Investigating the properties of humins foams, the porous carbonaceous materials derived from biorefinery by-products

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 m(2) g(-1) after 20 min and 1482 m(2) 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. (c) 2020 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).