Exploiting Saturation Regimes and Surface Effects to Tune Composite Design: Single Platelet Nanocomposites of Peptoid Nanosheets and CaCO.

Mineral-polymer composites found in nature exhibit exceptional structural properties essential to their function, and transferring these attributes to the synthetic design of functional materials holds promise across various sectors. Biomimetic fabrication of nanocomposites introduces new pathways for advanced material design and explores biomineralization strategies. This study presents a novel approach for producing single platelet nanocomposites composed of CaCO and biomimetic peptoid (N-substituted glycines) polymers, akin to the bricks found in the brick-and-mortar structure of nacre, the inner layer of certain mollusc shells.

Sulfidation extent of nanoscale zerovalent iron controls selectivity and reactivity with mixed chlorinated hydrocarbons in natural groundwater.

Sulfidated nanoscale zerovalent iron (S-nZVI) exhibits low anoxic oxidation and high reactivity towards many chlorinated hydrocarbons (CHCs). However, nothing is known about S-nZVI reactivity once exposed to complex CHC mixtures, a common feature of CHC plumes in the environment. Here, three S-nZVI materials with varying iron sulfide (mackinawite, FeS) shell thickness and crystallinity were exposed to groundwater containing a complex mixture of chlorinated ethenes, ethanes, and methanes.

A novel, direct-push approach for detecting sulfidated nanoparticulate zero valent iron (S-nZVI) in sediments using reactive and non-reactive fluorophores.

Injection of microparticulate and nanoparticulate zero valent iron has become a regularly used method for groundwater remediation. Because of subsurface inhomogeneities, however, it is complicated to predict the ZVI transport in the subsurface, meaning that tools capable of determining its distribution after injection are highly useful. Here, we have developed a new direct-push based technique, which combines fluorescent and visible imaging, for detection of sulfidized nanoparticulate zero valent iron (S-nZVI) in the subsurface.

Capabilities of an optical direct push probe for 2D-subsurface imaging.

Characterization of hydrological conditions at polluted sites is critical for understanding of contaminant distribution and transport. Standard techniques for site characterization, such as soil coring together with well installation for piezometric measurements and water sampling, allow only some insights into subsurface properties and processes. To obtain additional data, direct-push techniques are often used in soils and unconsolidated formations.

Effects of metal cation substitution on hexavalent chromium reduction by green rust.

Chromium contamination is a serious environmental issue in areas affected by leather tanning and metal plating, and green rust sulfate has been tested extensively as a potential material for in situ chemical reduction of hexavalent chromium in groundwater. Reported products and mechanisms for the reaction have varied, most likely because of green rust's layered structure, as reduction at outer and interlayer surfaces might produce different reaction products with variable stabilities. Based on studies of Cr(III) oxidation by biogenic Mn (IV) oxides, Cr mobility in oxic soils is controlled by the solubility of the Cr(III)-bearing phase.

Effects of common groundwater ions on the transformation and reactivity of sulfidized nanoscale zerovalent iron.

Sulfidized nanoscale zerovalent iron (S-nZVI) is an Fe-based reactant widely studied for its potential use for groundwater remediation. S-nZVI reactivity has been widely investigated testing various contaminants in various water matrices, but studies on S-nZVI corrosion behaviour and reactivity upon exposure to complex groundwater chemistries are limited. Here, we show that anoxic aging of S-nZVI for 7 days in the absence and presence of key groundwater solutes (i.

A Combined X-ray Absorption and Mössbauer Spectroscopy Study on Fe Valence and Secondary Mineralogy in Granitoid Fracture Networks: Implications for Geological Disposal of Spent Nuclear Fuels.

Underground repository in crystalline bedrock is a widely accepted solution for long-term disposal of spent nuclear fuels. During future deglaciations, meltwater will intrude via bedrock fractures to the depths of future repositories where O left in the meltwater could corrode metal canisters and enhance the migration of redox-sensitive radionuclides. Since glacial meltwater is poor in reduced phases, the quantity and (bio)accessibility of minerogenic Fe(II) in bedrock fractures determine to what extent O in future meltwater can be consumed.

The Structure of Sulfidized Zero-Valent Iron by One-Pot Synthesis: Impact on Contaminant Selectivity and Long-Term Performance.

Sulfidized zerovalent iron (sZVI) is widely studied because of its remarkable reactivity with a number of groundwater contaminants. Nonetheless, its nanoscale structure is not well understood. As such, there is an uncertainty on how sZVI structure controls its reactivity and fate in the subsurface environment.

Trivalent Actinide Uptake by Iron (Hydr)oxides.

The retention of Am(III) by coprecipitation with or adsorption onto preformed magnetite was investigated by X-ray diffraction (XRD), solution chemistry, and X-ray absorption spectroscopy (XAS). In the coprecipitation experiment, XAS data indicated the presence of seven O atoms at 2.44(1) Å, and can be explained by an Am incorporation at Fe structural sites at the magnetite surface.

Rapid carbon mineralization for permanent disposal of anthropogenic carbon dioxide emissions.

Carbon capture and storage (CCS) provides a solution toward decarbonization of the global economy. The success of this solution depends on the ability to safely and permanently store CO2 This study demonstrates for the first time the permanent disposal of CO2 as environmentally benign carbonate minerals in basaltic rocks. We find that over 95% of the CO2 injected into the CarbFix site in Iceland was mineralized to carbonate minerals in less than 2 years.

Structural disordering of de-alloyed Pt bimetallic nanocatalysts: the effect on oxygen reduction reaction activity and stability.

Platinum bimetallic alloys are well-known for their ability to catalyze the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). Pt(x)Co(1-x) colloidal nanoparticles were synthesized with varying initial Pt : Co ratios, but constant size to investigate how the initial metal composition affects their electrocatalytic performance. The results show that upon contact with acid environment the Co leaches out of the particles leading to almost identical compositions, independent of the initial differences.

Microbially enhanced carbon capture and storage by mineral-trapping and solubility-trapping.

The potential of microorganisms for enhancing carbon capture and storage (CCS) via mineral-trapping (where dissolved CO(2) is precipitated in carbonate minerals) and solubility trapping (as dissolved carbonate species in solution) was investigated. The bacterial hydrolysis of urea (ureolysis) was investigated in microcosms including synthetic brine (SB) mimicking a prospective deep subsurface CCS site with variable headspace pressures [p(CO(2))] of (13)C-CO(2). Dissolved Ca(2+) in the SB was completely precipitated as calcite during microbially induced hydrolysis of 5-20 g L(-1) urea.