In this research, traditional macroscopic studies were complemented with XAS analyses to elucidate the mechanisms controlling Pb(II) sorption onto ferrihydrite as a function of pH, ionic strength, and adsorbate concentrations. Analyses of XANES and XAFS studies demonstrate that Pb(II) ions predominantly sorb onto ferrihydrite via inner-sphere complexation, not retaining their primary hydration ...

Ferritin is a protein nano-cage that encapsulates minerals inside an 8 nm cavity. Previous band gap measurements on the native mineral, ferrihydrite, have reported gaps as low as 1.0 eV and as high as 2.5-3.5 eV. To resolve this discrepancy we have used optical absorption spectroscopy, a well-established technique for measuring both direct and indirect band gaps. Our studies included controls o...

Phenazines are small redox-active molecules produced by a variety of bacteria. Beyond merely serving as antibiotics, recent studies suggest that phenazines play important physiological roles, including one in iron acquisition. Here we characterize the ability of four electrochemically reduced natural phenazines--pyocyanin (PYO), phenazine-1-carboxylate (PCA), phenazine-1-carboxamide, and 1-hydr...

Surface complexation models (SCMs) provide a mechanistic and thermodynamicallybased description of sorption reactions on mineral surfaces and can thus be used in geochemical modelling to predict contaminant sorption under a variety of geochemical conditions. In the last years, substantial effort has been put into obtaining multiple lines of evidence for the types of complexes formed on mineral ...

The competitive adsorption of arsenate and arsenite with silicic acid at the ferrihydrite-water interface was investigated over a wide pH range using batch sorption experiments, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, extended X-ray absorption fine structure (EXAFS) spectroscopy, and density functional theory (DFT) modeling. Batch sorption results indica...

Low iron (Fe) and phosphorus (P) ocean regions are often home to the globally important N2-fixing cyanobacterium Trichodesmium spp., which physiologically adapted Fe/P co-limitation. Given Trichodesmium's eminent ability capture particles common associations between Fe P in sediments aerosols, we hypothesized that mineral bio-dissolution by spp. may enable them co-acquire P. We present a new se...

Natural bacteriogenic iron oxides (BIOS) were investigated using local-analyzable synchrotron-based scanning transmission X-ray microscopy (STXM) with a submicron-scale resolution. Cell, cell sheath interface (EPS), and sheath in the BIOS were clearly depicted using C-, N-, and O- near edge X-ray absorption fine structure (NEXAFS) obtained through STXM measurements. Fe-NEXAFS obtained from diff...

batch experiments were conducted to study the adsorption behaviors of lead ion (pb2+) onto ferrihydrites prepared using three different procedures which were characterized  by textural analysis (bet). the adsorption removal of pb2+ by the three ferrihydrites (called fh-1, fh-2 and fh-3, respectively) were compared, and fh-3 shows fast adsorption kinetics as well as high adsorption capacities, t...

UNLABELLED The transformation of ferrihydrite to stable iron oxides over time has important consequences for biogeochemical cycling of many metals and nutrients. The response of methanogenic activity to the presence of iron oxides depends on the type of iron mineral, but the effects of changes in iron mineralogy on methanogenesis have not been characterized. To address these issues, we construc...

Abstract Temperature is an important factor affecting the leaching of contaminants from waste deposits, especially in Nordic region where temperature change more drastic than other areas. In this study, impact variation sulphate, Co, Fe, Mn, Ni and Zn Ballangen tailings deposit, northern Norway, was investigated using a column experiment. Unoxidized were fed into four columns, which subsequentl...