NarrativeHow can ‘organic’ sodium be used as a reducing agent to neutralise hazardous waste materials which create toxins lethal to humans? In our increasingly congested world, major chemical pollution remains a frequent threat to human life. Among the most harmful pollutants are ‘halogenated hydrocarbons’, many of which are extremely toxic to humans and are known to cause cancer and endocrine malfunction.
One easily recognised group of halogenated hydrocarbons are polychlorinated biphenyls (PCB’s), which were outlawed internationally under a United Nations treaty in 2001, yet continue to present a significant ‘end of life’ disposal issue due to their use in ‘closed systems’, such as transformers and capacitors, across the world.
The search for improved ways of detoxifying halogenated hydrocarbons presents a lucrative commercial prize, if safer and cheaper ways can be found to dispose of waste chemicals. Halogenated hydrocarbons tend to be very stable compounds and do not decompose readily, making them one of the most expensive chemical types to dispose of. Specialist contracting firms using incineration, ultrasound, irradiation, pyrolysis, microbial or chemical methods are extensively regulated.
The chemical alkali-metal treatment method, using metallic sodium, has been used commercially for 20 years, treating and neutralising halogenated hydrocarbons, but it is potentially hazardous on a large scale. Real-life sodium is a highly reactive reducing agent which transfers electrons to the halogenated hydrocarbon molecules and produces a stable polymeric material with low volatility/toxicity.
If there was a man-made equivalent organic compound that might mirror its activity, then this could, theoretically, be used to neutralise the halogenated hydrocarbons and alleviate the handling challenges associated with metallic sodium.
Strathclyde researchers, with funding from the EPSRC through its Pathways to Impact programme, and with the academic supervision of Professor John A Murphy, are looking at the possibility of dehalogenation using compounds that mimic sodium, with a Strathclyde University PhD researcher using the funds to explore the options in a three-month project, entitled: Treatment of Halogenated Hydrocarbon Waste Using Compounds which Demonstrate Exceptional Electron Donor Characteristics.
This is an exciting and highly innovative scientific challenge. Preliminary steps are being identified, and this could lead to significant commercial applications. The longer-term aim is to be able to take a new ‘organic sodium’ solution to the large waste management companies to see if there is a cost-effective breakthrough.
As disposal capacity for dangerous chemical wastes around the world continues to shrink, new technologies in the sphere of chemical remediation would be the longer term answer for major waste disposal companies, for governments and local authorities.
“It might be more beneficial for companies dealing with their own waste more effectively rather than sending to a central place of disposal,” says Prof Murphy. “As we’ve been looking towards making some organic substances, which behave like sodium, we’ve started to ask what sort of other things they might do. Increasingly, there are all sorts of things in biology that they might be able to do.”
For the University of Strathclyde’s Chemistry department, the theoretical exploration of such new ‘reduction’ reactions could have far-reaching applications elsewhere, such as turning carbon dioxide, CO2, into methane, CH4. Consideration is already being given to applications relating to carbon (i.e. CO2) capture from fossil fuel-fired power stations, where conversion of the waste gas into methane, for use as a vital energy feedstock, would be extremely attractive. In all, the research funding represents a fresh horizon for empirical research at the University of Strathclyde.
|Category of impact||Quality of life and safety, Environment and sustainability - natural world and built environment|