Research Progress of Environmental Risk Substances in the Preparation of Biochar

Abstract

Biochar is a kind of solid material containing high carbon, which is obtained from biomass such as agricultural and forestry wastes through photosynthesis in oxygen free or low oxygen environment and pyrolysis at high temperature. It has many advantages, such as wide source of raw materials, high specific surface area, developed pores, and high stability. With the wide application and promotion of biochar in various fields, some hazardous substances to the environment generated in its preparation process, such as heavy metals and metalloids, polycyclic aromatic hydrocarbons, persistent free radicals, soluble organics and metal cyanide, should also be focused on and studied. In this paper, three types of environmental risk substances (i.e. heavy metals, polycyclic aromatic hydrocarbons and persistent free radicals) are studied, and their harm to the environment and ecological are explored, as well as the prospects for future development. Through careful selection of raw materials and the optimization of preparation conditions, the toxicity and harm can be suppressed to some extent.