Comparing different commercial zero valent iron nanoparticles to immobilize As and Hg in brownfield soil M. Gil-Díaz a, ⁎, J. Alonso a , E. Rodríguez-Valdés b , J.R. Gallego b , M.C. Lobo a a IMIDRA, Finca “El Encín”, Alcalá de Henares, Madrid, Spain b Universidad de Oviedo, Mieres, Asturias, Spain HIGHLIGHTS • Three types of commercial nZVI were tested in brownfield soil polluted with As and Hg. • nZVI reduced As and Hg availability in soil. • Different types of nZVI differed in effec- tiveness for As and Hg immobilization. • Soil properties affected nZVI effective- ness. GRAPHICAL ABSTRACT abstract article info Article history: Received 23 December 2016 Received in revised form 2 February 2017 Accepted 2 February 2017 Available online xxxx Nanoscale zero valent iron (nZVI) particles obtained by different methods differ in their structure, which lead to different reactivity, and therefore a likely difference in the remediation efficiency. The present study compares the effectiveness of three commercial ZVI nanoparticles to immobilize As and Hg in two soils (A and B) collected from a brownfield highly contaminated by mining and metallurgy activities. Scarce data are available on the ef- fectiveness of nZVI for Hg immobilization in soil. Two commercial nZVI slurries from Toda (RNIP and RNIP-D) and one from Nano Iron (25S) were used at different doses (1, 5 and 10%). The metal(loid) availability and mobility was evaluated with the TCLP test and Tessier extraction procedure. The influence of nZVI application on As and Hg speciation was also evaluated as well as its impact on soil pH, electrical conductivity and soil phytotoxicity to vetch germination. The three commercial nZVI particles significantly reduced As and Hg availability in the two soils studied, which led to a decrease in soil phytotoxicity. At the dose of 5% of nZVI a decrease of exchange- able-As higher than 70% was observed for both soils, whereas in the case of Hg, a higher dose of nZVI (10%) was necessary to achieve reductions of exchangeable-Hg between 63 and 90% depending on the type of nZVI and soil. No impact on soil pH and electrical conductivity was observed. The effectiveness of metal(loid) immobilization depended on type of nZVI, soil properties and metal(loid) characteristics. Nanoparticles from Nano Iron showed better results for As immobilization whereas RNIP nanoparticles were more effective for Hg. Overall, 25S at the dose of 5% resulted more effective than RNIP nanoparticles for the reduction of exchangeable-As (in the range of 6–14%), whereas RNIP and RNIP-D were 10 and 13% more effective, respectively, for the reduction of Keywords: nZVI Metal(loid) availability Arsenic Mercury Nanoremediation Science of the Total Environment xxx (2017) xxx–xxx ⁎ Corresponding author. E-mail address: mar.gil.diaz@madrid.org (M. Gil-Díaz). STOTEN-21948; No of Pages 9 http://dx.doi.org/10.1016/j.scitotenv.2017.02.011 0048-9697/© 2017 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv Please cite this article as: Gil-Díaz, M., et al., Comparing different commercial zero valent iron nanoparticles to immobilize As and Hg in brownfield soil, Sci Total Environ (2017), http://dx.doi.org/10.1016/j.scitotenv.2017.02.011