In situ chemical oxidation of contaminated groundwater using a sulfidized nanoscale zerovalent iron-persulfate system: Insights from a box-type study.

We report the potential of a sulfidized nanoscale zerovalent iron-persulfate (S-nZVI-PS) system for in situ chemical oxidation (ISCO) of groundwater pollutants. The study was conducted using a sand-filled rectangular box with a permeable reactive barrier of S-nZVI as a facsimile of the ISCO system. Synthetic water contaminated with a target pollutant (reactive black-5, RB-5) was continuously passed through the box. The injection of PS led to the complete removal of RB-5 and the system remained reactive for approximately 12 days. This system has a benefit that the oxidation products of S-nZVI (i.e., Fe3O4, Fe2O3, and FeSO4) can further activate PS to retain its reactivity. In a separate trial, this method exploited oxidation, reduction, adsorption and co-precipitation mechanisms that conspired to remove two different groundwater pollutants- arsenite and 1,4-dioxane. These results confirmed the utility of S-nZVI-PS as a mediator of ISCO processes to degrade groundwater pollutants.