Search

The capture of highly radiotoxic 90Sr from an acidic waste solution during used fuel reprocessing and environmental remediation in a nuclear accident is desirable and challenging. Herein, we show a metal organic framework material (SNU-200) functionalized with an 18-crown-6-ether, whose specific binding site with an excellent affinity toward strontium leads to excellent Sr2+ adsorption capability under acidic conditions. This material exhibits a high adsorption capacity (44.37 mg g−1 at pH = 3), remarkable affinity (Kd = 3.63 × 104 mL g−1) and ultrahigh selectivity in the presence of interfering coexisting ions such as Na+, K+, Cs+, Mg2+, and Ca2+.

Thermal energy storage (TES) is among the most powerful tools to alleviate the risk of fossil energy depletion. Latent heat density and thermal conductivity are the two most important parameters to evaluate the performance of TES materials. In this work, for the first time, we embed knitting aryl network polymers (KAPs) on the skeleton of copper foam (CF) in a biomimetic protocol, where the preparation process is inspired by the growing process of a natural coral and the obtained phase change material (PCM)-holding medium exhibits a bird nest-type morphology. Excellent energy storage performance was determined, where the thermal conductivity was up to 55.37 W m−1 K−1 and the encapsulation rate could reach 62.1% without the observation of any enthalpy attenuation even after a 300 energy charging and releasing cyclization, due to the relatively high surface area, i.e., 1079.1 m2 g−1 and high thermal conductivity of the copper skeleton inside. Further study revealed the good applicable properties in terms of shape adjustability, light-to-thermal and light-to-electric conversion.

The all-in-one solar steam generation device renders a feasible technical support for freshwater supply in arid areas, where traditional large-scale desalination cannot be applied. In this work, we designed and assembled a paper-based integrated evaporation device (IED) for efficient solar steam generation, in which the self-hardening polyurethane foam was ingeniously fixed on the carbon nanotube (CNT) loaded filter paper connecting with four paper belts to perfectly integrate light absorption, water supply and thermal insulation into one device. Moreover, the effects of CNT concentration and illumination intensity on evaporation performance were experimentally investigated. The results showed that the maximum thermal conversion efficiency of the IED was as high as 88.1% at 1 kW m−2. Our research indicated that the IED as an easily-enlarged and all-in-one evaporation device was one of the ideal choices for applications in solar steam generation and provided a new resource for seawater desalination.

Catalytic performance of Cu and Zn catalysts was investigated during rice husk (RH) high-temperature pyrolysis under isothermal conditions in a micro-fluidized bed reactor. The results showed that the presence of Cu and Zn evidently influenced the release characteristics and conversion of the gas components. The impregnated Cu promoted the conversion of H2, CH4, CO and CO2, while Zn showed positive catalytic effect on the conversion of H2, CH4 and CO2 and negative effect on the conversion of CO. The X-ray diffraction patterns of the residue chars revealed that metallic copper nanoparticles (Cu0) were formed during Cu impregnated biomass pyrolysis. Textural characterization and SEM images showed that the impregnation of Cu and Zn, particularly Zn, promoted the generation of micropores and mesopores, with the pore sizes predominantly at around 1.3 nm and 3.9 nm. Reaction kinetics for generating these gases was studied based on model fitting method, and the most probable reaction mechanism was obtained based on the relative error between experimental and calculated conversion data. The resulting apparent activation energies were 85.08, 12.56, 49.72 and 38.37 kJ/mol for the formation of H2, CO, CH4 and CO2 from pure RH pyrolysis. The presence of Cu decreased the forming activation energies of the four gases, and Zn decrease the forming activation energies of H2, CH4 and CO2 while increased the value for the formation of CO.

The work aims to investigate an effective method of catalytic reforming of tar during biomass high-temperature pyrolysis using rice husk char (RHC) and metal impregnated (Fe, Cu and K) char in a dual-stage reactor. The char and char-supported catalysts exhibited high catalytic performance, in terms of the high tar conversion efficiencies of 77.1% for RHC, 82.7% for K-RHC, 92.6% for Fe-RHC and 90.6% for Cu-RHC at 800 °C. Moreover, K-RHC and Cu-RHC catalysts after three cycles still exhibited high activity for tar removal. The catalytic tar conversion by char or char-supported catalysts contributes to improving the yield of syngas, particularly the combustible gases of H2, CO and CH4, corresponding to the syngas yield increasing from 196.6 mL/g for thermal reforming to 269.6 mL/g for K-RHC, 274.9 mL/g for Cu-RHC and 342.7 mL/g for Fe-RHC at 800 °C, respectively. The results from GC–MS analysis illustrated that the addition of char and char-supported catalysts promoted the transformation of larger polycyclic aromatic hydrocarbons into lighter tar compounds, leading to an increase in the proportion of single-ring tars. XRD results indicated that the most active phases of the fresh K-RHC, Cu-RHC and Fe-RHC for tar cracking and reforming were KCl, Cu and Fe, respectively. Textural characterization showed the addition of Fe and Cu was in favor of producing highly porous carbon materials and led to the increase in specific surface area and total pore volume.

Isothermal pyrolysis of rice husk catalyzed by iron and nickel was conducted in a microfluidized bed reactor to investigate the forming characteristics and kinetics of the main gas components. Results indicated that both Fe and Ni showed a catalytic effect on the releasing behavior of gaseous products during rice husk pyrolysis. The forming reaction rate of H2 and CO2 was significantly promoted with the addition of Fe or Ni, while that of CH4 was inhibited. For CO, Ni showed a positive effect while Fe showed a negative effect on its forming rate. The char evolution of rice husk was also influenced by the presence of Fe and Ni from the SEM-EDX and BET results. The model fitting method was used to calculate the kinetics of gas releasing to further investigate the effect of Fe and Ni, and the most probable reaction mechanism was obtained based on the relative error between experimental and calculated conversion fraction. Corresponding to the changing trend of reaction rate, the obtained activation energies f...

This work aims to investigate the importance of biomass char and the metal oxides in the ash in tar cracking during the volatile–char interactions. Experiments were carried out in a two-stage fixed reactor, and corncob, one typical agricultural biomass rich in potassium, was chosen as raw material. Results showed that char and char-supported potassium catalysts have good activity for tar elimination due to the good absorbability of char and catalytic property of potassium. In particular, tar conversion efficiency can reach 95.8% by using 1.5 K-char catalyst at 700 °C. The reforming reactions can be significantly enhanced during the volatile–char interactions in the presence of char and char-supported potassium catalysts. As a result, the syngas yield increased significantly with increasing temperature and supported K+, particularly the combustible gases including H2, CO and CH4. Physical and chemical structure of char changed due to reforming reactions related to the carbon, while the content of potassium was almost unchanged.

Influence of potassium on the gas releasing behaviors during rice husk high-temperature pyrolysis was investigated under isothermal conditions in a two stage micro-fluidized bed reactor. Reaction kinetics for generating H2, CO, CO2 and CH4 was investigated based on the Friedman and model-fitting approaches. Results indicated that different gas species had different times to start and end the gas release process, particularly at 600 °C, representing different chemical routes and mechanics for generating these gas components. The resulting apparent activation energies for H2, CO, and CO2 decreased from 23.10 to 12.00 kJ/mol, 15.48 to 14.03 kJ/mol and 10.14 to 7.61 kJ/mol respectively with an increase in potassium concentration from 0 to 0.5 mol/kg, while that for CH4 increased from 16.85 to 19.40 kJ/mol. The results indicated that the addition of potassium could promote the generation reactions of H2, CO and CO2 while hinder the generation reactions of CH4. The pyrolysis reaction was further found to be subject to the three-dimensional diffusion model for all the samples.

Development of latent functionally thermal fluid (LFTF) with excellent optical absorption and controllable heat transfer properties for direct absorption solar collector (DASC) is crucial in solar thermal utilization. In this study, the microcapsule, with melamine-formaldehyde (MF) resin shell and octadecane core, was prepared via in situ polymerization, as its shell was modified by reduced graphene oxide (rGO) and its core was doped with oleic acid coated Fe3O4 magnetic nanoparticles (OA-MNs). The microstructure, optical, thermal and magnetic properties of rGO modified magnetic phase change microcapsules (rGO-MPCMs) were investigated by means of various characterizations. The experimental results revealed that adding rGO substantially enhanced the thermal conductivity of magnetic phase change microcapsules (MPCMs) and only had tiny impact on the phase change behavior of MPCMs. Meanwhile, the thermal stability of octadecane in rGO-MPCMs was remarkably improved due to MF resin shell served as protective barrier. Furthermore, the rGO-MPCMs slurry exhibited better optical absorption and thermal storage capacities compared with MPCMs slurry and deionized water, thus enhancing photo-thermal conversion performance. Under an external magnetic field, the rGO-MPCMs in slurry presented excellent controllability and recyclability. Our research demonstrated that the rGO-MPCMs slurry, as a desirable working fluid, showed spacious application prospect for DASC.

Dynamic strain measurement is rather important for the characterization of mechanical behaviors in electromagnetic forming process, but it has been hindered by high strain rate and serious electromagnetic interference for years. In this work, a simple and effective strain measuring technique for physical and mechanical behavior studies in the electromagnetic forming process has been developed. High resolution (∼5 ppm) of strain curves of a budging aluminum tube in pulsed electromagnetic field has been successfully measured using this technique. The measured strain rate is about 10(5) s(-1), which depends on the discharging conditions, nearly one order of magnitude of higher than that under conventional split Hopkins pressure bar loading conditions (∼10(4) s(-1)). It has been found that the dynamic fracture toughness of an aluminum alloy is significantly enhanced during the electromagnetic forming, which explains why the formability is much larger under electromagnetic forging conditions in comparison with conventional forging processes.