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We investigated the effect that two common types of cationic polyelectrolytes used in papermaking might have on the performance of paper diagnostics using blood typing as an example. The results were analyzed in terms of red blood cells (RBC) retention and antibody-antigen specificity. Two questions were addressed: (1) can poly(amido-amine) epichlorohydrin (PAE) typically used for paper wet strength affect the diagnostic performance? (2) can high molecular weight cationic polyacrylamide (CPAM) employed as retention aid enhance or affect the selectivity and sensitivity of paper diagnostics? A series of paper varying in type of fibers and drying process were constructed with PAE and tested for blood typing performance. Residual PAE has no significant effect on blood typing paper diagnostics under normal conditions. Positives are unaffected with PAE, while negatives lose slight sharpness as some RBCs are unselectively retained. CPAM, the most common retention aid, can also be used to retain cells and biomolecules on paper. Paper towel was treated with CPAM solutions varying in polymer concentration and charge density and tested for blood typing. We found that CPAM dried on paper can retain RBC. CPAM affects the negative tests by retaining non-specifically individual RBC on fibers. RBC retention increases non-linearly with the CPAM charge density and concentration. As expected, wet CPAM retain RBCs at concentrations higher than 0.1wt%. As paper diagnostics are becoming a reality, more realistic papers than the Whatman filter paper will be engineered. This study provides guidance on how best use the required polymeric wet-strength and retention agents., (Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.)

Diffuse reflectance spectroscopy can be successfully used for the quantitative determination of small amounts of pollutants like metals. The remission function was found to be linearly proportional to the concentration, when we applied the Kubelka-Munk equation. The color reactions of Cu(II), Co(II), and Ni(II) with dithiooxamide, were realised on filter paper. Reaction between Fe(III) and ammonium thiocyanate was realized on filter paper and gelatine matrix. All measurements were accomplished with a laboratory-constructed reflectometer. We have obtained a calibration curve by plotting the optical density of reflectance A(R) vs log of the mol l(-1) concentration. Limits of detection at the 10(-4) M level were estimated for all the compounds. Linear dynamic range extend over one order of magnitude and shows the potential of device for the quantitative analysis of environmental pollutants.

Cationized birch xylan was prepared and its use as a papermaking chemical was evaluated. The focus was on studying the effects of cationized birch xylan on the wet and dry strength of fine paper. The results of the laboratory experiments show that the addition of 3 percent of cationized birch xylan to birch kraft pulp improved the initial wet strength of the web by 30 percent compared to base stock at a solids content of 55%. Furthermore, the tensile stiffness of the wet web increased by approximately a third and the dry tensile strength improved by 26%, while the dry elastic modulus was not changed. The improvements in the strength properties were clear when compared to the base stock, but not as high as achieved with conventionally used cationized starch. The difference between the xylan and starch is most likely due to the shorter polymer chain length of the cationized xylan. [ABSTRACT FROM AUTHOR]

Highlights: [•] Improvement of the direct quantification with analytical pyrolysis. [•] Optimization of the chromatographic parameters after pyrolysis of cationic starch. [•] Quantification of cationic starches in cellulose matrixes. [•] Validation of the cationic starch quantification in paper samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • GQD-DDT and GQD-MPA was synthesized using novel hydrothermal protocol. • GQD-DDT and GQD-MPA was used for the identification of cations using colorimetric and spectrophotometric assay. • GQD-DDT and GQD-MPA have well activity for ion sensing in aqueous solution. This study describes the synthesis of various types of thiolated-graphene quantum dots (GQDs) for the simultaneous multi-sensing of heavy metal ions using one-droplet microfluidic paper-based analytical devices (OD- µ PADs). For the first time, functionalized GQDs were synthesized and stabilized on the surface of hydrophobic fiber-glass with simple manufacturing and assembly strategy towards colorimetric chemosensing of ions including iron, copper, cobalt, mercury, chrome, manganese, and nickel. For this purpose, GQDs are functionalized by various organic species including cysteamine, decanethiol, and mercaptopropionic acid (MPA) towards specific electrostatic interaction with metal ions of Fe (II), Cu (II), Co(II), Hg (II), Mn (II), and Ni (II). Therefore, an innovative GQDs-based miniaturized chemo-system was proposed for the environmental analysis. Additionally, the results were confirmed using fluorescence spectrometry as an optical detection method. Finally, this simple and efficient colorimetric platform was used for facile metal ions detection in human urine models, and environmental fluids, which can provide a commercial device for sensing contaminants by non-professional users in biomedical/environmental mixture. As an economical technique, this platform presents a "mix-and-sense" system without dye (as a side substance) or chemical treatments. The low instrumental requirements, the color uniformity, and the disposability of OD- μ PADs approve the commercial application of the engineered ion-chemosensor. [ABSTRACT FROM AUTHOR]

A new approach for the chemical modification of the surface of paper based on the application of colloidal mixtures containing cationic starch and polyoxometalates on uncoated base paper is presented. Polyoxometalates with the Keggin-type structure and physical properties similar to those presented by coating pigments, namely H3PW12O40∙23H2O, H4SiW12O40∙24H2O, and K7PW11O39∙9H2O, have been used in order to improve the quality of inkjet printing. The analysis of the different samples by FTIRATR spectroscopy showed the presence of the polyoxometalates (and the cationic starch) on the top surface of the paper. In addition, the determination of surface energy parameters, namely the polar component (σsp) and the dispersive component (σsd) of the surface energy, by contact angle measurements revealed that, for the new samples, the polar component level was much higher than that of the uncoated base paper. The quality of inkjet printing, evaluated by parameters such as the gamut area and the optical density, was considerably improved by these surface treatments. [ABSTRACT FROM AUTHOR]

Accumulation of interfacial space charge in oil-paper interface is a critical issue in insulation diagnostics of transformers. This interfacial charge mainly accumulates due to the conductivity difference of oil and paper. Accumulation of interfacial charge leads to localized field enhancement, which further leads to partial discharges and acceleration in the aging of insulation. Therefore, from the point of view of transformer insulation diagnostics, assessment of interfacial charge is very important. However, it is not easy to estimate interfacial space charge behavior from the transformer diagnostics methods currently in use. In case of Polarization-Depolarization Current (PDC) measurement, a well known method for transformer condition monitoring, the effect of interfacial charge is reflected in the non-linearity of current response during polarization and de-polarization. During de-polarization process, a part of the interfacial charge accumulated during polarization period is absorbed by the electrodes producing a current, which is difficult to separate using conventional linear dielectric theory. In this paper, an attempt has been made to separate this current component from de-polarization current through considering charge de-trapping mechanism. Terming this current component as de-trapping current, its relationship with other parameters of transformer insulation is discussed. The developed methodology has been applied on several practical transformers. It was observed that the time constant of de-trapping current is related to the paper conductivity, oil conductivity, dissipation factor and age of the insulation. [ABSTRACT FROM PUBLISHER]

Abstract: This study examines and quantifies the effect of cationic polyacrylamide (CPAM) dissolution kinetics and charge density on the adsorption and aggregation state of gold nanoparticles (AuNPs) on paper and the resulting Surface Enhanced Raman Scattering (SERS) performance. Dissolution kinetics of CPAM of different charge density was studied by monitoring their viscosity and hydrodynamic diameter over regular intervals of time. It was found that the degree of dissolution of CPAM greatly affected the surface coverage and aggregation of AuNPs on the CPAM pre-adsorbed paper substrate and their SERS reproducibility. CPAM of higher charge density dissolves faster and produced a more uniform aggregation and higher surface coverage of AuNPs on paper for a higher and more reproducible Raman EF. Understanding the CPAM dissolution process enables the optimization of SERS performance of the AuNPs-paper as a bio-diagnostic platform. [Copyright &y& Elsevier]

Abstract: This study examines and quantifies the effect of cationic polyelectrolyte adsorption on paper on the aggregation and retention of gold nanoparticles (AuNPs) to optimize their Surface Enhanced Raman Scattering (SERS) enhancement factor and sensitivity. Aggregation of metallic nanoparticles is known as a key factor for intense SERS enhancement. Paper substrates were treated with aqueous solutions of cationic polyacrylamide (CPAM) varying in concentration, charge density, and molecular weight to control the AuNPs’ aggregate size distribution and surface coverage on paper. The Raman Enhancement Factor of AuNPs-CPAM paper was almost an order of magnitude greater than for the untreated AuNPs paper. The high loading and uniform distribution of AuNPs aggregates on CPAM pre-treated paper contributed toward the excellent SERS reproducibility, sensitivity, and high enhancement factor. This configuration of AuNP on paper was favoured by treating the substrate with CPAM solutions of higher concentrations, higher charge density, and greater molecular weight. [Copyright &y& Elsevier]

1-octadecanol is known to be a highly effective agglomerating agent for laser toner ink. However, the office waste paper used in the actual production often contains various types of inks. The effect of the offset ink and types of surfactants with different charge characteristics were studied relative to the agglomeration of the laser toner ink under neutral pulping conditions. It was found that the addition of a small amount of the offset ink printed waste paper was beneficial for the agglomeration of the laser toner ink. The optimal percentage of addition is 12.5% to 25%. The offset printed ink had a positive charge of 0.001±0.0005 mEq/g when the offset ink was treated by 70°C water at neutral conditions. Addition of a proper amount of cationic surfactant was beneficial to improve the agglomeration at any ratio of the mixed laser printed and offset waste papers. When the percentage of offset waste paper was less than 50%, the addition of anionic surfactant and nonionic surfactant was harmful for agglomeration, and there was no significant effect at higher offset content. [ABSTRACT FROM AUTHOR]

Abstract: Large numbers of soil samples are routinely analyzed using methylene blue (MB) titration to determine clay content. Although, the MB filter paper spot test titration is simple, it is labor-intensive, subjective, and leaves no record for subsequent re-examination. Preliminary thermometric monitoring of the titration indicated a switch from endothermic to exothermic reaction during titration. We examined this nearly universal property of physicochemical processes as a potential replacement method to automate the MB clay titration, making use of literature data. We translated the isothermal enthalipmetric titration of montmorillonite using MB by Rytwo and Ruiz-Hitzky to an adiabatic thermometric titration (2003). The plot of temperature versus titrant volume gave two intersecting linear segments dependent on the titrated percentage of the clay''s cation exchange capacity (CEC). The MB filter paper spot test endpoint reflects the first excess MB that persists in the solid suspension, which also happens to be a function of the clay''s CEC. The spot test endpoint is correlated to the thermometric indicator point and, for montmorillonite, the two are related by an exact factor of two. Although this factor will naturally be dependent on the clay minerals in the samples, the analyses show that the thermometric indicator titration method is a viable replacement for the spot test. The proposed automation is commonplace as it is practiced with other types of titrations. [Copyright &y& Elsevier]

Novel polyepinephrine-modified NaYF 4 :Yb,Tm upconversion luminescent nanoparticles (UCNP@PEP) were prepared via the self-polymerization of epinephrine on the surfaces of the UCNPs for selective sensing of Fe 3+ inside a cell and for intracellular imaging. The proposed UCNP@PEP probe is a strong blue light emitter (λ max  = 474 nm) upon exposure to an excitation wavelength of 980 nm. The probe was used for detecting Fe 3+ owing to the complexation reaction between UCNP@PEP and Fe 3+ , resulting in reduced upconversion luminescence (UCL) intensity. The proposed probe has a detection limit of 0.2 μM and a good linear range of 1-10 μM for sensing Fe 3+ ions. Moreover, the UCNP@PEP probe displays high cell viability (90%) and is feasible for intracellular imaging. The ability of the probe to sense Fe 3+ in a human serum sample was tested and shows promising output for diagnostic purposes. The prepared UCNP@PEP probe was characterized by using UV-visible (UV-Vis) absorption spectrometry, fluorescence (FL) spectrometry, field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR).

The results of applying heterogeneous chemiluminescent analysis for determination of micro-components are generalized, and the possibility of using this method for determination of toxic anions in waters is demonstrated. Anions undergo conversion beforehand, which causes formation of new analytical forms, i.e., derivates being active in chemiluminescent reactions with luminol. If volatile products are generated as analytical forms, they undergo gas extraction from the matrix with detection using a chemiluminescent indicator in the carrier gas stream at the interface gas-liquid (aqueous solution of luminol). Thus, the techniques for determination of Cl, Br, I, ClO, BrO, IO, NO, NO, S, CrO, AsO, Cl and chloramines are developed. The detection limit (DL) is 0.5-5.0 μg/l, and the analysis time is 2-9 min. In another case, products of conversion are sorbed from the solution on a solid sorbent, and detection is carried out by a luminol solution on the solid surface. A series of heteropoly acids (phosphorus, arsenic, silicon, and germanium) and their ion associates with cation surfactants, along with other large anions, are determined in the form of sorbable ion associates. The DL is 0.02-0.7 μg/l, and the analysis time is 30 min. The advantages of application of heterogeneous chemiluminescent analysis over analysis in homogeneous media are indicated, and the prospects for development of the theoretical bases and field of application are demonstrated. [ABSTRACT FROM AUTHOR]

This article was written to serve as an introduction to this issue of the Canadian Journal of Chemistry that honors the contributions to chemistry of Professor D.R. Arnold. It summarizes the observations reported in a communication that appeared in the Journal of the American Chemical Society 30 years ago in June 1973. This historically important communication laid the foundation for his program on the photochemical generation and reactivity of radical ions in solution and also served as a guide for a developing area of interest of many other research groups. [ABSTRACT FROM AUTHOR]

Studying the adsorption behavior of cationic surfactants can help to develop more effective strategies to limit their dispersion in the environment. However, there have few studies on the adsorption of cationic surfactants from the perspective of critical micelle concentration (CMC). In this study, with cetyltrimethylammonium bromide (CTAB) and octadecyl trimethylammonium bromide (OTAB) serving as the model cationic surfactants, the effect of CMC on the adsorption behavior of cationic surfactant onto the surface of sodium alginate/silica (SA/SiO 2 ) microspheres was systematically revealed. The adsorption mechanism relative to CMC was investigated under different conditions, including surfactant concentration, pH, temperature, and adsorption time. The results suggest that at identical concentrations, the smaller the CMC value of the cationic surfactants, the greater the adsorption amount (q t ). q t for CTAB and OTAB were 583.2 and 678.0 mg/g respectively, with the concentration higher than their CMC value. When the concentration was lower than the CMC value of the cationic surfactants, q t for CTAB and OTAB were 123.2 and 138.7 mg/g, respectively. The CMC value of CTAB was lower than that of OTAB under identical conditions, suggesting that the adsorption of cationic surfactants is related to their CMC. These results are beneficial for the removal of cationic surfactants by adsorption methods., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Developing the delivery systems with high therapeutic efficacy and low side effects is of great interest and significance for anticancer therapy. Compared to the high cost in synthesizing new chemotherapeutic drugs, exploring the anticancer potentials of existing chemicals is more convenient and efficient. Sodium bicarbonate (BC), a simple inorganic salt, has shown its tumor inhibition capacity via regulating the acidity of tumor microenvironment. However, the effects of intracytoplasmic BC on tumor growth and the potentials of BC to serve as an anticancer agent are still unknown. Herein, we developed a BC-loaded cationic liposome system (BC-CLP) to deliver BC into the cytosol of cancer cells. The in vitro studies showed that the BC-CLP containing 1% BC (w/v) had a size of 112.9 nm and a zeta potential of 19.1 mV, which reduced the viability of the model cancer cells (human oral squamous cell carcinoma HSC-3 cells) to 13.7%. In contrast, the neutral BC-LP caused less than 50% viability reduction. We further found that BC-CLP released BC directly into cytoplasm via membrane fusion pathway rather than endocytosis, leading to the remarkable increase of cytosolic pH, which may contribute to the anticancer effect of BC-CLP. Our findings indicate that BC-CLP is a potential system for high-efficiency cancer therapy without causing drug-related side effects or resistance., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Antiphase bursting related to the rhythmic motor behavior exhibits complex dynamics modulated by the inhibitory synaptic current (Isyn), especially in the presence of the hyperpolarization-activated cation current (Ih). In the present paper, the dynamics of antiphase bursting modulated by the Ih and Isyn is studied in three aspects with a theoretical model. Firstly, the Isyn and the slow Ih with strong strength are the identified to be the necessary conditions for the antiphase bursting. The dependence of the antiphase bursting on the two currents is different for low (escape mode) and high (release mode) threshold voltages (Vth) of the inhibitory synapse. Secondly, more detailed co-regulations of the two currents to induce opposite changes of the bursting period are obtained. For the escape mode, increase of the Ih induces elevated membrane potential of the silence inhibited by a strong Isyn and shortened silence duration to go beyond Vth, resulting in reduced bursting period. For the release mode, increase of the Ih induces elevated tough value of the former part of the burst modulated by a nearly zero Isyn and lengthen burst duration to fall below Vth, resulting in prolonged bursting period. Finally, the fast-slow dynamics of the antiphase bursting are acquired. Using one-and two-parameter bifurcations of the fast subsystem of a single neuron, the burst of the antiphase bursting is related to the stable limit cycle, and the silence modulated by a strong Isyn to the stable equilibrium to a certain extent. The Ih mainly modulates the dynamics within the burst and quiescent state. Furthermore, with the fast subsystem of the coupled neurons, the silence is associated with the unstable equilibrium point. The results present theoretical explanations to the changes in the bursting period and fast-slow dynamics of the antiphase bursting modulated by the Isyn and Ih, which is helpful for understanding the antiphase bursting and modulating rhythmic motor patterns. [ABSTRACT FROM AUTHOR]

β-lactoglobulin (BLG) is the major whey protein with negative charges at neutral pH in aqueous media. Thus, the interaction with mucins, the major polyanionic component of mucus, is very weak due to the electrostatic repulsion between them. The present study postulates that cationization of BLG molecules may reverse the interaction characteristics between BLG and mucin from repulsive to associative. To this end, cationic-modified BLGs were prepared by grafting positively charged ethylenediamine (EDA) moieties into the negatively charged carboxyl groups on the aspartic and glutamic acid residues and compared with non-modified BLG upon mixing with porcine gastric mucin (PGM). To characterize the structural and conformational features of PGM, non/cationized BLGs, and their mixtures, various spectroscopic approaches, including zeta potential, dynamic light scattering (DLS), and circular dichroism (CD) spectroscopy were employed. Importantly, we have taken surface adsorption with optical waveguide lightmode spectroscopy (OWLS), and tribological properties with pin-on-disk tribometry at the sliding interface as the key approaches to determine the interaction nature between them as mixing PGM with polycations can lead to synergistic lubrication at the nonpolar substrate in neutral aqueous media as a result of an electrostatic association. All the spectroscopic studies and a substantial improvement in lubricity collectively supported a tenacious and associative interaction between PGM and cationized BLGs, but not between PGM and non-modified BLG. This study demonstrates a unique and successful approach to intensify the interaction between BLG and mucins, which is meaningful for a broad range of disciplines, including food science, macromolecular interactions, and biolubrication etc., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Nucleic acid delivery by viral and non-viral methods has been a cornerstone for the contemporary gene therapy aimed at correcting the defective genes, replacing of the missing genes, or downregulating the expression of anomalous genes is highly desirable for the management of various diseases. Ostensibly, it becomes paramount for the delivery vectors to intersect the biological barriers for accessing their destined site within the cellular environment. However, the lipophilic nature of biological membranes and their potential to limit the entry of large sized, charged, hydrophilic molecules thus presenting a sizeable challenge for the cellular integration of negatively charged nucleic acids. Furthermore, the susceptibility of nucleic acids towards the degrading enzymes (nucleases) in the lysosomes present in cytoplasm is another matter of concern for their cellular and nuclear delivery. Hence, there is a pressing need for the identification and development of cationic delivery systems which encapsulate the cargo nucleic acids where the charge facilitates their cellular entry by evading the membrane barriers, and the encapsulation shields them from the enzymatic attack in cytoplasm. Cycloamylose bearing a closed loop conformation presents a robust candidature in this regard owing to its remarkable encapsulating tendency towards nucleic acids including siRNA, CpG DNA, and siRNA. The presence of numerous hydroxyl groups on the cycloamylose periphery provides sites for its chemical modification for the introduction of cationic groups, including spermine, (3-Chloro-2 hydroxypropyl) trimethylammonium chloride (Q188), and diethyl aminoethane (DEAE). The resulting cationic cycloamylose possesses a remarkable transfection efficiency and provides stability to cargo oligonucleotides against endonucleases, in addition to modulating the undesirable side effects such as unwanted immune stimulation. Cycloamylose is known to interact with the cell membranes where they release certain membrane components such as phospholipids and cholesterol thereby resulting in membrane destabilization and permeabilization. Furthermore, cycloamylose derivatives also serve as formulation excipients for improving the efficiency of other gene delivery systems. This review delves into the various vector and non-vector-based gene delivery systems, their advantages, and limitations, eventually leading to the identification of cycloamylose as an ideal candidate for nucleic acid delivery. The synthesis of cationic cycloamylose is briefly discussed in each section followed by its application for specific delivery/transfection of a particular nucleic acid., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The coexistence of metal cations is often accompanied by organic pollution and could affect the environmental fate of organics by mediating the formation of cation bridges. However, the environmental fate and risk of organics in cation co-existing environments are poorly understood due to the lack of accurate identification of cation bridge formation and stability. In this study, the sorption of sulfamethoxazole (SMX) on montmorillonite (MT) with the coexistence of three different valence metal cations (Na + , Ca 2+ , and Cr 3+ ) was investigated. Ca 2+ and Cr 3+ can significantly promote the sorption of SMX on MT for about 5∼10 times promotion, respectively, while Na + bridges displayed little effect on the sorption of SMX. The sorption binding energy of SMX with MT-Ca (-44.01 kcal/mol) and MT-Cr (-64.57 kcal/mol) bridges was significantly lower than that with MT-Na (-38.45 kcal/mol) and MT (-39.39 kcal/mol), indicating that the sorption affinity of SMX on Cr and Ca bridges was much stronger. The higher valence of the cations also resulted in a more stable adsorbed SMX with less desorption fluctuation. In addition, the relatively higher initial concentration of SMX and the valence of cations increased the bonding density of the cation bridges, thus promoting the apparent sorption of SMX on MT to a certain extent. This work reveals the formation and function of cation bridges in the sorption of SMX on MT. It lays a theoretical foundation for further understanding the environmental fate and risk of organics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The aging process of microplastics (MPs) could significantly change their physical and chemical characteristics and impact their migration behavior in soil. However, the complex effects of different cations and humic acids (HA) on the migration of aged MPs through saturated media are not clear. In this research, the migration and retention of pristine/aged PSMPs (polystyrene microplastics) under combined effects of cations (Na + , Ca 2+ ) (ionic strength = 10 mM) and HA (0, 5, 15 mg/L) were investigated and analyzed in conjunction with the two-site kinetic retention model and DLVO theory. The findings showed that the aging process accelerated PSMPs migration under all tested conditions. Aged PSMPs were less susceptible to Ca 2+ than pristine PSMPs. Under Ca 2+ conditions, pristine/aged PSMPs showed higher retention than under Na + conditions in the absence of HA. Furthermore, under Na + conditions, the migration of aged PSMPs significantly increased at higher concentrations of HA. However, under Ca 2+ conditions, the migration of aged PSMPs decreased significantly at higher concentrations of HA. In higher HA conditions, HA, Ca 2+ , and PSMPs interact to cause larger aggregations, resulting in the sedimentation of aged PSMPs. The DLVO calculations and two-site kinetic retention models' results showed the detention of PSMPs was irreversible under higher HA conditions (15 mg/L) with Ca 2+ , and aged PSMPs were more susceptible to clogging. These findings may help to understand the potential risk of migration behavior of PSMPs in the soil-groundwater environment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

A series of laboratory experiments are conducted to simulate the acidification and subsequent recovery of a sand aquifer exploited by in situ recovery (ISR) mining. A sulfuric acid solution (pH 2) is first injected into a column packed with sand from the Zoovch Ovoo uranium roll front deposit (Mongolia). Solutions representative of local groundwater or enriched in cations (Na + , Mg 2+ ) are then circulated through the column to simulate the inflow of aquifer water. pH and major ion concentrations (Na + , Cl - , SO 4 2- , Ca 2+ , Mg 2+ ) measured at the column outlet reproduce the overall evolution of porewater chemistry observed in the field. The presence of minor quantities of swelling clay minerals (≈6 wt% smectite) is shown to exert an important influence on the behavior of inorganic cations, particularly H + ) measured at the column outlet reproduce the overall evolution of porewater chemistry observed in the field. The presence of minor quantities of swelling clay minerals (≈6 wt% smectite) is shown to exert an important influence on the behavior of inorganic cations, particularly H + , via ion-exchange reactions. Numerical models that consider ion-exchange on smectite as the sole solid-solution interaction are able to reproduce variations in pH and cation concentrations in the column experiments. This highlights the importance of clay minerals in controlling H + mobility and demonstrates that sand from the studied aquifer can be described to a first order as an ion-exchanger. The present study confirms the key role of clay minerals in controlling water chemistry in acidic environments through ion-exchange processes. In a context of managing the long-term environmental footprint of industrial and mining activities (ISR, acid mine drainage…), this work will bring insights for modeling choices and identification of key parameters to help operators to define their production and/or remediation strategies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)