Concurrent elimination of arsenic and hydrated silica from natural groundwater by electrocoagulation using iron electrodes

Formation of Arsenic Minerals in Aqueous Media During Electrocoagulation using Iron Electrodes

“…We also performed XRD analysis to characterize the solid phases of the residues for Sample 1 and Sample 2 after electrocoagulation with an iron electrode (Figure 6). As shown in Figure 6A, for the solid residue of Sample 1, diffraction lines associated with spinelloid, Mg 2 SiO 4 (31.02°, 34.75°, 35.18°, 37.83°, 37.92°, 38.58°, 41.23°, 42.73° 2θ), magnetite (41.38°, 43.31°, 50.44°, 57.44° 2θ), iron sodium oxide, FeNaO 2 (39.27°, 40.58°, 42.21° 2θ), scorodite, FeAsO 4 ⋅ 2H 2 O (19.78°, 25.58°, 26.85°, 32.54°, 35.34° 2θ), ferrihydrite, Fe 2 O 3 ⋅ 0.5H 2 O (19.62°, 30.41°, 35.13, 40.79° 2θ), [39,40] fayalite, Fe 2 SiO 4 (29.16°, 36.90°, 39.75°, 40.84°, 41.96°, 43.59° 2θ) [40] calcite, CaCO 3 (34.27°, 46.10°, 50.56° 2θ) and brownmillerite, Ca 2 Fe 2 O 5 (26.55°, 28.01°, 34.06°, 37.35°, 39.27°, 38.58° 2θ) were detected. For Sample 2, in addition to the minerals mentioned above, including spinelloid, magnetite, ferrihydrite, fayalite, and scorodite (15.3°, 27.99°, 33.05° 2θ), the goethite, FeOOH (34.8°, 42.73°, 50.56° 2θ) was identified as well (Figure 6B).…”

“…We also performed XRD analysis to characterize the solid phases of the residues for Sample 1 and Sample 2 after electrocoagulation with an iron electrode (Figure 6). As shown in Figure 6A, for the solid residue of Sample [39,40] fayalite, Fe 2 SiO 4 (29.16°, 36.90°, 39.75°, 40.84°, 41.96°, 43.59°2θ) [40] calcite, CaCO 3 (34.27°, 46.10°, 50.56°2θ) and brownmillerite, Ca 2 Fe 2 O 5 (26.55°, 28.01°, 34.06°, 37.35°, 39.27°, 38.58°2θ) were detected. For Sample 2, in addition to the minerals mentioned above, including spinelloid, magnetite, ferrihydrite, fayalite, and scorodite (15.3°, 27.99°, 33.05°2θ), the goethite, FeOOH (34.8°, 42.73°, 50.56°2 θ) was identified as well (Figure 6B).…”