Nanoscale zero-valent iron: Future prospects for an emerging water treatment technology

► Contemporary knowledge of nano-Fe0 synthesis, modification and toxicity is reviewed. ► Discrepancies in the literature are highlighted with regard to testing parameters. ► Compared to “real-systems” nano-Fe0 performance has been largely overestimated. ► A universal testing procedure and reactivity scale are suggested to effectively compare future nano-Fe0 materials.