Papers by Keyword: Sepiolite

Abstract: The effects of sepiolite mineral nanofiber on strength and toughness of ceramics were investigated by bone china with addition of sepiolite mineral nanofiber. The flexural strength and fracture toughness were tested by three point bending method and single edge notched beam (SENB) method, and the microstructure of the ceramics was studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and optical microscopy. The results indicated that the structure pattern of sepiolite mineral nanofiber became much shorter and thicker after calcinations. Proper addition of sepiolite mineral nanofiber would increase the strength and toughness of bone china. The sepiolite mineral nanofiber can yield the bone china with fracture toughness and flexural strength values as high as 5.65 MPa·m^1/2 and 112.66 MPa to 5.87 MPa·m^1/2 and 118.90 MPa, mainly due to crack bridging, crack deflection and pullout by sepiolite mineral nanofiber.

Abstract: To improve the compatibility and dispersion of the sepiolite in polymers, a surfactant of octadearyl dimethyl ammonium chloride（OTAC）was used to modify sepiolite. The experiment was used to analyze the effects of OTAC dosage, reaction temperature and reaction time on the wettability of organically-modified sepiolite. The effects on the structure performance of sepiolite were investigated by XRD, SEM and contact angle measurements. The orthogonal experimental esults show that the optimum amount of OTAC, reaction temperature and reaction time are 400 mmol/kg, 90 °C and 120 min, respectively.

Abstract: Two sepiolites (SEPs) were respectively used as the fillers in glycerol plasticized-cassava starch (GPS) matrix by the casting process. Scanning electron microscopy proved that SEPs were dispersed well in the GPS matrix. Fourier transform infrared spectroscopy indicated that silanol groups at the external surface of SEPs could form the interaction with C-O-H and C-O-C groups in starch molecules. The introduction of SEPs improved the tensile strength, thermal stability, the pasting viscosity and restrained water vapor permeability, but reduced the elongation at break of the composites. SEP-fiber imparted the composites better properties than SEP-velvet, except for the resistance of moisture adsorption. SEP-velvet could decrease the water contents at the equilibrium of the composites.

Abstract: The porous nanocomposites consisting of starch and sepiolite were prepared by a solvent exchange technique, i.e. replacing ice crystals in frozen sepiolite/starch gel with ethanol. The influence of sepiolite contents on pore size, apparent density, moisture adsorption, oil adsorption capacity and dye adsorption of porous sepiolite/starch composites (SPPSs) was investigated. The addition of sepiolite reduced pore size, apparent density and moisture adsorption of SPPSs. The oil adsorption and the methylene blue adsorption of SPPSs could respectively reach 10.1 g/g and 2.07 mg g-1 at the maximal, while those of PS were only 5.83 g/g and 1.55 mg g-1.

Abstract: Sepiolite has good adsorptivity due to their high surface area and structural channels. During the process of making aluminium silicate fiber paper, inorganic binders retaintion was little because of the smooth surface of aluminium silicate fibers. In this study, sepiolite was used to improve tensile strength of the sheet by increasing inorganic binders retaintion rate through its high adsorptivity. The effect of sepiolite on the tensile strength of alimunium silicate fiber paper was investigated. The results showed that the best mass ratio of aluminium silicate fibers to spiolite was 7:3. Under this condition, the tensile strength of the sheet was 4.79 N•m/g, which increased by 24.2% from the one without sepiolite.

Abstract: Rigid polyurethane foams were prepared using sepiolite nanofibers as main functional fillers. The effect of sepiolite nanofibers on the properties of polyurethane foams was studied systematically. Through characterization by scanning electron microscope, X-ray diffraction and property test, it was found that the thermal insulation effect can be maintained, and the mechanical properties can be improved due to the good interfacial bond between sepiolite nanofibers and rigid polyurethane foams.

Abstract: In this paper, it was investigated the changes of structure of sepiolites under different conditions of acid treatments and heat treatments using fourier transform infrared spectroscopy(FTIR). At the same time, through the tannin adsorption experiments, it was studied the changes adsorption properties of sepiolites by acid treatments and heat treatments. The H2SO4 treatment was found to be more effective for the removal of tannin than HCl and HNO3 treatments. With increasing the acid concentration and acid treatment time of H2SO4, the removal rates and adsorption capacity of tannin by sepiolites were first increased and then decreased. The removal rates and adsorption capacity were 61.0% and 23.7mg/g when the acid concentration was 4.0mol/l. And the removal rates and adsorption capacity were 62.5% and 24.3mg/g when the acid treatment time was 16 hours. The calcinations treatment exhibited significant effects on the adsorption of tannin. The removal rates and adsorption capacity were 77.9% and 30.8mg/g when the calcined temperature was 400°C. However, when the calcined temperature was 700°C, the removal rates and adsorption capacity were only 54.1% and 20.8mg/g.

Abstract: In this work, the breakthrough curves of styrene in fixed beds packed separately with hydrochloric acid-modified sepiolite were determined. And the Temperature Programmed Desorption (TPD) method is applied to research the desorption activation energy on modified sepiolite and untreated sepiolite. The results showed that in compared with the original sepiolite, the hydrochloric acid-modified sepiolite had more surface basic groups, pore volume and higher surface area so that their adsorption capacities of styrene were improved. The sepiolite modified with 12% hydrochloric acid solution had more micropore volume and higher surface area than the other modified sepiolite, and thus its adsorption capacity of styrene was the highest. The activation energy for desorption of styrene on the modified is higher than on the original sepiolite, this show that using hydrochloric acid modified sepiolite can enhance its adsorption of styrene.

Abstract: Cu supported on acid-treated sepiolite catalysts (xCu/H-Sep, x = 0  20.0 wt%) or Cu-Fe mixed supported on acid-treated sepiolite catalysts (yFe-10Cu/H-Sep, y = 0  20.0 wt%) were prepared by the incipient wetness impregnation method. The xCu/H-Sep and yFe-10Cu/H-Sep catalysts were characterized by means of XRD, BET, XRF, XPS, and H2-TPR techniques, and their catalytic activities were evaluated for the SCR of NO with propylene. XPS and XRD results indicate that there was the co-presence of Cu+-Cu2+ and Fe2+-Fe3+ over the surfaces of yFe-10Cu/H-Sep catalysts, and there was a strong interaction between Cu, Fe and sepiolite. High promotional effect of iron additive on the catalytic performance of Cu/H-Sep catalyst were found in C3H6-SCR of NO reaction. The highest activity of 65% NO conversion was obtained over 15Fe-10Cu/H-Sep catalyst at 280 oC under the condition of 1000 ppm NO, 1000 ppm C3H6, and 5% O2. The high catalytic activity of 15Fe-10Cu/H-Sep catalyst for NO reduction was due to its high reducibility to activate C3H6 to selectively reduce NO in the presence of excess O2. The high dispersion of copper oxides and strong metal-support interaction over 15Fe-10Cu/H-Sep catalyst also improve its catalytic performance.

Abstract: The modification method and its eftect on the behavior of sepiolite, especially its ability to remove heavy metals, have be reaen systematically studied. Different pretreatment methods have led to various surface structures, which resulted in various effects on removal heavy metals. The processes of modification and removal of heavy metals have been optimized. The highest removal rate for Pb canch more than 96%.