One-step fabrication of artificial humic acid-functionalized colloid-like magnetic biochar for rapid heavy metal removal.

Abstract A novel functional colloid-like magnetic biochar (Col-L-MBC) with high dispersibility is prepared by the one-step method with the prepared porous biochar as the skeleton. Notably, A-HA obtained from waste biomass through hydrothermal humification (HTH) technology has rich functional groups (i.e., phenolic-OH, -COOH, etc.), which is conducive to the uniform dispersion of magnetic nanoparticles on the porous biochar skeleton, providing rich active sites for heavy metal ion removal. Interestingly, the introduction of A-HA can also lead to the formation of new iron species. Besides, A-HA coated on the surface of the magnetic substance also improves the dispersion of the magnetic biochar (Col-L-MBC) in the solution, forming a colloid-like magnetic biochar adsorbent, bringing superior removal performance for Cd2+ (maximum removal capacity up to 169.68 mg/g). Various removal mechanisms, including Cd-π interaction, complexation, ion exchange, and precipitation are introduced, making a great contribution to rapid removal performance.