The potential of Kraft black liquor to produce bio-based emulsion-templated porous materials

Emulsion-templated porous monoliths based on castor oil-in-black liquor and on 1,2-dichloroethane-in-black liquor medium internal phase emulsions have been prepared in order to evaluate a possible valorisation of that undervalued by-product of the paper mill Kraft process. The cross-linking behaviour of the different polymers originally contained in the black liquor was investigated. It appears that both lignin and hemicellulose fragments are involved. Characterisation of the monoliths by scanning electronic microscopy and mercury intrusion porosimetry showed that using either castor oil or 1,2-dichloroethane allowed to obtain macrocellular morphology along with a high porosity. However, higher concentration of the internal phase is possible in emulsions prepared with 1,2-dichloroethane than with castor oil, leading to more attractive materials from both chemical and environmental aspects.