Vol. 11, Issue 12 (2022)

A carbon-rich substance with great environmental stability, biochar is mostly made from biomass. The direct use of biochar as a renewable energy source, as a soil additive to increase soil fertility and reduce soil greenhouse gas emissions, and as a filter medium for wastewater treatment. Making biochar results in less air pollution than burning agricultural waste outside, which can release noxious gases (CO, SOx, NOx), as well as smoke particles that contain carcinogens. In addition to the particle pollutants, open burning of agricultural waste in fields produces a 16 polyaromatic hydrocarbon that is harmful to human health. Mostly carbon-based chemicals make up biochar. Additionally, there are traces of hydrogen, oxygen, sulphur, nitrogen, and ash. The type of biomass employed, the reactor design, and the production conditions all have an impact on the composition and properties of biochar.

The most important factors affecting the adsorption qualities of biochar are its chemical composition, porosity, quantities of inorganic metals initially present in the feedstock, and the process conditions. Similar to activated carbon, biochar has a surface heterogeneity. Because of its large surface area, higher carbon content, high cation and anion exchange capacity, and stable structure, biochar reportedly outperforms activated carbon in the removal of a variety of contaminants, including pathogenic organisms, organic matter, surfactants, nitrogen (N), micropollutants, heavy metals, and other pollutants. The pore network of biochar is evenly distributed and has a vast surface area, with micropores as large as 2 nm, macrospores as small as 50 nm, and micropores ranging from 2 to 50 nm. It has a specific adsorption effect on heavy metals and organic ammonia nitrogen in the water because of its huge specific surface area. In other instances, the biochar's surface area was found to be less than activated carbon, although it had a greater capacity for adsorption. This is owing to the fact that the adsorption of water causes swelling within the biochar, increasing the internal surface area, and as a result, increasing the adsorption capacity.