, solid solution etc).  The most common example out there is that for stainless steels because these typically contain iron and two other elements – they have been extensively studied as a result of industrial drivers and hence are well known systems.

Within a phase diagram you can select a composition point within the ‘space’ and ‘tie lines’ can be used to help determine the composition of the material at that point.  Here’s a link which has a nice basic description of how a ternary phase diagram works.

And now here is an example of a phase diagram that I want to work towards –

Phase equilibrium of a scientist

Phase equilibrium of a scientist

Sorry about the crappy resolution on some of the font…I’m not very arty or very phunctional in Photoshop – I might fix it one day, but my laziness about blog posting will probably deem otherwise.

2 Comments leave one →
  1. March 24, 2009 12:16 AM

    Now that the phase diagram is uploaded it looks even worse than when I drew it – oh well :oP. It might have been better if I’d gone old school with coloured markers and a ruler.

  2. Mayfly permalink
    March 25, 2009 3:37 PM

    This brings back memories… awww…
    As for the “Phase Diagram”, brilliantly explains it! lol

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