Mechanical effects in the Surf Zone – In situ Electrochemical Sensing

Hachem Kassem, Dr Peter Birkin, UoS; Associate Professor Guy Denuault, UoS;
Rationale: 

The pollution of the natural environment with plastics and their subsequent role in the ecosystems, is of concern.  Plastics are ubiquitous materials which by design are extremely chemically stable and physically robust.  However, understanding their lifecycle in the oceans is part of a wider effort to assess their impact.  The breakdown of plastic in the ocean is different depending on the location [1].  For example, mechanical effects are thought to be significantly increased in breaking waves in the surf zone where plastics are known to concentrate.  The aim of this project is to study the effect of particle (sand) impact in the surf zone on surfaces including common plastics with the aim of understanding the conditions necessary to age and cause damage to these materials.  This will involve both lab systems and sensors deployed in the surf zone to characterize the conditions within this environment.

Methodology: 

In a recent set of papers [2,3], it has been shown that the individual effects of erosive agents, including particles, on surfaces can be characterized using electrochemical sensors with a time resolution approaching 1 µs.  These studies have also been extended and tested in the surf zone in preliminary experiments.  The aim of this project is to use this novel technology in order to characterize erosive effects in the surf zone.  Here a dual approach will be adopted.  First, erosion in a flowing system will be used to develop new sensors designed to study plastic degradation in these dynamic environments.  To do this a plastic modified electrode will be used to follow pitting and other mechanical damage as individual particles impinge on the surface.  This will be followed using high-speed electrochemical measurements in combination with high-speed cameras.  A number of different plastics will be investigated (e.g., PET, BAS etc.) as well as plastics exposed to UV radiation.  Second, a set of surf zone experiments, recording the conditions within a breaking wave will be performed.  These two sets of experiments will then be combined to correlate the physical conditions to the damage and subsequent breakdown of plastics under the same conditions.   

Location: 
University of Southampton, Highfield Campus
Training: 

The INSPIRE DTP provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners. The student will be registered at the University of Southampton and hosted in Chemistry. The student will benefit from the wide range of courses (both postgraduate and undergraduate) available.  These include training in analytical chemistry and electrochemistry.  We also offer courses covering transferable skills.  The student can partake in seminars and group meetings as well as interact with other academics within UoS and outside through, for example, the Electrochemistry Summer School.

 

Eligibility & Funding Details: 

Please see https://inspire-dtp.ac.uk/how-apply for details.

 

Background Reading: 

1]        N. H. E. Ho and C. Not, Selective accumulation of plastic debris at the breaking wave area of coastal waters, Environ. Pollut., 2019, 245, 702–710.

[2]       P. R. Birkin and J. L. Barber, Particle induced surface erosion – Tumbling and direct impact; a high-speed electrochemical, acoustic and visual study, Wear, 2019, 428429, 147–153.

[3]        P. R. Birkin, R. Lear, L. Webster, L. Powell and H. L. Martin, In-situ detection of single particle impact, erosion/corrosion and surface roughening, Wear, 2021, 464465, 203527.