Assessing the effect of surface hydrophobicity/hydrophilicity on pollutant leaching potential of biochar in water treatment

This study investigated the role of surface hydrophobicity/hydrophilicity of biochar on its pollutant leaching potential (pollutants originally in biomass feedstock), including nutrients, organic matter and metals, in water treatment applications. The study outcomes confirmed that biochar with greater hydrophilic surface leached comparatively higher loads of nutrients and organic matter compared to biochar with mostly hydrophobic surface, while biochar with greater hydrophilic surface leached lower metal loads. This trend is attributed to the changes to the physical and chemical properties of biochar including specific surface area and surface functional groups, as well as being related to the binding forces between the biochar surface and the different compounds. Further, the study results substantiated the significant influence of surface characteristics of biochar, and its preparation process on pollutant leaching potential. The study outcomes provide essential guidance on the appropriate use of biochar as an adsorbent in water treatment, including raw biomass selection and the production processes to be adopted.