Table 1.

Molecular weight and solubility characteristics of common lignins used in fabrication of various carrier materials for active substances.

Lignin source	Type[a]	Isolation process	Typical impurities
softwood, hardwood	KL	kraft pulping	carbohydrates <5 %
softwood, hardwood	LS	sulfite pulping	salts
softwood, hardwood	OS	ethanol–water organosolv pulping	carbohydrates, extractives
annual plants	SL[a]	soda pulping	carbohydrates <10 %, silica
annual plants	HTL	autohydrolysis or acid‐catalyzed pretreatment and extraction	carbohydrates <10 %
various types of biomass	EHL	solid fraction recovered after saccharification of pretreated biomass	carbohydrates >10 %

[a] Type of lignin: SL—soda lignin, HTL—hydrothermal lignin, EHL—enzymatic hydrolysis lignin.