Engineered Biochar As Gas Adsorbent

From the 1100 s B.C to the present, biochar and adsorption technologies have been constantly evolving with a remarkable history. Biochar as a gas adsorbent is a biomass-derived material that has satisfactory properties for gas adsorption application. Since then, the mechanism, kinetics, and thermodynamics of gas adsorption have been investigated with the development of a series of novel models. Gas adsorption models are evaluated based on experimental adsorption isotherm, from which surface parameters of biochar can be derived. The surface and physicochemical characteristics of engineered biochar are ultimately determined by the type of the raw material and methods of char making including carbonization, physical activation, and chemical modification. Morphology, pH, total surface area, pore-volume, porosity, and surface functional groups are decisive factors for the gas adsorption capacity. Until now, biochar for gas adsorption is engineered for universal application to some gases such as CO2, H2S, CH4, and N2O, which are the main components of greenhouse gas emissions. Previous studies have shown the high efficiency of using engineered biochar as a gas adsorbent. However, it is still undeniable that this type of material still has certain limitations related to technical, economical, and environmental problems due to the knowledge gaps of mechanism, large-scale system, or regeneration process. Thus, in response to the current industrialization situation, it is mandatory to develop modern appropriate techniques to actualize the use of biochar as a gas adsorbent in the market.