Remediation of Per- and Poly-Fluoroalkyl Substance (PFAS)-Impacted Waters using Ultrasound
Per- and polyfluoroalkyl substances (PFASs) comprise a group of ~3,000 man-made chemicals used since the 1940’s across a range of applications.
The scholarship is based on the RCUK rates. For the academic year commencing October 2018 this is £14,777 per annum for stipend (tax free maintenance grant) and £4,260 per annum for fees (these are full time rates, part time rates are £7,388.50 and £2,130 respectively). RCUK increases these values annually in line with a GDP deflator.
Per- and polyfluoroalkyl substances (PFASs) comprise a group of ~3,000 man-made chemicals used since the 1940’s across a range of applications. The physicochemical properties of PFASs, conferred by their high degree of fluorination and the strength of the carbon-fluorine bond, leads to unique partitioning behaviour (i.e., both hydrophobic and oleophobic properties) and thermal stability which were sought after commercial properties. But these properties bring extreme recalcitrance and resistance to chemical attack as a result of their stability, making PFASs extremely difficult to remove and destroy using conventional water or soil treatment technologies. These properties challenge many types of remediation technologies.(1-3)
Sonolysis (the use of ultrasonic waves to break down a substance) utilises ultrasound’s unique quasi-adiabatic bubble collapse that results in localised temperatures >5,000 K and pressures ~1000 atm. Sound waves at frequencies generally between 20 kHz to 1 MHz facilitate cavitation in water. As sound waves move through water, oscillating cycles of rarefaction and compression, cause cavitation and allow bubble growth. The microbubbles collapse during compression cycles, and significant energy is released in the form of point sources of extreme heat and plasma-like conditions.
Changes in reactor configuration (liquid height, geometry, flow characteristics, frequency…) and solution properties will have significant effect on the ultrasound wave field inside the vessel.(4) As a result the cavitation activity, which is dependent on ultrasound wave field is affected. This in turn will affect the efficiency of the sonolysis. Hence to scale-up sonolysis, there are many optimisation factors that can be explored due to the impact of parametric variation.
This PhD will aim to address the following key research questions:
- What are the required cavitation conditions and related mechanisms for sonolytic destruction of PFASs?
- What are the key ultrasonic parameters that effect the degradation of PFASs?
- How can the required cavitation conditions for PFAS destruction be implemented at a larger scale?
Drs Bussemaker and Lee are the leaders of the Sonochemistry Ultrasonics Research Group (SURG)(5) at the University of Surrey and will be the academic supervisors for the project. The PhD will be done in collaboration with Arcadis, an international company with extensive applied experience in the PFAS contamination issue where Dr Ian Ross will act as the industrial supervisor.
1. Kucharzyk, K., et al., 2017, J Env Manag 204(Pt 2): 757-64.
2. Higgins, C. and E.R. Dickenson, Water Research Foundation, 2016. WRF report 4322: 1-123.
3. Appleman, T.D., et al., 2014, Water Res., 2014. 51: 246-55.
4. Wood, R. et al., 2017, Ultrason Sonochem., 38:351-70.
5. Sonochemistry Ultrasonics Research Group (SURG)
Applicants should have (or expect to obtain by the start date) at least a 2:1 bachelors degree, and preferably a masters degree, in an appropriate discipline (e.g. engineering, material sciences, physics or related subject).
If English is not the first language, IELTS 6.5 or above (or equivalent) is required, with no sub-test score less than 6.
Open to European/UK students only.
How to apply
This is a multi-disciplinary course and hence good candidates from chemistry, chemical engineering or physics with experimental experience and willingness to learn will be considered.
Please send CV and cover letter to firstname.lastname@example.org and apply though our PhD Chemical and Process Engineering course page.
Skype interviews for the position will be held by 29 June, early applications may be interviewed when first convenient. Confirmation of acceptance will be expected by 5 July.
Please state the project title and supervisor clearly on all applications – preferably as part of the project title.