Synthesis of ferrate (Fe(vi))-coated sand for stabilized reactivity and enhanced treatment of phenol

Abstract

Fe(VI) is a multifunctional water treatment agent of interest due to its benign environmental impact yet effective disinfecting, coagulating, and oxidizing capabilities. Fe(VI) decomposition in water produces short-lived Fe(V) and...

Simultaneous Oxidation of Trace Organics and Sorption of Trace Metals by Ferrate (Fe(VI))-Coated Sand in Synthetic Wastewater Effluent

“…19 Briefly, Ottawa sand, initially coated with tetraethylorthosilicate (TeOS), was added to a K 2 FeO 4 solution and stirred for 24 h at 4 °C. 19 The wet Fe(VI)-coated sand composite was dried under vacuum. 19 Surface analyses of the media were conducted to complement aqueous in situ characterization analyses reported in our previous study.…”

“…19 Surface analyses of the media were conducted to complement aqueous in situ characterization analyses reported in our previous study. 19 Scanning electron microscopy (SEM) imaging of the Fe(VI)-coated sand morphology was performed with a FEI (Hillsboro, OR) Sirion XL30 SEM instrument following platinum sputtering of the media to increase electrical conductivity. The elemental composition on the surface of the Fe(VI)-coated sand was also evaluated via SEM energy dispersive X-ray spectroscopy (SEM-EDS) following carbon coating of the media.…”

“…40,41 Additionally, an assessment of pH effects on the aqueous stability of the Fe(VI)-coated sand demonstrated that the Fe(VI)-coated sand was more stable at pH 9, as reported in our previous publication. 19 Batch kinetics experiments were conducted in four different reaction systems: (i) all three trace organics in a pH 9, 10 mM sodium borate buffer solution (O9 system); (ii) all three trace metals in a pH 9, 10 mM sodium borate buffer solution (M9 system); (iii) trace organics and metals together in a pH 9, 10 mM sodium borate buffer solution (MO9 system); and, (iv) trace organics and metals together in a pH 7.5, 10 mM sodium borate buffer solution (MO7.5 system). The concentration of the contaminants was targeted at 500 μg/L each, and the dose of the Fe(VI)-coated sand was 2 g/L for all reaction systems explored in this study.…”

“…This dose (2 g/L) of Fe(VI)-coated sand was previously found to maximize removal of phenol. 19 At designated time intervals, a 2 mL aliquot of samples containing the organic compounds was quenched with 20 μL of 500 mM Na 2 SO 3 to stop the reaction between Fe(VI) and the organic compounds and then filtered with a 0.2 μm, 25 mm-diameter cellulose acetate syringe filter before analysis using high-performance liquid chromatography (HPLC) methods (Text S2). Liquid chromatography-mass spectrometry (LC-MS) grade methanol (500 μL) was added to 500 μL of the quenched and filtered aliquot for high-resolution mass spectrometry (HRMS) analyses (Text S3) to determine transformation products of the organic compounds.…”

“…These data suggest that Fe(III) phases formed as a result of oxidation of trace organics and subsequent Fe(VI) reduction can increase Pb and Zn removal. At pH 9, Fe(VI) is stable and reacts slowly with water to form Fe(III), 19 but this reduction can be accelerated in the presence of organic compounds reacting with and reducing Fe(VI). This is evidenced by the slower decrease in aqueous Fe(VI) concentrations seen in the M9 system (Figure S4A) compared to the faster decrease in the O9 system (Figure S4B) and MO9 systems (Figure S4C) when trace organics are present.…”