Biochar-supported zerovalent iron for removal of various contaminants from aqueous solutions

This work describes the synthesis and testing of a novel environmental sorbent that combines the advantages of biochar, chitosan, and zerovalent iron (ZVI). Chitosan was used as a dispersing and soldering reagent to attach fine ZVI particles onto bamboo biochar surfaces. Characterization of the resulted ZVI-biochar composites (BBCF) indicated that chitosan effectively soldered the iron particles onto carbonaceous surfaces within the biochar pore networks. The BBCF showed enhanced ability to sorb heavy metals (Pb(II), Cr(VI), and As(V)), phosphate (P), and methylene blue (MB) from aqueous solutions. The removal of Pb(II), Cr(VI), and MB by the biochar-supported ZVI was mainly controlled by both the reduction and surface adsorption mechanisms. Removal of anionic contaminants (As(V) and P) was likely controlled by electrostatic attraction with the iron particles on the BBCF surfaces. An additional benefit is that the contaminant-laden BBCF could be removed from aqueous solution easily by magnetic attraction.