Production of Ferromagnetic Adsorbents from Solid Products of Biowaste Carbonization in a Fluidized Bed in a Medium of Superheated Water Vapor

Consideration has been given to problems of chemical activation of a solid product of hydrothermal carbonization (hydrochar) of biomass. Pellets from a mixture of poultry litter and straw subjected to carbonization in a fluidized bed in a medium of superheated water vapor at a temperature of 300°C were impregnated with water solution of ferric nitrate, dried in the air at a temperature of 100°C, and held for 2 h at a temperature of 300°C for degradation of iron(III) nitrate and its transformation into iron oxides. The pellets were activated at a temperature of 700–800°C in a horizontal tube furnace in an inert argon atmosphere. The obtained ferromagnetic sorbents have a rather developed system of micro- and mesopores. Furthermore, a twofold increase in the duration of activation results in an 18% increase of the pore specific surface, and the rise in the temperature of the activation process leads to an increase in this surface by 45%.