Biochar-supported zerovalent iron reclaims silver from aqueous solution to form antimicrobial nanocomposite.

In this work, zerovalent iron (ZVI)-biochar composite (BBCF) was used to remove and reclaim silver ions from aqueous solution. Sorption experimental data showed that BBCF quickly and efficiently removed Ag+ from aqueous solutions with a capacity greater than 600 mg/g. The strong sorption of silver on BBCF was mainly controlled by a reduction mechanism between the ZVI and Ag+, which was confirmed by the characterization of the post-sorption sorbent (BBCF-Ag). The characterization results also showed that the sorbed silver on biochar surfaces were nanoparticles with an average size of 28 nm. As a result, the BBCF-Ag showed strong antimicrobial ability and effectively inhibited the growth of Escherichia coli (E. coli), while the original BBCF without silver nanoparticle promoted their growth. These findings suggest that, not only can biochar-supported ZVI be used to remove silver ions from aqueous solutions, but the products formed represent a new value-added nanocomposite.