Title: Impact of Sodium Humate Coating on Collector Surfaces on Deposition of Polymer-Coated Nanoiron Particles.

Authors: Micić, Vesna; Schmid, Doris; Bossa, Nathan; Gondikas, Andreas; Velimirovic, Milica; von der Kammer, Frank; Wiesner, Mark R; Hofmann, Thilo

Published In Environ Sci Technol, (2017 Aug 15)

Abstract: The affinity between nanoscale zerovalent iron (nano-ZVI) and mineral surfaces hinders its mobility, and hence its delivery into contaminated aquifers. We have tested the hypothesis that the attachment of poly(acrylic acid)-coated nano-ZVI (PAA-nano-ZVI) to mineral surfaces could be limited by coating such surfaces with sodium (Na) humate prior to PAA-nano-ZVI injection. Na humate was expected to form a coating over favorable sites for PAA-nano-ZVI attachment and hence reduce the affinity of PAA-nano-ZVI for the collector surfaces through electrosteric repulsion between the two interpenetrating charged polymers. Column experiments demonstrated that a low concentration (10 mg/L) Na humate solution in synthetic water significantly improved the mobility of PAA-nano-ZVI within a standard sand medium. This effect was, however, reduced in more heterogeneous natural collector media from contaminated sites, as not an adequate amount of the collector sites favorable for PAA-nano-ZVI attachment within these media appear to have been screened by the Na humate. Na humate did not interact with the surfaces of acid-washed glass beads or standard Ottawa sand, which presented less surface heterogeneity. Important factors influencing the effectiveness of Na humate application in improving PAA-nano-ZVI mobility include the solution chemistry, the Na humate concentration, and the collector properties.

PubMed ID: 28682625

MeSH Terms: Ions*; Iron; Metal Nanoparticles*; Polymers; Silicon Dioxide; Sodium*