Structural characterisation of Ca2+-containing complexes of humic acid (HA) and cationic polyelectrolyte

Humic acid (HA) exists ubiquitously in aquatic environments and does affect the water quality of drinking water. For its removal complexation with polycations is an essential step. In our experiment we will investigate PDADMAC and Quaternized Chitosan as polycations to characterise the structure of complexes formed with HA. We will focus on the effect of Ca2+, which enhances aggregation of HA complexes. Shape and size of the formed aggregates, especially their compactness and local structure will be determined by SANS as a function of mixing ratio, type of polycation, and Ca2+ concentration. This will lead to a detailed understanding of how the structure of HA complexes is affected by Ca2+ and polycation, respectively. This is fundamentally important for an improved understanding of this step in water treatment and allow for systematic improvements of HA removal in water industry.