Porous Structure and Krypton Sorption Capacity of Carbon Sorbents Prepared from a Composite of Hydrolytic Lignin and Phenol-Lignin-Formaldehyde

Abstract—The porous structure of granular activated carbons from a composite of hydrolytic lignin and phenol-lignin-formaldehyde resin was studied. The volumes of characteristic pore types, characteristic adsorption energy, and main technical characteristics were determined. The possibility of obtaining microporous, mechanically strong sorbents based on hydrolyic lignin (hazard class 3 waste) by adding phenol-lignin-formaldehyde resin to the starting composite raw material was shown. Thirty five percent combustion loss was found to be optimum for activated carbons from this type of raw material and makes it possible to obtain a sorbent with a micropore volume of 0.36 cm³/g and mechanical abrasion strength of at least 82%, which is equivalent to commercial activated carbons in sorption and technical characteristics. It was shown that the carbonizate from lignin and phenol-lignin-formaldehyde resin has pronounced molecular sieve properties: the pore volume of 0.30 cm³/cm³ is available only for molecules with a diameter of no more than 0.44 nm. The possibility of using active carbons from lignin for sorption of radioactive noble gases was evaluated using krypton sorption as an example.