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Pyrolysis of biorenewable feedstocks and iron oxides is potentially a greener and more sustainable pathway to producing zerovalent iron (ZVI) for environmental rehabilitation. The resulting biochar-zerovalent iron (BC-ZVI) also shows improved remediation kinetics of trichloroethylene over conventional ZVI. Understanding the transformations of iron to ZVI and the influence of feedstock chemistry on ZVI is critical to the production of BC-ZVI and has not been reported previously. BC-ZVI production was studied by one-step pyrolysis of cellulose, corn stover, dried distillers' grain, red oak, and switchgrass pretreated with FeCl 3 . Pyrolysis at 900 °C effectively reduced Fe to ZVI with most feedstocks; however, the association of silicon (Si) and phosphorus (P) with Fe resulted in formation of fayalite and Fe phosphates and phosphides, which limited ZVI production efficiency and/or facilitated corrosion of ZVI. Dispersion of ZVI phases on biochar surfaces and association with Si facilitated oxidation of ZVI due to greater accessibility to oxygen and enhanced corrodibility of ZVI in association with fayalite. Feedstocks low in Si and P such as cellulose and red oak yield BC-ZVI suitable for environmental applications.

The removal of arsenic(V) from water was investigated under various coagulation conditions and compared to a variety of coagulation agents, including polymeric ferric chloride, polymeric ferric sulfate, polymeric aluminum chloride, polymeric aluminum sulfate, ferric chloride, ferric sulfate, aluminum chloride, and aluminum sulfate. Coagulation conditions evaluated include pH, temperature, type of coagulant, the addition of a coagulation aid, and initial arsenic(V) concentration. Results indicated that the arsenic removal efficiencies of polymeric coagulants were typically 10 to approximately 20% higher than those of their conventional coagulant counterparts. Water Environ. Res., 75, 308 (2003).