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Fly ash (FA) is characterized by its porous structure and richness in silicon and aluminum oxides; thus, it can be used as an adsorbent for heavy metals. In order to enhance the absorption efficiency and stabilization effect, we prepared a new fly ash (FAKCa) using calcium hydroxide (Ca(OH)2) and phosphate (KH2PO4) through a simple one-step low-temperature alkali dissolution method and investigated its adsorption performance for lead and cadmium in water solutions and the stabilization effects of lead and cadmium in soils under flooding condition. Results showed that the Langmuir model best fit the adsorption behavior of lead and cadmium, and the maximal adsorption capabilities of lead (128 mg/g) and cadmium (39.1 mg/g) for FAKCa were increased by 236% and 14.5% compared with the unmodified FA, respectively. The adsorption of lead and cadmium by FAKCa was better fitted to the second-order kinetic model. The enhancement of adsorption capacities for lead and cadmium may be partly due to the specific surface area of FAKCa, which was increased by 94.0% compared to unmodified FA. FTIR, XRD, and XPS analysis showed that the Si-O and Al-O functional groups, carbonate, and hydroxide precipitation were facilitated by the adsorption of lead and cadmium. Thus, ion exchange, surface complexation, and formation of metal hydroxide and carbonate precipitation were the main adsorption mechanisms for lead and cadmium by FAKCa. In addition, the application of 0.1–0.6% FAKCa increased soil pH by 0.19–0.67 units and decreased the CaCl2-extractable lead by 12.3–86.5% compared to FA. Meanwhile, FAKCa was more effective in transforming lead and cadmium from exchangeable to stable fractions. This study shows that calcium hydroxide–phosphate-modified fly ash could effectively increase the adsorption and stabilization of lead and cadmium and, thus, has great potential for large-scale applications in contaminated soil. [ABSTRACT FROM AUTHOR]

Permanent magnet coupling (PMC) generates a large amount of thermal energy due to the eddy current induced in the metal isolation cylinder, resulting in performance degradation. The magnetic-thermal-mechanical coupling analysis has an important impact on the design and operation of PMC devices. In this paper, the Maxwell equations are solved based on the separated variable method; the 3D eddy current loss and magnetic torque equations are proposed; and the electrical conductivity, the convective heat transfer coefficient, and the magnetic-thermal-mechanical properties of PMC are presented. The 3D analytical coupling model calculates the temperature field and presents an uneven distribution of temperature along the coolant flow direction, and it then obtains a more precise magnetic field and torque under various temperatures. Furthermore, the working conditions such as rotor speed, coolant flow rate, and applied load are taken into consideration in the 3D analytical model. The results show that the eddy current loss is proportional to the square of the speed. With an increase in the load, the eddy current decreases. However, with an increase in the coolant flow, more eddy current loss would be produced, but the generated heat would be taken away by the increased coolant flow, resulting in a decrease in the temperature. The 3D analytical coupling model results are in good agreement with the experimental data, which is helpful to the design and optimization of the PMC system. [ABSTRACT FROM AUTHOR]