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Indonesian Journal of Chemistry

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Published by Universitas Gadjah Mada

ISSN : 14119420 EISSN : 24601578 DOI : -

Core Subject : Science, Engineering,

Chemical Engineering, Chemistry & Bioengineering Chemistry

Indonesian Journal of Chemistry is an International, peer-reviewed, open access journal that publishes original research articles, review articles, as well as short communication in all areas of chemistry including applied chemistry. The journal is accredited by The Ministry of Research, Technology and Higher Education (RISTEKDIKTI) No : 21/E/KPT/2018 (in First Rank) and indexed in Scopus since 2012. Since 2018 (Volume 18), Indonesian Journal of Chemistry publish four issues (numbers) annually (February, May, August and November).

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Articles 25 Documents

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Search results for , issue "Vol 20, No 4 (2020)" : 25 Documents clear

Bioleaching Ability of Fungi Isolated from an Indonesian Sulfurous River Sediment Serafica Btari Christiyani Kusumaningrum; I Wayan Warmada; Wahyu Wilopo; Endah Retnaningrum
Indonesian Journal of Chemistry Vol 20, No 4 (2020)
Publisher : Universitas Gadjah Mada

The unique characteristics of sulfurous river sediment located in Ungaran, Indonesia, are a reservoir of novel fungi with manganese bioleaching properties. Fungi are known to produce metabolic organic acids that have a potential for the industrial application of leaching metal from the ores. This application has high advantages, including low cost, low energy, and creates minimal environmental damage. Therefore, this research was performed to analyze the manganese bioleaching activities of two fungal isolates (KA2B2 and KB4B) from Indonesian sulfurous river sediment on pyrolusite and determine their phenotypic characters. These activities were investigated in terms of changes in fungal biomass, soluble manganese concentration, pH reduction, and organic acid production during 16 days of leaching. Soluble manganese concentrations were measured by atomic absorption spectrometry (AAS), whereas organic acid concentrations were analyzed by high-performance liquid chromatography (HPLC). According to bioleaching investigations, KA2B2 strain was more efficient than KB4B1 strain in extracting manganese from 0.02 g/cm3 pyrolusite. It also produced higher levels of organic acids, such as oxalic acid and citric acid, than KB4B1 strain, proving that strain of KA2B2 could be used to extract manganese from pyrolusite. Based on the phenotypic characters, both strains were identified as genus Penicillium.

Cobalt Doping on Zirconium Titanate as a Potential Photocatalyst with Visible-Light-Response Emilya Faridatul Sulaikhah; Rian Kurniawan; Mokhammad Fajar Pradipta; Wega Trisunaryanti; Akhmad Syoufian
Indonesian Journal of Chemistry Vol 20, No 4 (2020)
Publisher : Universitas Gadjah Mada

Synthesis of cobalt-doped zirconium titanate (Co-doped ZrTiO4) as a potential photocatalyst with visible-light-response had been conducted. Materials used in this research were titanium tetraisopropoxide (TTIP) as a precursor of TiO2, ZrO2 as another semiconductor for coupling, and CoSO4·7H2O as the source of cobalt dopant. The composite was prepared by the sol-gel method with various cobalt contents and calcination temperatures. Composites with various Co dopant contents (0, 1, 3, 5, 7, and 9% (Co wt./Ti wt.)) were calcined at 500 °C for 4 h. In addition, the composite with 5% of dopant content was calcined at 700 and 900 °C to observe the influence of calcination temperature. All samples were characterized by using X-ray powder diffraction method (XRD), Fourier-transform infrared spectroscopy (FTIR), specular reflectance UV-Vis spectroscopy (SRUV), and scanning electron microscopy equipped with X-ray energy dispersive spectroscopy (SEM-EDS). Co-doped ZrTiO4 with the lowest bandgap (2.94 eV) was achieved in a sample containing 3% of cobalt content calcined at 500 °C.

Kinetic study of HTPB (Hydroxyl Terminated Polybutadiene) Synthesis Using Infrared Spectroscopy Heri Budi Wibowo; Widhi Cahya Dharmawan; Ratih Sanggra Murti Wibowo; Adi Yulianto
Indonesian Journal of Chemistry Vol 20, No 4 (2020)
Publisher : Universitas Gadjah Mada

A kinetic study of HTPB synthesis by radical polymerization of butadiene with hydrogen peroxide initiator was conducted using infrared spectroscopy. HTPB conversion was determined based on the conjunction termination rate constant, and all polymerization kinetics were evaluated to identify the constant. All polymerization steps (decomposition, initiation, propagation, conjunction, and proportional termination) can be evaluated based on polymer conversion and functionality from data provided by infrared spectroscopy. The investigation variables included the initial molar ratio of initiator to monomer (H2O2/butadiene) and the reaction temperature. These steps were assumed as the first-order reactions, giving constant reaction rates of kd, ka, kp, kt, ktc, and ktd. The reaction rates obtained for these constants were 4.2 × 10–5 sec–1, 8.9 × 10–4, 7.7 × 103, 8.5 × 107, 3.2 × 107 and 5.3 × 107 L mol–1 sec–1, respectively, with activation energy of 7608, 14188, 2247, 105, 87 and 135 kJ mol–1, respectively. The determining step of the reaction rate was identified as the initiation reaction. HTPB conversion can be measured if all polymerization kinetics constants have been evaluated.

Synthesis, Characterization, and Stability Evaluation of β-Carotene Encapsulated in Starch-Chitosan/Tripolyphosphate Matrices Agnes Dyah Novitasari Lestari; Dwi Siswanta; Ronny Martien; Mudasir Mudasir
Indonesian Journal of Chemistry Vol 20, No 4 (2020)
Publisher : Universitas Gadjah Mada

This study aims to investigate the synthesis and characterization of β-carotene encapsulated in the blending matrices of starch (native and hydrolyzed starch)-chitosan/TPP (tripolyphosphate) by examining the effects of starch-to-chitosan weight ratio, β-carotene addition level, and TPP addition level on the encapsulation efficiency (EE) and loading capacity (LC); and to evaluate their storage stability. The encapsulation was done by the dropwise addition of ethanolic β-carotene dispersion into the blending matrices. The results of XRD analysis show that the encapsulation process significantly decreases the crystallinity of the starches, chitosan, and β-carotene. Scanning electron microscope (SEM) images reveal that the encapsulation products form irregular lumps. The EE and LC tend to increase with the increase in polymer fraction of matrices and β-carotene addition level, and with the decrease in TPP addition level. The addition of chitosan and the replacement of native starch by hydrolyzed starch tend to increase storage stability of β-carotene encapsulated in the starch matrix because chitosan can act as a good film-forming and antioxidant, while hydrolyzed starch contains amylose amylopectin with a short chain which is better in film-forming ability. These results promote the use of the hydrolyzed starch-chitosan/TPP as a matrix to enhance the stability β-carotene via encapsulations.

pH Dependence on Colorimetric Detection of Hg2+ by Histidine-Functionalized Gold Nanoparticles Dewi Eviane; Dwi Siswanta; Sri Juari Santosa
Indonesian Journal of Chemistry Vol 20, No 4 (2020)
Publisher : Universitas Gadjah Mada

In this study, we successfully developed gold nanoparticles capped with histidine (His-AuNPs) for Hg2+ detection using trisodium citrate as the reducing agent. The optimum pH for the detection of Hg2+ by His-AuNPs was 12. The addition of Hg2+ to the His-AuNPs caused the color change from red to black-blue, which is readily detectable by the naked eye. This color change is followed by a decrease in the intensity of the primary Surface Plasmon Resonance (SPR) peak at a wavelength (λ) of 525 nm and an increase in the secondary peak at λ = 650 nm. His-AuNPs effectively detected Hg2+ with limits of detection and quantitation of 1.77 µM and 5.89 µM, respectively. His-AuNPs exhibited good performance for the detection of Hg2+ in waste water collected from a steel industrial facility in Banten Province, with a recovery and a percent relative standard deviation of 115% and 1.02%, respectively.

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