Papers by Keyword: Aerogel

Abstract: nanoTiO₂/cellulose composite gels have been uniformly blended during the dissolving process of cellulose in ionic liquids (ILs). After the regeneration process, the obtained hydrogel was finally dried through supercritical CO₂ to obtain the TiO₂/cellulose composite aerogel. The structure and properties of the composite aerogel were characterized by XRD, SEM, FT-IR, UV-vis, and photocatalytic degradation tests. The porous structure and hydroxyl groups in the regenerated cellulose matrix provided cavities and affinity for the immobilization of TiO₂ in the cellulose gels through electrostatic and hydrogen bonding interactions. The TiO₂/cellulose composite gels exhibited a good photocatalytic activity for photodegradation of Rhodamine B (RhB) under UV light irradiation. This research highlights another opportunity for the development of the portable and flexible photocatalyst.

Abstract: Carboxymethyl chitosan aerogel was prepared by freeze-drying method with glutaraldehyde as crosslinking agent. The effect of different concentrations of crosslinking agent and solvent on the gel time and porosity was investigated. The absorption capacity of aerogel was investigated with different oils (gasoline, diesel oil, peanut oil, dimethyl silicone). The results were shown as 1) the highest porosity of the aerogel was 95.01% and the lowest density was 0.026g/cm³. 2) The optimum preparation condition was the concentration of crosslinking agent 20%, the solvent concentration 2%. Oil absorption capacity of the aerogel was up to the maximum of 28.6g/g (to dimethyl silicone), which was higher than to the other three oils. This work offered a preparation method for the high porosity, high oil-absorbing massive carboxymethyl chitosan aerogel and revealed its potential application in the treatment of oil pollution.

Abstract: Thermal barrier coating (TBC) system has been developed for high temperature applications along with the used of yttria stabilized zirconia (YSZ) as topcoat. Recently, developing coating material made from nanoparticles is widely explored. Thus, maerogel could become a potential candidate for this purpose because it consists of nano porous particle with low in density and low in thermal conductivity. The coating is expected to improve the formation of thermally grown oxide (TGO), thermal stability and increase the insulating capability. However, maerogel need agglomeration process before coating can be made because of it has low mass and high specific area.

Abstract: Dye-sensitized solar cell (DSSC) is one of the very promising alternative renewable energy sources to anticipate the diminishing in the fossil fuel reserves in the next few decades and to make use of the abundance of intensive sunlight energy in tropical countries like Indonesia. TiO₂ nanoparticles have been used as the photo electrode in DSSC because of its high surface area and allow the adsorption of a large number of dye molecules. In the present study, TiO₂ aerogel have been synthesized via sol-gel process with water to inorganic precursor ratio (R_w) of 2.00, followed with subsequent drying by CO₂ supercritical extraction (SCE). As comparison, the TiO₂ xerogel was also prepared by conventional drying and annealing. Both types of gels were subjected to conventional and multi-step annealing. The resulting nanoparticles in aerogel and xerogel have a band-gap energy of 3.10 and 3.04 eV, respectively. The open circuit voltage (V_oc) measurement reveals that the DSSC fabricated with aerogel provided a higher voltage (21,40 mV) than xerogel (1,10 mV).

Abstract: In this paper, the compound shellac fruit wax was prepared by SiO₂ aerogel, shellac, sodium hydroxide, fungicide. The obtained fruit wax was used to preserve the mango in tropical area. The results show that the compound shellac fruit wax with 0.2% SiO₂ aerogel can suppresses water loss, adjust the respiration, reduce the rot rate, thus extending the preservation time of mango.

Abstract: The technology of synthesis nanomaterial by diisopropylamine as a replaced drying solvent has been studied.The products of Al (OH)₃ and SiO₂ are found to be amorphous aerogel.The nanoparticle of TiO₂ produced by it is found to be smaller than that produced by n-butyl alcohol as a replaced drying Solvent.

Abstract: Building insulation is an important part of building energy conservation. The heat insulation coating preapred from modified expanded perlite has been a potential building thermal insulation material. In this paper, aerogel was filled into the pores of expanded perlite by vacuum impregnation method to produce aerogel-modified expanded perlite at ambient pressure. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and N2 adsorption–desorption techniques. The results revealed that aerogel could be well filled into the pores of expanded perlite, and the resultant aerogel-modified expanded perlite possessed nanoporous structure with higher specific surface area of 196 m2·g-1, and low thermal conductivity of 0.063 W·m-1·K-1 less than that of expanded perlite by 13.3%. Heat insulation coatings prepared from aerogel-modified expanded perlite had good thermal insulation effect, indicating that the product showed potential aplication in the field of building energy conservation.

Abstract: Silica aerogel has been prepared by ambient pressure drying technique using water glass as starting materials. Solvent exchange and surface modification were simultaneously conducted by immersing the wet hydrogel in EtOH/TMCS(Tri Methyl Chloro Silane)/hexane solution. The silica aerogel was obtained with the density of 0.110g•cm^-3 and 95.2% porosity. The specific surface area of the silica aerogel was 472.5m²•g^-1 with a average pore size distrubution of 27.5nm. FT-IR spectrum analysis showed that the surface of the silica aerogel was modified by Si-CH₃ groups, which allowed the aerogel to be hydrophobic.

Abstract: The preparation and characterization of Unsaturated Polyester Resin (UPR) filled recycled Expanded Polystyrene (EPS) composite systems were systematically investigated. Additives such as Alumina and silica aerogel powder were added to the composite for Infrared reflection and insulation enhancement. The effect of differing alumina weight percentage on the thermal properties, i.e. thermal conductivity and glass transition temperature, T_g were determined. The fabricated composite undergoes thermal analysis by using a DSC and a hand-held thermal probe, and characterized by a FTIR. There is little variation of the T_g across the samples tested. Specific heat capacity, c_p from the DSC thermogram was significantly affected by incorporation of silica aerogel; 565 J/kgK compared to the unfilled sample result of 1706 kJ/kg. The thermal conductivity showed a minimum at 0.147 W m^-1 K^-1 from integrated silica aerogel only sample, and alumina addition increases the thermal conductivity above the minimum k value in the ranges 0.227-0.313 W m^-1 K^-1. Alternative C_p values from the thermal probe followed similar trend as the DSC C_p. Thermal diffusivity from the probe also showed an increase upon silica aerogel and alumina incorporation.

Abstract: Nano-porous V2O5 aerogel films were prepared by dip-coating vanadium oxide sol onto ITO substrate, using V2O5 powder, Benz alcohol, Isopropanol as precursor materials. The nano pores were characterized by scaning electron microscope (SEM). The electrochemical properties were investigated by chronopotenyiometry(CP) and cyclic voltammograms(CV). Results showed that this porous V2O5 aerogel film exhibited good cycling stability with initial discharge capacity of 143mAh/g and 128 mAh/g after 18 cycles, staying 89.5 % of the initial discharge capacity, at a charge/discharge current density of 200 mA/g.