Open Positions
PhD topic of project B3: 57Fe-Mössbauer-Spectroscopy to understand precipitation reactions in P recovery from wastewater
In this PhD project, the decisive processes in phosphate precipitation with iron salts are to be tracked. A set-up is to be realized that allows samples for Mössbauer spectroscopy to be taken from an experimental reactor for precipitation and crystallization reactions of phosphates. The project focuses on precipitation reactions with FeCl3, FeSO4 and K2FeO4.
The metal-oxide phases thus formed as a function of the process conditions and the size distribution of the micro- and nanoparticles formed during precipitation are to be determined within the framework of WERA using temperature- and field-dependent Mössbauer spectroscopy, Raman spectroscopy and supplementary electron microscopy and X-ray diffraction. A further focus of the project is on the temporal development of the nucleation process including the first fast steps in which aggregates of only a few iron centers and/or very small or amorphous particles are formed. With the help of pH jump experiments with 57Fe-containing salt solutions and freezing of the mixture down to the millisecond range, the decisive first steps of the nucleation process during precipitation will also be investigated with the help of 57Fe-Mössbauer spectroscopy and synchrotron-based nuclear inelastic scattering (NIS). By simulating the NIS data with the aid of quantum chemical density functional calculations, structural models for the reaction intermediates will be obtained.
The most important scientific questions of this PhD will be:
- Which intermediate species occur during phosphate precipitation with iron salts?
- What is the temporal development of the type and size of the iron species during phosphate precipitation under laboratory and real wastewater conditions?
- To what extent are superparamagnetic iron phases present in sewage sludge containing vivianite? Do they contribute to the magnetic separation behavior?
Requirements for applicants:
- Excellent Master degree (M.Sc.) or equivalent in physics, chemistry or biophysics
- Very good experimental skills
- Experience relating to X-ray spectroscopy is beneficial though not essential
- Proficient in the English language and willingness to learn German (for non-German speaking persons)
Application:
You can send your application for this PhD topic to Prof. Dr. Volker Schünemann: schuene[at]rptu.de