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All Journal Indonesian Journal of Chemistry

Eko Sri Kunarti

Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Sekip Utara BLS 21, Bulaksumur, Yogyakarta 55281, Indonesia

Author-ID : 3960423

Chemical Engineering, Chemistry & Bioengineering Chemistry

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Articles

Synthesis and Application of Fe3O4/SiO2/TiO2 Nanocomposite as Photocatalyst in CO2 Indirect Reduction to Produce Methanol Yudha Ramanda; Nuryono Nuryono; Eko Sri Kunarti
Indonesian Journal of Chemistry Vol 19, No 4 (2019)
Publisher : Universitas Gadjah Mada

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 majorfractions; 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.

Antibacterial Activity of Silver Nanoparticles Capped by p-Aminobenzoic Acid on Escherichia coli and Staphylococcus aureus Dian Susanthy; Sri Juari Santosa; Eko Sri Kunarti
Indonesian Journal of Chemistry Vol 20, No 1 (2020)
Publisher : Universitas Gadjah Mada

This paper describes the antibacterial performance of silver nanoparticles (AgNPs) which have been synthesized by using p-aminobenzoic acid as reducing and stabilizing agent simultaneously. The silver nitrate with various concentrations was reacted with pH 11-adjusted p-aminobenzoic acid with a concentration of 5 × 10–3 mol L–1 for 30 min in a boiling water bath. The synthesized AgNPs were characterized by UV-Vis spectrophotometry, Transmission Electron Microscope (TEM), and Particle Size Analyzer (PSA). The antibacterial performance of the synthesized AgNPs was evaluated by agar well diffusion method on Escherichia coli and Staphylococcus aureus. The higher silver nitrate concentration, the bigger the nanoparticle size, the wider particle size distribution, and the higher number of AgNPs formed. AgNPs synthesized from higher silver nitrate concentration had higher antibacterial activity. It is an indication that the antibacterial activity of AgNPs is mainly controlled by the silver ion concentration which influences the AgNPs particle size and existence of silver ion in the AgNPs colloidal solution

Co-Authors Dian Susanthy Nuryono Nuryono Sri Juari Santosa Yudha Ramanda

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