Trivalent Salts Research Articles

Protein Crystallization in the Presence of a Metastable Liquid–Liquid Phase Separation

We study protein crystallization in solutions of human serum albumin (HSA) exhibiting a metastable liquid–liquid phase separation (LLPS) in the presence of trivalent salts. Specifically, we focus o...

Predicting the size of salt-containing aqueous Na-AOT reverse micellar water-in-oil microemulsions with consideration for specific ion effects

HypothesisReverse micellar solutions are thermodynamically stable systems in which surfactant molecules surround water droplets within a continuous organic phase. Among their many applications, they can be used for the synthesis of nanoparticles of controlled agglomeration. Here, we consider the role specific ion effects play in reverse micelle size reduction. ExperimentsDynamic light scattering measurements and the Gouy-Chapman electrical double layer model were combined to study water/AOT/isooctane reverse micellar systems (wo = 10). Linear relationships between the solvodynamic diameter (D) of reverse micelles containing various concentrations of FeSO4, Mg(NO3)2, CuCl2, Al(NO3)3, Fe(NO3)3, Y(NO3)3, NaBH4, ZrOCl2, and NH4OH, and their calculated Debye screening lengths, κ−1, were observed with decreasing D and increasing salt concentration (c). FindingsBy comparing the linear fits for reverse micelle size as a function of c−1/2, we determined the size can be described as a function of the Debye screening length, cation valency (z), and specific anion hydrated radius (ran), where D = 3.1z κ−1 + bi, and bi is linearly related to ran. Our model accurately predicts reverse micelle sizes with the addition of monovalent, divalent, and trivalent salts for which the primary hydrolyzed cation species has a charge that is equal to the cation valency.

Colloidal stability of cellulose nanocrystals in aqueous solutions containing monovalent, divalent, and trivalent inorganic salts

Aggregation kinetics and surface charging properties of rod-like sulfated cellulose nanocrystals (CNCs) have been investigated in aqueous suspensions containing monovalent, divalent, or trivalent inorganic salts. Electrophoresis and time-resolved dynamic light scattering (DLS) were used to characterize the surface charge and colloidal stability of the CNCs, respectively. The surface charge and aggregation kinetics of the sulfated CNCs were found to be independent of solution pH (pH range 2–10). For the monovalent salts (CsCl, KCl, NaCl, and LiCl), the critical coagulation concentration (CCC) followed the order of Cs+ < K+ < Na+ < Li+, which follows the direct Hofmeister series, indicating specific interaction of the cations with the CNCs surface. The experimental aggregation kinetics of CNCs were in very good agreement with predictions based on the classic Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. A Hamaker constant of 3.6 × 10−20 J for the CNCs in aqueous medium was derived, for the first time, from the colloidal stability curves with monovalent salts. This value is consistent with a previous value determined by direct force measurements for cellulose surfaces in aqueous solutions. For the divalent salts (MgCl2, CaCl2, and BaCl2), the CCC values followed the order Mg2+ > Ca2+ > Ba2+, which is in the reverse order of the counterion ionic size. For the trivalent salts (LaCl3, AlCl3, and FeCl3), the CNCs suspension was destabilized much more effectively. The observed complex stability curves with AlCl3 and FeCl3 are attributed to charge neutralization and charge reversal imparted by the adsorption of aluminum and ferric hydrolysis species on the CNC surface. The significant charge reversal induced by the ferric hydrolysis species led to the restabilization of suspensions. Our results on the colloidal stability of CNCs are of central importance to the nanotechnology and materials science communities working on various applications of CNCs.

Surface Morphologies of Planar Ring Polyelectrolyte Brushes Induced by Trivalent Salts

The morphology of a polymer brush is of great importance in determining surface properties, such as lubrication. In light of this, we systematically study the morphologies of ring polyelectrolyte b...

Synthesis of calcium‐layered double hydroxide based nanohybrid for controlled release of an anti‐inflammatory drug

AbstractThe study proposed an approach for synthesis‐Layered Double Hydroxide nanoparticles by the coprecipitation method in solution containing two divalent and trivalent metal salts, calcium, and aluminum. The synthesized calcium‐layered Double Hydroxide (CAL) used for intercalating an anti‐inflammatory drug with the purpose of obtaining controlling release rate, protecting of drug from decomposition and raising the poor aqueous solubility of drug. Mefenamic acid (ME) as anti inflammatory drug was intercalated into CAL from ion‐exchange route to preparation CAL/ME nanohybrids. An increase in the space of interlayer of the (002) plane from 8.06 Å in pristine CAL to 34.51 Å in the nanohybrid confirmed successful intercalation of ME anion into CAL framework, which was ordered in a bilayer fashion with the carboxylate functional groups in the interlayer gallery of CAL. The x‐ray diffraction and FTIR study indicated that the ME was successfully intercalated into interlayer space of CAL. The chemical composition of samples was evaluated by ICP‐OES and energy‐dispersive spectrum analysis. TG analysis confirmed that the thermal stability of intercalated ME in the form of nanohybrid was enhanced. dynamic light scattering and field emission scanning electron microscopy were determined the size of CAL particles. Finally, in vitro drug release experiments of nanohybrid at a PH of 4.8 and 7.4 showed sustained release profiles with ME anions as an anti‐inflammatory model drug.

Magnetite–Activated Carbon Nanocomposites: Synthesis, Sorption Properties, and Bioavailability

Two approaches were considered in searching for an efficient procedure for preparing magnetic nanocomposites based on activated carbon and magnetite nanoparticles by chemical precipitation: preliminary synthesis of magnetite nanoparticles by chemical precipitation from solutions of bi- and trivalent iron salts, followed by introduction of the nanoparticles into the activated carbon matrix, and synthesis of magnetite nanoparticles in the activated carbon matrix. A comparative analysis of the content of magnetite nanoparticles and functional characteristics (textural parameters, sorption capacity, saturation magnetization, and coercive force of the nanocomposites) was made. The ex situ synthesis proved to be the best procedure for preparing nanocomposite sorbents based on activated carbon and magnetite nanoparticles by chemical precipitation, as judged from the yield and functional characteristics of the target product. In biological testing, the maximal harmless (inactive) concentration of the magnetic nanocomposite in the test system with microalgae appeared to be higher by an order of magnitude than that in the test system with ciliates.

A detailed study on the synergistic corrosion inhibition impact of the Quercetin molecules and trivalent europium salt on mild steel; electrochemical/surface studies, DFT modeling, and MC/MD computer simulation

For the first time, Quercetin (3,3′,4′5,7-Pentahydroxyflavone) and Eu ions were used in 3.5 wt% NaCl solution for mild steel (MS) corrosion mitigation. Tafel outcomes demonstrated the effectiveness of Quercetin:Eu compounds in the corrosion inhibition of the steel samples via mixed-type mechanism. The EIS and Tafel results showed about 98% and 90% efficiencies during 48 h of MS exposure to 3.5 wt% NaCl solution containing 200:600 ppm Quercetin:Eu, respectively. Also, EIS measurements displayed that in the presence of 200:600 ppm Quercetin:Eu inhibitor, the total resistance reached 69,751 Ω·cm2 after 48 h of immersion. The Tafel curves indicated that the icorr diminished to 0.71 μA·cm−2 after 48 h of MS subjection to the electrolyte. The FE-SEM micrographs proved that after introducing 200:600 ppm Quercetin:Eu complex, a compact and almost smooth inhibitive layer covered the MS surface. Based on the AFM test results, the average roughness reached 96 nm after 200:600 ppm Quercetin:Eu complexes adsorption on the MS surface. Detection of 17 wt% Eu element on the protected metal surface clarified the successful Quercetin:Eu complex adsorption. The theoretical (i.e., DFT and MC/MD) results further ensured the Quercetin:Eu complexes adsorption on the metallic surface.

Translocation of a Polyelectrolyte through a Nanopore in the Presence of Trivalent Counterions: A Comparison with the Cases in Monovalent and Divalent Salt Solutions.

A polyelectrolyte threading through a nanopore in a trivalent salt solution is investigated by means of molecular dynamics simulations under a reflective wall boundary. By varying the chain length N and the strength E of the driving electric field applied inside the pore, the translocation time is carefully calculated to get rid of the bouncing effect because of the boundary. The results are analyzed under the scaling form ⟨τ⟩ ∼ NαE–δ and four driving force regimes; namely, the unbiased, the weakly driven, the strongly driven trumpet, and the strongly driven isoflux regime, are distinguished. The exponents are calculated in each regime and compared with the cases in the monovalent and divalent salt solutions. Owing to strong condensation of counter ions, the changes of the exponents in the force regimes are found to be nontrivial. A large increase in translocation time can be, however, achieved as the driving field is weak. The variations of the chain size, the ion condensation, and the effective chain charge show that the process is proceeded in a quasi-equilibrium way in the unbiased regime and deviated to exhibit strong nonequilibrium characteristics as E increases. Several astonishing scaling behaviors of the waiting time function, the translocation velocity, and the diffusion properties are discovered in the study. The results provide deep insights into the phenomena of polyelectrolyte translocation in various salt solutions at different driving forces.

Removal efficiency of methylene blue from aqueous medium using biochar derived from Phragmites karka, a highly invasive wetland weed

The potential of biochar derived from pyrolysis of Phragmites karka—an invasive wetland plant biomass—for the adsorption of methylene blue (MB) dye from the aqueous medium was studied. The physico-chemical properties of the resultant char were studied using SEM-EDS, FTIR, TGA, ICP-MS, and Brunauer–Emmett–Teller (BET). Batch adsorption experiments were carried out to investigate the effect of different operational parameters on MB adsorption. Experimental data were analyzed by adsorption isotherm and kinetic models. Study results revealed that dye adsorption increased with biochar dosage, contact time, initial dye concentration, and solution pH. Contrary to the monovalent NaCl salt system, the presence and increase of the FeCl trivalent salt system increased the adsorption process. The process of adsorption followed the pseudo-second-order kinetic model. The equilibrium data was found well fitted by the Langmuir model, with a maximum dye adsorption capacity of 438.2 mg g−1. Interactions including surface precipitation, physical and electrostatic attraction, cation exchange, intermolecular hydrogen boding and n-π interactions are proposed to be the combined adsorption mechanisms behind the MB adsorption. The reusability of the spent adsorbent was comparatively high even after several adsorption–desorption cycles. The better dye adsorption capacity could be attributed to the innate properties of biochar as revealed through the characterization study. The study result indicated that the preparation of biochar from P. karka plant biomass and its further utilization as an effective adsorbent is a viable strategy towards wastewater treatment and wetland weed management.

Nanoplatelet interactions in the presence of multivalent ions: The effect of overcharging and stability

HypothesisThe stability of colloidal dispersions in the presence of multivalent ions depends strongly on the electrostatic interactions between the suspended particles. Of particular interest are colloidal particles having dimensions in the nanometric range and with an anisotropic shape due to its high surface area per unit mass, for example clay, which has the key characteristic of a negatively charged surface, surrounded by an oppositely charged rim. ExperimentsIn this study, we investigate the interactions in nanoplatelet dispersions for the model system of Laponite® clay with addition of mono- and multivalent salt. Molecular dynamics simulations with enhanced umbrella sampling have been utilised in combination with the experimental techniques of zeta-potential measurements, dynamic light scattering, and transmission electron microscopy. FindingsIt was observed that tactoid formation and tactoidal dissolution due to overcharging occur upon the addition of trivalent salt. The overcharging effect was captured from calculated potential of mean force and confirmed from the zeta-potential, which changed sign from negative to positive when increasing the stoichiometric charge-ratio between the positive salt ions and the clay. Consequently, the gained information could provide useful physical insight of nanoplatelet interactions in the presence of multivalent ions.

Hydrophobicity-Tuned Periodic Mesoporous Organo-Silica Nanoparticles for Photodynamic Therapy.

Since their invention, periodic mesoporous organosilicas (PMOs), an innovative class of materials based on organic as well as inorganic hybrid nanocomposites, have gathered enormous interest owing to their advantageous physicochemical attributes over the pristine mesoporous silica nanoparticles (MSNs). To further increase the interactions with the therapeutic guest species and subsequent compatibility as well as the physicochemical properties of PMOs, we demonstrate the post-hydroxylation of benzene-bridged PMO-based nanoparticles for photodynamic therapy (PDT). Initially, the hydrophobic benzene group in the PMO framework is modified through electrophilic substitution-assisted hydroxylation mediated by Fenton as well as Fenton-like reactions utilizing divalent and trivalent metal salts, respectively. These post-grafted PMOs with tuned hydrophobicity resulted in improved biocompatibility as well as drug loading efficiency through governing the interactions in host–guest chemistry by changing the physicochemical properties of the PMO frameworks. Furthermore, the photosensitizer, protoporphyrin IX (PpIX) molecules, encapsulated in the PMO frameworks showed a significant PDT effect in colon carcinoma (HT-29 cell line) and Gram-negative bacterial strain, Escherichia coli (E. coli). Furthermore, the light-induced cytotoxic properties in vitro are confirmed by various tests, including lactate dehydrogenase (LDH) assay for cell membrane damage and caspase assay for apoptosis determination. Indeed, the delivered PpIX molecules from PMOs generated deadly singlet oxygen species intracellularly under visible light irradiation, resulting in cell death through concomitantly triggered apoptotic caspases. Together, our findings demonstrate that this post-modified PMO design is highly advantageous and can be used as an effective PDT platform.

Specificity and affinity of multivalent ions adsorption to kaolinite surface

Understanding the specific adsorption mechanism(s) of multivalent ions onto clay mineral surfaces in a high salinity environment is theoretically and practically important in many areas including mineral separation and tailings disposals. This paper focuses on both qualitative and quantitative studies to describe the effect of multivalent-ion specificity on the kaolinite surface. The measured zeta potential of kaolinite particles treated with di- and trivalent chloride salts (up to 100 mM) was used to quantify the surface binding constant of metal ions to the kaolinite surface by the surface complexation model. The model results show that ion-pairing and hydration energy are two main factors that control the adsorption of di- and trivalent ions onto the kaolinite surface. The established affinity series of adsorption to kaolinite surface, Al3+ > Fe2+ > Fe3+ > Mg2+ > Ca2+, matches the hydration energy and calculated ion-pairing concentration. Further XPS analysis and molecular dynamics simulation revealed that Al3+ and Fe2+ could directly form inner-sphere complexes due to their high electronegativity and weak pairing ability with Cl− ion, while Mg2+ and Ca2+ ions adsorb onto the outer-sphere of kaolinite surface because of their strong pairing ability with Cl− ion and low electronegativity. However, higher electronegativity with large negative hydration energy leads to weaker affinity to kaolinite surface, as in the case of Fe3+. A linear relationship between surface binding constant and first hydrolysis constant of metal and kaolinite surface was also established. The outcomes of this work shed a new insight into the multivalent ion adsorption to kaolinite in controlling the selectivity and efficiency of mineral separation and dewatering processes.

In‐vitro DNA binding and antimicrobial studies of trivalent transition metal ion based macrocyclic complexes

AbstractIn the current research work diaminotoluene based tetra‐azamacrocyclic‐14 membered [N4] macrocylic complexes of nitrate, chloride and acetate trivalent transition metals salts of Cr(III) and Fe(III) have been synthesized by taking the route of template methodology. The synthesized complexes were fully characterized by spectroscopic and physico‐analytical techniques like IR, ESI‐MS, ESR, Powder XRD, TGA, UV‐visible, magnetic moment, molar conductance, in addition to the elemental analysis measurements. The monomeric and electrolytic nature of the complexes is elucidated by the help of ESI‐MS and molar conductance values that reveals about the 1:2 electrolytic behaviour. On the basis of above analytical techniques the complexes may be empirically formulated as [MLX]X2 in which L is macrocyclic ligand obtained from the [2+2] condensation reaction of 3,4‐diaminotoluene (DAT) and dibenzoylmethane (DBM). The thermal data provides an indication towards the absence of water molecular and various decomposition steps in the complexes. Further the compounds were screened for their antimicrobial potency against few strains of bacteria and fungus and fair results were found from the above studies. In addition to these DNA binding activity was also performed in order to elucidate the mode of binding the newly synthesised complexes.

Predictions on High-Power Trivalent Metal Pentazolate Salts.

High-energy-density materials (HEDMs) have been intensively studied for their significance in fundamental sciences and practical applications. Here, using the molecular crystal structure search method based on first-principles calculations, we have predicted a series of metastable energetic trivalent metal pentazolate salts MN15 (M= Al, Ga, Sc, and Y). These compounds have high energy densities, with the highest nitrogen content among the studied nitrides so far. Pentazolate N5- molecules stack up face-to-face and form wave-like patterns in the C2221 and Cc symmetries. The strong covalent bonding and very weak noncovalent interactions with nonbonded overlaps coexist in these ionic-like structures. We find MN15 molecular structures are mechanically stable up to high temperature (∼1000 K) and ambient pressure. More importantly, these trivalent metal pentazolate salts have high detonation pressure (∼80 GPa) and velocity (∼12 km/s). Their detonation pressures exceeding that of TNT and HMX make them good candidates for high-brisance green energetic materials.

Preparation and characterization of ceramic nanofiltration membrane prepared from hazardous industrial waste

AbstractKiln rollers, which are widely used in ceramic tiles production, are usually subjected to surface grinding to remove the contaminations. The resulted fine powder is considered useless waste and a hazardous source of environmental pollution particularly as it contains health‐threatening fine free silica. In the present paper, the grind waste from kiln rollers was reused as raw material in the fabrication of nanofiltration ceramic membrane. The samples of produced ceramic membranes were formed into disks by adding 15% (by weight) organic binder solution with 2% concentration, then pressed at 35 MPa, dried and fired at temperatures range from 1100°C to 1300°C for 1 hour soaking time. It was found that the best firing temperature to produce nanofiltration ceramic membrane is 1250°C, where the ceramic membrane provides high removal of turbidity and high monovalent, divalent, and trivalent salts separation percentage.

Estimation of Aspect Ratio of Cellulose Nanocrystals by Viscosity Measurement: Influence of Aspect Ratio Distribution and Ionic Strength.

The influence of the cellulose nanocrystal (CNC) aspect ratio (L/d) distribution and ionic strength of different salts on the L/d estimation by viscosity measurement were investigated. The L/d distribution was controlled by mixing two CNC, with different L/d, which were prepared by acid hydrolysis from wood and bacterial cellulose. The results demonstrated that the L/d distribution did not affect the accuracy of the CNC L/d estimated by viscosity measurements using the Batchelor equation, and the calculated L/d was the number-average L/d. Moreover, monovalent (NaCl), divalent (CaCl2), and trivalent (AlCl3) salts were chosen to study the influence of ionic strength on the CNC L/d estimation by viscosity measurement. It was found that NaCl and CaCl2 could be added to the CNC suspension to screen the electro-viscous effect and estimate the actual physical CNC L/d by viscosity measurement, and the content of NaCl and CaCl2 can be predicted by the Debye–Hückel theory. However, a small amount of AlCl3 induced CNC aggregation and increased intrinsic viscosity and predicted L/d.

Metal Ions Activate the Human Taste Receptor TAS2R7.

Divalent and trivalent salts exhibit a complex taste profile. They are perceived as being astringent/drying, sour, bitter, and metallic. We hypothesized that human bitter-taste receptors may mediate some taste attributes of these salts. Using a cell-based functional assay, we found that TAS2R7 responds to a broad range of divalent and trivalent salts, including zinc, calcium, magnesium, copper, manganese, and aluminum, but not to potassium, suggesting TAS2R7 may act as a metal cation receptor mediating bitterness of divalent and trivalent salts. Molecular modeling and mutagenesis analysis identified 2 residues, H943.37 and E2647.32, in TAS2R7 that appear to be responsible for the interaction of TAS2R7 with metallic ions. Taste receptors are found in both oral and extraoral tissues. The responsiveness of TAS2R7 to various mineral salts suggests it may act as a broad sensor, similar to the calcium-sensing receptor, for biologically relevant metal cations in both oral and extraoral tissues.

The effect of inorganic salt in wastewater on the viscosity of coal water slurry.

The preparation of coal water slurry (CWS) using wastewater, which contains inorganic and organic components, is one method of wastewater utilization. In this study, the effect of inorganic salts on the viscosity of CWS was examined. The results show that monovalent salts (NaCl, KCl) decreased the viscosity of CWS. The viscosity of CWS was not affected by bivalent salts (CaCl2, MgCl2). However, CWS combined with trivalent salt (AlCl3) sharply increased the viscosity. The zeta potential of CWS with inorganic salts increased which can enhance the electric repulsion and beneficial to reduce the viscosity. The content of free water in CWS with trivalent salt decreased, and the freedom of the free water in CWS with trivalent salt decreased which were all bad to the viscosity and the adsorption of the dispersant on the particles. Compared with the surface polarity of the particles without inorganic salts, the surface polarity of the particles with divalent salts was similar to those without inorganic salts. Under the comprehensive influence, divalent salt has little effect on the viscosity of CWS.

Adsorption mechanism of hexavalent chromium onto layered double hydroxides-based adsorbents: A systematic in-depth review.

An attempt has been made in this review to provide some insights into the possible adsorption mechanisms of hexavalent chromium onto layered double hydroxides-based adsorbents by critically examining the past and present literature. Layered double hydroxides (LDH) nanomaterials are typical dual-electronic adsorbents because they exhibit positively charged external surfaces and abundant interlayer anions. A high positive zeta potential value indicates that LDH has a high affinity to Cr(VI) anions in solution through electrostatic attraction. The host interlayer anions (i.e., Cl-, NO3-, SO42-, and CO32-) provide a high anion exchange capacity (53-520 meq/100 g) which is expected to have an excellent exchangeable capacity to Cr(VI) oxyanions in water. Regarding the adsorption-coupled reduction mechanism, when Cr(VI) anions make contact with the electron-donor groups in the LDH, they are partly reduced to Cr(III) cations. The reduced Cr(III) cations are then adsorbed by LDH via numerous interactions, such as isomorphic substitution and complexation. Nonetheless, the adsorption-coupled reduction mechanism is greatly dependent on: (1) the nature of divalent and trivalent salts utilized in LDH preparation, and the types of interlayer anions (i.e., guest intercalated organic anions), and (3) the adsorption experiment conditions. The low Brunauer-Emmett-Teller specific surface area of LDH (1.80-179 m2/g) suggests that pore filling played an insignificant role in Cr(VI) adsorption. The Langmuir maximum adsorption capacity of LDH (Qomax) toward Cr(VI) was significantly affected by the natures of used inorganic salts and synthetic methods of LDH. The Qomax values range from 16.3 mg/g to 726 mg/g. Almost all adsorption processes of Cr(VI) by LDH-based adsorbent occur spontaneously (ΔG° <0) and endothermically (ΔH° >0) and increase the randomness (ΔS° >0) in the system. Thus, LDH has much potential as a promising material that can effectively remove anion pollutants, especially Cr(VI) anions in industrial wastewater.

Relation between Color and Surface Morphology of Electrodeposited Chromium for Decorative Applications

Electrolytes for decorative chromium plating based on trivalent chromium salts are known since several decades. As the use of conventional, hexavalent chromium based plating baths is more and more restricted by governmental regulations, these electrolytes gain ground in electroplating industry. However, compared to hexavalent chromium electrolytes, trivalent chromium electrolytes cannot fully meet the requirements with regard to appearance of the electrodeposited chromium, and there is little knowledge about the influencing factors on the shade of color. In this paper, chromium plated from a solution of chromium(III) sulfate was characterized by colorimetry, SEM and AFM and compared to a sample plated from a chromic acid electrolyte in order to reveal correlations between visual appearance and surface morphology. A relation between an increase of grain size and a color shift from blueish to yellowish was observed. Unlike in hexavalent based systems, grain size, roughness and color depend on layer thickness as the grain growth mechanism appears to be different. A model based on the theory of light scattering at rough surfaces is provided that links roughness and reflection behavior of the chromium surface.