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Phase equilibrium mixtures of Na2SO4-H2O mixtures

B.Sc. Project Description

Supervisors: Surika van Wyk / Louis van der Ham

Topic Phase equilibrium mixtures of Na2SO4-H2O mixtures

Supercritical water desalination is a new zero liquid discharge (ZLD) desalination technique, in which salt can be directly separated from water at supercritical conditions. This is done without the addition of chemicals or the production of concentrated brine streams. One of the salts of interest for separation is Na2SO4. The phase behaviour of Na2SO4-H2O mixtures needs to be investigated in order to understand the separation of Na2SO4 from H2O at supercritical conditions (T > 374 °C and P > 22.5 MPa). The isobaric temperature-composition phase diagrams can be constructed by experimentally measuring the solubility of the salt in the vapour (supercritical) phase. In Figure 1, a schematic of the laboratory scale set-up for the measurement of phase equilibrium is given.

Figure 1: Laboratory scale setup for phase equilibrium measurements

The main tasks of this B.Sc. project are as follows.

  1. Literature review.
  2. Learning to operate the laboratory scale set-up and doing safety analysis.
  3. Do isobaric equilibrium measurements at 250 and 300 bar respectively.
  4. Investigate different concentrations of Na2SO4-H2O mixtures (0.5 to 10 wt.%) at supercritical temperatures (380 to 500 °C).
  5. Report and presentation.

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