Relationship between pore structure and hydration activity of CaO from carbide slag

CaO needs to show high activity to be used as Ca-sorbent and slagging agent. Hydration activity is an important characteristic to evaluate the activity of CaO. In this study, carbide slag from polyvinyl chloride (PVC) industry was utilized as precursor for preparing high activity CaO. The roles of crystallite grain, average pore diameter (APD) and volume fraction of pore < 200 nm in diameter (VF200) in hydration activity of CaO from carbide slag (CS-CaO) were respectively investigated. The hydrolysis kinetics model of CaO shows a three-dimensional spherically symmetric diffusion model (D4), which suggests that hydration activity was mainly associated with APD and VF200 of CS-CaO with limited correlation to the crystal size. Specifically, the hydration activity of CS-CaO is increased with increasing VF200, while decreased with increasing APD. Under the invariable calcination temperature, the core-shell structure formed by the addition of graphite or CaCO₃ to CS effectively inhibits the sintering of CS-CaO and improves VF200. Consequently, the hydration activity of CS-CaO increased from 22.79℃·min^-1 to 27.19℃·min^-1 and to 29.27℃·min^-1, with addition of 5% graphite or 5% CaCO₃ into carbide slag, respectively.     

The potential of pervaporation for biofuel recovery from fermentation:An energy consumption point of view

Recovering alcohols from dilute fermentation broth is an emergent task in bio-fuel production process. Since they are primary planned for fuels, energy required to separate these alcohols should be considered in evaluating the potential of a separation technology. A membrane-based process, pervaporation, is of special interest because of its environmental friendliness and easy integrating character. This review probes into the fundamentals of pervaporation especially in terms of the heat required for evaporation. Meanwhile, the separation data of the most representative alcohol-selective pervaporation membranes reported in the literatures are collected and compared with the vapor–liquid equilibrium curve, which represents the distillation selectivity. They include:inorganic membranes, silicon rubber based membranes, Mixed Matrix Membranes and some other special materials. By doing so, the status of alcohol recovery via pervaporation would be more clear for researchers.For ethanol recovery, it is selectivity rather than flux that is in urgent need of solution. While for butanol recovery,membranes with satisfactory selectivity have been developed, increasing the separation capacity would be more pressing.     

Elimination mechanism of micropores on bonding interface during solid-state crystal growth method

A pure yttrium aluminum garnet (YAG) ceramic/YAG single crystal composite material is prepared using the optimized solid-state crystal growth (SSCG) method. The micropores on the bonding interface of the composite sample are eliminated for the first time during the SSCG process and the transmittance is very close to the theoretical value, which reached 83.14% at 1064 nm. Meanwhile, the mechanism of elimination and migration of the pores under high temperature is studied. Additionally, the single crystal growth rate has significantly improved and the time of composite sample preparation has also significantly reduced proving that the SSCG method is an effective method for producing high quality composite material.     

Influence of LiBO2 addition on the microstructure and lithium-ion conductivity of Li1+xAlxTi2−x(PO4)3(x = 0.3) ceramic electrolyte

Concerning the safety problems of conventional Li-ion batteries with liquid electrolytes, it is crucial to develop reliable solid-state electrolytes with high ionic conductivity. Li_1+xAl_xTi_2?x(PO₄)₃ (LATP, x = 0.3) is regarded as one of the most promising solid electrolytes due to its high ionic conductivity and excellent chemical stability to humidity.Herein, a new strategy is proposed for improving the sintering behavior and enhancing the ionic conductivity of LATP by using LiBO₂ as the sintering aid via liquid phase sintering. The as-prepared sample LATP with homogeneous microstructure and high relative density of 97.1% was successfully synthesized, yielding high total ionic conductivity of 3.5 × 10^?4 S cm^?1 and low activation energy of 0.39 eV at room temperature. It was found that the addition of LiBO₂ could effectively enhance the densification and increase the ionic conductivity of LATP electrolyte, proving an effective way to synthesis LATP ceramics by a simple and reliable route.     

Aminolysis of ethyl acetate in continuous flow and its reaction kinetics

The aminolysis of ethyl acetate was promoted significantly via continuous reaction in a tubular reactor. N-propylacetamide was thus synthesized without presence of solvent and catalyst. The optimum conditions were obtained as follows:the reaction temperature is 218℃, the reaction pressure is 3.5 MPa, the molar ratio (ethyl acetate:N-propylamine) is 1:1, and the residence time is 350 min. Accordingly, the conversion of ethyl acetate is up to 94.8%. Furthermore, the kinetics of the rapid reaction stage (when the conversion of ethyl acetate is 20%-80%) can be expressed as lnk--4629:44 1/T + 2:1366, and the apparent activation energy is E_a=38489 J·mol^-1.     

Enhanced piezoelectric properties and temperature stability of Bi4Ti3O12-based Aurivillius ceramics via W/Nb substitution

Bi₄Ti₃O₁₂ (BIT), a typical Aurivillius ceramics with high Curie temperature (T_c ? 675 °C), has great potential for high temperature applications. This work provides an effective method of inducing structure distortion, relieving the tetragonal strain of the TiO₆ octahedron and decreasing the concentration of oxygen vacancies to improve the piezoelectricity and temperature stability of BIT ceramics. Bi₄Ti_2.98W_0.01Nb_0.01O₁₂ possesses an optimum piezoelectric coefficient (d₃₃) of 32 pC/N, a high T_c of 655 °C and a large resistivity of 3 × 10⁶ Ω·cm at 500 °C. The maximum d₃₃ reported here is approximately quadruple than that of pure BIT (?7 pC/N). Moreover, the d₃₃ of W/Nb co-doped BIT and the in-situ temperature stability of the compression-mode sensor present a highly stable characteristic in the range of 25–600 °C. These results imply that W/Nb-modified BIT ceramics is a promising candidate for application at high temperatures of up to 600 °C.