Robertson Group Unveils Solar Water Purification Technology for Rural Communities

Recent research conducted by the Robertson group, now published in Advanced Sustainable Systems, unveils an exciting breakthrough in water purification technology that could revolutionize access to clean water in rural communities. They have developed a low cost, easy to synthesise semiconductor photocatalyst, designed to treat water using nothing more than sunlight. This study's success marks a significant milestone in the potential for solar photocatalysis to provide sustainable water treatment solutions in remote areas of the world.

This research overcomes several challenges in water treatment. Conventional water treatment methods can be expensive, energy-intensive, and unsustainable, especially in regions with limited resources. By harnessing solar energy, the new photocatalyst offers an eco-friendly, affordable alternative that could be scaled for widespread use. The substrate used in this study is glass chips made by recycling waste glass bottles, obtained from Midlothian-based Dryden Aqua, which further adds to the sustainability of this research.

The paper reports results from field tests conducted in rural India on two water sources showing high levels of coliform bacteria: well water used for drinking, and pond water used for washing and bathing. After treatment in simple plastic bottles with the catalyst-coated glass chips and exposure to sunlight, total coliform counts were reduced by up to 99% and E. coli by up to 99.9% in just 2 hours, with excellent results in reusability tests. The ability to degrade bacteria so significantly after just two hours’ exposure to sunlight has transformative potential worldwide in areas where people currently drink untreated surface water. The study demonstrates the potential of solar photo catalysis to be used in real world drinking water treatment and will promote future advancements in the field.

A companion paper, in collaboration with EPFL Lausanne and published in Frontiers in Environmental Science, extends the research to understand the impact of uncertainties such as varying rate constant, initial contamination level, solar light intensity, treatment times and catalyst life on the treatment efficiency. This study will be particularly valuable for designing photocatalytic reservoirs that can handle fluctuating water inputs and optimise treatment times accordingly.

To further extend this research, the team also undertook field studies in 2024 to address other issues which will influence the wider adoption of the technology, including the social acceptability of the technology by local communities and the costs associated with it. 

The study was conducted in partnership with Indian Institute of Technology Kharagpur (IIT KGP), where experts helped the group delve deeper into the region-specific water quality challenges. IIT KGP partners facilitated smooth interactions with local communities during the field trials, allowing the group to better understand local issues. This collaboration has not only strengthened the research but also provided insights about the local communities which will be particularly valuable as the work moves towards pilot scale testing.

Robertson Group Research

The Robertson Group’s research involves molecule-based materials and nanomaterials with conducting, optical and electrochemical properties, used for functional electronic materials and devices, in applications such as solar cells, photocatalysts, transistors and supercapacitors.

The group’s research makes use of the School of Chemistry’s advanced facilities including advanced characterization techniques such as X-Ray Diffraction (XRD), Inductively coupled plasma optical emission spectroscopy (ICP-OES), Scanning Electron Microscope (SEM), Diffuse Reflectance Spectroscopy (DRS) and Mott- Schottky analysis, allowing them to thoroughly test and study the catalyst and analyse its effectiveness for contaminant reduction.

Funding

This research was funded by E4 DTP (NERC) and the Hydronations Scholarship Programme. Research visits to India were supported by Royal Society of Chemistry, E4 DTP, and School of Chemistry Impact Funding 2024.