Sodium lignosulfonate (CAS 8061-51-6) is a byproduct of the waste liquor from the sulfite pulping process in papermaking. It is obtained through concentration, sugar removal, and drying. It is an aromatic polymeric anionic surfactant with sulfonic acid groups (strongly hydrophilic) in its molecules. It has a wide molecular weight distribution and appears as a yellowish-brown to brownish-red powder, the color of which is affected by the raw materials and processing. It is readily soluble in water, and its aqueous solution is weakly alkaline (pH 7–9). It precipitates easily in strong acids. It is non-toxic and biodegradable.