Understanding aqueous solubility of lignosulfonates at higher concentrations

The behaviors of commercially available grades of sodium lignosulfonate and calcium lignosulfonate in aqueous solutions were studied by Nuclear Magnetic Resonance (NMR) relaxometry, Differential Scanning Calorimetry (DSC) and Dynamic Light Scattering (DLS). The combined techniques provided strong evidence that both the sodium and calcium lignosulfonate were fully dissolved in water up to concentrations of at least 30% w/v based upon their dynamic NMR relaxation behavior and observed depression of the enthalpy of melting of their aqueous mixtures. The Time Domain (TD) NMR Spectroscopy in conjunction with other complementary techniques was confirmed to be a powerful tool to elucidate the aqueous solution behavior of lignosulfonates and opens up new opportunities to investigate the aqueous solution and dispersion behaviors of polymers in general.