Binary Solutions Research Articles

A novel measurement method for measuring the concentration-dependent mutual diffusion coefficients based on finite volume method

This paper presents a novel measurement method based on the finite volume method (FVM), which can be used for measuring the concentration-dependent mutual diffusion coefficient D(C) in binary solution. The measurement principle of D was derived by integrating the Fick’s second law in the control volume and establishing discretization equation. By simulating the diffusion process of binary solution, discussed the feasibility of this method. This new method can be used by an experimental system that can monitor changes in concentration distribution, such as optical interferometry. A set of 20 binary mixtures was tested to verify the method. The experimental results showed good agreement with and the literature, which verifies the accuracy of the method. The relative expanded combined uncertainty for the proposed method is estimated to 2.2 %. In addition, D(C) of LiTSFI aqueous solution was measured by the new method based on the digital holographic interferometry system at 288.15 K, 298.15 K and 308.15 K over the mass fraction range of 0 ∼ 0.447 (0 ∼ 2 mol/L). The temperature and concentration influences of D were discussed and a semi-empirical correlation was built.

Measurement and molecular simulation of the solubility properties of 4-tert-Butyl-2, 6-dinitro-3-methoxytoluene in single and binary solvents

The solubility of 4-tert-Butyl-2, 6-dinitro-3-methoxytoluene (musk amberette) in methanol, ethanol, n-propanol, n-butanol, acetonitrile, N, N-dimethylformamide, N, N-dimethylacetamide, tetrahydrofuran and methanol + tetrahydrofuran at 278.15 K to 318.15 K were determined. All measurement data obtained good results by merging Van’t Hoff, modified Apelblat, λh, Yaws, NRTL, Wilson, Jouyban-Acree and Sun model. The deviation analysis between fitting values and experimental values indicates that the Yaws model was more effectively in fitting the solubility of musk amberette. In addition, the ΔsolH°, ΔsolG°, ΔsolS° of musk amberette solution were discussed by Van’t Hoff equation. Their fruits implied that the dissolution of musk amberette is found to be accompanied by heat absorption and entropy gain processes. This is consistent with the positive slope of the T-x1 curve, which means that high temperature is advantage for the continued dissolution of musk amberette. In contrast, the presence of strong hydrogen bonds between alcohol solvents results in their lowest solubility for musk amberette. As an important task, the melting performance and crystal structure of musk amber were tested through instruments. The same characteristics exclude the presence of solvates or polymorphs. Finally, molecular visualization analysis was used to summarize the interatomic interactions within the crystal of musk amberette. The relationship between HSP, π, α, β, CED and their ability to dissolve musk amberette was discussed. It has been proven that high CED of the solvent is the main obstacle to the dissolution of musk amberette. The interaction between the O atom of musk amberette and hydroxyl H atom of alcohol in binary mixed solutions was obtained through molecular dynamics. Further, elucidated the relationship between mixed solvents and solubility. In summary, these studies will provide strong guidance for the upgrading of musk amberette production processes.

Optimization of synergistic extraction of calcium ion via an emulsion liquid membrane using dicyclohexano-18-crown-6 and D2EHPA carriers: A design of experiment study

Calcium ions play an important role in various fields, with their stable isotopes being of particular importance in medical research and in the production of superheavy metals. Emulsion liquid membranes (ELMs) offer a promising alternative to conventional methods for metal ion extraction due to their remarkable mass transfer rates. However, the effectiveness of crown ethers as carriers in ELM processes has been hindered by their limited ability to extract calcium ions. The aim of this study is to optimize the extraction of calcium ions using an ELM containing dicyclohexano-18-crown-6 (DC18C6) as a carrier and di-(2-ethylhexyl) phosphoric acid (D2EHPA) as a synergistic carrier. To achieve this objective, a two-level fractional factorial design (FFD) was initially implemented to screen the key factors. Subsequently, a central composite design (CCD) was employed to optimize the four identified key factors. The CCD method yielded a quartic regression model for calcium extraction efficiency. The optimum values were: DC18C6 concentration at 0.035 mol/L, feed phase pH of 4, a feed/emulsion volume ratio of 2.3, and a W/O/W stirring time of 23.4 min. Under these optimal conditions, DC18C6 exhibited negligible extractability, while D2EHPA achieved an extraction efficiency of 62.2%. Combining both carriers, however, significantly increased the extraction efficiency to 97.3%, indicating a synergistic effect that enhanced the extraction of Ca(II) ions. Furthermore, the selectivity of the ELM towards Ca(II) ions was examined in binary solutions of Ca(II)/Li(I), Ca(II)/Na(I), and Ca(II)/Mg(II). The ELM demonstrated selectivity for Ca(II) over Li(I), Na(I), and Mg(II) with separation factors of 4.4, 2.0, and 8.1, respectively. It is noteworthy that the combination of carriers positively influenced calcium selectivity exclusively in the Ca(II)/Mg(II) solution. Conversely, no noticeable effect on selectivity was observed in the Ca(II)/Li(I) solution, while the combination had an adverse effect on calcium selectivity in the Ca(II)/Na(I) solution.

Verification of Gaia Data Release 3 Single-lined Spectroscopic Binary Solutions With Three Transiting Low-mass Secondaries

While secondary mass inferences based on single-lined spectroscopic binary (SB1) solutions are subject to degeneracies, this degeneracy can be lifted through the observations of eclipses. We combine the subset of Gaia Data Release 3 SB1 solutions consistent with brown dwarf-mass secondaries with the Transiting Exoplanet Survey Satellite (TESS) Object of Interest (TOI) list to identify three candidate transiting brown dwarf systems. Ground-based precision radial velocity follow-up observations confirm that TOI-2533.01 is a transiting brown dwarf with orbiting TYC 2010-124-1 and that TOI-5427.01 is a transiting very low-mass star with orbiting UCAC4 515-012898. We validate TOI-1712.01 as a very low-mass star with transiting the primary in the hierarchical triple system BD+45 1593. Even after accounting for third light, TOI-1712.01 has a radius nearly a factor of 2 larger than predicted for isolated stars with similar properties. We propose that the intense instellation experienced by TOI-1712.01 diminishes the temperature gradient near its surface, suppresses convection, and leads to its inflated radius. Our analyses verify Gaia DR3 SB1 solutions in the low Doppler semiamplitude limit, thereby providing the foundation for future joint analyses of Gaia radial velocities and Kepler, K2, TESS, and PLAnetary Transits and Oscillations light curves for the characterization of transiting massive brown dwarfs and very low-mass stars.

The effect of atmospherically relevant aminium salts on water uptake

Abstract. Atmospheric new particle formation is initiated by clustering of gaseous precursors, such as small acids and bases. The hygroscopic properties of those precursors therefore affect the hygroscopic properties of aerosol particles. In this work, the water uptake of different salts consisting of atmospheric small acids and amines was studied computationally using the conductor-like screening model for real solvents (COSMO-RS). This method allows for the prediction of water activities in atmospherically relevant salts that have not been included in other thermodynamics models. Water activities are reported here for binary aqueous salt solutions, as well as ternary solutions containing proxies for organic aerosol constituents. The order of the studied cation species regarding water activities is similar in sulfate, iodate, and methylsulfonate, as well as in bisulfate and nitrate. Predicted water uptake strengths (in mole fraction) conform to the following orders: tertiary > secondary > primary amines and guanidinos > amino acids. The addition of water-soluble organic to the studied salts generally leads to weaker water uptake compared to pure salts. On the other hand, water-insoluble organic likely phase separates with aqueous salt solutions, leading to minimal effects on water uptake.

Preparation of copolymer brush‐type restricted access microspheres with adjustable adsorption selectivity to variety of dyes

AbstractRestricted access materials (RAMs) with adjustable selectivity was developed for the removal and detection of residual dyes for the solve problems of dye contamination. In this work, using homemade poly(4‐vinylbenzyl chloride‐co‐divinylbenzene) (PVBC/DVB) microspheres as substrate and successive two‐step surface‐initiated atom transfer radical polymerization (SI‐ATRP) as synthesis method, the two types of monomers, sodium 4‐vinylbenzene sulfonate (Nass) and styrene (St) were first grafted for constructing mixed interactions of adsorption sites, and then the hydrophilic glycidyl methacrylate (GMA) was polymerized, following by hydrolysis to construct diol groups on the external PVBC/DVB as the restricted access sites. The developed PVBC/DVB@poly(St‐co‐Nass)@poly(GMA) of adsorption properties was investigated by six dyes including methylene blue (MB), basic fuchsin (BF), acid fuchsin (AF), neutral red (NR), methyl orange (MO), and Congo red (CR), the adsorption capacities of those dyes and the removal rate for the binary mixed dye solution both rely on the ratio of St/Nass, confirming the adjustable adsorption selectivity. When PVBC/DVB@poly(St‐co‐Nass)@poly(GMA) was packed as solid phase extraction adsorbent in couple with UV–vis spectrum, it was applied to the determination of MB and BF in the water, fish and shrimp, good linearity with satisfactory recoveries for MB and BF are obtained to show the favorable practicability.

Dual-Channel-Ion Conductor Membrane for Low-Energy Lithium Extraction.

The development of energy-efficient and environmentally friendly lithium extraction techniques is essential to meet the growing global demand for lithium-ion batteries. In this work, a dual-channel ion conductor membrane was designed for a concentration-driven lithium-selective ion diffusion process. The membrane was based on a porous lithium-ion conductor, and its pores were modified with an anion-exchange polymer. Thus, the sintered lithium-ion conductors provided highly selective cation transport channels, and the functionalized nanopores with positive charges enabled the complementary permeation of anions to balance the transmembrane charges. As a result, the dual-channel membrane realized an ultrahigh Li+/Na+ selectivity of ∼1389 with a competitive Li+ flux of 21.6 mmol·m-2·h-1 in a diffusion process of the LiCl/NaCl binary solution, which was capable of further maintaining the high selectivity over 7 days of testing. Therefore, this work demonstrates the great potential of the dual-channel membrane design for high-performing lithium extraction from aqueous resources with low energy consumption and minimal environmental impact.

Computer modeling of thermotransport in a uniform binary liquid solution with equimolar n-alkane mixtures

By means of molecular dynamics (MD), two novel methods, a thermal mean-path that may outline temperature profiles effectively in the MD system and a modified coarse-grained force field potential (the MCG-FFP) that may depict inter/intra-molecular interactions fairly well among n-alkane species, are employed to simulate a thermotransport process in a uniform liquid solution with two equimolar n-pentane (nC-5) and n-decane (nC-10) mixtures. In addition, all the MD simulations are running under two constraints: a weak thermal gradient exerting on the MD system from its hot through cold boundary sides and the standard-state acting on the MD system from its outer environment. During the whole MD simulations, coefficients of thermal diffusion and mass mutual diffusion, and the Soret coefficient (SC) for the MD system are calculated by using the MCG-FFP. As a result, the MD simulations indicate that nC-5 species with light molar-mass would migrate toward the hot boundary region, while nC-10 species with heavy molar-mass would migrate toward the cold one. Coefficients calculated from the MCG-FFP are found to meet relevant experimental outputs fairly well. Furthermore, an empirical formula developed by means of relevant continuum methods is used for calculating coefficients of mass mutual diffusion in solutions mixing with multimolar nC-5 and nC-10 species. Its one output is found to corroborate pretty well with that from the MD simulations. This may expect that such the formula would perform universally when characterizing properties of mass mutual diffusion in binary liquid solutions with other multimolar alkane mixtures in the petroleum engineering.

Estimation of CO2 solubility in aqueous solutions of commonly used blended amines: Application to optimised greenhouse gas capture

One of the key concerns in the 21st century, alongside the growing population, is the increase in energy consumption and the resulting global warming. The impact of CO2, a prominent greenhouse gas, has garnered significant attention in the realm of CO2 capture and gas purification. CO2 absorption can be enhanced by introducing some additives into the aqueous solution. In this study, the accuracies of some of the most up-to-date computational approaches are investigated. The employed machine learning methods are hybrid-adaptive neuro-fuzzy inference system (Hybrid-ANFIS), particle swarm optimization-adaptive neuro-fuzzy inference system (PSO-ANFIS), least-squares support vector machines (LSSVM) and genetic algorithm-radial basis function (GA-RBF). The developed models were used in estimating the solubility of CO2 in binary and ternary amines aqueous solutions. i.e. blends of monoethanolamine (MEA), triethanolamine (TEA), aminomethyl propanol (AMP), and methyldiethanolamine (MDEA). This modeling study was undertaken over relatively significant ranges of CO2 loading (mole of CO2/mole of solution) as a function of input parameters, which are 0.4–2908 kPa for pressure, 303–393.15 K for temperature, 36.22–68.89 g/mol for apparent molecular weight, and 30–55 wt % for total concentration. In this work, the validity of approaches based on different statistical graphs was investigated, and it was observed that the developed methods, especially the GA-RBF model, are highly accurate in estimating the data of interest. The obtained AARD% values for the developed models are 18.63, 8.25, 12.22, and 7.54 for Hybrid-ANFIS, PSO-ANFIS, LSSVM, and GA-RBF, respectively.

Piezoelectric, ferroelectric and dielectric characterizations of a new ceramic solid solution (1-x)Ba(Cu1/3Nb2/3)O3-xPbTiO3 with morphotropic phase boundary

The understanding of structure-property co-relations is a key to utilising the materials for their best performances. This paper focuses on the physical property characterization of a new binary solid solution series with formula (1-x)Ba(Cu1/3Nb2/3)O3-xPbTiO3. A unique type of crystal structure evolution as a function of composition has been observed for this solid solution series, where a two-phase coexistence is observed in a very large span of compositions at room temperatures. The microstructure, piezoelectric, ferroelectric and dielectric properties along with their entanglement with crystal structure, have been investigated in detail. The compositional homogeneity of selected compositions has been verified with EDS and XPS. The higher responses in the physical properties have been observed near morphotropic phase boundary compositions. On heating above room temperature, peaks in dielectric permittivity responses have been observed that correspond to the phase transitions of non-centrosymmetric phases. The solid solution's best piezoelectric and ferroelectric responses are observed for the x = 0.70 composition showing higher densification, larger grain size and low dielectric losses, and lies near the morphotropic phase boundary region. The solid solution has enormous potential in piezoelectric industries as it possesses morphotropic phase boundary and high-temperature piezoelectricity.

Membrane crystallization for recovery of lithium carbonate crystals: Study on process parameters and salts effect for Li2CO3-NaCl-KCl-LiCl solutions

In this work, membrane crystallization (MCr) process was employed for recovery of lithium carbonate (Li2CO3) crystals from synthetic brine solutions. First, the effect of the main operating conditions in MCr, including feed temperature (40, 50, and 60 °C) and flowrate (0.81, 1, and 1.3 L/min) was investigated on the crystallization of Li2CO3 in a binary solution. Next, the effect of main inorganic salts in the brine solutions (i.e., NaCl, KCl, and LiCl) and the mixture of them on the MCr performance and crystallization of Li2CO3 were investigated. In-line microscope, light microscope, scanning electron microscope, and X-ray diffraction test were used to observe the crystallization and characterize the obtained crystals. The obtained results revealed that feed temperature is the main parameter to dominate the nucleation and crystal formation and growth. Thus, the higher the feed temperature, the faster the crystal formation and the larger the crystals. The average crystal size increased from 9.59 to 30.51 μm, when the feed temperature increased from 40 to 60 °C, respectively. However, smaller crystals were observed with adding NaCl and KCl to the solution. Moreover, none of the operating parameters nor the salts additives did affect the crystals shape and the obtained Li2CO3 crystals possess needle-like shape.

Separation of rare earth elements using chelation-assisted electrodialysis

Rare earth elements (REE) find crucial applications in electronics, clean energy, aerospace, automotive, and defense sectors. However, the conventional solvent extraction (SX) technique currently dominates the process of isolating individual REE into pure elements, presenting challenges due to its extensive stage requirements and environmental footprint. To address these limitations, this study explores chelation-assisted electrodialysis (ED) as a promising alternative to SX for efficiently separating light and medium REE from binary and tertiary solutions. By incorporating chelating agents into the ED process, we aim to enhance separation efficiency while mitigating the drawbacks associated with SX. A laboratory-scale ED system with a microflow cell consisting of five pairs of Neosepta® cation and anion exchange membranes in an alternating configuration was utilized. Aminopolycarboxylic acids such as Ethylenediaminetetraacetic acid (EDTA), diaminocyclohexanetetraacetic acid (DCTA), N-(2-hydroxyethyl) ethylenediaminetriacetic acid (HEDTA) and diethylenetriamine-pentaacetic acid (DTPA) were employed as chelating agents to increase the selectivity of REE separation. The effects of operating voltage, operation mode, pH, type of electrolytes, and membrane configuration on the separation process were investigated. ED was conducted at varying concentrations of REE and chelating agents, and the system was optimized for the highest separation factors. It was observed that the separation factors increased by increasing the voltage due to the higher ionic mobility of non-chelated REE at higher voltages. Precipitation of REE in ED compartments was one of the main challenges in the tests. To prevent the precipitation, a modified membrane configuration and an optimized pH window of 3.0–4.5 were applied. At optimized operating conditions, the REE separation factors of up to 42 were achieved, which were up to 20 times greater than those reported for the conventional SX process. The final REE concentrations in the concentrate compartment were comparable with those calculated from the dissociation equilibrium equations and in most cases, less than 10 % error was observed between the experimental results and the calculations.

Stratospheric ozone depletion inside the volcanic plume shortly after the 2022 Hunga Tonga eruption

Abstract. Near-term in-plume ozone depletion was observed for about 10 d by the Aura Microwave Limb Sounder (MLS) right after the January 2022 Hunga Tonga–Hunga Ha'apai (HTHH) eruption. This work analyzes the dynamic and chemical causes of this ozone depletion. The results show that the large water injection (∼ 150 Tg) from the HTHH eruption, with ∼ 0.0013 Tg injection of ClO (or ∼ 0.0009 Tg of HCl), causes ozone loss due to strongly enhanced HOx and ClOx cycles and their interactions. Aside from the gas-phase chemistry, the heterogeneous reaction rate for HOCl + HCl → Cl2 + H2O increases to 104 cm−3 s−1 and is a major cause of chlorine activation, making this event unique compared with the springtime polar ozone depletion where HCl + ClONO2 is more important. The large water injection causes relative humidity over ice to increase to 70 %–100 %, decreases the H2SO4 / H2O binary solution weight percent to 35 % compared with the 70 % ambient value, and decreases the plume temperature by 2–6 K. These changes lead to high heterogeneous reaction rates. Plume lofting of ozone-poor air is evident during the first 2 d after the eruption, but ozone concentrations quickly recover because its chemical lifetime is short at 20 hPa. With such a large seawater injection, we expect that ∼ 5 Tg Cl was lifted into the stratosphere by the HTHH eruption in the form of NaCl, but only ∼ 0.02 % of that remained as active chlorine in the stratosphere. Lightning NOx changes are probably not the reason for the HTHH initial in-plume O3 loss.

Radioactive strontium ions sieving through reduced graphene oxide membrane

Partitioning of 90Sr from other radionuclides in radioactive liquid waste is crucial for treating high-level liquid waste (HLLW) generated during spent fuel reprocessing, as the unique high heat-generating and long half-life of 90Sr pose a significant challenge for the long-term storage of nuclear waste. However, it remains difficult to sieve 90Sr for membrane based on size-selective effect, as the radioactive liquid waste contains numerous typical divalent ions, such as 60Co, 63Ni, and 65Zn, which have the same valence and similar hydration diameters to 90Sr. Here, we experimentally demonstrate a rapid and efficient separation of radioactive 90Sr from other radioactive ions by a reduced graphene oxide membrane, which prepared by the amino-hydrothermal method from graphene oxide suspensions. For SrCl2/CoCl2, SrCl2/NiCl2, and SrCl2/ZnCl2 binary mixed solutions, SrCl2 can pass through efficiently, while the rejection rates for CoCl2, NiCl2, and ZnCl2 reached 99.9 %. The separation factors reached 3232, 4254, and 3314, which are about one or two orders of magnitude higher than the highest reported separation factors for membranes sieving divalent ions. Our findings offer a simple avenue for the precise treatment of radioactive liquid waste, which is vital for the advancement of nuclear energy technology.

Designing a new KBT-based binary solid solution as a candidate for dielectric energy storage materials

Dielectric energy storage capacitors offer great potential in pulsed power devices due to the high power density and fast charging-discharging rate. Designing a host material with high field-induced polarization is of importance for developing dielectric energy storage materials via further composition modulation. In this paper, we compare the microstructure, dielectric, and ferroelectric properties as well as the energy storage performance of samples K1/2Bi1/2TiO3(KBT), 75KBT-25BiFeO3 (KBTF25), and 88KBT-12Bi0.85Nd0.15FeO3 (KBNTF12) in detail. It is found that, among three samples, sample KBNTF12 possesses the most complex local structure coexisting of a four-distortions with different polarities; meanwhile, sample KBNTF12 behaves as a strong relaxor, thus giving a high field-induced polarization. Besides, sample KBNTF12 realizes the highest electric breakdown strength Eb among three samples, which is resorted to the highest resistivity of grain boundary. Highest ΔP and Eb of sample KBNTF12 among three samples render it achieve ultrahigh stored energy density Ws of 6.94 J/cm3, high recoverable energy density Wr of 5.23 J/cm3, and high efficiency η of 75.4%. Our work suggests that 88KBT-12BNF binary composition be an optimal candidate for dielectric energy storage ceramics.

Revisiting the SGTE lattice stability of bcc aluminum

The CALPHAD framework rests on the ability to assign well-defined free energies to all phases, including mechanically unstable ones. Given the experimental difficulties associated with the latter, researchers have turned to computational methods to obtain a theoretically justified definition of the free energy of mechanically unstable phases. Recently, a method called “inflection detection” has been shown to yield free energies that are broadly consistent with the current SGTE (Scientific Group Thermodata Europe) standard for pure elements, which were obtained through an extrapolation of stable solid solutions free energies towards unstable end members. Despite this general agreement, apparent failures for a few elements stand out, notably for the bcc–fcc enthalpy difference for the common element Al. Here we revisit the definition of the bcc Al enthalpy and show that a careful CALPHAD-based analysis of enthalpy trends in five different mechanically stable binary solid solutions in fact does agree very well with the inflection-detection approach.

Exploring the dynamic changes in hydrogen bond structure of water and heavy water under external perturbation of DMF

The Raman spectra of DMF-water/heavy water binary solutions at different volume ratios are measured to investigate the hydrogen bond structure between N, N-dimethylformamide (DMF) and water/heavy water. It was observed that when VDMF below 40 %, DMF reinforces the hydrogen bond among water molecules through the substitution of a small amount of water molecules within the tetrahedral structure. However, a similar enhancement phenomenon is not observed in heavy water. When VDMF is less than 60 %, the hydrogen bonds among DMF and heavy water molecules affect the symmetry of OD covalent bond. Furthermore, as VDMF exceeds 40 %/60 %, the tetrahedral structures of water and heavy water are gradually replaced by DMF·3H2O/3D2O, DMF·2H2O/2D2O, and DMF·H2O/D2O clusters. The transition point of hydrogen bond structure in DMF- aqueous solution moved to VDMF = 15 % under the influence of under the influence of dynamic high pressure caused by pulsed laser beam. This study provides valuable insights into the microstructure of water/heavy water clusters.

Spidroin-Inspired Hierarchical Structure Binder Achieves Highly Integrated Silicon-Based Electrodes.

As a promising component for next-generation high energy lithium-ion batteries, silicon-based electrode has attracted increasing attention by virtue of ultrahigh theoretical specific capacities. Nevertheless, fast capacity fade posed by tremendous silicon-based electrode volume changes during cycling remains a huge challenge before large-scale applications. Herein we develop an aqueous-oil binary solution based blend (AOB) binder characterized by a spidroin-like hierarchical structure for tolerating huge volume change of silicon-based electrodes. In AOB binder, the hydrophobic tetrazole groups-containing polymer (donate as PPB) and water-soluble amorphous poly(acrylic acid) mimicks the β-sheet and α-helix structure of spidroin, respectively. Benefitted by such biomimetic design, AOB binder enables both high tensile strength and elasticity, and strong electrode adhesion, therefore apparently stabilizing silicon-based electrode structure and rendering prolonged electrode cycle life. Such a strategy endows a 3.3 Ah soft package cells assembled with Si/C composite anode and NCM811 cathode with a discharge specific capacity of 2.92 Ah after 700 cycles. This work marks a milestone in developing state-of-the-art silicon-based electrodes towards high energy density lithium battery applications. This article is protected by copyright. All rights reserved.

Reliability-based topology optimization of fractionally-damped structures under nonstationary random excitation

This contribution proposes an effective reliability-based topology optimization (RBTO) framework for the layout of viscoelastic dampers of energy-dissipating structures under nonstationary seismic excitation, in which the constitutive behavior of viscoelastic damper is described by the novel fractional derivative models. To formulate the RBTO problem, the installation number of fractional viscoelastic dampers is minimized under the constraints of dynamic reliability, and the design variables are chosen as the damper parameters and the existence variables of the potential fractional viscoelastic dampers. The explicit responses are first established for the fractionally-damped structure, and the explicit response sensitivities with respect to the design variables are further derived through the adjoint variable method (AVM). On this basis, an explicit time-domain method (ETDM) is developed for explicit formulation of the statistical moments of responses and the moment sensitivities of the fractionally-damped structure, which are further employed to analytically derive the first-passage dynamic reliabilities and the reliability sensitivities of the structure based on the classical level-crossing process theory. Finally, the RBTO problem for the layout of fractional viscoelastic dampers is solved with the gradient-based method of moving asymptotes (MMA), in which the existence variables of fractional viscoelastic dampers can be driven to binary solutions by the solid isotropic material with penalization (SIMP) technique. An engineering application involving a building frame structure installed with fractional viscoelastic dampers is presented to validate the feasibility of the proposed ETDM-based RBTO framework.

Complexation-based selectivity of organic phosphonates adsorption from high-salinity water by neodymium-doped nanocomposite

Organic phosphonates have been widely used in various industries and are ubiquitous in wastewaters, and efficient removal of phosphonates is still a challenge for the conventional processes because of the severe interferences from the complex water constitutions. Herein, an Nd-based nanocomposite (HNdO@PsAX) was fabricated by immobilizing hydrated neodymium oxide (HNdO) nanoparticles inside a polystyrene anion exchanger (PsAX) to remove phosphonates from high-salinity aqueous media. Batch experiments demonstrated that HNdO@PsAX had an excellent adsorption capacity (∼90.5 mg P/g-Nd) towards a typical phosphonate (1-hydrox-yethylidene-1,1-diphosphonic acid, HEDP) from the background of 8 g/L NaCl, whereas negligible HEDP adsorption was achieved by PsAX. Attractively, various coexisting substances (humic acid, phosphate, citrate, EDTA, metal ligands, and anions) exerted negligible effects on the HEDP adsorption by HNdO@PsAX under high salinity. FT-IR and XPS analyses revealed that the inner-sphere complexation between HEDP and the immobilized HNdO nanoparticles is responsible for HEDP adsorption. Fixed-bed experiments further verified that HNdO@PsAX was capable of successively treating more than 4500 bed volumes (BV) of a synthetic high-salinity wastewater (1.0 mg P/L of HEDP), whereas only ∼2 BV of effective treatment capacity was received by PsAX. The exhausted HNdO@PsAX was amenable to a complete regeneration by a binary NaOHNaCl solution without significant loss in capacity. The capability in removing other organic phosphonates and treating a real electroplating wastewater by HNdO@PsAX was further validated. Generally, HNdO@PsAX exhibited a great potential in efficiently removing phosphonates from high-salinity wastewater.