Isolation and Investigation of Natural Rubber Latex from Taraxacum kok-saghyz with a High Solid Content

Roots of Taraxacum kok-saghyz (TKS) are a promising alternative source of natural rubber latex (NRL). This study demonstrated the novel possibility of extracting, stabilizing, and concentrating NRL from roots of TKS with a high solid content. In addition, some colloidal characteristics of the isolated products, which are of interest for latex processing, were determined. A scaled-up extraction sequence based on previous studies of flow extraction was applied with a setup comprised of an industrial slicer, stirring stations, and a hydraulic press. Significant amounts of natural rubber (NR) were separated along with removed biomass. Stabilization of NRL was successfully maintained during latex isolation using ammonia-free stabilizing solutions consisting of an ethanolamine/ethanolamine hydrochloride (ETA/ETA-HCl) buffer, sodium oleate, sodium sulfite, and benzalkonium chloride. Purified and preconcentrated raw latex was obtained through repeated creaming and redilution. While a direct further concentration of raw latex proved difficult, the isolation of latex with a high solid content was achieved through redilution before the final centrifugation. Gravimetry indicated a solid content of >54%. The products were characterized by a high viscosity, and dilution was possible without coagulation. ζ-potential (ZP) was determined to be −60 mV and approved the successful stabilization of high solid latex. Dynamic light scattering (DLS) confirmed the possibility of maintaining a bimodal particle size distribution (PSD) with hydrodynamic diameters of 104–231 nm for the first mode and 522–830 nm for the second mode.