Reactive carbon capture using saline water: evaluation of prospective sources, processes, and products.

Reactive carbon capture (RCC) processes involve the capture of carbon dioxide (CO) and conversion to a value-added product using a single sorbent/reaction medium. Not only can RCC processes generate valuable byproducts that can reduce the cost of carbon capture, but RCC tends to have lower energy demand than processes involving the transfer of CO between the mediums used for capture and subsequent reactions. Saline water has been proposed as a potential medium for RCC due to it's relative abundance and low cost.

ZeroCAL: Eliminating Carbon Dioxide Emissions from Limestone's Decomposition to Decarbonize Cement Production.

Limestone (calcite, CaCO) is an abundant and cost-effective source of calcium oxide (CaO) for cement and lime production. However, the thermochemical decomposition of limestone (∼800 °C, 1 bar) to produce lime (CaO) results in substantial carbon dioxide (CO) emissions and energy use, i.e.

Analyzing the upscaling potential and geospatial siting of calcination-free calcium hydroxide production in the United States.

This study evaluates the techno-economic feasibility and the embodied carbon dioxide intensity (eCI) of a novel process for producing nominally pure (>95 mass %) calcium hydroxide without the need for the thermal calcination of limestone. The process relies on the aqueous extraction of calcium from alkaline industrial wastes following which portlandite (Ca(OH): CH, a.k.

Effects of temperature and CO2 concentration on the early stage nucleation of calcium carbonate by reactive molecular dynamics simulations.

It is significant to investigate the calcium carbonate (CaCO3) precipitation mechanism during the carbon capture process; nevertheless, CaCO3 precipitation is not clearly understood yet. Understanding the carbonation mechanism at the atomic level can contribute to the mineralization capture and utilization of carbon dioxide, as well as the development of new cementitious materials with high-performance. There are many factors, such as temperature and CO2 concentration, that can influence the carbonation reaction.

High-Strength Organic-Inorganic Composites with Superior Thermal Insulation and Acoustic Attenuation.

We demonstrate facile fabrication of highly filled, lightweight organic-inorganic composites comprising polyurethanes covalently linked with naturally occurring clinoptilolite microparticles. These polyurethane/clinoptilolite (PUC) composites are shown to mitigate particle aggregation usually observed in composites with high particle loadings and possess enhanced thermal insulation and acoustic attenuation compared with conventionally employed materials (e.g.

Fly ash degree of reaction in hypersaline NaCl and CaCl brines: Effects of calcium-based additives.

The pozzolanic reaction of fly ashes with calcium-based additives can be effectively used to solidify and chemically stabilize (S&S process) highly concentrated brines inside a cementitious matrix. However, complex interactions between the fly ash, the additive, and the brine typically affect the phases formed at equilibrium, and the resulting solid capacity to successfully encapsulate the brine and its contaminants. Here, the performances of two types of fly ash (a Class C and Class F fly ash) are assessed when combined with different additives (two types of cement, or lime with and without NaAlO), and two types of brine (NaCl or CaCl) over a range of concentrations (0 ≤ [Cl] ≤ 2 M).

Electrolytic Seawater Mineralization and the Mass Balances That Demonstrate Carbon Dioxide Removal.

We present the mass balances associated with carbon dioxide (CO) removal (CDR) using seawater as both the source of reactants and as the reaction medium via electrolysis following the "" (") process. This process, extensively detailed in La Plante E.C.

Electrosteric Control of the Aggregation and Yielding Behavior of Concentrated Portlandite Suspensions.

Portlandite (calcium hydroxide: CH: Ca(OH)) suspensions aggregate spontaneously and form percolated fractal aggregate networks when dispersed in water. Consequently, the viscosity and yield stress of portlandite suspensions diverge at low particle loadings, adversely affecting their processability. Even though polycarboxylate ether (PCE)-based comb polyelectrolytes are routinely used to alter the particle dispersion state, water demand, and rheology of similar suspensions (e.

New insights into the early stage nucleation of calcium carbonate gels by reactive molecular dynamics simulations.

The precipitation of calcium carbonate (CaCO) is a key mechanism in carbon capture applications relying on mineralization. In that regard, Ca-rich cementitious binders offer a unique opportunity to act as a large-scale carbon sink by immobilizing CO as calcium carbonate by mineralization. However, the atomistic mechanism of calcium carbonate formation is still not fully understood.

Experimental evidence of auxeticity in ion implanted single crystal calcite.

We report initial experimental evidence of auxeticity in calcite by ion implanting (1010) oriented single crystalline calcite with Ar at room temperature using an ion energy of 400 keV and a dose of 1 × 10 cm. Lattice compression normal to the substrate surface was observed, which is an atypical result for ion implanted materials. The auxetic behavior is consistent with predictions that indicate auxeticity had been predicted along two crystallographic directions including [1010].

Removal of As(III) by Electrically Conducting Ultrafiltration Membranes.

As(III) species are the predominant form of arsenic found in groundwater. However, nanofiltration (NF) and reverse osmosis (RO) membranes are often unable to effectively reject As(III). In this study, we fabricate highly conducting ultrafiltration (UF) membranes for effective As(III) rejection.

Machine learning enables prompt prediction of hydration kinetics of multicomponent cementitious systems.

Carbonaceous (e.g., limestone) and aluminosilicate (e.

Topological origin of phase separation in hydrated gels.

Hypothesis: Depending on their composition, hydrated gels can be homogeneous or phase-separated, which, in turn, affects their dynamical and mechanical properties. However, the nature of the structural features, if any, that govern the propensity for a given gel to phase-separate remains largely unknown. Here, we argue that the propensity for hydrated gels to phase-separate is topological in nature.

Calcination-free production of calcium hydroxide at sub-boiling temperatures.

Calcium hydroxide (Ca(OH)), a commodity chemical, finds use in diverse industries ranging from food, to environmental remediation and construction. However, the current thermal process of Ca(OH) production limestone calcination is energy- and CO-intensive. Herein, we demonstrate a novel aqueous-phase calcination-free process to precipitate Ca(OH) from saturated solutions at sub-boiling temperatures in three steps.

Selective sulfur removal from semi-dry flue gas desulfurization coal fly ash for concrete and carbon dioxide capture applications.

High-sulfur mixed fly ash residues from semi-dry flue gas desulfurization units in coal-fired power plants are unsuitable for use as supplementary cementitious material (SCM) for concrete production or carbon dioxide utilization. In this work, we explore the potential for upcycling a representative spray dry absorber ash (10.44 wt% SO) into concrete-SCM by selective sulfur removal via weak acid dissolution while simultaneously exploring the possibility for CO capture.

Atomic Dislocations and Bond Rupture Govern Dissolution Enhancement under Acoustic Stimulation.

By focusing the power of sound, acoustic stimulation (i.e., often referred to as sonication) enables numerous "green chemistry" pathways to enhance chemical reaction rates, for instance, of mineral dissolution in aqueous environments.

Enhancing Polyvalent Cation Rejection Using Perfluorophenylazide-Grafted-Copolymer Membrane Coatings.

Surface modification offers a straightforward means to alter and enhance the properties and performance of materials, such as nanofiltration membranes for water softening. Herein, we demonstrate how a membrane's surface charge can be altered by grafting different electrostatically varying copolymers onto commercial membrane surfaces using perfluorophenylazide (PFPA) photochemistry for enhanced ion separation performance. The native membrane's performance-i.

Temperature-Induced Aggregation in Portlandite Suspensions.

Temperature is well known to affect the aggregation behavior of colloidal suspensions. This paper elucidates the temperature dependence of the rheology of portlandite (calcium hydroxide: Ca(OH)) suspensions that feature a high ionic strength and a pH close to the particle's isoelectric point. In contrast to the viscosity of the suspending medium (saturated solution of Ca(OH) in water), the viscosity of Ca(OH) suspensions is found to increase with elevating temperature.

Precipitation of calcium-alumino-silicate-hydrate gels: The role of the internal stress.

Concrete gains its strength from the precipitation of a calcium-alumino-silicate-hydrate (C-A-S-H) colloidal gel, which acts as its binding phase. However, despite concrete's ubiquity in the building environment, the atomic-scale mechanism of C-A-S-H precipitation is still unclear. Here, we use reactive molecular dynamics simulations to model the early-age precipitation of a C-A-S-H gel.

How clay particulates affect flow cessation and the coiling stability of yield stress-matched cementing suspensions.

The remarkable increase in the flow resistance of dense suspensions can hinder 3D-printing processes on account of flow cessation in the extruder, and filament fragility/rupture following deposition. Understanding the nature of rheological changes that occur is critical to manipulate flow conditions or to dose flow modifiers for 3D-printing. Therefore, this paper elucidates the influences of clay particulates on controlling flow cessation and the shape stability of dense cementing suspensions that typically feature poor printability.

Dispersing nano- and micro-sized portlandite particulates via electrosteric exclusion at short screening lengths.

In spite of their high surface charge (zeta potential ζ = +34 mV), aqueous suspensions of portlandite (calcium hydroxide: Ca(OH)2) exhibit a strong tendency to aggregate, and thereby present unstable suspensions. While a variety of commercial dispersants seek to modify the suspension stability and rheology (e.g.

Elucidating the corrosion-related degradation mechanisms of a Ti-6Al-4V dental implant.

The Ti-6Al-4V (TAV) alloy is commercially used as a dental implant material. This work seeks to elucidates the origins of degradation of Ti-6Al-4V (TAV) implant alloys that result in peri-implant bone loss. 
Methods: In this work, a combination of microstructure, surface, and solution analyses was utilized to study the corrosion mechanism of the TAV alloy in oral environments.

A Nitrogen- and Self-Doped Titania Coating Enables the On-Demand Release of Free Radical Species.

For potential applications such as suppressing the onset of peri-implant infections, a doped titania coating was developed to induce free radical release because of its ability for microbial elimination. The coatability of the sol-gel precursor is robust since the suspension's rheology can be modified to attain uniform and complete surface coverage. The coating is composed of a mixture of anatase and rutile polymorphs doped with nitrogen (N), and it contains substoichiometric Ti and Ti species.