Control of Interactions Between Organic Foulants and Hardness Ions for Fouling Mitigation

Membrane fouling and scaling are among the primary factors limiting the efficiency and sustainability of pressure-driven water treatment processes. In natural and industrial waters, organic foulants such as proteins and natural organic matter coexist with dissolved hardness ions, creating complex interactions that can either accelerate or suppress deposit formation on membrane surfaces. Understanding and predicting these coupled phenomena remain major challenges in membrane science.

In collaboration with the European Synchrotron Radiation Facility, we have developed an innovative approach to investigate foulant-ion interactions at the molecular level. The methodology utilizes Langmuir monolayers of representative organic foulants formed on controlled aqueous subphases containing dissolved salts. These model interfaces mimic key processes occurring at the membrane-water interface during filtration.

Using synchrotron-based techniques, including X-ray reflectivity (XRR) and grazing-incidence X-ray fluorescence (GIXRF), we quantify the adsorption of ions and organic molecules and reveal how their interactions influence interfacial structure and composition. The obtained descriptors provide a predictive framework for assessing fouling severity and scaling propensity.

The predictions generated from these interfacial studies show excellent agreement with reverse osmosis filtration experiments. This research establishes a direct connection between molecular-scale interfacial phenomena and membrane performance, enabling the development of more effective fouling mitigation strategies and more reliable water purification technologies.