Effect of Sb on precipitation of biogenic minerals during the reduction of Sb-bearing ferrihydrites

Pb-Bearing Ferrihydrite Bioreduction and Secondary-Mineral Precipitation during Fe Redox Cycling

“…The nature and concentration of the metals modify the Fh particles' physicochemical properties, which disrupts the bioreduction process, compared to metal-free Fh. Although no previous work has studied the effect of Pb on the bioreduction of Fh, our findings are in line with previous studies that have run with other elements [18,51]. While the Fh_Pb(0.02) reduction rates are comparable to those of Pb-free Fh, the reduction rate decreased by 60% when the Pb loading reached 5%.…”

“…The analysis at 4 K helped to clarify this complexity, where the shape-line and the deconvolution are similar to that of the biogenic minerals that are precipitated from Fh bioreduction, and it consists of five sextets of magnetite, and one sextet of goethite. As was expected for a poorly crystallized goethite, we observed, at 298 K, and simultaneously, a doublet and sextet that were governed by superparamagnetic relaxation [18,46]. It was that the spectrum at RT evolves drastically when the temperature decreases at 4 K with the collapse of the paramagnetic doublets and their transformation in the magnetic contribution, as was expected with the reduction in the thermal relaxation effects.…”

“…Similarly, an increase of 13% in aluminum decreased the bioreduction rate by 50% [51]. The same trend was observed in the presence of Sb and Ni, among others [18,52]. Increasing Pb loading may limit the accessibility of Fh surface sites and/or a significant loss of Fe(III) reactive sites, which thereby decreases the rate of reduction [53].…”

“…0.258 and 0.149 nm, respectively (data not shown). Such peaks are representative of pristine and metal-substituted 2-line ferrihydrite (for example, Sb-containing ferrihydrite) [18,37]. No other ferric phase was obtained, according to the XRD analysis that we performed.…”

“…Pb can precipitate as poorly soluble compounds, and it can be complexed by organic matter and/or adsorbed onto carbonates and clays, or onto Mn and Fe oxides [10][11][12][13]. Fe oxides account for up to 5% in the weight of specific fractions of surface soils and sediments, and they exert significant control on the reactivity, speciation, and mobilization of metals and metalloids, such as Pb, Ni, Co, As, and Sb [14][15][16][17][18]. This is due to their high surface areas and the reactive surfaces that they display, which confer significant sorption capacities for organic and inorganic species.…”