Kinetic characterization of Ca2+-involved complexation of humic acid (HA) by stopped-flow SAXS experiments for optimizing water treatment

In our proposed stopped-flow SAXS experiments we want to elucidate the structure of the initially formed complexes during the mixing of humic acid with oppositely charged cationic polyelectyolyte (cPE). The aim of the sf-SAXS experiment is to probe how the mesoscopic structure of formed complexes evolves over time under different conditions, such as the type of cPEs, their Mw, the mixing ratio and the solvent quality (e.g. the salt concentration). This shall allow for rationalising the tendency for further growth into flocs and precipitates, the compactness of formed complexes, and the tendency to form long-term stably dispersed aggregates – all aspects of central importance for ultimately understanding the flocculation process that is essential in raw water purification.