Release Of Cations Research Articles

Positive (Regulatory) and Negative (Cytotoxic) Effects of Dinitrosyl Iron Complexes on Living Organisms.

The proposed in our studies mechanism of dinitrosyl iron complex (DNIC) formation through the main step of disproportionation of two NO molecules in complex with Fe2+ ion leads to emergence of the resonance structure of dinitrosyl-iron fragment of DNIC, [Fe2+(NO)(NO+)]. The latter allowed suggesting capacity of these complexes to function as donor of both neutral NO molecules as well as nitrosonium cations (NO+), which has been demonstrated in experiments. Analysis of biological activity of DNICs with thiol-containing ligands presented in this review demonstrates that NO molecules and nitrosonium cations released from the complexes exert respectively positive (regulatory) and negative (cytotoxic) effects on living organisms. It has been suggested to use dithiocarbamate derivatives to enhance selective release of nitrosonium cations from DNIC in living organisms followed by simultaneous incorporation of the released NO molecules into the biologically non-active mononitrosyl iron complexes with dithiocarbamate derivatives.

Base cations release in soils along the 127‐year Hailuogou glacial retreat chronosequence

AbstractAt the Hailuogou glacial retreat chronosequence, a mature forest has surprisingly fast developed in ∼120 yr, although the glacial debris is dominated by nutrient‐poor granite with a small contribution of carbonate minerals. In previous work, we hypothesized that the fast vegetation development is synchronized with initial fast carbonate weathering followed by slow silicate weathering. To test this hypothesis, we (a) characterized the composition of the glacial debris to elucidate the sources of base cations and (b) determined the base cation release kinetics from topsoils (0–10 cm) along the chronosequence with a weathering experiment at a constant pH value (pHstat). Besides granitic rocks, the glacial debris contained some meta‐sedimentary and meta‐volcanic calc‐silicate rocks, amphibolite, mica schist, and quartzite. Although the total Ca concentration of the glacial debris was only about double that of Mg, K, and Na, during the 1st day of the pHstat experiment, the released mass of Ca was >10 times higher than that of Mg and K, and even about 100 times higher than that of Na. The size of the fast‐reacting Ca‐carbonate pool decreased quickly in the first approximately 40 yr, after which a slow‐reacting Ca‐silicate pool matched the fast‐reacting pool with a size of 1.9 ± 0.6 g kg–1 Ca. In contrast, for Mg, K, and Na the slow‐reacting pool dominated from the beginning, suggesting that these elements mainly originated from silicate weathering. Our findings support the view that the well‐synchronized interplay between carbonate and silicate weathering facilitated the fast vegetation succession.

Effect of dissolved Si on the corrosion of iron in deaerated and slightly alkaline solutions (pH ≈ 8.1) at 50 °C

Corrosion of iron in deaerated and slightly alkaline buffered solutions was investigated for different Si concentrations ([Si] varying from ≈0 to ≈110 mg L−1) over a ≈ 30 days period. In these solutions, iron corrosion led to the formation of a layer consisting of a mixture of Fe oxides and Fe silicates on the metal surface, but also to the precipitation of the same compounds in the medium and to the release of Fe cations. An increase in [Si] promoted the formation of Fe silicates at the expense of Fe oxides, but without increasing the total amount of iron corroded.

Ionophore based optical sensors using hydrophilic polymer matrix – Ratiometric, pH independent ion-selective optodes

Classical approach for cation selective optode sensing requires high lipophilicity of receptor matrix and optical transducer dye, its application is restricted to relatively narrow pH range. We propose an alternative approach to ion-selective optodes, benefiting from rather hydrophilic polymer - plasticized polycaprolacton. This results in presence of lipophlic (plasticizer) and hydrophilic (sample/polycaprolactone) domains within the nanoprobes proposed. In consequence, this approach allows benefiting from alternative optical transducer: Nile blue dye and its unique properties and in consequence to benefit from new optical transduction mechanism allowing ratiometric sensing with no restriction for the sample pH. The response mechanism involves ionophore and ion pair composed of cation-exchanger and Nile blue cation dissolved in the plasticizer phase. Analyte incorporation to the phase occurs on expense of dye cation release to the hydrophilic phase. Ultimately a red staining of plasticizer phase is observed due to incorporation of neutral dye molecules formed in course of spontaneous hydrolysis occurring in water phase. Thus herein proposed optodes offer observable emission change at two wavelengths (increase of intensity emission as well as decrease) allowing ratiometric sensing in a broad concentration range. Moreover, herein proposed approach is applicable both in acidic and alkaline media, also in the absence of buffer, thus it mitigates significant constrain of classical optodes. As model system potassium or calcium selective nanospheres were prepared.

Nanocomposite Electrodes for Detection of Hexavalent Chromium

Metal cations, when present in appropriate concentrations, serve an essential physiological function, however, their presence in larger concentrations has proven to be detrimental to human health. Modern industrial processes such as alloy treatment, coatings, and leather pigmentation, often result in the release of the heavy metal cations, causing adverse biological and ecological consequences. Amongst many, hexavalent chromium (Cr6+) is a major concern because of its carcinogenic properties. Therefore, it is imperative to develop a sophisticated technique for the early detection of Cr present in aqueous solutions. Numerous methods use techniques such as mechanical, optical, spectroscopic, and electrochemical for the detection of contaminants in aqueous solutions. Electrochemistry driven sensors have shown promise due to their possibility of miniaturization and low-cost. However, early and trace detection of such contaminants remains a challenge. Recently, atomically thin allotropes of carbon such as graphene or graphene oxide have been used to fabricate ultra-responsive and selective sensor platforms, owing to its excellent electrical conductivity, high surface area for functionalization, and physicochemical stability. In this work, we examine the use of electrically conducting polymer and atomically thin carbon materials as electrodes for the development of electrochemical sensors. Nanocomposite electrode films have been synthesized, and its performance as a function of number of cycles of deposition were analyzed. A capacitive microcomb sensor device has been fabricated, and the device performance using electrochemical, chemical, and morphological tests on electrodes as a function of deposition and electrolyte solutions will be highlighted. A fundamental understanding of reaction kinetics and identification of the rate-limiting steps will lead a path forward for developing robust sensors.

Antiviral Activity of Nitrosonium Cations against SARS-CoV-2 on a Syrian Hamster Model

The antiviral action of binuclear dinitrosyl iron complexes with glutathione along with diethyldithiocarbamate against the SARS-CoV-2 virus has been demonstrated on a Syrian hamster model after aerosol exposure of SARS-CoV-2-infected animals to the solutions of said compounds. EPR assays in analogous experiments on intact hamsters have demonstrated that the iron complexes and diethyldithiocarbamate are predominantly localized in lung tissues. These results have been compared with similar measurements on intact mice, which have shown the equal localization of these agents in both the lungs and liver. We assume that the release of the nitrosonium cations from the binuclear dinitrosyl iron complexes with glutathione occurs during their contact with diethyldithiocarbamate in the animal body. These cations caused S-nitrosation of host and viral cell proteases, leading to suppression of SARS-CoV-2 infection.

The Cytostatic Action of Dinitrosyl Iron Complexes with Glutathione on Escherichia coli Cells Is Mediated by Nitrosonium Cations Released from These Complexes.

This study demonstrates a bacteriostatic effect of binuclear dinitrosyl iron complexes with glutathione on Escherichia coli TN300 cells. It has been quantified by the colony formation assay. The bacteriostatic effect exerted by these complexes increases considerably in the presence of diethyldithiocarbamate. Our results suggest that this effect is caused by the intense release of nitrosonium cations, NO+, from the complexes, which decompose under the action of diethyldithiocarbamate. A similar effect is observed when E.coli cells are treated with diethyldithiocarbamate 40 min after the addition of sodium nitrite or S-nitrosoglutathione. Notably, the level of dinitrosyl iron complexes observed in the bacterial cells due to the effects of sodium nitrite or S-nitrosoglutathione is almost the same as that obtained after treatment with glutathione-containing complexes. The bacteriostatic effects of the NO molecules released from nitrite or S-nitrosoglutathione during their brief interaction with bacteria were significantly smaller than the bacteriostatic effect of NO+. Wededuce therefrom that the nitrosonium cations released from DNICs are responsible for the observed bacteriostatic effect of these complexes in E. coli cells.

Construction of seaurchin-like structured Ag2Se-Ag2S-CoCH/NF electrocatalyst with high catalytic activity and corrosion resistance for seawater electrolysis

It is extremely necessary and challenging to rationally design highly active, stable and anti-corrosion electrocatalysts for the hydrogen production by seawater electrolysis. Herein, we developed a new and effective strategy of monometallic cation release combined with hydrothermal reaction to successfully construct an Ag2Se-Ag2S-CoCH/NF seaurchin-like heterostructure on nickel foam substrate. The active species exposure, corrosion resistance, H2O dissociation ability and free energy of adsorbed hydrogen in Ag2Se-Ag2S active carrier were concurrently regulated to strikingly promote the HER/OER in alkaline water and seawater electrolysis. Concretely, the incorporation of CoCH into the Ag2Se-Ag2S binary superionic conductor, as reflected by the corresponding characterizations and theoretical calculations (DFT), not only enriches the vacancy defect structure for the effective exposure of active sites, but also strongly emerges the electronic structure effect between Ag2Se-Ag2S and CoCH, bringing about the reduction of hydrogen adsorption free energy. Besides, such unique seaurchin-like heterostructure has a large electrochemically active area and uninterrupted proton-electron transmission function as well as the interlayer anion exchangeability of CoCH nanoneedles to exhibit prominently water dissociation ability and good resistance to chlorine corrosion. Consequently, Ag2Se-Ag2S-CoCH/NF achieves a fairly low HER overpotential of 35 mV at 10 mA cm−2 and an OER overpotential of 440 mV at 100 mA cm−2 in alkaline water and seawater, which is one of the most effective HER electrocatalysts reported so far. Furthermore, Ag2Se-Ag2S-CoCH/NF can be acted as a bifunctional catalyst to display a decent overall seawater splitting performance in alkaline simulated seawater. It also demonstrates outstanding and stable HER activity along with favorable corrosion resistance in natural seawater. This work is important for the rationally constructing of efficient and anti-corrosion electrocatalysts applied in seawater electrolysis.

Molecular-scale mechanisms of CO2 mineralization in nanoscale interfacial water films.

The calamitous impacts of unabated carbon emission from fossil-fuel-burning energy infrastructure call for accelerated development of large-scale CO2 capture, utilization and storage technologies that are underpinned by a fundamental understanding of the chemical processes at a molecular level. In the subsurface, rocks rich in divalent metals can react with CO2, permanently sequestering it in the form of stable metal carbonate minerals, with the CO2-H2O composition of the post-injection pore fluid acting as a primary control variable. In this Review, we discuss mechanistic reaction pathways for aqueous-mediated carbonation with carbon mineralization occurring in nanoscale adsorbed water films. In the extreme of pores filled with a CO2-dominant fluid, carbonation reactions are confined to angstrom to nanometre-thick water films coating mineral surfaces, which enable metal cation release, transport, nucleation and crystallization of metal carbonate minerals. Although seemingly counterintuitive, laboratory studies have demonstrated facile carbonation rates in these low-water environments, for which a better mechanistic understanding has come to light in recent years. The overarching objective of this Review is to delineate the unique underlying molecular-scale reaction mechanisms that govern CO2 mineralization in these reactive and dynamic quasi-2D interfaces. We highlight the importance of understanding unique properties in thin water films, such as how water dielectric properties, and consequently ion solvation and hydration behaviour, can change under nanoconfinement. We conclude by identifying important frontiers for future work and opportunities to exploit these fundamental chemical insights for decarbonization technologies in the twenty-first century.

Pressure and temperature dependence of the relaxation of the electrical double layer in hydrated magnesite rock (leukolite)

The introduction of water into the pore space of naturally occurring magnesite (leukolite) induces an intense relaxation mechanism, which is related to the electric double layer (EDL) formed on opposing sides of the solid – mater interface. The relaxation of the EDL is studied by using Broadband Dielectric Spectroscopy at different conditions of combined temperature and hydrostatic pressure. The temperature evolution of the characteristic relaxation frequency, reveals two successive temperature regions: in the low temperature one, protonic conductivity over the network of water molecules in on the solid surface, couples to the ionic transport of charged defects occurring in the solid. At higher temperatures, near – zero activation energies are found: the phenomenon is discussed theoretically and attributed to decoupling and an exchange of protons with lattice site magnesium cations, the formation of a proton enriched sub-surface layer of magnesite and subsequent release of cations to the liquid. The values of the activation volume and their independence on temperature, support the aforementioned interpretation.

Mechanism of modification of bitumen zeta potential by sodium citrate: Interactions between bitumen metal content and ligands

Sodium citrate (Na3Cit) has been proved to significantly increase the negative charges on bitumen surfaces, which enhances bitumen liberation and prevents slime coating in the bitumen recovery process. To understand the in-depth theory of Na3Cit modifying the bitumen zeta potential, different assumptions of Na3Cit interacting with bitumen were proposed and experimentally verified in this study. Accordingly, chemicals with similar properties were selected and compared with Na3Cit to confirm the mechanisms. We found that adding Ethylenediaminetetraacetic acid (EDTA) and phosphate (PO43-), which act like citrate as a ligand, resulted in a more negatively charged bitumen surface at pH 8.5 compared with sodium chloride (NaCl). However, even though the sulfate ion (SO42-) carries multiple negative charges, increasing the concentration of sodium sulfate (Na2SO4) led to less negatively charged bitumen surfaces at the same pH, a trend similar to NaCl. Meanwhile, Na3Cit and EDTA promoted the release of metal cations from bitumen to the aqueous solution. However, the concentration of metal ions released by sodium phosphate dibasic (Na2HPO4) was much smaller than expected. Adsorption of Na3Cit, EDTA, and Na2HPO4 on the bitumen surface was observed through mainly outer-sphere complexation and minor inner-sphere complexation. Our study revealed that ligands such as Na3Cit could remove metal ions from bitumen and adsorb onto the bitumen surface, which were the dominant reasons for modifying the zeta potential at the bitumen/water interface.

Tris(pyridin‐2‐ylmethyl)amine‐Based Ion Pair Receptors for Selective Lithium Salt Recognition

AbstractTripodal ion pair receptors 1 and 2 consisting of tris(pyridine‐2‐ylmethyl)amine as a cation binding site linked with nitrophenyl urea or amidonitroindole groups as anion binding motifs have been synthesized. 1H NMR spectroscopic analyses carried out in 10 % DMSO in acetonitrile revealed that both ion pair receptors 1 and 2 are able to bind the LiCl ion pair with high selectivity over NaCl, KCl, RbCl, and CsCl. 1H NMR spectroscopic analyses in combination with molecular mechanics calculations proved that the lithium cation is bound to the tris(pyridin‐2‐ylmethyl)amine subunit while the chloride anion interacts with the NHs of urea or amido indole groups via hydrogen bonds. The addition of fluoride to the lithium cation complexes of receptors 1 and 2 leads to the release of the lithium cation from the receptors whereas chloride and bromide are co‐bound with lithium forming LiCl and LiBr ion pair complexes, respectively. The affinity of receptor 1 for the lithium cation was found to be improved by 5.0‐fold when the counter anion of Cl− is co‐bound within the receptor.

Superionic conductor Ag2Se modulated CoSe2 nanosheets prepared via monometallic cation release for efficient pH-universal water electrolysis into hydrogen

Superionic conductors regulated transition metal chalcogenides are the newly emerged electrocatalyst in water electrolysis into clean hydrogen and oxygen. However, there is still much room for the development of structural design, electronic modulation and heterogeneous interface construction to improve the overall water splitting performance in pH-universal solutions, especially in alkaline and neutral mediums. Herein, using β-cyclodextrin (β-CD) and citric acid (CA) organics with abundant hydroxyl (–OH) and carboxyl (–COOH), a special Ag2Se nanoparticles-decorated CoSe2 flower-like nanosheets loaded on porous and conductive nickel foam substrate (Ag2Se-CoSe2/NF) was successfully constructed by a new method of monometallic cation release of coordinated cobalt. The Ag2Se phase exerts the nature characteristics of superionic conductors to modulate the morphological and electronic structures of CoSe2 as well as improve its conductivity. The generated rich active interfaces and abundant Se vacancy defects facilitate numerous active sites exposure to accelerate the hydrogen ion transport and charge transfer. Compared to the single-phase Ag2Se/NF-8 and CoSe2/NF, the prepared Ag2Se-CoSe2/NF-8 with a two-phase synergistic effect achieves an outstanding pH-universal electrocatalytic hydrogen production performance by water electrolysis, as evidenced by a lower overpotential (60 mV, 212 mV and 85 mV vs RHE at 10 mA cm−2 for pH = 0.36, 7.00 and 13.70, respectively). Only a voltage of 1.55 V at 10 mA cm−2 is required to implement the overall water splitting in an alkaline electrolyzer. This work provides significant guidance for the future designation and practical development of transition metal chalcogenides with superionic conductors applied in the electrocatalytic field.

Acidic condition accelerates cation release from purple rock in Southwestern China

In spite of the fact that rock weathering performs an essential task in the evolution of the Earth’s surface, the quantitative assessment between pH and rates of chemical weathering remain unclear. This study aims to characterize the chemical weathering rate of purple rocks and then develops a model to calculate the release rates of cations (K+, Na+, Ca2+ and Mg2+) under various pH conditions. Two types of purple rock were sampled from the Shaximiao Group (J2s) and Penglaizhen Group (J3p), and a series of laboratory experiments were performed by soaking the purple rocks in solutions with pHs from 2.5 to 7.0, over 24 treatment cycles. The results showed that the release rates of cations apparently increased as the pH decreased. The release of Ca2+ was the dominant process of chemical weathering in J3p under various pH treatments, while K+ and Na+ were remarkably high in J2s (with the exception of the pH 2.5 treatment). Quantitative analysis revealed that the rate of cation release was significantly related to the H+ concentration (p < 0.001) and the air temperature (p < 0.001). The relationship between cation release and acidity was found to be an exponential function. Our results suggested that solution acidity serves as an important driving force for cation release rates from purple rocks and that environmental acidification would enhance rock weathering.

Impact of Phytase Treatment and Calcium Addition on Gelation of a Protein-Enriched Rapeseed Fraction

Rapeseed press cake was upcycled as a protein-enriched ingredient through dry fractionation. The protein-enriched fraction contained higher amounts of phytic acid compared to press cake, and phytase treatment was applied to decrease the phytic acid content from 6.8 to 0.5%. The effect of phytase treatment leading to the release of cations was also mimicked by extrinsic calcium addition. Both phytase treatment and calcium addition significantly improved the heat-induced gel properties but had a minor effect on protein solubility and dispersion stability at pH 8. Water and protein holding capacities of the gels were the highest for the phytase-treated sample (91 and 97%, respectively), followed by the sample with added calcium (86 and 94%, respectively) and control sample (60 and 86%, respectively). Gel firmness followed the same pattern. Scanning electron microscopy images revealed an interconnected structured network in the phytase-treated gel, while in the control gel, a more rigid and open structure was observed. The improved gelation properties resulting from the phytase treatment suggest that the protein and soluble dietary fibre-enriched rapeseed press cake ingredient serve as a promising raw material for gelled food systems. The positive effect of calcium addition on gel properties proposes that part of the improvement observed after phytase treatment may be caused by cations released from phytate.

Interrogating the Effect of Assay Media on the Rate of Virus Inactivation of High‐Touch Copper Surfaces: A Materials Science Approach

AbstractContamination of high‐touch surfaces with infected droplets of bodily secretions is a known route of virus transmission. Copper surfaces have been reported to inactivate human coronaviruses after several minutes, via the release of Cu cations. Utilization of copper alloys for high‐touch surfaces can be a pivotal preemptive strategy for preventing the next pandemic. Understanding the true efficacy by which copper, and copper alloys, inactivate the virus under realistic conditions is essential for tuning intrinsic alloy features such as composition, grain orientation, and surface attributes, to optimize for antiviral function. However, virus inactivation measurements depend on the presence of an assay media (AM) solution as a carrier for the virus, and its effects on the surface properties of pure copper that regulate oxidative copper release are previously unknown. Herein, these properties and the influence of AM on the efficacy of virus inactivation occurring on the surface of pure copper are investigated. The process is uncovered by which a five‐fold decrease in virus half‐life is observed in simulated real‐life conditions, relative to exposure to traditional AM. The investigation highlights the notion that virus inactivation on copper surfaces may be significantly more effective than previously thought.

Behaviors of sodium and calcium ions at the borosilicate glass-water interface: Gaining new insights through an ab initio molecular dynamics study.

We study reactivity and leaching at the calcium sodium borosilicate (CNBS)-water interface by means of a Car-Parrinello ab initio molecular dynamics simulation over a simulation time of 100ps. With an emphasis on the comparison between the behaviors of Ca2+ and Na+ cations at the CNBS glass-water interface, different mechanism events during the trajectory are revealed, discussed, and correlated with other density functional theory calculations. We show that Na+ ions can be released in solution, while Ca2+ cannot leave the surface of CNBS glass. This release is correlated with the vacancy energy of Ca2+ and Na+ cations. Here, we found that the CNBS structure with the Na+ cation vacancy is energetically more favorable than the structure with the Ca2+ cation vacancy. The calcium adsorption site has been shown to have a greater affinity for water than can be found in the case of the sodium site, demonstrating that affinity may not be considered a major factor controlling the release of cations from the glass to the solution.

Rate and capacity of cation release from ultramafic mine tailings for carbon capture and storage

Solid wastes produced during hard-rock mining have capacity to capture and store atmospheric CO2 via dissolution and precipitation of Mg-bearing carbonate minerals. However, there is a discrepancy in our understanding of weathering and dissolution in these wastes, with dissolution and reaction rates in field studies exceeding those predicted by experiments under far-from-equilibrium conditions. To reconcile these differences, a series of flow-through dissolution experiments at 25 °C and 1atm were performed to investigate the short-term dissolution kinetics of ultramafic tailings and minerals. Results show that mineral and tailings samples have two stages of dissolution: a fast, transient (or labile) stage, and a slow, stoichiometric stage. Fast releasing labile cations (i.e. labile Mg2+) are sourced from trace minerals with a high reaction rate (e.g. brucite) and from non-stoichiometric surface reaction processes of major minerals (e.g. serpentine). These cations are missing from most geochemical models for mineral weathering. The implication of these results is that the initial transient dissolution of minerals, which is typically ignored during geochemical investigations into bulk dissolution rates, is the missing ingredient for understanding dissolution of mine tailings. Labile cations released during the initial transient dissolution process have value for rapid and low-cost carbon capture and storage techniques as they represent reactivity, capacity, and the best opportunities to deploy low-cost carbon sequestration techniques using mine tailings and other industrial wastes. The presence of labile cations and changing reaction rates over time may also suggest that short-term reactivity examined during field tests may overestimate long-term carbon capture potential of some sites.

Promising Lipophilic PyTri Extractant for Selective Trivalent Actinide Separation from High Active Raffinate.

Within a spent nuclear fuel recycling strategy, in the past few years, the pyridine-bis-triazole unit was found to be rather effective and selective in minor actinide (MA) separation from synthetic high active raffinate (HAR). In this research work, the main features of the recently studied PTEH ligand were investigated in order to evaluate its potentialities in SANEX-like processes. Its applicability in advanced separation processes was demonstrated, even at process temperatures. It manifested satisfactory extraction properties for a successful selective An separation from Ln, easy cation release, and adequate extraction kinetics as well as outstanding hydrolytical and radiolytical stability. All the results collected in this work allowed the scientists on the committee of the H2020 GENIORS project to promote PTEH as a concrete alternative to the reference CyMe4-BTBP ligand.

Processes that control the dissolution of loess sediments and contribution of arsenic release in the Chaco-Pampean plain, Argentina

Groundwaters of the Chaco-Pampean Plain in Argentina are contaminated by arsenic released from weathered volcaniclastic loess sediments. To better understand As release, the dissolution of three loessial materials (loess, volcanic glass shards (VGS) and volcanic ash) that make up the sediments was studied at pH 2–12 and 10–50 °C using flow-through experiments.The variation in the output concentrations was reproduced by 1D reactive transport simulations, enabling us to infer that the reactivity of the phases controlling the overall dissolution of the loessial materials varies as a function of pH. Oligoclase dissolves faster than K-feldspar and the Al–Si-amorphous phase at acid pH whereas the K-feldspar and Al–Si-amorphous phases dissolve more rapidly at basic pH. The steady-state output Si concentrations attributed to the main dissolving phases at different pH were used to calculate the dissolution rates of the loessial materials, yielding faster rates at acid pH than at the circumneutral to basic pH. The variation in the dissolution rate (mol m−2 s−1) of the Al–Si-material making up the loess sediments in the shallow aquifers in the Chaco-Pampean Plain as a function of pH and temperature is expressed as Rdiss=10−2.25·aH+0.20±0.01·e−54RT+10−8.51·e−23.1RTSimulations indicate that an initially high release of cations is due to rapid dissolution of fine particles and cation exchange between the exchangeable cations (Na, Ca, K and Mg) of the Al–Si-amorphous phase and those of the electrolyte solution. At steady state, dissolution of the coarse fraction was responsible for the cations release. The variation in the output As concentrations was simulated by considering two arsenic sources: (i) the arsenic from the As-rich fluorapatite and Fe-(hydr)oxides (e.g. ferrihydrite) that dissolve at acid pH and desorb As at basic pH, releasing arsenic into the solution, and (ii) Al–Si phases (e.g. volcanic glass), the dissolution of which releases the arsenic from the solid structure into the solution at any pH. At the start of the experiments, fluorapatite, ferrihydrite, glass an aluminosilicates contributed arsenic to the solution. At steady state, As was mainly released from the glass and the aluminosilicates, and the rate of As release from the loessial materials that constitute the Chaco-Pampean loess sediments was calculated using the aqueous As/Si ratios ((9.2 ± 8.8)·10−5 and (7.4 ± 2.2)·10−5 at acidic and basic pH, respectively).