Natural antibacterial clays, when hydrated and applied topically, kill human pathogens including antibiotic resistant strains proliferating worldwide. Only certain clays are bactericidal; those containing soluble reduced metals and expandable clay minerals that absorb cations, providing a capacity for extended metal release and production of toxic hydroxyl radicals. Here we show the critical an...

Lead sorption efficiencies (sorption per surface area) were measured for a number of natural and synthetic Mn and Fe-oxides using a flow through reactor. The Mn-oxide phases examined included synthetic birnessite, natural and synthetic cryptomelane, and natural and synthetic pyrolusite; the Fe-oxides studied were synthetic akaganeite, synthetic ferrihydrite, natural and synthetic goethite, and ...

On the basis of the research literature of the last fifty years, we have reviewed the photochemical properties of different hydrolytic Fe(III) species and the photodegradation of organic compounds in aqueous solutions initiated by them (mainly including low-molecular-weight Fe(III)-OH complexes, Fe(III) oxides (Fe2O3) and Fe(III) hydroxides (FeOOH)). Furthermore, the feasibility and prospects o...

Iron oxides catalyze the conversion of hydrogen peroxide (H(2)O(2)) into oxidants capable of transforming recalcitrant contaminants. Unfortunately, the process is relatively inefficient at circumneutral pH values because of competing reactions that decompose H(2)O(2) without producing oxidants. Silica- and alumina-containing iron oxides prepared by sol-gel processing of aqueous solutions contai...

A reactive transport model based on one-dimensional transport and equilibrium chemistry is applied to synoptic data from an acid mine drainage stream. Model inputs include streamflow estimates based on tracer dilution, inflow chemistry based on synoptic sampling, and equilibrium constants describing acid/base, complexation, precipitation/dissolution, and sorption reactions. The dominant feature...

in this study, the effectiveness of kiwi shell was investigated to reduce the mobility of lead and cadmium in clay soil in different intervals. for this purpose a clay soil sample was contaminated with lead and cadmium in distinct dishes with 10 and 600 ppm concentrations respectively and mixed with 5% kiwi shell. samples were placed in incubator, and then sampling of soil in incubator was perf...

Unusual high-valence states of iron are stabilized in a few oxides. A-site-ordered perovskite-structure oxides contain such iron cations and exhibit distinct electronic behaviors at low temperatures, e.g. charge disproportionation (4Fe⁴⁺ → 2Fe³⁺ + 2Fe⁵⁺) in CaCu₃Fe₄O₁₂ and intersite charge transfer (3Cu²⁺ + 4Fe³·⁷⁵⁺ → 3Cu³⁺ + 4Fe³⁺) in LaCu₃Fe₄O₁₂. Here we report the synthesis of solid solution...

Black particles, collected by filtration (1.2~pm pore size) from the anoxic waters of a soft-water lake, were examined by a scanning proton microprobe which permitted quantitative elemental analysis by proton-induced X-ray emission (PIXE) and Rutherford backscattering (RBS). There was a uniform distribution of sulfur across the filter, but Fe, and to a lesser extent, Mn, was localized in -5-pm-...

Biosolids-borne trace elements may be released to the environment when biosolids are used as fertilizers in farm land. Trace element leachate concentrations from biosolids are known to be limited by both organic and inorganic sorbent surfaces; this experimental evidence has not been previously verified with geochemical modeling of sorption reactions. In this study, pH-dependent leaching experim...