With the growth of the use of carbon fiber-reinforced polymer (CFRP) in various fields, the recovery of carbon fibers from CFRP waste is becoming a significant research direction. In the present work, degrading epoxy resin and recycling carbon fibers from CFRP waste by microwave thermolysis and traditional thermolysis were studied. The carbon fibers were successfully recovered by thermolysis under an oxygen atmosphere in this study. The properties of the recovered carbon fibers were characterized by field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and Raman spectroscopy. The result shows that using microwave thermolysis to recover carbon fibers from CFRP waste is an attractive prospect. Compared to the traditional method, the reaction time was reduced by 56.67%, and the recovery ratio was increased by 15%. Microwave thermolysis is faster, more efficient, requires less energy, and obtains cleaner recovered carbon fibers than those recovered using traditional thermolysis.
Using diatomite and analytical pure SiO2 as silicon sources, Li4SiO4 sorbents for high temperature CO2 capture were prepared through solid-state reaction method. Phase composition was analyzed by X-ray diffraction, and the CO2 absorption capacity and absorptoin-desorption performance were studied by the simultaneous thermal thermogravimetric analyzer (TG-DSC). The results showed that silicon source had an important influence on CO2 absorption properties. The kinetic parameters for the chemisorption and diffusion processes were obtained by the isothermal study for different silicon sources. The results showed that the activation energies for these two processes were estimated to be 105.427 and 35.928 kJ/mol for the sample with analytical pure SiO2 (AS). While for the sample with diatomite (DS), the activation energies for these two processes were estimated to be 78.500 and 20.439 kJ/mol, respectively.
A new adsorbent(A-PGMA) has been synthesized via functionalizing poly(glycidyl methacrylate) microsphere with 2-aminothiazole and used to adsorb gold ions from aqueous solutions. The adsorbent was characterized by X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET), Zeta potential, scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR). The influence factors such as the pH value of the solution, the initial gold ion concentration and the contact time were examined. Simultaneously, the adsorption process of the gold ion on A-PGMA fitted well with the Langmuir and pseudo-second-order models, respectively. The results showed that the maximum adsorption capacity was 440.54 mg/g and the equilibrium time of adsorption was about 3 h under pH 4. Moreover, the adsorbent has a high reusability after five cycles and good selectivity from coexisting ions, including Zn(II), Mg(II), Cu(II), Ge(IV) and B(III). The adsorption mechanisms of gold ions were ion exchange and chelation between the sulfur and nitrogen groups on the surface of A-PGMA and AuCl4−. Therefore, the adsorbent has a great potential for adsorption of gold ions from aqueous solutions.
A new cyanuric-thiosemicarbazid (TSC-CC) chelating resin was synthesized and employed to selectively adsorb Ag+ from acid solutions. The effects of acid concentration, initial concentration of Ag+, contact time and coexisting ions were investigated. The optimal acid concentration was 0.5 mol/L. The adsorption capacity of Ag+ reached 872.63 mg/g at acid concentration of 0.5 mol/L. The adsorption isotherm was fitted well with the Langmuir isotherm model and the kinetic data preferably followed the pseudo-second order model. The chelating resin showed a good selectivity for the Ag+ adsorption from acid solutions. Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Scanning electron microscopy/energy dispersive spectrometer (SEM-EDS) and X-ray photoelectron spectroscopy (XPS) were used to study the adsorption mechanism. The chelating and ionic interaction was mainly adsorption mechanism. The adsorbent presents a great potential in selective recovery Ag+ from acid solutions due to the advantage of high adsorption capacity and adapting strongly acidic condition. The recyclability indicated that the (TSC-CC) resin had a good stability and can be recycled as a promising agent for removal of Ag+.
24 January 2018 in Research on Chemical Intermediates
Pyrolusite was carbothermally reduced using coal by microwave heating, and the crystal structures and microstructures of the samples were characterized after microwave heating using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). When the reductants proportion was of 10 percent, the reduction temperature was of 800 °C and the holding time was of 40 minutes, the reduction ratio of MnO2 to MnO was 97.2%, and Fe2O3 was almost completely transformed to Fe3O4 and there was no Fe(II) produced. Moreover, it was found that the low-grade pyrolusite was carbothermally reduced using microwave heating with lower temperature and shorter processing time. These results show that microwave heating can be applied effectively and efficiently to the carbothermal reduction processes of low-grade pyrolusite.