Recent advances in electrochemical applications of sustainable biomass-derived biochar for water purification and soil remediation

Biochar derived from rich biomass has been considered as a sustainable alternative in the development of electrochemical devices for environmental remediation because of its good electroactivity, cheapness, and eco-friendliness. In this review, we investigated the electrochemical applications of biochar in water purification and soil remediation. The electrochemical properties of biochar depend on the preparation conditions, including feedstock, pyrolysis temperature, and crushing and sieving. Multiple modification methods can be applied to improve its characteristics of specific surface area, pore structure, conductivity, heteroatom active sites, and surface functional groups. Furthermore, it has been widely used as an electrode material or electrode modifier in water/wastewater treatment and desalination. The common water purification devices include electrochemical advanced oxidation process, microbial fuel cell, microbial electrolysis cell, three-dimensional biofilm electrode reactor, and capacitive deionization. Biochar exhibits a great potential in soil electrochemical remediation as an electrode material or transmission medium of soil microbial fuel cell. Finally, we summarized the technical challenges of biochar in practical applications and discussed the possible development directions of biochar-based electrochemical remediation technology.