EcoProtect research is developing new electroconductive polymeric fibre sensors to detect the presence of hydrocarbons (e.g. diesel and petrol) in contaminated land to provide an early warning system for areas at high risk of hydrocarbon contamination e.g. petrol stations, fuel depots and pipelines. On detection of hydrocarbons the fibre sensors, which can be integrated in to an electrical circuit are designed to initiate an automatic alert to the facility owners or emergency services.
Contaminated land in England and Wales alone is estimated to be up to 325,000 sites (300,000 ha) with between five and twenty per cent of these requiring action to ensure that unacceptable risks to human health and the environment are minimised. The main contaminants at reported contaminated land sites in England and Wales in April 2006 were observed to be metal and metalloids (60%) and organic compounds (30%). A large proportion of the organic compounds are hydrocarbons with most being petroleum based. Common sources of hydrocarbon pollutants include fuel storage and distribution, disposed of lubricating oil, leakages of solvents from industrial sites and coal stores . Additionally, oil and fuel pipelines are at risk of leakage often in remote locations and a means of rapid alert and position location are essential.
The Environment Agency estimates there are 12,000 petrol stations and over 6,000 underground storage facilities, in the UK alone. There is a strong need for companies to have effective monitoring equipment. The first and second world market potential for this product is at least thirty times that of the UK. Therefore, assuming the filling station, petrol, oil and fuel storage as well as other underground sites are in excess of 30,000 the total global market would be in the region of 900,000 sites.
A new family of electroconductive fibres and thin films are formed from polymer-nanoparticle co-mixtures by casting and/or extrusion. Mechanically stable and highly reactive films have been produced that give characteristic electrical resistance response profiles depending on composition and the type of hydrocarbon. The sensors are also therefore capable of differentiating between different hydrocarbons (e.g. diesel, petrol, oil). The integration of these electroconductive polymeric films or filaments into simple electronic sensing circuits enables the formation of a “chemical fuse” that is triggered by contact with hydrocarbons. Contact with a water-hydrocarbon mixture induces rapid failure of the polymer, resulting in an interruption of the electrical circuit, triggering the sensor. The sensor has been found to function in a range of environmental conditions such as extremes of pH and temperature. Significant changes in electrical resistance during degradation have been measured. At present, the engineering design is focused on the assembly of a low-cost probe that can be inserted into the ground to enable detection at any point along the length of the probe and accounting for fluctuations in groundwater levels.
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