Investigating the properties of humins foams, the porous carbonaceous materials derived from biorefinery by-products
Résumé
Humins as biorefineries by-product can be converted with a direct heating treatment into new rigid
porous carbon materials known as humins foams. Currently, not many informations about this new
material are known. Here, a preparation protocol in two steps involving foaming and carbonization is
reported, while the materials have been investigated in terms of morphology, elemental content, water
adsorption–desorption, stability to solvents and high temperatures, and thermal conductivity. In order
to evaluate their potential uses in applications such as water purification, the pH associated to the zero
charge point has been identified. Foams prepared under air ventilated condition revealed an extremely
negative surface, which can be used in cation exchange applications. The surface’s groups have been identified
by Boehm titration, showing that this behavior can be associated to the presence of acid moieties,
while the basic species result absent. The humins foams have been also tested through CO2 adsorption
tests at realistic operation conditions, revealing that their performances can compete with materials
reported in literature. Finally, activated carbon monoliths from carbonized humins foams using CO2 activation
were tested, reaching a surface area of 1347 m2 g− 1 after 20 min and 1482 m2 g− 1 after 40 min of
activation. These monoliths have been characterized in terms of morphology and elemental content. The
results prove that the humins foams are very versatile materials, cost effective and easy to produce, with
promising properties that can be further tailored for foreseen applications.