Effect of borohydride as reducing agent on the structures and electrochemical properties of Pt/C catalyst

In this paper, we found that boron deposited on the surface of support when sodium borohydride used as reducing agent during the preparation of Pt/C catalyst. The deposition of boron markedly reduces particle size of Pt, raises electrochemical active surface (EAS) area of catalyst and electrochemical activity for hydrogen evolution or oxygen reduction reaction (ORR) compared with which prepared using other reducing agents (hydrogen and formaldehyde).     

Experimental study of the effect of drag reducing agent on heat transfer and pressure drop characteristics

The effect of the addition of polymeric drag reducing agent on water flow heat transfer and pressure drop was studied experimentally. Polyacrylamide (PAM) aqueous solutions at different concentrations (up to 100 ppm) at fully developed turbulent flow were used in a double tube heat exchanger. In contrast to previous studies, drag reduction due to using PAM was negligible. The addition of PAM, even at low concentrations, caused significant reduction in heat transfer. Results showed that increasing PAM concentration lowered the amount of heat transfer. Maximum heat transfer reduction of 25% occurred at the concentration of 100 ppm for PAM aqueous solution.     

Effects of (NH4)2SO4 on the characteristics of the deposits and properties of an electroless Ni-P plating solution

The effects of ammonium sulfate (AS) in bath on the deposition rate, hypophosphite efficiency, bath stability, and characteristics of electroless nickel-phosphorous (EN) deposits were studied. The deposition rate of EN deposits was estimated by the gravimetric method. The results showed that the deposition rate of EN can be improved by the addition of AS when its concentration is lower than 12 g dm⁻³. Bath stability test was used to determine the stabilization effect of AS. The stability of the EN bath can be significantly decreased by a low concentration of AS, whereas a minimal influence on bath stability was observed with an increased concentration of AS. The variation in the efficiency of hypophosphite was also examined by traditional methods of chemical analysis. Characterization of the deposits was carried out by potentiodynamic polarization experiments, scanning electron microscopy, and energy dispersive X-ray, which can analyze the Ni and P content. The results indicated that a low accumulation of AS (lower than 12 g dm⁻³) in the plating process did not adversely affect the characteristics of the deposits. An optimum concentration of AS can decrease grain size, refine microstructure, and improve corrosion resistance. However, a very concentrated AS plating bath may result in an increase in stress of the coating, hence creating a cracked cross-section morphology.     

Experimental and predictive study on the performance and energy consumption characteristics for the regeneration of activated alumina assisted by ultrasound

Activated alumina used in dehumidification should be regenerated at more than 110 °C temperature, resulting in excessive energy consumption. Comparative experiments were conducted to study the feasibility and performance of ultrasonic assisted regeneration so as to lower the regeneration temperature and raise the efficiency. The mean regeneration speed, regeneration degree, and enhanced rate were used to evaluate the contribution of ultrasound in regeneration. The effective moisture diffusivity and desorption apparent activation energy were calculated by theoretical models, revealed the enhanced mechanism caused by ultrasound. Also, we proposed some specific indexes such as unit energy consumption and energy-saving ratio to assess the energy-saving characteristics of this process. The unit energy consumption was predicted by artificial neural network (ANN), and the recovered moisture adsorption of activated alumina was measured by the dynamic adsorption test. Our analysis illustrates that the introduction of power ultrasound in the process of regeneration can reduce the unit energy consumption and improve the recovered moisture adsorption, the unit energy consumption was decreased by 68.69% and the recovered moisture adsorption was improved by 16.7% under 180 W power ultrasound compared with non-ultrasonic assisted regeneration at 70 °C when initial moisture adsorption was 30%. Meanwhile, an optimal regeneration condition around the turning point could be obtained according to the predictive results of ANN, which can minimize the unit energy consumption. Moreover, it was found that a larger specific surface area of activated alumina induced by ultrasound contributed to a better recovered moisture adsorption.     

Effect of ultrasound on the structural characteristics and oxidative stability of walnut oil oleogel coated with soy protein isolate-phosphatidylserine

In this study, the three-dimensional network system formed by rice bran wax (RBW) was used as the internal structure, and the external structure formed by soybean protein isolate (SPI) and phosphatidylserine (PS) was added on the basis of the internal structure to prepare walnut oil oleogel (SPI-PS-WOG). Ultrasonic treatment was applied to the mixed solution to make SPI-PS-WOG, on the basis, the effects of ultrasonic treatment on SPI-PS-WOG were investigated. The results showed that both β and β’ crystalline forms were present in all SPI-PS-WOG samples. When the ultrasonic power was 450 W, the first weight loss peak in the thermogravimetric (TGA) curve appeared at 326 °C, which was shifted to the right compared to the peak that occurred when the ultrasonic power was 0 W, indicating that the thermal stability of the SPI-PS-WOG was improved by the ultrasonic treatment. Moreover, when the ultrasonic power was 450 W, the oil holding capacity (OHC) reached 95.3 %, which was the best compared with other groups. Both confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) showed that the ultrasonic treatment of appropriate power succeeded in making the SPI-PS-WOG samples more evenly dispersed in the internal structure and denser in the external structure. In terms of oxidative stability, it was found that the peroxide value of SPI-PS-WOG remained at 9.8 mmol/kg oil for 50 days under 450 W ultrasonic power treatment, which was significantly improved compared with liquid walnut oil (WO). These results provide a new idea for the preparation of oleogels, and also lay a theoretical foundation for the application of ultrasonic treatment in oleogels.