Urea susbstitutes noble metal catalysts

… for the photodegradation of organic polluants.

A new laser-based technique developed by the Institute of Materials Science (ICMAB-CSIC) uses urea, a common substance in the chemical industry and a low-cost alternative to noble metal co-catalyst, to enable a more efficient, one-step production of hybrid graphene-based organic-inorganic composite layers for environmental remediation, photodegradation of antibiotic contaminants from wastewater. The composition and chemical bonds of the urea-enriched thin layers were studied in detail using synchrotron light at the ALBA Synchrotron.
Human activity is increasing the amount of pollutants in water and air, as well as in all sorts of materials at home and work place. The existence of antibiotic contamination is undeniably one of the most threatening challenges to date, at a time when antibiotic-resistant bacteria has already been flagged as the next world-wide pandemic crisis.
Semiconductor photocatalysts have long been investigated for environmental remediation because they can degrade or mineralize a wide range of organic contaminants as well as pathogens. Research focuses on addressing some drawbacks that prevent their use on a large scale. On the one hand, many photocatalysts are activated only by UV radiation which represents solely a small fraction of the total available solar emission. On the other hand, the recombination of the photogenerated  electron-hole pairs that enable the decomposition of the pollutant is usually faster than the oxidation reactions that cause the degradation of organic molecules. As a consequence, noble metal co-catalysts acting as electron scavengers, such as gold or platinum, are needed in the process.

Image: Researchers Ángel Pérez  del Pino and Enikö György from the ICMAB-CSIC together with Ibraheem Yousef, scientists responsible of MIRAS beamline at ALBA.

Mine tailings dumped into the sea analysed with synchrotron light

The case of Portmán Bay, at the Spanish Mediterranean coast, is one of the most extreme cases in Europe causing great impact on the marine ecosystem by disposal of mine tailings.

For more than 40 years, 60 million tonnes of mine waste were dumped directly into the sea, resulting from the open pit mining that took place in Sierra Minera in Cartagena. As a consequence, the Bay was literally filled with metal-rich artificial soil. Since 2014, a research group from the University of Barcelona (UB) has been studying Portmán Bay. Now, they have analysed samples of these sediments at ALBA because with synchrotron light they can obtain unprecedented information about the heavy metals contamination, such as arsenic.

Very few people know about Portmán Bay, where took place one of the most extreme cases of coastal ecological impact by mine activity in Europe. Figures speak for itself: the mining company Peñarroya dumped more than 60 million tonnes of mine waste into the sea through a 2km-long pipeline located at the west part of the bay. Over the years, the bay became totally filled with a mountain of artificial sediment. The shoreline moved 600m seaward and the trace of the pollution reached 12km out to sea.

>Read more on the ALBA website

Image: Miquel Canals putting sample supports, which were specifically designed and printed with 3D technology at ALBA, at the CLAESS beamline to be analysed with synchrotron light; with Carlo Marini, beamline scientist and Andrea Baza, PhD student from UB.