The love-hate relationship of pyrolysis biochar and water: a perspective.

Biochar is being considered for environmental sustainability by the scientific community and as a result is extensively investigated for various applications in agriculture, remediation and construction. Hence, a sound knowledge of biochar's physical and chemical properties is critical. However, the dynamics of biochar-water interaction remain ambiguous. We hypothesize that the hydrophobicity of a biochar made at low pyrolysis temperature is not permanent under water-rich conditions. Our results suggest that the aliphatic functional groups responsible for biochar's hydrophobicity are displaced when subjected to water which eventually increases the affinity of the biochar towards water. We envisage that commentary would stimulate researchers to investigate the biochar-water interaction in a new light and eventually help design a biochar which would be apt for their intended end use.