Dissolved organic matter (DOM) affects efficiency of engineered system including water treatment and remediation processes as well as natural aquatic environment. In recent years, the effects of DOM on the reactivity, stability and transport of engineered nanoparticles have attracted extensive interests. We investigated the effects of DOM on the stability and transformation of nanosized zero-valent iron (NZVI), which is widely used engineered nanoparticle for aquifer remediation.<br/>Suwannee River Humic Acid (SRHA) and Suwannee River Natural Organic Matter (SRNOM) were used as reference materials of allochthonous DOM, and Pony Lake Fulvic Acid (PLFA) was used as autochthonous DOM. NZVI particles were dispersed in each DOM solutions then reacted with DOM. When NZVI reacted with SRNOM and PLFA, both zeta-potential and hydrodynamic diameter of the particles decreased. Derjaguin–Landau–Verwey–Overbeek (DLVO) interaction energy of NZVI particles was calculated and it elucidated the colloidal stability of the particles was higher in the presence of both DOMs. Spectrophotometric and fluorometric measurements identified that aromatic/hydrophobic fractions of SRHA was sorbed onto NZVI surface. Sorbed DOM moieties block electron transfer between NZVI and water, resulting in mitigated oxidation of iron. Shift of Fe(II)/Fe(III) half-cell potential by sorbed DOM also altered the oxidation and transformation of NZVI. Allochthonous DOM affected both stability and transformation of NZVI more than autochthonous DOM.

Effects of dissolved organic matter on the fate and transformation of nanosized zero-valent iron in aqueous system

253rd National Meeting (2017)

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