Transport of PAA modified nanoscale zero-valent iron in water saturated porous media

To investigate the transport capability of nZVI in porous media, laboratory experiments including column and corrosion studies were conducted to investigate the transport capability of nanoscale zero-valent iron (nZVI) coated by different concentrations of polyacrylic acid (PAA) in quartz-sand filled porous medium and to observe their activity change after 6 hours' exposure to different electrolyte solutions. Utilizing transport distance and penetration rate, the transport performance of different iron materials in porous sandy media was characterized. The corrosion rate of nZVI in electrolyte solution was characterized by pH, ORP, Fe2+ concentration, XRD and Fe0 content changing curves with time. PAA adsorption on nZVI surface effectively improved transport performance of nZVI, but the corrosion raised by the PAA adsorption had been observed. Laboratory synthesized nanoscale zero-valent iron coated by 10% PAA presented the best performance in column test, with the penetration rate of 58.65% and Fe0 content moderately lost after 6 hours corrosion in electrolyte solution, which was less than the sample with 20% PAA adsorbed. Considering both the mobility in porous media and the reserved reactivity after aging for the nZVI with PAA modified, this study concludes that laboratory synthesized nZVI coated by 10% PAA is preferred for in-situ groundwater contamination remediation. © 2018, Editorial Board of China Environmental Science. All right reserved.