Complex Processing of Wood Waste into Hydrogen and Carbon Adsorbents Under Microwave Irradiation

This work considered an approach to modernize the process of carbonization of lignin-containing compounds induced by microwave radiation in order to obtain carbon adsorbents and hydrogen. Samples of hydrolyzed lignin were investigated as raw materials consisting almost entirely of lignin, as well as macadamia nut shells, which in addition to lignin contain cellulose and hemicellulose. As the raw material lacked sufficient microwave radiation absorption, alternative approaches were proposed to enhance the level of absorption. These included mechanical mixing of the raw materials with a selected brand of industrial activated carbon, AK-800, for hydrolyzed lignin and macadamia nutshells, and modifying the raw materials with metals for hydrolyzed lignin. Elemental analysis of the intermediate carbon residues was conducted, and chromatograms of the obtained gas products were generated. The data obtained indicate the possibility of synthesizing carbon adsorbents with different textural characteristics using the proposed method. Furthermore, the method allows for the enhancement of hydrogen yields during the carbonization process. Additionally, this technology has the potential to become waste-free due to the reuse of the obtained carbon residues in the carbonization cycle of lignin-containing waste.