Enhanced detection of benzene gas
Volatile organic compounds, or VOCs, are emitted as gases by certain solids and liquids. In other words, they evaporate into the air at room temperature (under normal conditions, making them particularly dangerous in consumer products) from which they can be inhaled or ingested or come in contact with the skin. They are carefully monitored and restricted due to their detrimental effects on human health and the environment. Benzene is a prominent VOC that is a natural constituent of crude oil and a known carcinogen. Despite its proven detrimental impact on health, benzene is still among the most common chemicals employed by industry. It is used extensively in the petrochemical industry and included in solvents, detergents and pharmaceuticals. Numerous benzene gas sensors abound that determine the amount of benzene in a sample measured in so-called parts per billion (ppb). Nanomaterials create the potential for highly sensitive and specific sensors given that they have surface structure and chemistry on the same scale as atoms and molecules. In other words, individual recognition and binding sites on nanomaterials could detect individual gas molecules. A European consortium sought to exploit functionalisation of carbon nanotubes (CNTs) enabling activation of specific sites for the development of significantly improved benzene detectors with EU funding of the Nano2hybrids project. CNTs are a type of nanomaterial that looks like rolled up chicken wire when seen under very high magnification. Scientists altered the CNT surface by applying metal nanoparticles of various sizes and distributions. Different deposition methods were used, some existing and some developed for the project, one of which was patented. Processes were carefully evaluated leading to identification of critical parameters and optimisation. Resulting materials were characterised extensively both for microscopic structure and benzene binding function. Integrating experiments and numerical modelling, the Nano2hybrids benzene sensor capable of detecting amounts less than 20 ppb far exceeded current state of the art and resulted in a pending patent. The project’s website has received international awards both for its format and usefulness and for the project itself. In fact, it is used as an example of best web practice by independent evaluators for the EU.
