•The facile preparation method of Ni@C composites is proposed.•Ni@C composites are magnetic and recoverable from water.•The removal rate of Ni@C composites is 98.71%.•The attractive force and the bond affect the adsorption ability of Ni@C composites.Carbon-encapsulated nickel particles (Ni@C composites) for removing Fe3+ in wastewater have been prepared by the carbonization of phenolic resin mixing with nickel particles. XRD results reveal that the Ni@C composites are consisted of C, Ni, and Ni3S2. The TG-DTG curves of Ni@C composites are almost same as that of phenolic resin. The morphology investigation shows that Ni is distributed randomly on carbon. Based on analysis of N2 adsorption-desorption isotherm, the surface area and pore volume of Ni@C composites are 187.47 m2 g−1 and 0.06900 cm3 g−1 nm−1, respectively. The saturation magnetization values for Ni@C composites are 68.99 emu·g−1 determined by the Vibrating Sample Magnetometer. Ni@C composites exhibit a high adsorption capacity for Fe3+. The adsorption behavior follows the pseudo-second-order kinetic and Langmuir model between the adsorbents and Fe3+. Furthermore, the adsorption capacity of Ni@C composites derives from the attractive force between the adsorbed anion and the surface positive charge of Ni@C composites, as well as the bond between the adsorbed cation and the COO− groups. From the above results Ni@C composites can be widely applied in wastewater treatment as a new efficiency and excellent recoverable adsorbent.

•Carbon micro- and nanofibers were prepared by using centrifugal spinning.•The distribution of fiber diameter showed a normal law with average diameter of 460 nm.•There were many pores on the surface of the carbon fibers with amorphous structure.•The highest specific surface area was found on the fiber with the minimum average diameter.•The finest carbon nanofibers also gained the best electrochemical performance.Carbon nanofibers were prepared by using centrifugal spinning with polyacrylonitrile as precursor. The microstructure and electrochemical properties of prepared samples were investigated by using scanning electron microscopy and electrochemical workstation, respectively. The results showed that the distribution of fiber diameter showed a normal law. The carbon fibers present good cycle stability at low scan rate. Moreover, the integral area of cyclic voltammetry curve reaches the maximum when the mass ratio of PAN/PMMA is 20:3. The specific capacitance of it is 102 F/g and 84 F/g, in case of the current density at 0.1 A/g and 0.2 A/g, respectively.Download high-res image (90KB)Download full-size image

In this study, the fatty acid eutectics (capric acid (CA) and lauric acid (LA) eutectics) were impregnated into the expanded perlite (EP) and expanded vermiculite (EVM) to form the two kinds of composite phase change material (PCM). The chemical structure, crystalloid phase were determined by the Fourier transformation infrared spectroscope, X-ray diffractometer. The results show that the eutectics with the EP and EVM do not undergo a chemical reaction and only undergo a physical combination. The SEM results proved that eutectics are well adsorbed in the porous structure of the EP and EVM. The thermal properties were determined by the differential scanning calorimeter (DSC). The DSC result shows that the melting temperatures and latent heat values of the PCMs are in the range of about 21–23 °C and 81–117 J/g. The maximum impregnation ratio of fatty acid eutectics into EP and EVM were 82.93% and 57.48%. The thermal cycling test proves that the composites have good thermal reliability. TG analysis revealed that the composite PCMs had high thermal durability property above their working temperature ranges. Besides, thermal conductivity of the CA-LA/EP and CA-LA/EVM was increased approximately as 89.14% and 87.41% by adding 5 wt.% expanded graphite (EG). It is envisioned that the prepared shape-stabilized PCMs have considerable potential for developing their roles in thermal energy storage system.

Carbon foams with phenolic resin as precursor and aluminosilicate as reinforcement were prepared at different final pyrolysis temperatures. The microstructures, mechanical and thermal properties of the foams were investigated by scanning electron microscopy, mechanical testing and the laser flash method, respectively. The results show that the cells are mainly open with incomplete cell membranes, and the alumninosilicate particles are located in cell walls. The surface of cell openings becomes rougher as the final pyrolysis temperature increases. The ultimate compressive strength increases from 0.45 to 1.74 MPa when increasing the final pyrolysis temperature from 1100 to 1550 °C. The thermal conductivity ranged from 0.37 to 0.52 W m−1 K−1 at room temperature and decreases with increasing the final pyrolysis temperature. The occurrence of the mullite phase plays a key role in the changes of the mechanical properties and thermal conductivity of the foams.

Aluminosilicate-reinforced carbon foams have been prepared by chemical foaming with phenolic resin as matrix precursor and aluminosilicate as the additive. The effects of the amount of aluminosilicate used on the microstructure, mechanical properties and oxidation resistance of the carbon foams have been investigated by scanning electronic microscopy, mechanical testing, and oxidation weight loss, respectively. The results show that the amount of aluminosilicate added has a significant influence on the surface roughness and the structure uniformity of carbon foams. The compressive strengths are usually higher than that of the pure carbon foam sample by as much as 60%. The percentage of weight loss of the carbon foams drops with increasing aluminosilicate content up to 11 wt%, but then increases.

Lauric acid(LA)/expanded vermiculite (EVM) form-stable phase change materials were synthesized via vacuum impregnation method. In the composites, lauric acid was utilized as a thermal energy storage material and the expanded vermiculite behaved as the supporting material. XRD and FT-IR results demonstrate that lauric acid and expanded vermiculite in the composite do not undergo a chemical reaction and only undergo a physical combination. Microstructural analysis indicates that lauric acid is sufficiently absorbed in the expanded vermiculite porous network, while displaying negligible leakage even under the molten state. According to DSC results, the 70 wt.% LA/EVM sample melts at 41.88 °C with a latent heat of 126.8 J/g and solidifies at 39.89 °C with a latent heat of 125.6 J/g. Thermal cycling measurements show that the form-stable composite PCM has adequate stability even after being subjected to 200 melting/freezing cycles. Furthermore, the thermal conductivity of the composite PCM increased by approximately 78% with the addition of 10 wt.% expanded graphite (EG). Thus, the form-stable composite PCM is a suitable option for thermal energy storage for building and solar heating system applications.