The presence of water constituents, such as natural organic matter (NOM) and arsenate, can greatly impact the nucleation kinetics and morphology of iron(III) (hydr)oxides, thus affecting their reactive surface area. In this study, <i>in situ</i> grazing-incidence small angle X-ray scattering was used to investigate the nucleation of iron(III) (hydr)oxides on quartz in the presence of NOM and arsenate. Precipitates were also characterized <i>ex situ</i> using atomic force microscopy, thermogravimetric analysis, UV-vis spectroscopy and high resolution X-ray diffraction. We found that the presence of NOM increased the sizes of heterogeneously formed particles. In addition, less precipitation was observed for both systems with NOM, and precipitates formed in the presence of NOM had higher water contents and lower zeta potentials, which can alter the electrostatic interactions between preformed nuclei and positively charged embryos in solution. Results have important implications for improving geochemical models of newly formed iron(III) (hydr)oxide reactive surface area evolution.

Natural organic matter impacts on heterogeneous iron(III) (hydr)oxide nucleation, growth, and composition in the presence of arsenate

249th National Meeting (2015)

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