Electrokinetic Measurements Research Articles

Recycled Jute Non-Woven Material Coated with Polyaniline/TiO2 Nanocomposite for Removal of Heavy Metal Ions from Water.

Growing volumes of textile waste and heavy metal pollution of water are emerging environmental challenges. In an attempt to tackle these issues, a non-woven sorbent based on jute fibers was fabricated by recycling the textile waste from the carpet industry. The influence of contact time, concentration, pH and temperature on the sorption of lead and copper ions from aqueous solutions was studied. In order to enhance the sorption capacity of the non-woven material, in situ synthesis of polyaniline (PANI) in the presence of TiO2 nanostructures was performed. The contribution of TiO2 nanoparticles and TiO2 nanotubes to the uniformity of PANI coating and overall sorption behavior was compared. Electrokinetic measurements indicated increased swelling of modified fibers. FTIR and Raman spectroscopy revealed the formation of the emeraldine base form of PANI. FESEM confirmed the creation of the uniform nanocomposite coating over jute fibers. The modification with PANI/TiO2 nanocomposite resulted in a more than 3-fold greater sorption capacity of the material for lead ions, and a 2-fold greater absorption capacity for copper ions independently of applied TiO2 nanostructure. The participation of both TiO2 nanostructures in PANI synthesis resulted in excellent cover of jute fibers, but the form of TiO2 had a negligible effect on metal ion uptake.

Dependence of oxygen evolution reaction catalysis at thin cathodically-deposited nickel-iron-selenide on Fe in the alkaline electrolyte vs. codeposited Fe

This study interrogated the role of Fe co-deposited in films versus Fe included from traces in the electrolyte on the electrochemical dynamics and kinetics for the oxygen evolution reaction (OER) in alkaline at a nickel-iron selenide OER pre-catalyst. Iron was co-included in the bulk of nickel selenide (NixSey) during cathodic deposition and is termed bulk-Fe (Febulk), and/or was included on its surface post-deposition by conditioning at anodic bias in alkaline with Fe traces and is termed surface-Fe (Fesurface). The electrochemical dynamics, OER kinetics, and sustainability of catalysis were studied in 1 M KOH stripped of Fe (Fe-free KOH) or containing Fe traces (KOH). The selenides transformed into a selenide/hydroxide with a few monolayers of surface hydroxide during the hours of conditioning and electrokinetic measurements at anodic bias in both solutions. Bulk-Fe did not enhance OER catalysis at nickel selenide, while surface-Fe promoted OER catalysis. Tafel slopes of ca. 40 mV/dec were recorded at (NiFebulk)xSey-Fesurface and NixSey-Fesurface in KOH, while Tafel-slopes of ca. 100 mV/dec were recorded at (NiFebulk)xSey in Fe-free KOH. Tafel slopes of 60–80 mV/dec were recorded in Fe-free KOH at (NiFebulk)xSey-Fesurface and NixSey-Fesurface that had been conditioned in KOH. OER catalysis at Fesurface-activated electrocatalysts was not sustained in alkaline stripped of Fe, neither at anodic bias nor subjected to potential cycling. The electrochemical data is consistent with a mechanism involving a low-coordination surface-Fe in the thin hydroxide layer of not more than few monolayers formed in-situ on the selenide. Surface-Fe is pictured as part of a dynamic catalytic site whose equilibrium density, to ensure sustainable catalysis, requires a greater than a threshold activity of Fe ions and lower than a threshold of activity of Ni, otherwise Fe will be in an inactive high-coordination state.

Graphene in Water is Hardly Ever Neutral.

Graphene in water is electrically charged in most conditions. The level of charge can be large enough to stabilize single (or few) layer graphene colloidal dispersions in water, without the need of using any other additive. In this work, potentiometric titration, isothermal titration calorimetry, electrokinetic measurements, Density Functional Theory calculations, Raman Spectroscopy, and direct force measurements using Atomic Force Microscopy to investigate this charge and explore its origin are combined. The body of data collected suggests that this charge is a consequence of the interaction between water ions (hydroxide and hydronium) and graphene, and can be conveniently tuned (in magnitude and sign) by changing the pH of water.

An evaluation of pyrite as a component of respirable coal dust

Over the past two decades, the rise in coal worker’s pneumoconiosis has prompted research into the effects of respirable coal dust components. This study explores how coal-pyrites produce hydroxyl radicals (•OH), a reactive oxygen species closely associated with particle toxicity, and assesses the ability of safe chemical additives to reduce •OH production at various pH levels. Promising candidates were evaluated in various solutions, including tap and process waters and simulated lung fluid. We employed electrokinetic measurements, infrared and X-ray photoelectron spectroscopies, and ab initio atomistic simulations to analyze particle surfaces. The study also looked at how surface aging affects •OH production. Our results show that •OH generation of the pyrite varies and is catalyzed by elements like silicon, aluminum, and iron in pyrite. Carboxymethyl cellulose was effective in reducing •OH production by targeting surface sulfide and silicon sites and affecting surface hydration and charge. Atmospheric aging was found to increase •OH production, especially in the pyrite with high iron and silicon and low calcium contents, relative to other samples. This highlights the role of the pyrite surface properties and chemical composition, and the solution pH and composition in •OH generation by coal-pyrites.

Aging effect on surface chemistry and sorption properties of atmospheric pressure plasma treated lignocellulosic jute fibers

Jute fibers are characterized by a heterogeneous chemical composition (cellulose and non-cellulosic components) and a complex layered structure with a hydrophobic surface outer layer responsible for their low wettability. In this work, after the removal of water-soluble components, raw jute fibers were subjected to atmospheric pressure dielectric barrier discharge (DBD) under different conditions (at 150 or 300 Hz) to tailor jute fiber surface structure and wettability. The research was focused on the aging effect during natural aging in a standard atmosphere investigated up to three weeks after DBD treatment. Alterations in the surface morphology of DBD-treated jute fibers were investigated by FE-SEM and AFM, while ATR-FTIR, XPS, and electrokinetic measurements were used to assess the changes in the jute fiber surface chemistry. Sorption properties were monitored through wetting time and capillary rise measurements. The sorption properties of DBD-treated jute fibers were improved (about 100 times lower wetting time and 15 % higher capillary rise height in comparison to untreated) due to the changes in surface chemistry (decreased lignin and hemicellulose content in parallel with cellulose oxidation) and morphology (about 4.6 times higher average roughness). The electrokinetic and sorption properties measurement confirmed the significance of aging effects in lignocellulosic fibers' functionalization using plasma.

Spectroscopic studies under properties of chlorpromazine conjugated to gold nanoparticles

Scientific studies have demonstrated that conjugates of anticancer drugs with metal nanoparticles (MeNPs) lead to a more effective deactivation of tumor cells compared to free drugs. Similarly, it has been established that conjugates of antibiotics with MeNPs exhibit higher biocidal activity against bacteria than their unbound counterparts. However, limited information is available regarding conjugates formed from drugs other than anticancer and antibiotics. Therefore, our research aims to develop synthesis methods for conjugates of chlorpromazine (CPZ), a neuroleptic, with gold nanoparticles (AuNPs). CPZ-AuNP conjugates were prepared through a ligand exchange reaction conducted on the surface of quasi-spherical, negatively charged citrate-stabilized TC-AuNPs with an average size of 55 ± 5 nm. UV–vis spectroscopy was employed to determine the stability range of the conjugates under controlled conditions of pH and ionic strength. Based on electrokinetic measurements, it was observed that the zeta potential of CPZ-AuNP conjugates strongly depends on the amount of CPZ adsorbed on the TC-AuNP surface. Additionally, the conjugates exhibited an isoelectric point at pH 8.8. Surface-enhanced Raman spectroscopy (SERS) and surface-enhanced infrared absorption spectroscopy (SEIRA) were employed to elucidate the adsorption structure of CPZ on TC-AuNPs. The interpretation of the spectra was conducted based on the Raman and FTIR spectra of CPZ, along with calculations performed using Density Functional Theory (DFT). The results indicated that CPZ primarily interacts with the TC-AuNP surface through the angularly oriented phenothiazine ring and the propylene bridge. Furthermore, it was demonstrated that the C-N-C fragment is perpendicular to the surface of the TC-AuNP with which it interacts. The findings from this analysis suggest the potential for further research on the use of these conjugates in biomedical applications.

ВЗАИМОДЕЙСТВИЕ ЛИПОПОЛИСАХАРИД-СВЯЗЫВАЮЩИХ БЕЛКОВ С РАЗЛИЧНЫМИ ФОРМАМИ ЛИПОПОЛИСАХАРИДОВ

Lipopolysaccharide-binding proteins from two common jellyfish species Aurellia aurita and Ropelema asamushi were isolated and purified, and the interaction of lipopolysaccharides (LPS) of various structural types with LBP was studied. By inhibiting the interaction, it was found that both proteins specifically bind to the lipid and core fragments of the LPS molecule. There are two types of binding sites in LBP with Kd = 3,28 × 10-6 M and Kd = 0,13 × 10-6 M (for the protein from A. aurita) and Kd = 3,66 × 10-6 M and Kd = 0,27 × 10-6 M (for protein from R. asamushi). It has been shown by dynamic light scattering that the binding of LBP to R-LPS leads to the dissociation of LPS micelles. The sizes of LPS aggregates decrease from 200 nm to 25–30 nm in the composition of LPS–LSB complexes. The data of electrokinetic measurements indicate the neutralization of the negative charge of Rd-LPS (-42,2 mV) in the LPS-LSB-R. asamushi complex up to -4,4 mV. S-LPS micelles from E. coli do not disaggregate upon binding to LBP, which is apparently due to the shielding of lipid A by O-specific chains in the S-LPS molecule. The binding of LPS to LBP may affect their endotoxic properties.

Poly(Allylamine Hydrochloride) and ZnO Nanohybrid Coating for the Development of Hydrophobic, Antibacterial, and Biocompatible Textiles.

In healthcare facilities, infections caused by Staphylococcus aureus (S. aureus) from textile materials are a cause for concern, and nanomaterials are one of the solutions; however, their impact on safety and biocompatibility with the human body must not be neglected. This study aimed to develop a novel multilayer coating with poly(allylamine hydrochloride) (PAH) and immobilized ZnO nanoparticles (ZnO NPs) to make efficient antibacterial and biocompatible cotton, polyester, and nylon textiles. For this purpose, the coated textiles were characterized with profilometry, contact angles, and electrokinetic analyzer measurements. The ZnO NPs on the textiles were analyzed by scanning electron microscopy and inductively coupled plasma mass spectrometry. The antibacterial tests were conducted with S. aureus and biocompatibility with immortalized human keratinocyte cells. The results demonstrated successful PAH/ZnO coating formation on the textiles, demonstrating weak hydrophobic properties. Furthermore, PAH multilayers caused complete ZnO NP immobilization on the coated textiles. All coated textiles showed strong growth inhibition (2-3-log reduction) in planktonic and adhered S. aureus cells. The bacterial viability was reduced by more than 99%. Cotton, due to its better ZnO NP adherence, demonstrated a slightly higher antibacterial performance than polyester and nylon. The coating procedure enables the binding of ZnO NPs in an amount (<30 µg cm-2) that, after complete dissolution, is significantly below the concentration causing cytotoxicity (10 µg mL-1).

Characterizing piezoelectric materials under mechanical stress in liquid media: An electrokinetic approach

Piezoelectric materials are an integral part of the modern world, as they find wide-ranging applications in various advanced domains such as telecommunications, automotive, electronics, and aerospace. Recently, these materials gained interest also for applications in liquid environments across diverse fields, including biomedical engineering, purification systems, electrocatalysis, fluid characterizations and micro/nano electromechanical systems (MEMS/NEMS). Despite their growing importance, many questions remain unanswered regarding their characterization and the evaluation of their performance in liquid media. It is critical to understand how these materials interact with surrounding ionic species under mechanical stress application. To address these questions, a novel experimental setup has been designed to characterize piezoelectric materials through electrokinetic measurements in a liquid environment. A polarized piezoelectric sample (lead zirconate titanate) is subjected to a mechanical stress, which is known to influence the piezoelectric surface charge state. This change in surface charge state can be monitored through measurement of the streaming potential. The results indicate that there is a strong correlation between the applied mechanical stress and the electrokinetic response of the piezoelectric sample. When the sample is subjected to a dynamic stress variation, its electrokinetic response closely follows the profile of the applied stress. In addition, the stress applied to the piezoelectric sample directly impacts the flow cell’s resistance. A non-piezoelectric material (alumina) is also subjected to similar stress conditions. Both electrokinetics and resistance of the flow cell remain almost unchanged for the non-piezoelectric alumina sample during the stress application. Finite element modeling is employed to model variation of surface charge on the piezoelectric sample due to stress application. The piezoelectric model is then coupled with electrokinetic and resistance models to explore the effect of stress on the electrical responses of the system. The modeling results exhibit high degree of consistency with the experimental observations.

Electrokinetic index: A new metric for advanced characterization of membranes with various geometries

Electrokinetic measurements to determine the electrical properties (zeta potential) of membrane surfaces have become increasingly popular in the toolbox of characterization techniques. However, it has been established in the literature that parasitic phenomena such as electrokinetic leakage can hamper data interpretation, leading to not only quantitative but also qualitative errors in membrane zeta potential determination. To date, the only method for highlighting and accounting for electrokinetic leakage is limited to flat-sheet membranes. In this letter, we propose an alternative method that is much less time-consuming and applicable to all membrane geometries. This method is based on the determination of the electrokinetic index, which we define as the ratio of the apparent zeta potentials determined from single measurements of the streaming current and streaming potential coefficients. We show that variation in the electrokinetic index reflects modifications occurring within the membrane matrix (in addition to surface properties alteration). The chemical degradation of polyethersulfone (PES)-based flat-sheet and hollow-fiber membranes is used as a proof of concept, but the proposed approach is readily transposable to other problems of practical interest, such as e.g. membrane fouling. This work also paves the way for the development of a new type of electrokinetic sensors for on-line monitoring of membrane operations.

Application of Potentiometric and Electrophoretic Measurements to Evaluate the Reversibility of Adsorption of Divalent Ions from a Solution on Titanium Dioxide

The adsorption of divalent ions on metal oxides is controlled by the pH of a solution. It is commonly assumed that this is a reversible process for pH changes. However, there are reports that the sorption of ions on oxides may not be reversible. To verify this, we used potentiometric titration, ion-selective electrodes (ISEs), and electrokinetic measurements to examine the reversibility of the adsorption of hydrogen ions and three metal ions (Ca2+, Cu2+, and Fe2+) on TiO2. The ferrous ion was used as a reference because its adsorption is entirely irreversible. The surface charge determined by potentiometric titration and the adsorption edges measured using ISE indicate that the adsorption of copper ions is reversible with changes in pH. In the case of calcium ions, the results suggest a certain degree of irreversibility. There are apparent differences in the electrokinetic potential data obtained during titration with base and acid, which suggests that the adsorption is irreversible. We have explained this contradiction by considering the complex and dynamic nature of electrophoretic mobility. In our opinion, potentiometric titration may be the simplest and most reliable method for assessing the reversibility of multivalent ion adsorption.

A COMPARATIVE STUDY OF ALUMINUM OXIDE NANOPARTICLES SYNTHESIZED IN PLASMA DISCHARGE UNDER ULTRASONIC CAVITATION AND BY LASER ABLATION FOR CREATION OF COMPOSITE MATERIALS

In this work, aluminum oxide nanoparticles were fabricated by two physical methods: laser ablation in liquid medium and plasma discharge under the action of intensive ultrasonic cavitation. Dynamic light scattering, scanning electron microscopy, and electrokinetic potential measurements were employed to comparatively examine the nanoparticles obtained by both methods. It was found that the synthesized particles had spherical shapes with a size range of about 50-70 nm and relatively narrow particle size distributions and were stable to aggregation and sedimentation. The electrokinetic potential values of the pure particles and the effects of the presence of water-soluble polymer polyethylene glycol were used to examine the surface properties of the nanoparticles. This study demonstrates the effect of ultrasonic action on particle surface activity.

Biophysical insights into sugar-dependent medium acidification promoting YfaL protein-mediated Escherichia coli self-aggregation, biofilm formation and acid stress resistance.

The ability of bacteria to interact with their environment is crucial to form aggregates and biofilms, and develop a collective stress resistance behavior. Despite its environmental and medical importance, bacterial aggregation is poorly understood and mediated by few known adhesion structures. Here, we identified a new role for a surface-exposed Escherichia coli protein, YfaL, which can self-recognize and induce bacterial autoaggregation. This process occurs only under acidic conditions generated during E. coli growth in the presence of fermentable sugars. These findings were supported by electrokinetic and atomic force spectroscopy measurements, which revealed changes in the electrostatic, hydrophobic, and structural properties of YfaL-decorated cell surface upon sugar consumption. Furthermore, YfaL-mediated autoaggregation promotes biofilm formation and enhances E. coli resistance to acid stress. The prevalence and conservation of YfaL in environmental and clinical E. coli suggest strong evolutionary selection for its function inside or outside the host. Overall, our results emphasize the importance of environmental parameters such as low pH as physicochemical cues influencing bacterial adhesion and aggregation, affecting E. coli and potentially other bacteria's resistance to environmental stress.

New insight into the temperature effect on adsorption of cationic guar gum on halloysite – properties of the obtain systems

The manuscript presents the new insight into temperature effect on the adsorption and adsorption kinetics of cationic guar gum (CGG) on the halloysite surface (NH). The polymer/clay mineral hybrid materials and stability of the CGG/NH suspensions were analyzed using the following methods: UV-Vis, FT-IR, XRD, SEM-EDX, nitrogen adsorption/desorption, CHN and electrokinetic potential measurements. According to the results the increase of temperature increases both the adsorption of CGG on NH and stability of the CGG/NH suspensions. Thus CGG can effectively stabilize the NH suspensions at higher temperatures. The textural properties of the obtained hybrid materials were also strongly influenced by temperature. It was also observed that the CGG adsorption on NH is spontaneous, endothermic and thermodynamically privileged (ΔGo15 C=-12.90kJ/mol; ΔGo25 C=-14.03kJ/mol; ΔGo35 C=-16.34kJ/mol; ΔHo15 C-30 C=37.15kJ/mol; ΔSo15 C-35 C=0.17kJ/mol). The mechanism of this process can be regarded as a physisorption. The adsorption kinetics was adjusted to the multi-exponential equation. The presented results have a great application potential in wastewater or water treatment processes.

Effect of pH on the Poly(acrylic acid)/Poly(vinyl alcohol)/Lysozyme Complexes Formation.

The interactions between poly(acrylic acid) (PAA), poly(vinyl alcohol) (PVA), and lysozyme (Lys) in an aqueous environment at pHs of 2, 4, and 7.4 were discussed considering the experimental data obtained by turbidimetry, electrokinetic and rheological measurements, and FTIR analysis. It was found that the increase in PAA amount reduces the coacervation zone by shifting the critical pHcr1to higher values while the critical pHcr2 remains unchanged. The coacervation zone extended from 3.1-4.2 to 2.9-4.7 increasing the Lys concentration from 0.2% to 0.5%. The zeta potential measurements showed that the PAA-PVA-Lys mixture in water is the most stable in the pH range of 4.5-8. Zero shear viscosity exhibited deviations from additivity at both investigated pHs, and a maximum value corresponding to a maximum hydrodynamic volume was revealed at PAA weight fractions of 0.4 and 0.5 for pHs of 4 and 7.4, respectively. The binding affinity to Lys of PAA, established by molecular dynamics simulation, was slightly higher than that of PVA. The more stable complex was PAA-Lys formed in a very acidic environment; for that, a binding affinity of -7.1 kcal/mol was determined.

Electrokinetic and Microstructural Peculiarities of the Portland Cement Hydration with Microadditives

AbstractThe results of given studies included a comparison of changes in temperature, redox potential, OH‐ions concentration and pH values in the Portland cement‐water‐additive system depending on the hydration time and features of hydration processes in the microstructure of the cement stone. The studied additives were selected taking into account the prospects for their use in the complex modifiers compositions for cement‐containing building materials. The results of electrokinetic measurements are presented and regularities and features of the influence of each studied additives on the processes of hydration structure and phase formation in Portland cement paste in the early stages of hardening are determined. The microstructure and fracture surfaces of cement stone samples formed during cement paste hardening with the optimal content of additives and features of hydration processes of cement stone were studied. The features of the mutual arrangement of individual phases in crystalline hydrate aggregates of cement stone, as well as the nature of the porosity of its microstructure, were investigated.

Advanced electrokinetic characterization of layer-by-layer assembled polyelectrolyte membranes: Consideration and use of the electrokinetic leakage phenomenon

The sensitivity of zeta potential to the sign of the surface charge of membranes makes it an interesting parameter for the characterization of layer-by-layer (Lbl) modified polyelectrolytes membranes. However, during tangential electrokinetic measurements, a non-negligible parasitic phenomenon referred to as “electrokinetic leakage” may occur. If not taken into account, this phenomenon can lead to dramatic quantitative and qualitative errors, especially when it comes to characterize the surface charge of layer-by-layer assembled polyelectrolyte membranes. In this work, we show that it can lead to substantial errors when interpreting experimental data, including misinterpreting the sign of the membrane surface charge density. An advanced protocol based on the measurement of the streaming current by varying the spacing between the two samples needed for the measurements allows to (i) correct the raw data for the electrokinetic leakage phenomenon and thus to correctly and accurately determine the zeta potential of the membrane surface and (ii) to detect whether polyelectrolytes are deposited only on the membrane surface or whether they can also penetrate into the membrane pores. The approach followed and the conclusions drawn in this study can be straightforwardly applied to any kind of membrane functionalization.

Leveraging Commercial Microfluidic Chips for Zeta Potential Characterization

Bacteria zeta potential, ζ, is one of the key parameters for the deposition of bacteria on an electrode, also called electrophoretic deposition (EPD) and depends on the strain, suspension composition and pH. Measuring directly with a zetasizer is challenging due to the non-spherical shape of bacteria and the need for a lower conductivity medium which could affect the value of ζ. Electrokinetic measurements are usually performed with microchannels in PDMS [1] or in PMMA [2], both of which require expensive tools for the fabrication of either the mold or the microchannel itself. Reducing the cost and time needed to perform such measurements would enable the broader use of this technique. We anticipate solving this challenge with commercially available microfluidic chips as will be outlined in this study.Under an electric field E in a microchannel, the electrokinetic velocity of particles in a fluid is linked to two phenomena: electrophoresis (EP) due to the zeta potential of the particle and electroosmosis (EO) due to the zeta potential of the channel wall. PMMA microchannels (Microfluidic ChipShop) with 200 µl reservoirs together with a voltage sequencer (Labsmith) controlled with LabVIEW were used to characterize the velocity of 1 µm and 2 µm polystyrene beads with different surface functionalizations (nonfunctionalized polystryrene (PS), Sulfate-modified (SU-modified), Carboxylate-modified (CO-modified) and Amine-modified (AM-modified) from Invitrogen and Magsphere suspended in 10 mM HEPES (pH 7) by applying different voltages between the inlet and outlet platinum electrodes for 90 s. Recorded time-lapse fluorescent image sequences were analyzed with ImageJ and TrackMate. Electrokinetic velocities obtained by Particle Tracking Velocimetry (PTV) at different voltages were fitted with a linear fit with a high coefficient of determination allowing the extraction of the different particle zeta potentials, which are in good agreement with the control measurements performed with a Zetasizer Ultra (Malvern Panalytical) [3]. Further, this methodology was used to characterize a prevalent strain of E. coli, yielding values in agreement with the literature.The use of commercially available microfluidic chips in electrokinetic characterization could alleviate the need for microfabrication and allow the wider adoption of this characterization method. These measurements are ultimately critical to better understand the role of the zeta potential in EPD of microbes for an array of applications.[1] S. Antunez-Vela, et al., Anal Chem, 2020[2] Q. Wang et al., Science Advances, 2019[3] J. Cottet, et al. In preparation

Antibacterial Activity of PVA Hydrogels Embedding Oxide Nanostructures Sensitized by Noble Metals and Ruthenium Dye.

Nanostructured oxides (SiO2, TiO2) were synthesized using the sol-gel method and modified with noble metal nanoparticles (Pt, Au) and ruthenium dye to enhance light harvesting and promote the photogeneration of reactive oxygen species, namely singlet oxygen (1O2) and hydroxyl radical (•OH). The resulting nanostructures were embedded in a transparent polyvinyl alcohol (PVA) hydrogel. Morphological and structural characterization of the bare and modified oxides was performed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), UV-Vis spectroscopy, and X-ray photoelectron spectroscopy (XPS). Additionally, electrokinetic potential measurements were conducted. Crystallinity data and elemental analysis of the investigated systems were obtained through X-ray diffraction and X-ray fluorescence analyses, while the chemical state of the elements was determined using XPS. The engineered materials, both as simple powders and embedded in the hydrogel, were evaluated for their ability to generate reactive oxygen species (ROS) under visible and simulated solar light irradiation to establish a correlation with their antibacterial activity against Staphylococcus aureus. The generation of singlet oxygen (1O2) by the samples under visible light exposure can be of significant importance for their potential use in biomedical applications.

Investigating the low salinity effect in a sandstone reservoir through electro-kinetic potential analysis

This study employs electro-kinetic potential measurements to predict the low salinity effect in a sandstone reservoir. Through comprehensive investigations utilizing Zeta potential, interfacial tension, FTIR spectroscopy, and contact angle measurements, valuable insights were obtained. Positive zeta potentials for Ethanoic-dodecane oil (+9.34) and Crude oil (+14.31), along with decreasing zeta potential values with decreasing NaCl and CaCl2 concentrations, indicated core aging and the adsorption of organic compounds. Wettability alteration and reduced contact angles further confirmed aging-induced changes. Negative Oil/Brine Zeta potentials and trends in interfacial tension supported the presence of the low salinity effect. This study enhances our understanding of low salinity effects in sandstone reservoirs by characterizing electro-kinetic potentials, wettability alterations, and interfacial tensions. It highlights the potential of electro-kinetic potential measurements as a predictive tool for evaluating the low salinity effect, enabling a more comprehensive assessment of its impact on reservoir performance.