Aqueous Solution System Research Articles

Designing Antifreeze Electrolytes with Colloid‐Like Structures for High‐Rate Performance in Aqueous Zinc‐Ion Batteries

AbstractOptimizing the electrolyte configuration is an effective strategy to enhance the cycle life of aqueous zinc‐ion batteries (AZIBs). A critical challenge in electrolyte development involves improving the antifreeze characteristics without compromising high‐rate performance for the AZIBs. This study selects the polymer polysaccharide konjac glucomannan (KGM) as an electrolyte additive, aiming to utilize its naturally formed stable colloidal system in aqueous solution, which exhibits superior rheological properties. This system can effectively balance the antifreeze performance of the electrolyte with the performance requirements of the cell under high‐rate charge–discharge conditions, thereby enhancing the overall performance of the cell. Therefore, the zinc anode exhibits stable cycling for 1250 h at 25 °C under conditions of 7 mA cm−2 and 3.5 mAh cm−2. At ‐10 °C, stable cycling is sustained for over 800 h at 7 mA cm−2 and 1 mAh cm−2. In full cells, the cell delivers a discharge capacity of 77.9 mAh g−1 after 7500 cycles at a current density of 15 A g−1 at 25 °C. Even at ‐10 °C, the cell delivers a discharge capacity of 102.7 mAh g−1 after 660 cycles at 3 A g−1. KGM offers a cost‐effective, environmentally friendly solution to improve AZIBs' reliability and antifreeze capabilities.

A self-assembled fluorescent nanoprobe recognized by FA1 site for specifically selecting HSA: Its applications in hemin detection, cell imaging and fluorescent tracing drug delivery.

As naturally essential biomacromolecule, HSA has become diagnostic indicators for various diseases and universal carriers for anticancer drug delivery, therefore, fluorescence detection and labeling for HSA possess significant application value in the biomedical field. In this paper, hydrazide Schiff base fluorescent probe NDQC was designed and synthesized, which self-assembled into nanoparticles in aqueous solution system and demonstrated excellent selectivity and sensitivity towards HSA. Through displacement assay and molecular docking simulation, the binding of NDQC with HSA in FA1 site was demonstrated, thereby no obvious fluorescence signal presented for homologous protein BSA due to their structural differences in binding site. Non-toxic probe NDQC is suitable for the fluorescence imaging of HSA in cells, and colocalization fluorescence images showed that NDQC-HSA could illuminate mitochondria. Based on the pH sensitivity of fluorescence emission for NDQC-HSA, discrimination of cancer cells and normal cells could be achieved. For practical applications, NDQC-HSA can be employed to measure the content of hemin. More importantly, NDQC could fluorescently label HSA and therefore NDQC-HSA complex act as the carrier for loading cisplatin. The present findings demonstrate that the probe NDQC has potential in exploring HSA at cellular levels and hold great promise in application of tracking drug-loading nanoparticles.

Effect of Deposition Conditions on Properties of Aluminum Deposit Obtained from Aluminum Chloride-Acetamide Melts

Introduction Since the standard electrode potential of aluminum (Al) (-1.67 V vs. SHE) is lower than that of hydrogen, Al electrodeposition from aqueous solution systems is difficult. Therefore, Al electrodeposition using nonaqueous solution systems, such as molten salts, ionic liquids, organic solvents, and deep eutectic solvents, have been widely studied. However, the synthesis cost of nonaqueous solution systems is not small. Therefore, Al electrodeposition using deep eutectic solvents has been studied, including from the viewpoint of low cost. For example, in the AlCl3-urea melt, the effect of mixing with EMIC and current density on the surface morphology of Al deposits has been reported.1 The AlCl3-acetamide (AcA) melt has been reported to produce better Al deposits than the ionic liquid AlCl3-EMIC melts in dry air. 2 However, in the Al deposition using the AlCl3-AcA melts, the effect of deposition conditions such as deposition potential on the properties of the deposit has not been clarified.3 Therefore, in this study, we obtained basic knowledge of Al electrodeposition using the AlCl3-AcA melt and then examined the effect of the deposition conditions such as deposition potential and operating temperature on the properties of the Al deposit. Experimental The electrolyte was prepared by mixing anhydrous AlCl3 and AcA in a molar ratio of 1.5 : 1. A three-electrode cell was fabricated using a glassy carbon (GC) electrode or a Cu plate as the working electrodes, an Al plate as the counter electrode, and an Al wire dipped in AlCl3-EMIC (molar ratio 2 : 1) melts as the reference electrode. Cyclic voltammetry (CV) was carried out for the electrochemical measurements. A potentiostatic electrodeposition method was performed with stirring at 50-90℃. The observation and crystal structure of the deposit were evaluated by ULV-SEM and XRD, respectively. Results and Discussion In the CVs, the Redox waves were observed in the AlCl3-AcA melt at the operating temperature of 50 °C and a scanning rate of 10 mV s−1. When the potentiostatic electrodeposition method was performed at the operating temperature of 50-90 °C and the set potential of −0.5 V (vs. Al / Al (Ⅲ)), the current efficiencies were about 90%.The effect of the electrodeposition conditions on the surface morphology of the Al deposit was investigated. Figure 1 shows the ULV-SEM images of the deposits obtained the Cu plate substrate from the AlCl3-AcA melt at the operating temperature of 50 °C and 90 °C. At the operating temperate of 50 °C, the grain shape was fine-scale, similar to the surface morphology of the deposit in the AlCl3-urea melt.4 In contrast, at the operating temperature of 90 °C, the grain shape changed to fine grains.Next, the effect of the operating temperature on the crystal structure of the Al deposits was investigated. The XRD patterns showed that all the peaks were attributed to Al, yielding a single phase of Al(fcc). In order to now discuss the crystal orientation of the resulting Al deposit, the orientation coefficient (N) was calculated using Wilson’s equation. A value of N greater than 1 indicates the preferential orientation to that plane. The preferential orientation to the {110} plane was observed at the operating temperature of 50 °C, but the preferential orientation to the {110} plane decreased as the bath temperature increased to 90 °C. Although the Al deposits from the AlCl3-based ionic liquids were mostly non-oriented, the surface morphology of the Al deposits obtained from the AcA bath was scale-like and the crystal structure showed preferential orientation.Based on these results, it was revealed that the grain shape and the preferential orientation of the resulting Al deposit obtained from the AlCl3-AcA melt would be correlated and temperature dependent. References T. Tsuda, et al., J. Electrochem. Soc, 169, 092520 (2022).M. Yamagami, et al., J. Electrochem. Soc, 169, 062502 (2022)V. S. Cvetković, et al., Trans. Nonferrous Met. Soc. China, 30, 823 (2020).L. Min, et al., Electrochim. Acta, 180, 811 (2015). Figure 1

Hydrate phase equilibrium of hydrogen with THP, DCM, TBAB+THF and sulfur hexafluoride +TBAB aqueous solution systems

Experimental hydrogen hydrate dissociation data with single thermodynamic additive: tetrahydropyran (THP, with oxygen-containing functional group) or dichloromethane (DCM, with halogen group), and thermodynamic additive mixtures: tetrahydrofuran (THF) + tetrabutylammonium bromide (TBAB) system and sulfur hexafluoride (SF6) +TBAB system were reported with temperature range from 275.33 to 282.98 K and pressure range from 1.65 to 12.63 MPa. Other experimental data were collected from the literature. The compared results showed that the oxygen-containing or halogen functional group can significantly affect the hydrogen bonding between water molecules, which present great promoting effects on hydrogen hydrates formation. Also, the promoting effects of mixture additives on the phase equilibrium of hydrogen hydrates were investigated. The results indicated that the combination of thermodynamic additives showed better promoting effects on hydrate formation compared to the individual ones. And the results obtained in this work would provide useful information to select suitable and effective thermodynamic additives for hydrate-based hydrogen storage technology.

Deciphering the Entropy-Driven Host-Guest Interactions within Single Covalent Organic Frameworks for Trapping of 131I.

By combining dark-field optical microscopy with an in situ thermochemical aqueous solution system, we report a single-particle imaging strategy to investigate the host-guest interactions between covalent organic framework-300 (COF-300) as a representative COF host and a series of linear-chain fatty amines. The thermodynamic parameters, such as dissociation constant, Gibbs free energy changes, enthalpy changes, and entropy changes for the binding events within COF-300 are quantified. Correlation between the hydrophobicity of various amines and other data suggests that the mechanism of the host-guest bindings arises from the entropy-driven noncovalent interactions such as hydrogen bonds and van der Waals forces. These mechanistic insights allow for the rational design and preparation of COF-300-encapsulated n-octylamine with enhanced trapping performance of radioactive 131I-. This study not only provides thermodynamic insights into the host-guest interactions within the COF framework but also establishes a structure-property relationship between fatty amines and energetic magnitude information.

Zinc Chemistries of Hybrid Electrolytes in Zinc Metal Batteries: From Solvent Structure to Interfaces.

Along with the booming research on zinc metal batteries (ZMBs) in recent years, operational issues originated from inferior interfacial reversibility have become inevitable. Presently, single-component electrolytes represented by aqueous solution, "water-in-salt," solid, eutectic, ionic liquids, hydrogel, or organic solvent system are hard to undertake independently the task of guiding the practical application of ZMBs due to their specific limitations. The hybrid electrolytes modulate microscopic interaction mode between Zn2+ and other ions/molecules, integrating vantage of respective electrolyte systems. They even demonstrate original Zn2+ mobility pattern or interfacial chemistries mechanism distinct from single-component electrolytes, providing considerable opportunities for solving electromigration and interfacial problems in ZMBs. Therefore, it is urgent to comprehensively summarize the zinc chemistries principles, characteristics, and applications of various hybrid electrolytes employed in ZMBs. This review begins with elucidating the chemical bonding mode of Zn2+ and interfacial physicochemical theory, and then systematically elaborates the microscopic solvent structure, Zn2+ migration forms, physicochemical properties, and the zinc chemistries mechanisms at the anode/cathode interfaces in each type of hybrid electrolytes. Among of which, the scotoma and amelioration strategies for the current hybrid electrolytes are actively exposited, expecting to provide referenceable insights for further progress of future high-quality ZMBs.

Speciation studies of binary and ternary complexes formed with fe(II) ion 2,6-pyridinedicarboxylic acid and several amino acids

The chemical speciation of ternary systems involving Fe(II), 2,6-pyridinedicarboxylic acid (H2Dipi), and various amino acids (glycine, β-alanine, α-alanine, leucine, methionine, lysine, phenylalanine, threonine, serine, proline, valine, and histidine) was investigated in this work. Potentiometric titrations were conducted for each system in aqueous solution at 25 °C using 1 mol dm−3 NaCl solution as the ionic medium. The resulting data were analyzed using the least-squares program LETAGROP. Additionally, the binary system of Fe(II)-2,6-pyridinedicarboxylic acid in aqueous solution at 25 °C with NaCl 1.0 mol dm−3 as the ionic medium was also examined. Species distribution diagrams were generated, and the relative stability parameter Δlog K was calculated.

An Artificial Light-Harvesting System based on Supramolecular AIEgen Assembly.

Photosynthesis is a complex multi-step process in which light collection is the initial step of photosynthesis and plays an important role in the utilization of solar energy. In order to improve the utilization of sunlight, researchers have developed a variety of artificial light-harvesting systems to simulate photosynthesis in nature. Here, we report a supramolecular artificial light-harvesting system in aqueous solution. Since β-cyclodextrin (β-CD) has a hydrophobic cavity and a hydrophilic outer surface, we adopt β-cyclodextrin (β-CD) as the host molecule and use adamantane as the guest molecule. At the same time, we modified β-CD with the donor molecule naphthalimide and adamantane with the tetraphenylethylene molecule which has aggregation-induced emission (AIE) effects. By using fluorescent molecules with AIE, the self-quenching effect caused by aggregation in aqueous solution can be effectively avoided. Due to the host-guest interaction of β-CD and adamantane, nanoparticles with stable structure and uniform size can be spontaneously assembled in water. Because of the close distance and strong spectral overlap between naphthalimide and tetraphenylethylene, Förster resonance energy transfer (FRET) was realized, and artificial light-harvesting system was successfully constructed in aqueous solution. Therefore, this study provides a new strategy for constructing artificial light-harvesting system, and the artificial light-harvesting system shows broad application prospects in aqueous solutions.

Interface properties and applications in laundry of the BS12-SAS mixed systems

In the BS12/SAS mixed systems, the solution exhibits acidity. BS12 can act as a cationic surfactant to form anionic-cationic complexes with SAS. In this study, the surface properties and application characteristics of the BS12/SAS mixed systems were investigated. The static surface tension, dynamic surface tension, and contact angle of BS12, SAS, and their different mixed molar ratios were measured at 25 °C to evaluate interaction parameters, activity coefficient, molar fraction, and thermodynamic variables of surfactants in the mixed micelles. The results demonstrated that the BS12/SAS mixed systems deviated from the ideal state due to the strong molecular attraction between the two components, resulting in a synergistic effect. The mixed systems exhibited higher surface activity and lower critical micelle concentration. Thermodynamic analysis indicated that the spontaneous micellization of binary mixtures of BS12 and SAS occurred through both enthalpy-driven and entropy-driven processes. The adsorption kinetics data revealed that the mixed systems followed a diffusion-adsorption process. Contact angle measurements demonstrated that BS12/SAS possesses superior ability to reduce surface tension, which facilitated rapid droplet diffusion and efficient wetting of the matrix within a short time period. Furthermore, the aggregation behavior of individual surfactants and the two composite systems in aqueous solutions was analyzed using DLS and TEM to investigate their effects on the wetting, emulsification stability, foaming stability, and decontamination capability of liquid paraffin.

Unveiling the Behavior of Perfluoro (2-Ethoxyethane) Sulfonic Acid Potassium (PESK) in Water/Gas System: Molecular Dynamics Simulation

Molecular dynamics method (MD) was used to study the distribution of potassium perfluoro (2-ethoxyethane) sulfonic acid (PESK) in water/gas systems. When the PESK aqueous solution system reaches equilibrium, the vast majority the fluorocarbon chain is facing toward the gas phase, while the sulfonic acid radical faces toward the water, with a very small quantity of PES− is still in the bulk solution. The weak intermolecular interactions were analyzed by IGMH method, and the interaction energy between PES− and water mainly comes from the h-bonds formed by the oxygen atom in the sulfonic acid group and hydrogen atom in water molecules. K+ are mainly distributed inside the aqueous solution, and there is only van der Waals interaction between K+ and H2O molecules. According to the distribution of ESP analysis of PES−, it is mainly the sulfonic acid groups that are negatively charged.

Metal halide perovskites for solar‐to‐chemical energy conversion in aqueous media

AbstractSolar‐driven energy conversion is a promising technology for a sustainable energy future and environmental remediation, and an efficient catalyst is a key factor. Recently, metal halide perovskites (MHPs) have emerged as promising photocatalysts due to their exceptional photoelectronic properties and low‐cost solution processing, enabling successful applications in H2 evolution, CO2 reduction, organic synthesis, and pollutant degradation. Despite these successes, the practical applications of MHPs are limited by their water instability. In this review, the recently developed strategies driving MHP‐catalyzed reactions in aqueous media are outlined. We first articulate the structures and properties of MHPs, followed by elaborating on the origin of instability in MHPs. Then, we highlight the advances in solar‐driven MHP‐based catalytic systems in aqueous solutions, focusing on developing external protection strategies and intrinsically water‐stable MHP materials. With each approach offering peculiar sets of advantages and challenges, we conclude by outlining potentially promising opportunities and directions for MHP‐based photocatalysis research in aqueous conditions moving forward. We anticipate that this timely review will provide some inspiration for the design of MHP‐based photocatalysts, manifestly stimulating their applications in aqueous environments for solar‐to‐chemical energy conversion.

Ligand-free Cs2PdBr6 perovskite microcrystals with narrow bandgap and high photoelectrochemical performance in aqueous solution

The exploration of efficient lead-free perovskite photoelectric active materials to develop high-performance photoelectrochemical (PEC) systems in aqueous solution is crucial to expand their PEC applications. Herein, we successfully constructed a high-performance PEC platform using ligand-free perovskite Cs2PdBr6 microcrystals (MCs) as the photoactive substance. The Cs2PdBr6 MCs showed narrow bandgap, wide absorption range, high electronic mobility and good stability in aqueous solutions. Particularly, the Cs2PdBr6 MCs exhibited an excellent photoresponse, the photocurrent density could reach as high as 98 μA/cm2 under 10.18 mW/cm2 light irradiation in the absence of other electron acceptors. In addition of the extremely wide range of response wavelength, wide pH range and accelerated interfacial carrier transfer, the Cs2PdBr6 MCs demonstrated the significant potential of photocathode active material for applications in PEC sensors and optoelectronic devices. Therefore, this work indicates that Cs2PdBr6 MCs design is a highly efficient way to solve the intrinsic issues of perovskite material, predicting a promising strategy for high performance PEC application in aqueous ambience.

Pourbaix diagrams for iron-chromium alloys in lithium bromide absorption machines

The influence of lithium bromide concentration on the Pourbaix diagrams for iron-chromium alloys is evaluated in this work, which allows for predicting the corrosion to stainless steels exposed to the aggressive operating conditions of lithium bromide absorption machines (concentrations ranging from: 400–992 g/L). The novelty of this work is found in the development of Pourbaix diagrams for the Fe-Cr-Br–-H2O quaternary system in aqueous solutions with a high concentration of lithium bromide, a topic which has not yet been studied. Results show that the corrosion region at acid pH corresponding to the aqueous species FeBr2(aq), FeBr3(aq), Cr+2, CrOH+2, Cr+3 or CrBr+2 shifts to higher pHs with increasing lithium bromide concentration, which decreases the immunity region of iron and chromium and decreases the passivation region of the solid species FeCr2O4, Fe2O3 and Cr2O3.

The Theoretical Calculation of the Cu Isotope Fractionation Effect in Solution/Hydrothermal Solution Systems.

Copper (Cu) is an important transition metal, and its isotopes have important applications in geology, environmental science, soil science, and other fields. Cu isotope fractionation can occur in many natural processes. However, the mechanism of Cu isotope fractionation in solution/hydrothermal solution systems is not very clear. In this study, the fractionation effects of complexes of Cu(I) and Cu(II) in solution/hydrothermal solution systems were systematically studied by means of an ab initio method based on first principles. In the simulation of an aqueous solution system, the theoretical treatment method used is the "water-droplet" method. The results show that the heavy Cu isotope (65Cu) enrichment capacity of the Cu-bearing complex solutions is greatly affected by the ligand types both for Cu(I) and Cu(II). For Cu(I) complex solutions, the heavy Cu isotope enrichment sequence is [Cu(HS)2]-·(H2O)42 > [Cu(HS)(H2O)]·(H2O)42 ≈ [Cu(HS)(H2S)]·(H2O)42 > [CuCl]·(H2O)42 > [CuCl2]-·(H2O)42 > [CuCl3]2-·(H2O)42. For the aqueous solutions of Cu(II) with an inorganic ligand (such as H2O, OH-, NO3-, SO42- and CN-), the order of heavy Cu isotope enrichment is as follows: [Cu(H2O)6]2+·(H2O)42 > [Cu(NO3)2]·(H2O)42 > [Cu(OH)2]·(H2O)42 > [CuSO4(H2O)3]·(H2O)42 > [CuNO3(H2O)4]+·(H2O)42 > [CuCN]+·(H2O)42. For the Cu(II) complex solutions with a halogen as ligands, the change order of 1000lnβ is [CuCl]+·(H2O)42 > [CuCl2]·(H2O)42 > [CuBr2]·(H2O)42 > [CuCl3]-·(H2O)42. The sequence of 1000lnβ for Cu(II) organic complex aqueous solutions is [Cu(HOC6H4COO)]+·(H2O)42 > [Cu(CH3CH2COO)]+·(H2O)42 > [Cu(COOHCOO)]+·(H2O)42. The calculation also found that for Cu(I) complex aqueous solutions, the difference in Cu isotope fractionation parameters (1000lnβ) between [CuCl2]-·(H2O)42 and [Cu(HS)2]-·(H2O)42 is relatively large. At 100 °C, the 1000lnβ of the two species are 1.14 and 1.55 (‱), respectively. The difference between the two could be reached up to 0.41 (‱). The Cu isotope fractionation parameter obtained with the "water droplet" method is also very different from the results of previous studies, which indicate that the Cu isotope fractionation behavior of the two is similar. At the same time, the exciting discovery is that the enrichment capacity of heavy Cu isotopes is significantly different between Cu(I) complex aqueous solutions and Cu(II) complex aqueous solutions. At 100 °C, the 1000lnβ of 6 Cu(I) complex aqueous solutions and 13 Cu(II) complex aqueous solutions ranged from 0.90 to 1.55 and 2.24 to 3.25(‱), respectively. It also shows that the REDOX reaction has a significant effect on the Cu isotope fractionation, especially in ore-forming fluids. Therefore, the ligand type is a factor that cannot be ignored when considering the mechanism of Cu isotope fractionation in solution/hydrothermal solution systems. Whether the solvation effect of an aqueous solution is considered or not has a great influence on the numerical values of the final Cu isotope fractionation factors. Hence, the solvation effect of an aqueous solution is an essential determinant in the theoretical calculation of the Cu isotope fractionation factors for Cu-bearing complex solutions.

Lead (Pb) Sorption Kinetics by Clay Minerals: Bentonite and Zeolite

Background: Heavy metal pollution chiefly lead (Pb) causes various environmental disequilibrium and health hazards. Immobilization of lead (Pb) usingclay minerals is cost effective for metal remediation due to their higher surface area and negative charges. Methods: This study was taken up to assess the Pb removal potentials of bentonite and zeolite from contaminated water and to study the effect of sorbent dosage, initial Pb2+ concentrations and incubation time intervals on Pb adsorption and desorption was studied. Result: Zeolite was effective in immobilising Pb (78.0%) than bentonite (70.9%) which increased with increasing sorbent dosage and time intervals. The pseudo second-order kinetic model described the Pb adsorption precisely. Chemisorption was the dominant mechanism operating in aqueous solution system, hence, it could be concluded that zeolite can be utilized as an efficient sorbent for wastewater treatment.

In-situ self-assembly growth of controllable gold nanoparticles film

Because of the strong light absorption and/or scattering, nano scaled gold has many favorable optic and electric properties. With the continuous miniaturization of nano photoelectronic devices and nano electromechanical systems, there is an urgent demand for controllable and tailored gold nanoparticles film with excellent performance. Here, a modified HAuCl4-NaOH-CTAB (cetyltrimethylammonium bromide) aqueous solution system was utilized to self-assembly synthesize gold nanofilm on glass substrates. The high concentration NaOH is not only reducing Au3+ to Au0, but facilitating interfacial assembly of gold nanostructure at liquid–solid interface via etching glass surface. Based on this growth kinetic, the gradient, well-designed and in-situ growing gold nanoparticles film can be achieved on any SiO2 contained substrates by controlling the growth time in the reaction system. Furthermore, the in-situ self-assembled gold nanoparticles film can be act as plasmon substrates for surface-enhanced Raman scattering (SERS) or plasmonic enhanced semiconductor lasing, even gold electrodes.

Investigation of morphology and structure of drug-loaded PLA-b-PEO-b-PLA polymeric micelle: A dissipative particle dynamics simulations study.

The dissipative particle dynamics (DPD) simulation was used to study the morphologies and structures of the paclitaxel-loaded PLA-b-PEO-b-PLA polymeric micelle. We focused on the influences of PLA block length, PLA-b-PEO-b-PLA copolymer concentration, paclitaxel drug content on morphologies and structures of the micelle. Our simulations show that: (i) with the PLA block length increase, the self-assemble structure of PLA-b-PEO-b-PLA copolymers with paclitaxel vary between onion-like structure (core-middle layer-shell) to spherical core-shell structure. The PEO shell thins and the size of the PLA core increases. The onionlike structures are comprised of the PEO hydrophilic core, the PLA hydrophobic middle layer, and the PEO hydrophilic shell, the distribution of the paclitaxel drug predominantly occurs within the hydrophobic intermediate layer; (ii) The system forms a spherical core-shell structure when a small amount of the drug is added, and within a certain range, the size of the spherical structure increases as the drug amount increases. When the drug contents (volume fraction) cdrug = 10%, it can be observed that the PLA4-b-PEO19-b-PLA4 spherical structures connect to form rod-shaped structures. With the length of PLA block NPLA = 8, as the paclitaxel drug concentrations cdrug = 4%, PEO has been insufficient to completely encapsulate the PLA and paclitaxel drug beads. To enhance drug loading capacity while maintaining stability of the system in aqueous solution, the optimal composition for loading paclitaxel is PLA4-b-PEO19-b-PLA4; the drug content is not higher than 4%; (iii) The paclitaxel-loaded PLA4-b-PEO19-b-PLA4 micelle undergo the transition from onionlike (core-middle layer-shell) to spherical (core-shell) to rod-shaped and lamellar structure as the PLA4-b-PEO19-b-PLA4 copolymer concentration increases from ccp = 10% to 40%.

Phosphorylated porous phenolic resin for efficient extraction of low-concentration rare earth elements from tailing wastewater

Efficient extraction and recycling of rare earth elements (REEs) from low-concentration complex tailing wastewater is critical to meeting the growing industrial demands and optimizing resource utilization. In this work, three phosphorylated porous phenolic resins (PO-PPRs) were prepared via the phosphorylation of phenolic hydroxyl groups with POCl3, and employed to extract REE3+ from both simulated and practical low-concentration REE3+-containing aqueous solution. The PO-PPRs, characterized by hierarchical pore structures, exhibit high adsorption capacities for both light and heavy REE3+ ions over a broad pH working range from 3.0 to 7.0, along with fast adsorption kinetics (<30 min). And the maximum adsorption capacities of PO-PPRs for Nd3+, Dy3+ and Y3+ were found to be 104.1, 118.0 and 63.9 mg/g, respectively. Furthermore, the introduction of phosphonic groups significantly improves the REE3+ adsorption selectivity against various interfering metal ions such as Na+, K+, Ca2+, Mg2+, and Al3+. For instance, the Nd3+/Al3+ separation factor (S.F.) of 24 exceeded that of most commercial resins and reported materials. In a simulated mixed multi-element aqueous solution system containing Nd3+, Dy3+, Y3+, Al3+, Ca2+, Mg2+, Mn2+, K+ and Na+, PO-PPR-1 extracted 82.5% of total REE3+ while maintaining Al3+ adsorption efficiency of less than 13%. Moreover, the extraction efficiency of total REE3+ for PO-PPR-1 in pretreated practical wastewater from ion-adsorbed ores tailing reached 99.6%. Additionally, PO-PPRs demonstrated easy regeneration and excellent recycling performance after 5 consecutive adsorption–desorption cycles, confirming their promising application potential in low-concentration REEs extraction.

The relevance of the initial conditions in glassy carbon electrode sensing applications: the ferri/ferrocyanide redox reaction model system in aqueous solution

Carbon electrodes, especially the glassy carbon electrodes (GCE) are widely accepted as very versatile sensing platforms. However, correlating the behaviour of the ferri/ferrocyanide redox couple ([Fe(CN)6]3-/4−) with the GCE's surface modification is challenging. The surface modification can be achieved by applying a pre-conditioning electrochemical activation procedure. Hence, we report the investigation performed in order to provide further insights into the electrochemical behaviour of the commonly used redox probe in aqueous solutions. To that aim we took advantage of powerful and complementary electrochemical analytical techniques, like cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Thus, this work highlights the critical role of the GCE initial conditions for optimizing the charge transfer processes and therefore to improve the [Fe(CN)6]3-/4− performance in sensing applications. The best results were obtained in phosphate buffer saline solution with previous electrochemical activation by fast potential cycling between [-0.5 and +1.8] V (vs. Ag|AgCl (KCl sat.)). Finally, one can consider this an eco-friendly and simple procedure to be carried out in the lab, however, its use must be carefully optimized when exploring other systems, as highlighted herein.

The Influence of Initiators, Particle Size and Composition on the Electrokinetic Potential of N-(Isopropyl)acrylamide Derivatives.

The aim of this study was to characterize and compare the zeta potential of particles sensitive to external thermal stimuli. Poly N-(isopropyl) acrylamide (PNIPA) was selected as the thermosensitive polymer with a volume phase transition temperature (VPTT) between 32 and 33 °C. The hydrodynamic diameter (DH) of the nanoparticles was measured by dynamic light scattering. Zeta potential (ZP) measurements were performed with the same instrument used for DH measurements. ZP measurements allow the prediction of the stability of colloidal systems in aqueous solutions. These measurements were combined with a pH study before and after the purification process of the particles. The ZP was measured to determine the electrostatic interactions between the particles, which can lead to particle aggregation and decrease their colloidal stability. The effect of the composition of the synthesized particles on the ZP was assessed. One of the most important factors influencing ZP is pH, especially in aqueous solutions. The initiator did not significantly affect the DH of the particles, but it did significantly affect the ZP. The synthesized particles were subjected to a visible radiation absorption study in the selected temperature range to determine the VPTT.