Deciphering strontium sulfate precipitation via Ostwald's rule of stages: From prenucleation clusters to solution-mediated phase tranformation.

Multiple-step nucleation pathways have been observed during mineral formation in both inorganic and biomineral systems. These pathways can involve precursor aqueous species, amorphous intermediates, or metastable phases. Despite the widespread occurrence of these processes, elucidating the precise nucleation steps and the transformation mechanisms between each step remains a challenging task.

In Situ Formation of Silver Nanoparticles (Ag-NPs) onto Textile Fibers.

Silver nanoparticles (Ag-NPs) adhered/inserted on textile fibers have an effective antimicrobial role. However, their release due to low adherence and their fate in the natural settings have been questioned in terms of toxicity level. In order to overcome this recurrent problem of adherence, the in situ formation of Ag-NPs in five textile fibers (cotton (untreated and chemically bleached), sheep's wool, polyamide, and polyester) was assessed.

Arsenite and chromate sequestration onto ferrihydrite, siderite and goethite nanostructured minerals: Isotherms from flow-through reactor experiments and XAS measurements.

Sorption isotherms remain a major tool to describe and predict the mobility of pollutants in natural and anthropogenic environments, but they are typically determined by independent batch experiments. In the present study, the sequestration of As(III), Cr(VI) and competitive As(III)-Cr(VI) on/in 6L-ferrihydrite, siderite and goethite nanostructured minerals was reinvestigated using stirred flow-through reactor experiments. Herein, sorption isotherms were particularly determined from breakthrough curves for inert and reactive tracers monitored simultaneously in a single percolation experiment.

Sequestration of Antimony on Calcite Observed by Time-Resolved Nanoscale Imaging.

Antimony, which has damaging effects on the human body and the ecosystem, can be released into soils, ground-, and surface waters either from ore minerals that weather in near surface environments, or due to anthropogenic releases from waste rich in antimony, a component used in batteries, electronics, ammunitions, plastics, and many other industrial applications. Here, we show that dissolved Sb can interact with calcite, a widespread carbonate mineral, through a coupled dissolution-precipitation mechanism. The process is imaged in situ, at room temperature, at the nanometer scale by using an atomic force microscope equipped with a flow-through cell.

Sequestration of selenium on calcite surfaces revealed by nanoscale imaging.

Calcite, a widespread natural mineral at the Earth's surface, is well-known for its capacity to sequester various elements within its structure. Among these elements, selenium is important because of its high toxicity in natural systems and for human health. In the form of selenite (Se((IV))), selenium can be incorporated into calcite during growth.

Experimental assessment of CO2-mineral-toxic ion interactions in a simplified freshwater aquifer: implications for CO2 leakage from deep geological storage.

The possible intrusion of CO2 into a given freshwater aquifer due to leakage from deep geological storage involves a decrease in pH, which has been directly associated with the remobilization of hazardous trace elements via mineral dissolution and/or via desorption processes. In an effort to evaluate the potential risks to potable water quality, the present study is devoted to experimental investigation of the effects of CO2 intrusion on the mobility of toxic ions in simplified equilibrated aquifers. We demonstrate that remobilization of trace elements by CO2 intrusion is not a universal physicochemical effect.

Nucleation and growth of chrysotile nanotubes in H2SiO3/MgCl2/NaOH medium at 90 to 300 °C.

Herein, we report new insights into the nucleation and growth processes of chrysotile nanotubes by using batch and semi-continuous experiments. For the synthesis of this highly carcinogenic material, the influences of temperature (90, 200, and 300 °C), Si/Mg molar ratio, and reaction time were investigated. From the semi-continuous experiments (i.

Removal of oxyanions from synthetic wastewater via carbonation process of calcium hydroxide: applied and fundamental aspects.

Removal of oxyanions (selenite, selenate, arsenate, phosphate and nitrate) during calcite formation was experimentally studied using aqueous carbonation of calcium hydroxide under moderate pressure (P(CO2) congruent with 20 bar) and temperature (30 degrees C). The effects of Ca(OH)(2) dose (10 and 20 g), Ca(OH)(2) source (commercial pure material or alkaline paper mill waste) and oxyanion initial concentration (from 0 to 70 mg atom/L) were investigated for this anisobaric gas-liquid-solid system. The Ca(OH)(2) carbonation reaction allowed successfully the removal of selenite (>90%), arsenate (>78%) and phosphate (congruent with 100%) from synthetic solutions.

Mineral sequestration of CO(2) by aqueous carbonation of coal combustion fly-ash.

The increasing CO(2) concentration in the Earth's atmosphere, mainly caused by fossil fuel combustion, has led to concerns about global warming. A technology that could possibly contribute to reducing carbon dioxide emissions is the in-situ mineral sequestration (long term geological storage) or the ex-situ mineral sequestration (controlled industrial reactors) of CO(2). In the present study, we propose to use coal combustion fly-ash, an industrial waste that contains about 4.

Synthesis of a red iron oxide/montmorillonite pigment in a CO2-rich brine solution.

The homoionic calcium-montmorillonite was used to synthesize a red iron oxide/clay pigment in a CO2-rich brine solution (0.5 M of NaCl) by using an agitated batch-reactor (engineer autoclave). The operating conditions were 15 days of reaction, 200 bars of pressure and 150 degrees C of temperature.

A simplified method to estimate kinetic and thermodynamic parameters on the solid-liquid separation of pollutants.

The aim of the present study was to propose a simplified experimental-theoretical method for estimating the kinetic and thermodynamic parameters for the solid-liquid separation of pollutants by using kinetic studies with batch reactors, i.e., the removed quantity of dissolved ion as a function of time at different initial concentration.