MDHO dengan rendemen 93,[80][81]. Penggunaan siklopentanon pada metode sonokimia selama 45 menit menghasilkan cairan kental berwarna kuning metil 8-(3-oktil-1,4-dioksaspiro[4.4]nonan-il)oktanoat dengan rendemen 50,51%. Senyawa lain,

Synthesis of Fe3O4/SiO2/TiO2 nanocomposite and its application as photocatalyst in Carboxymethyl Cellulose (CMC) photocracking had been conducted. Magnetite preparation was carried out by sono-coprecipitation method. The deposition of SiO2 and TiO2 were performed by sol-gel method under ultrasonic irradiation. All material products were characterized by X-ray diffraction (XRD), Fourier transform infra-red spectrophotometry (FT-IR), and transmission electron microscopy (TEM). The final material product was also analysed by specular reflectance UV-Visible (SR-UV-Vis). The product of photocracking was analysed by gas chromatography – mass spectrometry (GC-MS).The XRD diffractogram and FT-IR spectra confirmed the presence of Fe3O4, SiO2, and anatase phase of TiO2. The TEM image revealed the presence of nanocomposite with core-shell structure. The SR-UV-Vis spectrum was used to determine band gap energy of the photocatalyst and it gave a result of 3.22 eV. The GC chromatogram of photocracking product indicated some major fractions. The MS spectra showed that some major fractions were smaller molecules including methanol, the component of biofuel.

This study focuses on the synthesis and application of a Fe3O4/SiO2/TiO2 nanocomposite as a photocatalyst in CO2 indirect reduction. The synthesis was started by preparation of magnetite (Fe3O4) followed by silica (SiO2) coating and titania (TiO2) deposition. Magnetite was prepared by the sono-coprecipitation method, then the coating of SiO2 and deposition of TiO2 were performed by the sol-gel method under ultrasonic irradiation. All the material products were characterized by an X-ray diffractometer (XRD), Fourier-transform infrared spectrophotometer (FTIR), and transmission electron microscope (TEM). The final material product was also analyzed by a specular reflectance UV-Visible spectrometer (SR-UV-Vis) and the turbidimetry method. The product of the indirect reduction was analyzed by a gas chromatography-mass spectrometer (GC-MS). The XRD diffractograms and FTIR spectra confirmed the presence of Fe3O4, SiO2, and the anatase phase of TiO2. The TEM images revealed the presence of a core-shell nanocomposite with an average diameter of 19.22 ± 1.25 nm. The SR-UV-Vis spectrum was used to determine the band gap energy of the photocatalyst, with the result being 3.22 eV. Turbidimetry aimed to measure the magnetic recoverability of the final material, and the result was that it had better recoverability compared to a non-magnetic photocatalyst composite. The GC chromatogram of the indirect reduction product indicated four major fractions; the MS spectra showed these to be methanol, formaldehyde, formic acid, and CO2. The GC-MS results revealed that CO2 indirect reduction achieved 73.91% conversion of CO2 and 55.01% selective to methanol.