Surface carbon influences on the reductive transformation of TCE in the presence of granular iron.

•Commercial iron suffered declines in non-reactive sorption, and increases in reactive sorption with aging.•Electrolytic iron exhibited weak non-reactive sorption at all times, and a slight increase in reactive sorption with aging.•Both iron types suffered declines in the effective surface reaction rate constants with aging.•The role of reactive sorption differs between commercial and electrolytic irons.•Electrolytic iron is limited as a model for ZVI in lab studies.