Efficient lignin fractionation from Scots pine (Pinus sylvestris) using ammonium-based protic ionic liquid : process optimization and characterization of recovered ligninKhan, Sharib; Rauber, Daniel; Shanmugam, Sabarathinam; Kay, Christopher W. M.; Konist, Alar; Kikas, TimoPolymers2022 / art. 4637, 13 p. : ill https://doi.org/10.3390/polym14214637 Journal metrics at Scopus Article at Scopus Journal metrics at WOS Article at WOS