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A novel ionic liquid (IL) functionalized with thiodiglycol amic acid containing a soft S donor was synthesized for the effective and efficient extraction of platinum group metals (Ru, Rh, and Pd) from aqueous nitric acid solutions, such as high-level radioactive liquid waste (HLLW). The IL enabled rapid extraction of Pd(II) with an extraction ratio of approximately 100%. The extractions of Ru(III) and Rh(III) by the IL were slower than that of Pd(II), but the rates were accelerated by temperature elevation. The extractions of Ru(III) and Rh(III) at 50 °C reached equilibrium within 4 and 8 h, respectively, with the extraction ratios of over 90% without assisting agents or other methods for the extraction system. Furthermore, the IL could extract more than 90% of Ru(III), Rh(III), and Pd(II) from the simulated HLLW within 2 h at 50 °C.

This paper presents a method for junction temperature estimation using the mathematical thermal model in a two-level insulated-gate bipolar transistor (IGBT) inverter for motor drives. A power conversion system (PCS) comprises various components, and IGBT switches are the key components determining the reliability of the PCS. One of the challenges with regard to a PCS is improving its reliability. The failure of IGBTs is mainly due to variations in the junction temperature. To predict the lifetime of the PCS, the thermal behavior of the IGBT must be defined. The thermal behavior is dependent on the current that flows to the IGBT, and the load current profile is specific to the application. Generally, the switch module is encapsulated; therefore, an additional manufacturing process is necessary for measuring the junction temperature. The presented temperature estimation method using a mathematical model does not require an additional process for temperature measurement. An experiment is conducted using a diode-doped FS150R12KT4 module to determine the thermal profile of the IGBT for 11-kW interior permanent magnet synchronous motor drives. The effectiveness of the presented estimation method is verified by the simulation and experimental results.

Aiming at selective adsorption and separation of Y(III) from the Y(III)-Sr(II) group in acid solution, a silica-based TODGA impregnated adsorbent [(TODGA+1-dodecanol)/SiO2-P-F600] has been prepared. Batch adsorption experiments were conducted under the effect of contact time, acid concentration, solution temperature, and adsorption capacity etc. Chromatography recovery of more than 90% Y(III) was successfully achieved under elution with 0.01 M DTPA solution in nitric acid adsorption system, and 0.1 M HCl solution in hydrochloride adsorption system, respectively.

In the present study, a porous silica-based covalent organic framework incorporated composite was prepared using a solvothermal reaction and the following wet-impregnation method. Multiple characterization methods including Scanning electron microscope, Fourier transform infrared spectroscopy, X-ray powder diffraction confirmed the surface morphology, thermal stability, and pore structure of the as-prepared composite. The adsorption performances of the prepared composite toward palladium [Pd(II)] from simulated high-level liquid waste were systematically investigated using batch experiments under the effect of contact time, solution temperature, and nitric acid solution.

(HDEHP + Hexa)/SiO2-P, a silica-based adsorbent, was prepared and used to separate Y(III) from a mixed solution of Sr(II) and Y(III). The adsorption behavior of the adsorbent was investigated using batch tests. The adsorbent exhibited high adsorption performance for Y(III) in low nitric acid concentrations and weak adsorption performance for Y(III) at higher concentrations. In contrast, Sr(II) was not adsorbed in either acid concentration range. The same tendency was observed under hydrochloric acid conditions. Y(III) separation from a mixed solution of Sr(II) and Y(III) was verified by a column test. Overall, the (HDEHP + Hexa)/SiO2-P adsorbent can separate Y(III) from Sr(II).

A hydrophobic ionic liquid including an amino moiety ([DiOcAPmim][NTf2]) was synthesized. Its extraction behaviors towards Pd(II), Ru(III), Rh(III) were investigated in nitric acid aqueous solution as a function of contact time, effect of concentration of nitric acid, effect of temperature, and effect of co-existing metal ions. The extraction kinetics of Pd(II) was fairly fast and extraction equilibrium can be attained within only 5 min under the [HNO3] = 2.05 M. When [HNO3]< 1 M, the extraction percentage of Pd(II), Ru(III), Rh(III) were all above 80%. When [HNO3] reached 2 M, all of the extraction percentage decreased and in an order of Pd(II)>Ru(III)>Rh(III). When [HNO3]> 2 M, the extraction performance gradually recovered. The effect of temperature can slightly affect the extraction performance of Pd(II). Furthermore, in simulated high-level liquid waste, [DiOcAPmim][NTf2] showed a better preference towards Pd(II) under the interference of various other co-existing metal ions.

A novel silica-based adsorbent was synthesized by impregnating macroporous silica polymer composite (SiO

To efficiently separate Pd(II) from high-level liquid waste (HLLW), a (TEHTDGA + dodecanol)/SiO2-P silica-based adsorbent (TEHTDGA resin) was synthesized by impregnating SiO2-P particles with N,N,N���,N���-tetra-2-ethylhexyl-thiodiglycolamide (TEHTDGA) and dodecanol. Our experimental results indicate that TEHTDGA resin exhibits high distribution coefficients for Pd(II) at HNO3 concentrations from 0.1 M to 5.0 M. The adsorption behavior of Pd(II) was found to quickly reach an equilibrium state, with a nearly 100% uptake ratio. Based on adsorption isotherm analyses, the experimental results for Pd(II) fit well with the Langmuir isotherm model. TEHTDGA resin was also confirmed to exhibit high adsorption capacity for Pd(II). The adsorption behavior of Pd(II) was hardly affected by temperature. In an evaluation of the amount of leaked sulfur, TEHTDGA resin demonstrated good chemical stability. The results of a chromatography separation experiment indicate that almost all the Pd(II) could be successfully separated and recovered from simulated HLLW using 0.1 M thiourea in 0.01 M HNO3 solution as an eluent.

Aiming at selective adsorption and separation of Pd(II) in nitric acid solution, a hybrid soft N and hard O donor adsorbent (TAMIA-EH+TOA)/SiO2–P (P = Polymer) was successfully synthesized. The adsorption performances of (TAMIA-EH+TOA)/SiO2–P adsorbent towards Pd(II) were systematically investigated as a function of contact time, effect of concentration of nitric acid, effect of temperature etc. Adsorption speed of Pd(II) was fairly fast and can reach equilibrium state within only 0.5 h. The distribution coefficient of Pd(II) was more than 103 when [HNO3] = 0.1. Though it decreased gradually with an increase in the concentration of HNO3, the adsorption selectivity of (TAMIA-EH+TOA)/SiO2–P adsorbent towards Pd(II) was still significant than other co-existing metal ions in the whole HNO3 range from 0.1 to 5 M. The adsorption isotherm of Pd(II) onto (TAMIA-EH+TOA)/SiO2–P adsorbent fitted well with Langmuir adsorption model but Freundlich isotherm model. The calculated results of adsorption thermodynamic parameters indicated that the adsorption process of Pd(II) was exothermic and happened in a natural way. Furthermore, the separation chromatography experiment by utilizing (TAMIA-EH+TOA)/SiO2–P adsorbent packed column was carried out. Based on the results of plotted elution curves, it was found that the successful recovery of Pd(II) (96.27%) was achieved by eluting with thiourea solution.

There is a great demand for a dispersion evaluation method that can be applied even when a nano-sized filler is incorporated, that can evaluate a three-dimensional (3D) quantitative dispersion of a composite material, and that is not expensive and time consuming. Here, we proposed light-intensity dispersion index (LDI) to quantitatively evaluate the dispersion based on the light scattering distribution on divided optical microscopy (OM) images. Difference in the light-intensity is determined by the dispersion and agglomeration of the filler in the polymer matrix; therefore, the smaller the distribution and the number of peaks of light-intensity, the more uniform the dispersion. The reliability of the developed LDI was improved by introducing an agglomeration size weighting factor. Furthermore, the validity of the LDI was also verified in comparison with the experimental results. In conclusion, we have successfully developed a method for the 3D quantitative dispersion evaluation of nanocomposites with minimal cost and time consumption.

Adsorption and separation performances of a microporous silica-based (DAMIA-EH + TOA)/SiO2-P adsorbent towards Pd(II) were systematically investigated under the effect of contact time, temperature, concentration of nitric acid, chromatography etc. in a simulated high-level liquid waste containing 14 kinds of representative co-existing metal ions. Successful recovery of around 97.95% Pd(II) was achieved under the elution with 0.01 M Tu (pH = 2) solution in column experiment.

The adsorption behaviors of a silica-based hybrid donor adsorbent (TAMIA-EH+1-dodecanol)/SiO2-P towards Pd(II) were investigated under the effect of the contact time, temperature etc. in simulated high-level liquid waste. The adsorption rates of Pd(II) and Re(VII) were fairly fast and could reach the equilibrium state in only 1 h compared with other co-existing metal ions. The adsorption kinetics of Pd(II) was found to fit well with the pseudo-first order model. Even though with increasing the concentration of HNO3 above 1 M, the adsorption performance of (TAMIA-EH+1-dodecanol)/SiO2-P decreased gradually; it still exhibited a better selectivity towards Pd(II) when [HNO3] > 0.5 M. The adsorption isotherms of Pd(II) and Re(VII) were well-described by the Langmuir isotherm model, while the Freundlich isotherm model was considered to be more suitable for the adsorption of Ru(III), Zr(IV) and Mo(VI). A high temperature of an aqueous solution was not good for the effective recovery of Pd(II). The calculated thermodynamic parameters revealed that the adsorption of Pd(II) was exothermic in nature.

There is a growing demand for the development of a melt process-based nanocomposite manufacturing process capable of minimizing the incorporation of expensive carbon nanotubes (CNTs) by inducing a uniform dispersion of multi-walled CNTs (MWNTs). In this study, we proposed a nanocomposite manufacturing process that includes both physical particle mixing using high-speed rotation and anionic polymerization of e-caprolactam (CL) to induce a uniform dispersion of MWNTs. MWNTs were uniformly dispersed by powder mixing and then wrapped with polyamide 6 polymers by in-situ polymerization of CL. The synergistic effect of the two sub-processes resulted in an enhanced dispersion of MWNTs and prevented aggregation of the MWNTs. The composites fabricated by the proposed process exhibited electrical conductivities of 4.49 × 10−5 S/m and 1.45 × 10 S/m at 1 wt% and 3 wt% MWNTs, respectively, indicating that by applying the proposed process it is possible to incorporate a smaller amount of MWNT to achieve electrical conductivities applicable for electrostatic discharge (ESD) (>1 X 10−5 S/m) and electromagnetic interference shielding effectiveness (EMI SE) (>10 S/m) applications. An ESD chip tray and EMI SE mobile phone case were fabricated using the prepared composite, and it was verified that the ESD and EMI SE performances can be realized.

An acid-stable 2D covalent organic framework (COF TpPa-1) was synthesized by a reversible Schiff-base reaction and the following irreversible enol-keto tautomerism. The adsorption behaviors of COF TpPa-1 towards Pd(II) in simulated high-level liquid waste (HLLW) were investigated under the effect of contact time, the concentration of nitric acid etc. The obtained experimental results supported that the utilization of this type of acid-stable COF in HLLW to recover metal ion was feasible.

Silica aerogels have attracted great interest for several decades because of their super thermal insulation property, but their fragility has limited their application in every-day products. Here we describe a method to fabricate flexible and thermally-insulated composites by using a flexible poly(dimethylsiloxane) (PDMS) matrix and by preventing matrix impregnation of the silica aerogel pores. The silica aerogel was first mixed with ethanol to prevent impregnation of the silica aerogel pores with PDMS molecules. After composite fabrication, the ethanol was removed. The optimum PDMS composite had super thermal insulation (0.018 W/m·K) and was flame-retardant, in addition to being flexible. This method described here will facilitate the application of silica aerogel-incorporated composites as thermal insulation materials for products that require flexibility and flame-retardant properties.

Techniques for optimizing the dispersion of carbon nanotubes in composites by applying small amounts of additives in a simple manner are recognized as one of the most important core technologies in nanocomposite engineering. In this study, we reported the feasibility of phenyl glycidyl ether (PGE) as an effective noncovalent functionalization agent and suggested a facile and low-temperature process that applied high-speed rotation based on a planetary centrifugal mixer to improve the dispersion of multiwalled carbon nanotube (MWCNT) in the polyamide 6 (PA6) composite. PGE molecules were introduced on MWCNTs based on the π-π* interaction, resulting in enhanced MWCNT dispersion by preventing of the aggregation between the MWCNTs due to the van der Waals force. The tensile strength of the PA6 composite fiber filled with 1 wt% MWCNTs was improved up to 31.8% by the PGE treatment, indicating that PGE molecules were an effective noncovalent functionalization agent.

To separate Y(III) from a Sr(II)–Y(II) mixture, two silica-based adsorbents, CMPO/SiO2-P and (CMPO + Dodec)/SiO2-P were prepared by impregnating octyl(phenyl)-N,N-diisobutylcarbamoyl methylphosphine oxide (CMPO) extractant and a molecule modifier (1-Dodecanol) into macroporous silica/polymer composite support (SiO2-P). The Adsorbents showed high adsorption affinity to Y(III) and weak adsorption affinity to Sr(II) in HNO3 solution. The amount of adsorbed Y(III) increased with the HNO3 in the solution. The amount of adsorbed Y(III) increased with contact time and reached equilibrium within 30 min. The results showed that a pseudo-second-order kinetic model with a high correlation coefficient described the adsorption process better than other kinetic models. Successful Y(III) separation from Sr(II)–Y(III) mixture in HNO3 solution was achieved.

We herein propose a facile approach to fabricate foldable and coatable silica aerogel polyurethane composites (APCs). For the flexibility control, the soft segment of polyurethane (PU) is manipulated. The change in soft segment length induces a difference in overall glass transition temperature of PU. When the silica aerogel content is increased, the PU with a shorter soft segment length shows brittle fracture behavior, while the PU with a longer soft segment length shows no breakage after bending. The thermal insulation properties of APCs were enhanced by 72% reduction in thermal conductivity upon 30 wt% aerogel loading and theoretically verified by a micromechanics-based thermal conductivity model considering the effects of interface and agglomeration. In addition, for the combustion behavior measurements, heat release rate and heat release capacity are substantially reduced for the APCs compared to neat PUs. Those enhanced thermal insulation properties may have a commercial impact on thermal insulation applications.

The thermally insulating, fire-retardant, smokeless and flexible polymer nanofiber is an incredibly important material for mankind. This polymer nanofiber is expected to breed technological innovations in applications such as thermally insulated clothing and building materials. Here, we propose an electrospinning process to fabricate silica aerogel-filled polymer nanofibers by modifying the typical sol–gel chemistry process for the synthesis of silica aerogel. Silica aerogel-filled polyvinylidene fluoride (PVdF) nanofiber webs, fabricated using the proposed process, were fire-retardant, smokeless and flexible; they also exhibited a low thermal conductivity of 0.028 W·m−1·K−1, which was 26.3% lower than that of pure PVdF nanofiber webs. To study the unique thermal characteristics of nanofibers theoretically, a micromechanics-based, two-scale multiphase model was proposed, with consideration of fiber structure including nano and micro pores. These developments make an important contribution to bringing silica aerogel products to everyday life.

Recently, studies have been reported to synergistically improve the electrical conductivity of polymer composites by simultaneously incorporating hybrid fillers, but systematic studies on filler loading and ratio are still scarce. In this study, a one-step process was proposed to induce the incorporation of uniformly dispersed fillers with a high content, and synergistic improvement in the electrical conductivity of polymer composites was studied by applying two types of carbon fillers: nano-sized multi-walled carbon nanotube (MWCNT) and micro-sized pitch-based carbon fiber (PCF). Based on the proposed process, it was possible to fabricate a polymer composite in which the filler was uniformly dispersed within 40 wt%. The electrical conductivity of the composite containing up to 10 wt% MWCNT which was the percolation plateau content and 30 wt% PCF was 3940 S m−1, showing the maximum performance. This result was improved by 595% and 586%, respectively, compared to the electrical conductivity of the composite containing only 40 wt% MWCNT or PCF. These findings can contribute to expanding the application of conductive composites in the fields of antistatic or electromagnetic interference shielding by providing insight into the optimal design of hybrid filler systems to improve the electrical conductivity of composites.

In this study, the synergistic adsorption behavior of palladium [Pd(II)], molybdenum [Mo(VI)], and zirconium [Zr(IV)] in simulated high-level liquid waste was systematically investigated based on various factors, such as the contact time, concentration of nitric acid, adsorption amount, and temperature using a silica-based adsorbent impregnated with N,N′-dimethyl-N,N′-di-n-hexyl-thiodiglycolamide (Crea) and 2, 2′, 2′ -nitrilotris[N,N-bis(2-ethylhexyl)acetamide] (TAMIA-EH). The adsorption rates of Pd(II), Mo(VI), and Zr(IV) in this synergistic adsorption system were high; thus, equilibrium states could be obtained in only 1 h with high uptake percentages of more than 90%. The adsorption abilities of Pd(II), Mo(VI), and Zr(IV) were only slightly affected by variation in the concentration of nitric acid in the range of 0.1–5 M and solution temperature in the range of 288–313 K. Selective stripping of the adsorbed Re(VII), Pd(II), Zr(IV), and Mo(VI) was successfully achieved under elution with 5 M HNO3, 0.2 M Tu (pH 1), 50 mM DTPA (pH 2), and 50 mM DTPA dissolved in 0.5 M Na2CO3 (pH 11) solutions using the chromatography method. In addition, the adsorption performance in solid-state was studied using the particle-induced X-ray emission (PIXE) method; the obtained results were in good agreement with the results obtained via column separation.