Papers by Keyword: Sepiolite

Abstract: Sepoilite was surface-modified by the mixture of ethanolamine and n, n-dimethyl ethanolamine. The XRD, SEM, FT-IR, BET and TGA were used to characterize the material structure and the adsorption property in CO2. The results showed that the weight percentage of CO2 adsorption rose from 4.01% for pure sepoilite to 19.28% for the modified sepoilite at room temperature.

Abstract: Zeta potential of purified sepiolite in aqueous system was studied as a function of pH and solid content. From the experimental results, it was found that sepiolite surface acquired a negative charge in water at natural pH, and the value of zeta potential decreased with the increase of pH value. Solid content had effect on zeta potential, but it can be minimized by the increase of time.

Abstract: The sepiolite samples were defibered by using microwave chemical technique, and then different sepiolite samples were obtained with different treatment process. The effect of reaction time on the defibering for sepiolite fiber bundles was studied systematically. Through characterization by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscope (FTIR), it was found that the defibered sepiolite samples had an average diameter of about 100 nm and length greater than 20μm. The defibering effect of sepiolite samples as prepared reached optimum at the reaction time of 13 min, and the structural stability of sepiolite was kept after defibering treatment.

Abstract: The intumescent flame retardant poly-pentaerythritol diphosphonate dichloride- hexamethylendiamine (PSPHD) grafting sepiolite (PSPHD-SEP) and LDPE/PSPHD-SEP/IFR composites have been prepared. Cone calorimeter technique was employed to characterize the combustion behavior of LDPE/PSPHD-SEP/IFR composites. The results show that the peak and average heat release rates decreased significantly when 5% PSPHD-SEP was added in LDPE. The PSPHD-SEP can promote the char layer to form earlier and be more compact and increase the char residue yield. The compact char residue layer can prohibit the transfer of gas and heat during the burning, showing the improvement of flame retardance.

Abstract: A series of polyurethaneurea (PUU) nanocomposites based on clay-like sepiolite (Sp) with the modification of γ-aminopropyltriethoxysilane (KH550) were prepared via in situ polymerization from poly(propylene glycol), tolylene-2,4-diisocyanate (TDI) and 3,3'-dichloro-4,4'- diamino-diphenylmethane(MOCA). Morphology and structure of nanocomposites were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The results indicated that KH550-Sp was dispersed homogeneously in the PUU matrix, which facilitated the formation of chemical bonds between KH550-Sp and the hard segment of PUU. The thermostability and mechanical properties were studied by the thermogravimetric (TG) analysis and tensile tests. The results showed that the onset decomposition temperature and tensile strength of nanocomposites was higher than those of pure PUU.

Abstract: Sepiolite/poly (sodium acrylate-acrylamide) composite was synthesized by using inverse suspending polymerization method under different dispersant content, neutralization degree and ratio of monomer with orthogonal experiments. The surface morphology, structure and humidity controlling properties of composite were observed and determined. The results show that sepiolite/ poly (sodium acrylate-acrylamide) composite is in a fine particle with rough surface. During the polymerization process, acrylate and acrylamide monomer is grafted with hydroxyl on the surface of sepiolite and then intercalated successfully into the silica layers of sepiolite. The impact of three factors on the humidity controlling behavior of composites increases by the order of dispersant content, ratio of monomer and neutralization degree. The optimum preparation parameters are dispersant content of 10%, neutralization degree of 85% and ratio of monomer 2:1.

Abstract: Effect of acidizing conditions such as hydrochloric acid concentration, acidizing temperature and acidizing time etc. on moisture adsorption and desorption properties of sepiolite in closed space at constant temperature was studied. Relationships between moisture adsorption and desorption properties and microstructure of treated and untreated sepiolite were discussed by means of microscopic testing methods such as X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM)and Brunauer-Emmett-Teller (BET). The results indicated that acidizing conditions had significant effect on moisture adsorption and desorption properties and microstructure of sepiolite in closed space. The optimum acidizing condition in this experimental program was obtained by treatment with 5 wt.% hydrochloric acid at 98 °C for 9 h. Fibers in the treated sepiolite become thinner and shorter, and carbonates in layers and pore canals were dissolved. Specific surface of sepiolite treated with the optimum acidizing condition increases from 35.64 m2/g to 84.86 m2/g ,and its average pore diameter decreases from 16.84 nm to 12.68 nm.

Abstract: Lauric acid/stearic acid as the binary phase change materials, modified sepiolite as the inorganic carrier, organic/inorganic composite energy storage materials was prepared by melting adsorption.Comprehensive experiment results show that binary phase change material is lower than single one at initial phase change temperature and phase change peak temperature, and it has good energy storage results, the composite material can be used in energy storage and heat recovery system to save energy.

Abstract: The sepiolite and CuFe₂O₄ were combined to prepare the sepiolite/CuFe₂O₄ composite. The magnetic composite was characterized by X-ray diffraction (XRD), transmission electronic microscopy (TEM) and vibration sample magnetometer (VSM) and N₂ adsorption isotherms. Adsorption characteristics of the composite were examined by using Cu²⁺ and methylene blue as adsorbates. The results show that CuFe₂O₄ particles adhere to the surface of sepiolite fiber to form the sepiolite/CuFe₂O₄ composite which show well characteristic of superparamagnetism and is effective for the removal of Cu²⁺ or methylene blue. When the mass ratios of sepiolite and CuFe₂O₄ is 7:3, the saturation and remanence magnetization are 7.140 and 0.0246 A·m²/kg, and coercive force is 0.0180 A/m for magnetic sepiolite. The saturated adsorption capacity for Cu²⁺ and the removal rate of methylene blue is 15.72 mg/g, 99.48%, respectively.

Abstract: Based on the pretreatment including acidification, purification and sodium ion exchange, the crude sepiolite was modified by microwave radiation-wet process and CTAB as modifier. The orthogonal experiment was used to optimize the modification process. Then the crude sepiolite and modified sepiolite were characterized by SEM, FTIR, XRD, TG-DSC and BET. The results showed that the optimum modification process parameters included CTAB dosage (1.0 cation exchange capacity (CEC)), microwave radiation time (4 minutes), ethanol concentration (50%/V:V) and radiation power (800W). Compared with crude sepiolite, oil removal rate from steel rolling wastewater increased from 41.34% to 96.78% with modified sepiolite prepared at the best process. Characteristic peaks of organic functional groups, enlarged interlayer distance (0.007nm larger than crude sepiolite), enhanced hydrophobicity, amplified specific surface area (104.4m2/g) and mesopore volume had been received from above characterization methods after modification. All of the above had proved that CTAB was successfully grafted onto sepiolite.