Solution Temperature Research Articles

Investigating dye adsorption: The role of surface-modified montmorillonite nanoclay in kinetics, isotherms, and thermodynamics

Abstract The study presents a straightforward, eco-friendly method for removing toxic dyes, such as methylene blue (MB) and acid red (AR), from aqueous solutions through solid-phase extraction using adsorption on surface-modified montmorillonite nanoclay. The nanoclay, containing 25–30 wt% methyl dihydroxyethyl hydrogenated tallow ammonium (MM-MDH nanoclay), functions as the environmentally benign adsorbent. The physical properties of MM-MDH nanoclay were characterized utilizing scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and surface area analysis. Optimal conditions for dye removal, including solution pH, nanoclay dosage, contact time, solution temperature, and ionic strength, were systematically investigated. Experimental results demonstrated that MM-MDH nanoclay effectively removed the majority of dyes within 90 min. Isotherm data indicated an adsorption capacity of 34.33 mg/g for AR dye and 20.19 mg/g for MB dye under optimal conditions. The adsorption process was analyzed kinetically and thermodynamically, revealing that the pseudo-second-order kinetic model accurately described the adsorption behavior. Thermodynamic analysis confirmed that the process was spontaneous and exothermic for AR dye and spontaneous and endothermic for MB dye. The effectiveness of MM-MDH nanoclay was further validated by removing dyes from three different real samples, demonstrating high performance in dye removal over four consecutive cycles.

RGD peptide-conjugated polydopamine nanoparticles loaded with doxorubicin for combined chemotherapy and photothermal therapy in thyroid cancer

ObjectiveTo construct polydopamine (PDA)-based nanoparticles (NPs) for combined chemotherapy (CT) and photothermal therapy (PTT) of thyroid tumors by conjugating doxorubicin (DOX) via Schiff base reaction and decorating with RGD peptide.MethodsPDA NPs were synthesized using dopamine hydrochloride (DA) as the raw material and reacted with DOX-PEG-NH2 to obtain PDA-DOX NPs. Subsequently, RGD peptide was coupled with PDA-DOX NPs for modification. Their size, charge, and shape were characterized using DLS and SEM. The assembly of DOX was verified by ultraviolet–visible spectroscopy (UV–Vis), and the release efficiency of DOX under different pH conditions was calculated. The antitumor effect of RGD@PDA-DOX was validated in KTC-1 cells and tumor-bearing nude mice.ResultsThe prepared RGD@PDA-DOX exhibited excellent dispersion, stability, and biocompatibility. PDA-DOX possessed superior photothermal conversion efficiency, capable of rapidly elevating the solution temperature within 5 min. In vitro studies revealed that the inhibitory rate of RGD@PDA-DOX combined with 808 nm laser on KTC-1 cells reached 92% (p < 0.05). In vivo experiments demonstrated that RGD@PDA-DOX exhibits no cytotoxicity. The modification with RGD peptides enables RGD@PDA-DOX to target tumor regions and accumulate over an extended period. Additionally, RGD@PDA-DOX, when combined with an 808 nm laser, significantly inhibits tumor growth.ConclusionRGD@PDA-DOX can effectively accumulate in tumor regions and demonstrates excellent anti-tumor efficacy. It may serve as a feasible approach for the effective treatment of thyroid tumors, providing further evidence and data for clinical translation.

Synthesis of (5Z)-3-Allyl-5-{[5-(4-methoxyphenyl)thiophen-2-yl]methylidene}-2-sulfanylidene-1,3-thiazolidin-4-one in L-Proline-Based Deep Eutectic Solvent

3-N-allylrhodanine was condensed with 5-(4-methoxyphenyl)-thiophene-2-carbaldehyde in an L-proline-based deep eutectic solvent (DES) to obtain the π-conjugated heterocyclic rhodanine compound (5Z)-3-allyl-5-{[5-(4-methoxyphenyl)thiophen-2-yl]methylidene}-2-sulfanylidene-1,3-thiazolidin-4-one (2). Compound 2 was characterized by NMR spectroscopy, and its UV-vis spectrum was compared with that of the related derivative 3-allyl-5-(4-methoxybenzylidene)-2-sulfanylidene-1,3-thiazolidin-4-one (1). Preliminary results revealed that compound 2 is emissive at room temperature in solution.

Flotation extraction of copper and zinc ions with N-nonanoyl-N’-methanesulfonylhydrazine

The patterns of concentrating Cu(II) and Zn(II) ions from aqueous solutions with N-nonanoyl-N’-mesylhydrazine by the ion flotation method were studied, depending on the initial concentration of the collagents, the pH value of the solution, conditioning time, and temperature. Based on IR spectroscopy and elemental analysis data, a hypothesis about the composition of the floated compounds was made. It was shown that the extraction of Zn(II) is significantly dependent on the initial concentration of the metal and the conditioning time of the solution. A decrease in the extraction degree of the studied ions with an increase in the solution temperature was established, with this effect being more pronounced for Cu(II). The kinetics of the process were described using the classical first-order model; the obtained flotation rate constants for Zn(II) ions were five times higher than for Cu(II). The conditions for the selective separation of Cu(II) ions in collective flotation conditions were determined.

Critical Casimir levitation of colloids above a bull's-eye pattern.

Critical Casimir forces emerge among particles or surfaces immersed in a near-critical fluid, with the signof the force determined by surface properties and with its strength tunable by minute temperature changes. Here, we show how such forces can be used to trap a colloidal particle and levitate it above a substrate with a bull's-eye pattern consisting of a ring with surface properties opposite to the rest of the substrate. Using the Derjaguin approximation and mean-field calculations, we find a rich behavior of spherical colloids at such a patterned surface, including sedimentation toward the ring and levitation above the ring (ring levitation) or above the bull's-eye's center (point levitation). Within the Derjaguin approximation, we calculate a levitation diagram for point levitation showing the depth of the trapping potential and the height at which the colloid levitates, both depending on the pattern properties, the colloid size, and the solution temperature. Our calculations reveal that the parameter space associated with point levitation shrinks if the system is driven away from a critical point, while, surprisingly, the trapping force becomes stronger. We discuss the application of critical Casimir levitation for sorting colloids by size and for determining the thermodynamic distance to criticality. Our results show that critical Casimir forces provide rich opportunities for controlling the behavior of colloidal particles at patterned surfaces.

Kinetics and thermodynamics of methylene blue adsorption onto black plum seed-based graphene oxide

Abstract The kinetics and thermodynamics of methylene blue adsorption from aqueous solution was studied using low-cost biomass graphite (CVDM) and graphene oxide (SGO) derived from black plum seed. The effects of pH in the range of 2.2–12.5, adsorbent dosage in the range of 25–100 mg and solution temperature in the range of 28.7–90 °C were studied. The optimum conditions were recorded at pH 4.8, dosage of 25 mg and solution temperature of 70 °C. The pseudo-second-order model demonstrated the best fit to experimental data (R 2 → 1 and SSE = 3.69), rapid rate constant (K s = 0.0868 g/mg.min) and empirical adsorption capacity of 4.12 mg/g. The adsorption of methylene blue onto SGO increased with solution temperature to 70 °C before it decreased, suggesting a weakening of the attractive adsorbent-adsorbate forces due to collisions among methylene blue molecules.

Rabies virus phosphoprotein exhibits thermoresponsive phase separation with a lower critical solution temperature.

Rabies virus (RABV) generates membrane-less liquid organelles (Negri bodies) in the cytoplasm of its host cell, where genome transcription and replication and nucleocapsid assembly take place, but the mechanisms of their assembly and maturation remain to be explained. An essential component of the viral RNA synthesizing machine, the phosphoprotein (P), acts as a scaffold protein for the assembly of these condensates. This intrinsically disordered protein forms star-shaped dimers with N-terminal negatively charged flexible arms and C-terminal globular domains exhibiting a large dipole moment. Our study shows that in vitro self-association of RABV P drives a complex thermoresponsive phase separation with a lower critical solution temperature. Protein dimers assemble already below the saturation concentration, and condensation is driven by attractive conformation-specific interactions leading to reentrant liquid phase separation over a narrow range of salt concentration. We propose a minimal molecular model in which P can adopt three limit conformational states and the disordered N-terminal arms control the interactions between giant dipoles that is consistent with our observations.

A controlled co-assembly approach to tune temperature responsiveness of biomimetic proteins.

The controlled co-assembly of biomacromolecules through tuneable interactions offers a simple and fascinating opportunity to assemble multiple molecules into a single entity with enhanced complexity and unique properties. Herein, our study presents a dynamic co-assembled system using the multistimuli responsive intrinsically disordered protein Rec1-resilin and the adhesive hydrophilic protein silk sericin (SS). We utilized advanced characterization techniques including circular dichroism (CD) spectroscopy, dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), and small/ultra-small angle neutron scattering (SANS/USANS) to elucidate the detailed co-assembly behavior of the system and its evolution over time and temperature. To achieve sufficient neutron contrast, we successfully biosynthesised deuterium-labeled Rec1-resilin (D-Rec1). Our research demonstrates that this co-assembly allows the formation of a robust entity with dynamic conformational assembly and disassembly, exhibiting both the upper critical solution temperature (UCST) and lower critical solution temperature (LCST) with reversibility. The assembly and disassembly dynamics of the co-assembled entity at UCST are very fast, while the process is kinetically controlled at LCST. This study provides significant new insights into the interplay of a hydrophilic, multi-responsive IDP and a highly hydrophilic protein, shaping the thermoresponsive and stable properties of the co-assembled entity.

Feasible Preparation of Naphthalimide-Functionalized Zeolitic Imidazolate Framework-8 for Control, and Fluorescence Detection of Virus: Optimization of Model Study.

The onset of the coronavirus has highlighted the critical need to swift diagnostic techniques to identify the virus. Metal Organic Frameworks (MOFs) have attracted considerable attention in the field of sensing due to the remarkable characteristics. The present research examines the microwave preparation of naphthalimide-functionalized zeolitic imidazolate framework-8 (NI/ZIF-8) to the detection of coronavirus as a probe. The microwave synthesis approach facilitates an environmentally sustainable, and effective production of NI/ZIF-8. Characterization techniques have validated the material's high crystallinity and thermal behaviour. In order to enhance the performance of the probe, a 23 factorial model is implemented. This model facilitates the influences of control parameters, including NI/ZIF-8 dose, solution temperature, and buffer pH, on quenching response. The findings indicate the 27°C, pH 8.2, and a NI/ZIF-8 dose of 0.6mg/mL yields the maximum quenching response (83.21%). Additionally, it has been determined that photo electron transfer plays a significant role within the quenching process. The sensor demonstrated remarkable sensitivity to the COVID-19 RNA, achieving an exceptionally detection limit of 5.45 pM and a quick sense (20min), alongside a high detection selectivity of RNA. This project underscores the applicability of NI/ZIF-8 as an effective and eco-friendly sustainable substance for the rapid and accurate detection of RNA of COVID-19.

Corrosion test and corrosion fatigue numerical simulation research on marine structures

The corrosion tests on Q235B steel in artificial seawater with conventional room temperature and high-temperature & high-humidity are first conducted. The test results show that increasing the acidity and temperature of the corrosion solution, as well as adopting the alternating dry-wet, can significantly enhance the corrosion rate of materials. In addition, the corrosion tests exhibit good simulation and acceleration characteristics compared to at sea tests. Then, the corrosion and corrosion-fatigue numerical simulation methods based on COMSOL and MATLAB are proposed. Meanwhile, the corrosion of Q235B steel in neutral artificial seawater and corrosion fatigue damage of a T-shaped structure under the coupling of artificial seawater with fatigue load are simulated and analyzed. The corrosion simulation results indicate that when the temperature is 40 °C and 20 °C, the average corrosion rates of specimens increase by 96.61% and 15.25%, respectively. Furthermore, when the temperature is 20 °C, the average corrosion rates obtained from numerical simulation and corrosion test are 0.068 mm/a and 0.062 mm/a, respectively, with a relative error of 9.7%, verifying the validity of the corrosion numerical simulation method. Based on the corrosion fatigue simulation, it is found that the maximum corrosion thickness increases by about 23% compared to pure corrosion condition in the weld region, and the structural fatigue damage increases by about 21.36% compared to pure fatigue condition after 10 years of corrosion.

Hot Bending–Quenching Characteristics of Heat Treatable A6063 Aluminum Tubes

This study investigates the application of hot bending–quenching technology to heat-treatable A6063 aluminum tubes, focusing on the bending formability and mechanical properties after aging treatment under various heating conditions. High-frequency induction heating was used to uniformly heat aluminum tubes to the solution treatment temperature of 560 °C. The effect of wall thickness on bending formability was explored, revealing that thinner tubes (2 mm) experienced significant flattening defects, whereas thicker tubes (5 mm) exhibited superior formability with reduced shrinkage and wall thinning. Additionally, the pre-quenching temperature was found to influence the mechanical properties of the tube with a thickness of 5 mm. Tubes held at the solution temperature for 1 min 30 s or longer maintained higher temperatures during transfer, resulting in improved tensile strength and hardness after aging. The findings confirm the feasibility of applying hot bending–quenching technology to aluminum tubes, though careful control of temperature loss during continuous industrial processes is required to ensure optimal mechanical performance.

Recombinant Fusion Proteins with Embedded Sensing Functions as Versatile Tools for Protocell Development.

Sensory capabilities are crucial for cells to interact with their environment. To mimic these functions in synthetic cells, we developed sensory globular protein vesicles (GPVs) made entirely of recombinant fusion proteins through self-assembly under aqueous conditions. GPVs demonstrate sensory functions via the formation of the FKBP-FRB ternary complex with the signaling molecule, rapamycin. The sensory domain of FKBP or FRB was genetically fused to a fluorescent protein and leucine zipper, which self-assemble into vesicles by forming amphiphilic building blocks through high-affinity binding to a counter leucine zipper fused to an elastin-like polypeptide (ELP) above its lower critical solution temperature. We observed intervesicle aggregation in a time- and concentration-dependent manner upon rapamycin binding, confirmed by colocalization studies and statistical analysis. This system enhances our understanding of protein vesicle functionality for sensing and offers a basis for exploring GPVs as models to replicate key cellular processes in synthetic cells.

Influence of deformation temperature on flow stress and dynamic metallurgical phenomena in Al–5.81Zn–1.65Mg alloy subjected to thermomechanical processing

To advance the T5 treatment process for Al–5.81Zn–1.65Mg alloys, this study explored the influence of deformation temperature on the solution temperature, ultrafine grain (UFG) formation via dynamic recrystallization (DRX), and strain-induced dynamic precipitation (SIDP) during thermomechanical processing at 300–500 ℃, with a 70% reduction and a strain rate of 1s−1. The flow curve exhibited pronounced work hardening (WH) at 300–350 ℃, whereas a dynamic recovery-type flow curve was observed at 450–500 ℃. As the temperature increased from 300 to 500 °C, the 1st WH rates (ε=0.2–0.4) were 55, 37.5, 20, 8.5, and 10MPa, respectively. Larger DRX grains were formed at higher temperatures. The DRX rate ranged 20%–30% at 300–400 ℃ and increased to 60% at 500 ℃. The texture gradually transitioned from Goss {011}<100> to brass {110}<112> with an increase in the deformation temperature from 300 to 500 ℃. Discontinuous DRX occurred mainly near the grain boundaries and precipitates at 300–400 ℃, shifting to continuous DRX at temperatures ranging from 400 to 500 ℃. At 300 and 400 ℃, larger precipitates (10–50nm) and smaller ones (<10nm) were observed within grains and along boundaries. Precipitates at 300 ℃ were larger and denser than those at 400 ℃, with η’, and T’ phases formed through SIDP. For this alloy, considering the formation of UFG and ensuring sufficient solubility, the appropriate deformation temperature range was 400–500 ℃.

Evaluation of H2O2, H2, and bubble temperature in the sonolysis of water and aqueous t-butanol solution under Ar: Effects of solution temperatures and inorganic additives of NaCl and KI

The yields of H2O2 and H2 formed in the sonolysis of aqueous solution under noble gas are representative indexes for understanding the chemical effects of ultrasonic cavitation bubbles. In this study, the yields of H2O2 and H2 formed under Ar were evaluated as a function of the concentration of NaCl or KI. When these yields were analyzed by using a normalization technique, it was confirmed that the yields of H2 were more clearly related to Ar solubility than those of H2O2, suggesting that H2 is a more real probe to understand the chemical effects of cavitation bubbles in water. The effects of NaCl on sonochemical formation of oxidants were also compared with those of KI. When aqueous t-butanol solution was sonicated, the yields of H2 and the maximum temperature attained in a collapsing bubble (bubble temperature) decreased with increasing solution temperature and salt concentration, suggesting that these parameters affected the quantity related to the number (and/or size) of active bubbles as well as the quality related to the bubble temperatures.

Effect of discharge thermal action in ECDM on electrochemical behaviours of matrix material and its recast layer in glycol-based solution

The interaction between thermal and electrochemical corrosion in the ECDM process remains unclear. This study clarifies the effect of discharge thermal action on electrochemical corrosion. Real-time temperature curves indicate that the solution temperature in the electrochemical corrosion zone increased significantly due to discharge thermal action. The corrosion resistance of the recast layer’s passive film is superior to that of the matrix due to the enrichment of Cr2O3. As the electrolyte temperature rises, the passive film thickens but shows lower polarization resistances and poorer corrosion resistance due to a loose and weak structure. The matrix material and its recast layer dissolved uniformly, resulting in a considerably flat surface in a glycol-based solution, with enhanced levelling efficiency due to discharge thermal action.

Design and development of wire-mesh packed bed liquid desiccant dehumidifier to reduce pressure-drop and carryover

In response to the high air-pressure drop and desiccant carryover experienced in liquid desiccant-packed bed dehumidifiers, which adversely affect the room environment and system economics, this study explored various modified wire-mesh packed bed designs. It experimentally evaluated dehumidification efficiency, and thermal performance across different corrugated wire-mesh packings, introducing a new design for cost-effective moisture removal while reducing pressure drop and desiccant carryover. Three specially designed packings (P-1, P-2, and P-3) were tested against standard commercial options like Celdek (7090, 6090, 5090) and Mellapak 250Y, focusing on optimizing performance. At a constant optimal concentration of the desiccant solution, the effects of airflow rates (ma), solution flow rates (ms), and solution temperatures (Ts) on the performance of the system was analyzed. The findings indicated that P-1 performed better than others, particularly in terms of condensation rate (CR) and moisture effectiveness (εm). Specifically, it outperformed the acrylonitrile butadiene styrene (ABS) (benchmark) packing by 22.1 % and 8 % respectively at a solution concentration of 40 wt% and ma of 0.025 kg/s under ambient conditions of nearly 0.02921 kg/kg specific humidity and 31 °C temperature. Increasing the void fraction led to a reduction in air pressure drop while enhancing the wettability, and dehumidification efficiency. The packing, P-1, made of stainless steel (SS340) with 0.3 cm mesh was finally proposed to obtain better performance for dehumidification applications in buildings. Additionally, its potential to reduce air-pressure drop and desiccant carry-over can provide improved energy efficiency and enhanced air quality, making it a practical choice for sustainable building cooling solutions.

Comprehensive analysis and optimization of an efficient combined power and refrigeration cycle suitable for recovering low/mid-grade waste flue gas

To effectively recover low/mid-grade waste flue gas and provide larger refrigeration capacity, an efficient combined power/refrigeration cycle only using ammonia water as the working fluid is proposed and studied. Parametric analysis is conducted from the perspectives of thermodynamics, exergoeconomics, and environment, the results demonstrate that the low/mid-grade waste flue gas within a wide range of temperature can be sufficiently recovered by the proposed cycle, and the cycle performance is significantly affected by the turbine inlet pressure, work/basic concentration and separation temperature of work solution. Based on the heat source condition of 300°C/10 kg·s-1, the results of single-objective optimization show that the maximum effective exergy efficiency, reduction amount of CO2 emission and waste heat recovery ratio that can be achieved are 0.5989, 262 kg/h and 0.97 respectively, and the achievable minimum unit cost of produced exergy is 8.432 $·GJ-1. Besides, the multi-objective optimization indicates that the optimal comprehensive thermodynamic efficiency is 0.5458 with net power output of 372.5 kW and larger refrigeration capacity of 545.7 kW, and the associated effective exergy efficiency, unit cost of produced exergy, reduction amount of CO2 emission and waste heat recovery ratio are 0.5701, 9.187 $/GJ, 258.3 kg/h and 0.9574, respectively.

Corrosion of nickel foam electrodes during hydrothermal reactions: The influence of a simple protective carbon black coating

Nickel foam (NF) substrates are widely used to support electrocatalysts, and this is frequently achieved using hydrothermal reactions, where the NF is immersed in the hydrothermal reactor together with the electrocatalyst precursors. However, other reactions including the corrosion of the NF and changes to the pH occur simultaneously, and these can affect the quality of the final electrocatalyst. Herein, a simple approach is devised to minimise these unwanted reactions. Carbon black (CB) was non-covalently functionalised at room temperature using tannic acid to give very stable and good dispersions of fCB in deionised water. Using a simple sonication step, the NF was coated with a uniform layer of the dispersed fCB. This layer served to minimise the corrosion of the underlying NF during the hydrothermal reactions with very good protection observed up to a temperature of 160 °C in deionised water at a pH of 2.0. The corrosion currents of the NF and fCB@NF were estimated at 8.7 µA and 3.9 µA, respectively, at room temperature in this acidic solution. Using a model reaction, the successful nucleation and growth of MnCo2O4 cubes was observed at fCB@NF, but not at the corroding NF.

Layered graphene oxide membrane for heavy metal separation via molecular dynamics simulation

Purification of water and industrial wastewater, especially those containing toxic metals, is a critical challenge for developing societies. Nano membranes, including two-dimensional graphene oxide nanomaterials, have recently gained prominence as an alternative to traditional polymer membranes. However, the efficacy of these membranes for the removal of heavy metals has not been extensively studied. In this work, molecular dynamics simulation is used to investigate the performance of graphene oxide membranes, with the oxidation ratio of 20 %, for the removal of mercury and arsenic ions at a concentration of 0.5 M, via reverse osmosis at 200 Mpa pressure. Results demonstrate that graphene oxide membranes are effective for separating heavy metal ions while maintaining good water flow. The mechanism of water molecule passage through the graphene oxide membrane is also investigated by analyzing the structural images of water molecules between the layers, water density diagrams in the nanochannel, and the number of hydrogen bonds at various channel inter-layer distances. In addition, raising the temperature of the aqueous solution from 300 to 340 K increases the water flux and decreases ion rejection. Increasing the concentration of mercury and arsenic ions from 0.5 to 1 M in the feed water leads to decrease in water flux with the least impact on ion rejection. Furthermore, the influence of membrane geometry on its performance is also investigated. By comparing the cross-flow and dead-end geometries, it is found that the cross-flow geometry performs better than the dead-end geometry both in water flux and the removal efficiency of mercury and arsenic ions. The potential of graphene oxide membranes in the treatment of wastewater containing heavy metals is highlighted by these findings, which provide insights into optimizing their design and operational parameters.

Effect of heat treatment on microstructure and mechanical properties of WE43 alloy fabricated by wire arc additive manufacturing

Heat treatment is an effective method to improve the mechanical properties of Wire Arc Additive Manufacturing (WAAM) WE43 alloy. This study investigates the effects of heat treatment on the microstructure and mechanical properties of the WE43 alloy processed by WAAM. The as-deposited samples exhibit a uniform equiaxed crystal structure, with grain size gradually increasing as the number of deposited layers grows. The as-deposited microstructure comprises eutectics and a small amount of cubic phases, and the phase content escalates as the amount of deposited layers increases, influenced by the cumulative effect of multiple thermal cycles. At lower solid solution temperatures (480 ℃ × 8h), most of the eutectic phase remains undissolved. During tensile testing, undissolved eutectics tend to cause stress concentrations, leading to cracks that result in sample fractures, negatively affecting the mechanical properties. At higher solid solution temperatures (520 ℃ × 8h), most of the eutectic dissolves, but abnormal grain coarsening (AGC) in the interlayer fine-grain region occurs, causing a significant reduction in the sample's mechanical properties. After solid solution treatment at 500 °C for 8hours, only a small amount of eutectics remains undissolved, and the AGC phenomenon is not observed, resulting in an optimal solid solution effect. Subsequently, after aging treatment at 225 °C for 18hours, dense nanoscale β′′ phases precipitated within the alloy grains, significantly improving the mechanical properties. The samples achieved optimal performance, with UTS, YS, and EL of 323±15.2MPa, 225±11.3MPa, and 8.4±1.1%, respectively.