Ions In Solution Research Articles

Physical, chemical and biological properties of MTA Angelus and novel AGM MTA: an in vitro analysis

IntroductionMineral trioxide aggregate (MTA) is a calcium silicate-based cement that has changed conventional dental therapeutic approaches. This study aimed to evaluate physical, chemical and biological properties of novel AGM MTA, in comparison with MTA Angelus.MethodsThe samples were prepared according to the manufacturer’s instructions. The initial and final setting times were measured via a Gillmore needle following the ISO 6876:2012 standard. The radiopacity of the materials was evaluated against an aluminium step wedge on the basis of the ISO 6876 and 13,116 standards. The pH changes were measured at intervals of 3, 6, 24, 72, 96 and 144 h postimmersion in Hank’s solution and calcium ion release was analysed after 168 h of immersion via inductively coupled plasma optical emission spectroscopy (ICP‒OES). Moreover, the cytotoxicity was assessed through the MTT assay on human dental pulp stem cells (hDPSCs) after 24 and 72 h of exposure to the set/fresh status of various dilutions of MTA extracts, following the ISO 10993-12 standard.ResultsNo significant difference was found between the initial setting times of the two materials (Angelus: 11.0 ± 1.0 min, AGM: 10.3 ± 1.5 min); however, MTA Angelus demonstrated a significantly shorter final setting time. Both materials met the minimum radiopacity requirements according to the ISO 6876 standard, with MTA Angelus exhibiting greater radiopacity than AGM MTA. Both materials created an alkaline environment without presenting any differences in each time point and AGM MTA released significantly greater amounts of calcium ions. In the cytotoxicity assessment, while the diluted extracts of both materials did not elicit any cytotoxic effects, the nondiluted samples, after 72 h of exposure, as well as the 30-min set AGM MTA after 24 h of exposure, were shown to be cytotoxic.ConclusionsIn conclusion, MTA Angelus presented a faster setting time and lower cytotoxicity, while AGM MTA demonstrated greater calcium ion release. However, both materials presented clinically acceptable properties and AGM MTA could be a potential alternative to MTA Angelus. However, further clinical studies are required to confirm its application.

Development of detection system for lead ions in mixture solutions using UV-Vis measurements with peptide immobilized microbeads

Environmental pollution caused by heavy metals are problems worldwide. In particular, pollution and poisoning by lead ions (Pb2+) continue to be common and serious problems. Hence, there is a need for a widely usable method to easily detect Pb2+ from solutions containing organic materials from environmental water such as seas, ponds, etc. Here, we established a system to easily detect Pb2+ from such mixture solutions using Pb2+ binding peptide immobilized beads (peptidyl beads) and ultraviolet (UV) absorption measurements. This method could detect Pb2+ at low concentrations equivalent to inductively coupled plasmon-atomic emission spectroscopy (ICP-AES). Using the detected values to create a calibration curve, it was found that there was a positive correlation between the concentration of Pb2+ and absorbance, which also made it possible to quantify sub-µM Pb2+ in the solutions. Furthermore, Pb2+ was detected and quantified under mixed conditions of environmental water such as seas, rivers, and ponds. This method is expected to become a versatile and easy-to-use Pb2+ detection method for end-users worldwide.

Multilayered Manufacturing Method for Microfluidic Systems Using Low-Cost, Resin-Based Three-Dimensional Printing

This work presents a multilamination method for fabricating microfluidic devices or analytical microsystems using commercial 3D printers and photocurable resins as primary components. The developed method was validated by fabricating devices for the colorimetric measurement of copper ions in aqueous solutions, achieving results comparable to traditional cyclic olefin copolymer (COC) systems. The microfluidic platforms demonstrated stability and functionality over a twelve-week testing period. Channels with minimum dimensions of 0.4 mm × 0.4 mm were fabricated, and the feasibility of using resin modules for optical applications was demonstrated. This study highlights the potential of combining 3D printing with multilamination procedures as a versatile alternative, offering flexibility through the selection of a variety of available resins and commercial printers, as well as the ease of design development. This method offers significant reductions in cost, time, and manufacturing complexity by eliminating the need for equipment such as CNC machines, presses, and ovens, which are typically required in other multilamination technologies like LTCC and COC.

Highly sensitive detection of mercury ions in aqueous solutions by laser-induced fluorescence spectroscopy.

Laser-induced fluorescence spectroscopy was used to detect mercury ions in aqueous solutions, in which CH-95 resin was used to chelate the ions to transform the liquid samples into solid ones. The experimental results showed that the fluorescence emission of the chelated solid-state samples excited by a low-power semiconductor laser at the wavelength of 447 nm was significantly enhanced due to the chelating reaction. The fluorescence intensity was proportional to the concentration of mercury ions with a linear correlation coefficient of R2 = 0.994, and the limit of detection was 0.117 ng/L, which was about 10,000 times lower than the permissible level of 1 µg/L for Hg(II) in drinking water. The method greatly improved the sensitivity for the detection of Hg in aqueous solutions.

Nanoplastic in aqueous environments: The role of chemo-electric properties for nanoplastic-mineral interaction.

Due to increasing plastic production, the continuous release of primary and secondary nanoplastic particles (NPs, <1μm) has become an emerging contaminant in terrestrial environments. The fate and transport of NPs in subsurface environments remain poorly understood, largely due to the complex interplay of mineralogical, chemical, biological, and morphological heterogeneity. This study examines interactions between abundant subsurface minerals and NPs under controlled water chemistry (1mM KCl, pH5.5). These conditions minimize potential chemical effects from ions in solution, isolating the impact of mineral complexity. Surface-modified polystyrene nanoparticles (-COOH and -NH2 functional groups) are proxies for degradation products and organic associations found in environmental plastics. Experimental results are compared with theoretical predictions using DLVO (Derjaguin-Landau-Verwey-Overbeek) double-layer force models. Despite all studied minerals maintaining negative surface charges across varying pH, electrostatic double-layer (EDL) interactions played a minor role in NP attachment. Instead, mechanisms such as specific ion-binding interactions (mediated by trace metal ions), bridging via divalent ions, and hydrogen bonding were more significant. Evidence suggests that kinetic effects for most mineral-NP combinations persist beyond 24h. This study highlights the critical role of biogeochemical and mineralogical composition in controlling NP attachment and release in subsurface environments, with implications for their transport and fate in aquifers.

Modified biochar with nanoscale zero-valent zinc, sodium citrate, and carboxymethyl cellulose as effective adsorbents for the removal of cadmium ions in aqueous solutions

Modified biochar with nanoscale zero-valent zinc, sodium citrate, and carboxymethyl cellulose as effective adsorbents for the removal of cadmium ions in aqueous solutions

Highly Green Fluorescent Carbon Dots from Gallic Acid: A Turn-On Sensor toward Pb2+ Ions.

Carbon dots (CDs) are emerging novel fluorescent sensing nanomaterials owing to their tunable optical properties, biocompatibility, and eco-friendliness. Herein, we report a facile one-pot hydrothermal route for the synthesis of highly green fluorescent CDs using gallic acid (GA) as a single carbon source in N,N-dimethylformamide (DMF) solvent, which serves as a nitrogen source and reaction medium. The optical properties of the synthesized GA-DMF CDs were systematically characterized by using UV-vis and photoluminescence spectroscopy, revealing strong green fluorescence. Further, to gain insights into their size and structural, elemental, and chemical composition, Fourier transform infrared, dynamic light scattering, high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction, and X-ray photoelectron spectroscopy characterization techniques were performed. HR-TEM analysis confirmed the formation of uniformly spherical GA-DMF CDs with an average particle size of 16 ± 6.1 nm. Notably, the GA-DMF CDs exhibited a highly selective and turn-on fluorescent response to Pb2+ ions in aqueous solutions, which was attributed to a chelation-enhanced fluorescence mechanism. The detection limit for Pb2+ ions was determined to be as low as 7.15 × 10-7 M, with a broad linear detection range of 30-130 μM, underscoring their sensitivity and practical application in water quality monitoring. This study introduces a novel, sustainable approach for synthesizing nitrogen-doped CDs with outstanding optical properties and highlights their unprecedented selectivity toward Pb2+ ions, advancing the development of efficient and eco-friendly sensing platforms for heavy metal detection.

Two-in-one strategy to enhance the stability of Ti3C2Tx in transition metal ion solutions.

Although MXenes have attracted significant attention across diverse fields, they exhibit a pronounced susceptibility to oxidation in aqueous environments, with oxidation significantly accelerated in the presence of transition metal ions (TMI) such as Fe3+ and Cu2+. This limitation impedes the synthesis of transition metal compounds/MXene-based composites and their potential for functional applications. In this study, we elucidate the mechanism of accelerated oxidation of Ti3C2Tx is that Fe3+ promotes the electron loss in Ti3C2Tx, thus leading to an increased production of hydroxyl radicals (OH) to oxidize Ti3C2Tx. Furthermore, a rational two-in-one strategy is provided with adding electron-rich ethylenediaminetetraacetic acid disodium zinc salt (ZnNa2EDTA) to enhance the stability of Ti3C2Tx by defect filling and electron donation. Consequently, the production of OH is significantly reduced and thus Ti3C2Tx remains well-preserved in the presence of Fe3+, which has also effectively enhanced the oxidation stability of Ti3C2Tx in the presence of Cu2+. This work is expected to pave a new pathway for targeted applications with coexisting Ti3C2Tx and TMI.

Facile Synthesis of Functional Mesoporous Organosilica Nanospheres and Adsorption Properties Towards Pb(II) Ions.

We successfully synthesize monodisperse sulfhydryl-modified mesoporous organosilica nanospheres (MONs-SH) via one-step hydrolytic condensation, where cetyltrimethylammonium chloride and dodecyl sulfobetaine are employed as dual-template agents with (3-mercaptopropyl)triethoxysilane and 1,2-bis(triethoxysilyl)ethane as the precursors and concentrated ammonia as the alkaline catalyst. The prepared MONs-SHs deliver a large specific surface area (729.15 m2 g-1), excellent monodispersity, and homogeneous particle size. The introduction of ethanol into the reaction systems could expand the particle size of the synthesized MONs-SH materials from 18 to 182 nm. Moreover, the successful modification of -SH groups endowed MONs-SHs with an excellent adsorption capacity (297.12 mg g-1) for Pb2+ ions in aqueous solution through ion exchange and complexation function. In addition, the established isotherm model and kinetic analyses reveal that the adsorption of Pb2+ ions on MONs-SHs follows the secondary reaction kinetic models, where both physisorption and chemisorption contribute to the adsorption of Pb2+ ions. The favorable recyclability of MONs-SHs is demonstrated with the maintained adsorption efficiency of 85.35% after six cycles. The results suggest that the synthesized MONs-SHs exhibit considerable application prospects for effectively eliminating Pb2+ ions from aqueous solutions.

Effect of the Electrolyte on the Oxygen Reduction Reaction with PCN-224(Co).

Electrocatalysis in metal-organic frameworks is an interplay between the diffusion of charges, the intrinsic catalytic rate, and the mass-transport of reactants through the pores. Here a systematic study is carried out to investigate the role of the electrolyte nature and concentration on the oxygen reduction reaction (ORR) with the PCN-224(Co) MOF in aqueous electrolyte. It was found that the ORR activity is slightly influenced by the nature of the ions in solution, providing that the ionic strength is high enough to minimize the resistivity during the measurement. The ORR activity was found to be 1.3-1.5 times lower in lithium acetate compared to sodium acetate, while the ORR activity in cesium acetate was 1.3-1.6 times higher compared to the activity in sodium acetate. Moreover, there was no dependency found of the ORR catalysis on the size of the anion, buffer concentration, or oxygen concentration. These findings suggest that ORR catalysis in PCN-224(Co) is limited by the intrinsic ORR rate at the active site rather than charge transport through the porous structure or substrate transport in the pores. Therefore, optimization of ORR catalysis with this MOF might be achieved by the optimization of the electronics at the cobalt active site.

Exploring and analyzing the causes of color in the earth

Color is an essential element of human visual perception, which exists in all aspects of our daily lives and plays a key role in scientific research and technological applications. Color is produced by various mechanisms, including absorption and reflection of chemical pigments, complex formation of transition metal ions, and micro- and nanostructural modulation of structural colors. This paper aims to comprehensively explore the scientific principles of color generation and its applications in different fields. The article first describes how transition metal ions exhibit colors by forming complexes and explains in detail the coordination process of copper ions in an aqueous solution and its resulting d-orbital splitting, which in turn absorbs light of specific wavelengths and exhibits complementary colors. Secondly, the article explores the mechanism of color expression of natural pigments in plants, significantly how pigment molecules containing conjugated double bonds, such as -carotene, can absorb specific wavelengths of light and exhibit vivid colors through electron delocalization and energy level jumps. Finally, the article illustrates the principles of structural color and its potential for industrial applications, including using micro- and nanostructures, such as photonic crystals, to modulate the scattering and absorption of light, thus enabling dynamic changes in color and environmental protection. The in-depth exploration of the mechanism of color generation enhances our understanding of the basic principles of color science. It provides theoretical support for technological innovation and practical applications in related fields.

Nano-Fibrillated Bacterial Cellulose Nanofiber Surface Modification with EDTA for the Effective Removal of Heavy Metal Ions in Aqueous Solutions.

Nano-fibrillated bacterial cellulose (NFBC) has very long fibers (>17 μm) with diameters of approximately 20 nm. Hence, they have a very high aspect ratio and surface area. The high specific surface area of NFBC can potentially be utilized as an adsorbent. However, NFBC has no functional groups that can bind metal ions, limiting its potential applications. In this study, the hydroxyl groups on the surface of NFBC were chemically modified with EDTA monoanhydride to convert NFBC into a metal adsorbent. The fiber morphology and crystal structures of the modified NFBC were almost identical to those of the unmodified NFBC, suggesting that the surface hydroxyl groups of NFBC were well-conjugated with the EDTA groups. Surface-modified NFBC preferentially adsorbed transition metals in aqueous solutions, such as Cu(II), Hg(II), Pb(II), and Cd(II), but hardly adsorbed Mg(II) and Cr(VI). The adsorption of heavy metal ions can be explained by the pseudo-second-order kinetics of the chemisorption process and the Langmuir isotherm model. Furthermore, the EDTA-modified NFBC is a renewable and recyclable adsorbent. The results of this study indicate that surface-modified NFBC can be utilized as a biosorbent for heavy metal removal in chemical, food, pharmaceutical, and other industrial fields.

Preparation, characterization of &lt;i&gt;Telfairia occidentalis&lt;/i&gt; stem extract-silver nanocomposite and application in remediation of lead (ⅱ) ions from oilfield produced water

Every production day in Nigeria, and in other oil producing countries, millions of barrels of produced water is generated. Being very toxic, remediation of the produced water before discharge into environment or re-use is very essential. An eco-friendly and cost effective approach is hereby reported for remediative pre-treatment of produced water (PW) obtained from Nigerian oilfield. In this approach, Telfairia occidentalis stem extract-silver nanoparticles (TOSE-AgNPs) were synthesized, characterized and applied as bio-based adsorbent for treating the PW in situ. The nanoparticles were of average size 42.8 nm ± 5.3 nm, spherical to round shaped and mainly composed of nitrogen and oxygen as major atoms on the surface. Owing to the effect of addition of TOSE-AgNPs, the initially high levels (mg/L) of Total Dissolved Solids (TDS), Biological Oxygen Demand (BOD) and TSS of 607, 3.78 and 48.4 in the PW were reduced to 381, 1.22 and 19.6, respectively, whereas DO and COD improved from 161 and 48.4 to 276 and 19.6 respectively, most of which fell within WHO and US-EPA safe limits. Particularly, the added TOSE-AgNPs efficiently removed Pb (II) ions from the PW at temperatures between 25 ℃ to 50 ℃. Removal of TOSE-AgNPs occurred through the adsorption mechanism and was dependent contact time, temperature and dose of TOSE-AgNPs added. Optimal remediation was achieved with 0.5 g/L TOSE-AgNPs at 30 ℃ after 5 h contact time. Adsorption of Pb (Ⅱ) ions on TOSE-AgNPs was spontaneous and physical in nature with remediation efficiency of over 82% of the Pb (Ⅱ) ions in solution. Instead of discarding the stem of Telfairia occidentalis, it can be extracted and prepared into a new material and applied in the oilfield as reported here for the first time.

Poly-(2-aminothiophenol) Functionalized Petroleum Coke for Fast Simultaneous Sequestration of Cd(II) and Pb(II) Ions from Industrial Effluents

Background: Nowadays, the challenge between clean water production and promoting an eco-friendly sorbent for the simultaneous fast and efficient removal of heavy metal ions is a hot topic and has attracted much attention. Objective: The objective of this study was to fabricate a novel material (PATP@PET) by incorporating poly-(2-amino thiophenol; PATP) into the matrix of Saudi Arabian petroleum coke (PET) for simultaneous fast and efficient removal of heavy metal ions. objective: The fabrication of a novel material (PATP@PET) by incorporating poly-(2-amino thiophenol; PATP) into the matrix of Saudi Arabian petroleum coke (PET) for simultaneous fast and efficient removal of heavy metal ions Method: The FTIR, EDX, SEM, and XRD techniques assessed the chemical structure and surface morphology of the thio-functionalized petcoke. The effects of medium pH, mass dosage of sorbent, metal ion concentration, and coexisting ions were investigated and optimized using batch sorption. Result: The excellent sorption capacity of PATP@PET sorbent towards the divalent lead and cadmium ions (98.44% and 312.5 mg.g-1 for Pb(II) and 90.15% and 217.4 mg.g-1 for Cd(II)) was realized by strong complex formation with the sulfur atoms of green petcoke and the thiol groups of poly-2- aminothiophenol moieties. The adsorption equilibrium data was best fitted to the pseudo-secondorder kinetic model and Langmuir adsorption isotherm. The reusability performance was tested for 10 cycles, and the simultaneous removal of Pb(II) and Cd(II) ions from industrial effluents was accomplished in 30 minutes with 100% removal efficiency at pH 6-7. Conclusion: PTAP-PET also demonstrated amazing performance for Cd(II) and Pb(II) removal in industrial wastewater samples. Subsequently, PTAP-PET contributes to developing fast, efficient, low-cost water remediation solutions for heavy metal ions that can potentially be translated into industrial- scale applications.

On the rate constant for reactions between ions in solution: a simple unification of the Born and Debye-Hückel models.

The rate of reaction between ions in solution depends on solvent properties like permittivity and ionic strength. The influence of a solution's ionic strength is described by the Brønsted-Bjerrum equation. We show how this equation can be derived directly from transition-state theory without introducing the concept of activity coefficients. The electrostatic contribution to the activation energy is extracted from the electric potential of an ion, according to the Debye-Hückel theory. The derivation also gives a contribution to the activation energy, which corresponds to the Born model for ions represented as spherical charged particles. That is, for a given solvent permittivity, the dependence on ion radii is also displayed. This approach provides enhanced physical insights into the description of reactions where ions are participating.

A study on the effects of dispersion coefficient on groundwater pollutant transport simulation.

A comprehensive scientific analysis of temporal and spatial fluctuations of pollutants during the migration of groundwater is essential for precisely predicting their dispersion patterns and promoting rational regional development planning. In this research paper, a field radial dispersion test was conducted in decentralized drinking water sources downstream of the Fu Tuan River basin in Rizhao City, Shandong Province, China (FRSC). Chloride ion (Cl-) solution was utilized as a tracer for the experiment. The longitudinal dispersion coefficient ( ) was determined by standard curve matching and using straight-line graphical methods. Additionally, the impact of on pollutant transport was investigated by creating the MT3DMS solute transport model with the help of GMS 10.4 software. The results indicate that the of the submerged aquifer varies depending on the distance from the source well in the main runoff direction. At distances of 10 and 15m, the values of were observed to be 0.56m and 0.88m, respectively. Moreover, when these observed values of are used as simulation parameters in solute transport modeling on the same space-time scale, the hydrodynamic dispersion effect exhibited by the well is found to be weaker than the actual hydrodynamic dispersion effect.

Modelling ligand exchange in metal complexes with machine learning potentials.

Metal ions are irreplaceable in many areas of chemistry, including (bio)catalysis, self-assembly and charge transfer processes. Yet, modelling their structural and dynamic properties in diverse chemical environments remains challenging for both force fields and ab initio methods. Here, we introduce a strategy to train machine learning potentials (MLPs) using MACE, an equivariant message-passing neural network, for metal-ligand complexes in explicit solvents. We explore the structure and ligand exchange dynamics of Mg2+ in water and Pd2+ in acetonitrile as two illustrative model systems. The trained potentials accurately reproduce equilibrium structures of the complexes in solution, including different coordination numbers and geometries. Furthermore, the MLPs can model structural changes between metal ions and ligands in the first coordination shell, and reproduce the free energy barriers for the corresponding ligand exchange. The strategy presented here provides a computationally efficient approach to model metal ions in solution, paving the way for modelling larger and more diverse metal complexes relevant to biomolecules and supramolecular assemblies.

Comparison of Column Adsorption Processes by Downflow and Upflow for Removal of Cupric (Cu2+) Ion Solutions Using Non Activated and Activated Charcoal from Rambutan (Nephelium lappaceum L.) Stems

Comparison of Column Adsorption Processes by Downflow and Upflow for Removal of Cupric (Cu2+) Ion Solutions Using Non Activated and Activated Charcoal from Rambutan (Nephelium lappaceum L.) Stems

Antibiofilm and Anticancer Activity of Multi-Walled Carbon Nanotubes Fabricated with Hot-Melt Extruded Astaxanthin-Mediated Synthesized Silver Nanoparticles.

Multi-walled carbon nanotubes (MWCNTs) were used as carriers for silver nanoparticles (AgNPs). In this process, MWCNTs were coated with mesoporous silica (MWCNT-Silica) for uniform and regular loading of AgNPs on the MWCNTs. In addition, astaxanthin (AST) extract was used as a reducing agent for silver ions to enhance the antioxidant, antibiofilm, and anticancer activities of AgNPs. In this process, AST was extracted from Haematococcus pluvialis (H. pluvialis) and processed by hot melt extrusion (HME) to enhance the AST content of H. pluvialis. AST has strong antioxidative properties, which leads to anticancer activity. In addition, AgNPs are well known for their strong antibacterial properties. The antibiofilm and anticancer effects were studied comprehensively by loading the AST AgNPs onto MWCNT-Silica. AgNPs-loaded MWCNT-silica (MWCNT-Ag) was prepared through the binding reaction of TSD and silanol groups and the aggregation interaction of Ag and TSD. To enhance the antioxidant, antibiofilm, and anticancer activities of AgNPs, HME-treated H. pluvialis extract (HME-AST) was used as a reducing solution of silver ions. The increased AST content of HME-AST was confirmed by high-performance liquid chromatography (HPLC) analysis, and the total phenol and flavonoid content analysis confirmed that HME enhanced the active components of H. pluvialis. The antibiofilm activity of MWCNT-AST was investigated by biofilm inhibition and destruction test, SEM, and CLSM analysis, and the anticancer activity was investigated by WST assay, fluorescent staining analysis, and flow cytometry analysis. MWCNT-AST showed higher antioxidant activity and antibiofilm activity than MWCNT-Ag against E. coli, S. aureus, and methicillin-resistant S. aureus (MRSA). MWCNT-AST showed higher anticancer activity against breast cancer cells (MDA-MB-231) than MWCNT-Ag, and lower toxicity in normal cells HaCaT and NIH3T3. MWCNT-AST exhibits higher antioxidant, antibiofilm, and anticancer activities than MWCNT-Ag, and exhibits lower toxicity to normal cells.

OFF–ON stirring potentiometry with solvent polymeric membrane ion-selective electrodes: A theory-guided approach to foreign ions

The response of ion-selective electrodes (ISEs) towards a foreign ion is comprehensively investigated as a function of the nature and concentration of the ion, and of the mass transport conditions in the outer solution. Notably, a striking transient potential drift is evidenced by sheer activation of stirring in an initially quiescent solution of the foreign ion, both in the absence and presence of the primary ion. This phenomenon is rationalized in terms of the ion exchange at the outer membrane side coupled to the mass transfer of ions. This has been modelled through a novel theoretical treatment of the corresponding time-dependent mass transport problem, leading to simple closed-form expressions for the membrane potential and for the interfacial ion concentrations in the unstirring and stirring periods. The theoretical predictions are corroborated experimentally by monitoring the potential of a nitrate ISE exposed to ions of very different affinity towards the membrane (tetraphenylborate, perchlorate and chloride) before and after switching on the agitation of the solution. Such OFF-ON stirring program enables the study of foreign ions, even simultaneously with the determination of the primary species by the joint analysis of the potentials before and after the activation of the stirring.