Nanoparticle tracking analysis characterises colloids in water

Particle and Surface Sciences Australia has reported on how nanoparticle tracking analysis (NTA), from Nanosight UK, is being implemented for the further characterisation of natural colloids (inorganic and organic) at the Institute of Water Resources and Water Supply at the Technical University Hamburg-Harburg in Germany.

Inorganic and organic colloids are widespread in aquatic systems, where they influence many water-quality treatment processes. Until recently there was a lack of an adequate analysis technique to measure the size fraction below 1000 nm. The research group of Professor Mathias Ernst of the Institute of Water Resources and Water Supply has adopted the use of NanoSight’s NTA technique to provide new insights into water quality.

PhD student Martin Schulz began his research at the Berlin Centre of Competence for Water, where he first used NTA to assess different water treatment processes, in particular looking at particle and colloid removal and water purification methods (eg, coagulation and ozonation). His work focused on membrane filtration, where he encountered the problem of membrane fouling when colloids would block the pores of the membrane. Schulz used NTA to predict the fouling potential of a water sample, thus providing time for the treatment plant to react with different pre-treatment options.

PhD student Martin Schulz with his NanoSight LM10 NTA system, used for the characterisation of colloids in water.

Speaking of the Institute of Water Resources and Water Supply, Schulz said, “The institute provides professional support to water companies and our industry partners for the optimisation of processes, problem solving and innovation. We expect to offer NTA as a support tool to regional water companies who have problems with particles and colloids in their treatment processes and water distribution systems.”

Other techniques have been applied to this application with mixed success. These include LC-OCD (liquid chromatography-organic carbon detection) and flow cytometry (using fluorescence markers). NTA has proved to be a suitable complement as it is only by combining all of these techniques that full characterisation of a water sample over a broad size range can be established.

Schulz said, “NTA is perfect for the concentration range of water and wastewater samples. It provides reliable size detection in polydisperse samples which occur in almost all natural water samples. The fast and precise detection of the smallest colloid fraction (< 200 nm) is a huge advantage. It also has potential for making online measurements. In simple words, we use NTA as an additional water-quality parameter.”