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Indonesian Journal of Chemistry

ijc
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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 1,981 Documents

81 82 83 84 85

Effect of Soaking Treatment on Anthocyanin, Flavonoid, Phenolic Content and Antioxidant Activities of Dioscorea alata Flour Ratnaningsih Ratnaningsih; Nur Richana; Sakae Suzuki; Yoshiharu Fujii
Indonesian Journal of Chemistry Vol 18, No 4 (2018)
Publisher : Universitas Gadjah Mada

Purple Dioscorea alata is one kind of tuber crops that rich in polyphenolic compounds. In Indonesia, the utilization of this yam is still very limited because it is easily damaged on the fresh form. Due to its high perishability, then the fresh tuber have to be processed into dried materials to expand its utilization. This study investigated the effect of browning inhibition treatments (immersion in water, Na-bisulfite, and ascorbic acid) on moisture, color, anthocyanin, flavonoid and phenolic content, and determined the antioxidant activities of D. alata flour. The moisture content of D. alata flour ranged between 6.89 to 7.71% db, which still in the range of wheat flour moisture content standards using Codex Standard. Browning inhibition treatment improved the color appearances and provided better values on anthocyanin, phenolic, and flavonoid content of D. alata flour. The color and antioxidant activities of D. alata flour were significantly correlated with its functional properties.

Density-Functional-Theory Calculations of Formation Energy of the Nitrogen-Doped Diamond Sholihun Sholihun; Hana Pratiwi Kadarisman; Pekik Nurwantoro
Indonesian Journal of Chemistry Vol 18, No 4 (2018)
Publisher : Universitas Gadjah Mada

The geometry optimization of the nitrogen-doped diamond has been carried out by the density functional theory (DFT) calculations. We model the defective diamond of substitutional and interstitial nitrogen atoms by using a simple-cubic supercell. Atoms in the supercell are relaxed by allowing them to move so that the atomic forces are less than 5.0 × 10-3 eV/Å. We calculate the formation energy for substitutional and interstitial sites. We find that the formation energy for the substitutional defect is10.89 eV. We check the convergence of the calculation with respect to the k×k×k - Monkhorst-Pack grids. We show that the energy difference between k = 4 and 6 is very small (7.0 meV). We also check the calculations by using a 216-sites supercell and find that the energy difference is 0.10 eV. Thus, the calculations of the formation energy converge well. As for the interstitial defect, we model some possible configurations and find that the smallest formation energy is 21.88 eV. Therefore, the most stable configuration of the nitrogen-doped diamond belongs to the substitutional site.

Bioconversion of Glycerol to Biosurfactant by Halophilic Bacteria Halomonas elongata BK-AG18 Mieke Alvionita; Rukman Hertadi
Indonesian Journal of Chemistry Vol 19, No 1 (2019)
Publisher : Universitas Gadjah Mada

The increasing production of biodiesel is typically followed by the increasing number of glycerol as co-product. The abundance of glycerol will cause an environmental problem since it can be used as the carbon source for bacterial growth including pathogenic bacteria. In this study, four moderate halophilic bacteria indigenous from Bledug Kuwu Mud Crater, Central Java, Indonesia were screened based on their capability to bioconvert glycerol to biosurfactant. This study found Halomonas elongata BK-AG18 as the potential bacterium that able to perform such bioconversion. The optimum condition for the bioconversion of glycerol into biosurfactant was attained when the bacterial inoculum was grown in the medium containing 2% (v/v) glycerol, 0.3% (w/v) urea, and 5% (w/v) NaCl at 35 °C and pH 6. The resulted biosurfactant has emulsification index (EI24) about 53.6% and CMC about 275 mg/L. Preliminary structural analysis using FTIR and 1H-NMR indicated that biosurfactant produced by H. elongata BK-AG18 was likely a glycolipid type. The biosurfactants have antibacterial activity against Staphylococcus aureus with a minimum inhibitory concentration of 433 mg/L. Our study thus showed that H. elongata BK-AG18 was the potential halophilic bacteria that can bioconvert glycerol into glycolipid type of biosurfactant with antibacterial activity.

Processing of Chloride-Containing Productive Solutions after Uranium in situ Leaching by Ion Exchange Method Svetlana Titova; Sergey Skripchenko; Alexey Smirnov; Vladimir Rychkov
Indonesian Journal of Chemistry Vol 19, No 1 (2019)
Publisher : Universitas Gadjah Mada

The uranium sorption from productive solutions containing chloride ions using anion-exchange resins was investigated. The VPAE ion exchanger had the highest values of the sorption capacity, which for the experiment in the static mode was 13 kg U m-3, and for the experiment in the dynamic mode, it was equal to 36 kg U m-3. The use of VPAE anion exchanger will make it possible for uranium recovery from productive solutions with an increased content of chloride without sacrificing the productivity of the sorption plant. The process of saturated resins regeneration by various reagents was investigated. The use of ammonium nitrate solution with sulfuric acid ensured maximum value of uranium recovery from the saturated resin phase (76–97%).

Synthesis, Structural, Density Functional Theory, and X-Ray Diffraction Study of Zn(II) N-Isopropylbenzyldithiocarbamate: Anti-Corrosion Screening in Acid Media Noor Syafiqah Habdul Latif; Sheikh Ahmad Izaddin Sheikh Mohd Ghazali; Erna Normaya Abdullah; Azizul Hakim Lahuri; Mohammad Fadzlee Ngatiman; Nur Nadia Dzulkifli
Indonesian Journal of Chemistry Vol 18, No 4 (2018)
Publisher : Universitas Gadjah Mada

Corrosion of metal is a serious issue across many industries and is considered costly. Acids used during the cleaning process in industries may contribute to metal erosion. Dithiocarbamate is a ligand that can act as a corrosion inhibitor due to the presence of sulfur and nitrogen as electronegative atoms. Zn(II) N-isopropylbenzyldithiocarbamate (Zn[N-isopbenzdtc]2) complex was synthesized through direct synthetic method of < 4 °C and characterized using Fourier Transform Infrared-Attenuated Total Reflectance (FTIR-ATR), Ultraviolet-Visible (UV-Vis), Nuclear Magnetic Resonance (NMR), X-ray crystallography study, molar conductivity, melting point, and gravimetric analysis. Corrosion inhibition of mild steel was studied for different corrosive media (1 M HCl and 1 M H2SO4). The synthesized inhibitor was studied at different concentrations of 1, 2, 3, 4, and 5 mM at 40 °C. As a conclusion, as the inhibitor concentration decreased, the efficiency of the corrosion inhibitor also decreased at a constant temperature. In this study, it showed that the corrosion activity of mild steel in 1 M H2SO4 was higher compared to 1 M HCl due to the higher concentration of H+, which makes H2SO4 more corrosive than HCl.

Determination of Stevioside and Rebaudioside A in Stevia rebaudiana Bertoni Leaves Using near Infrared Spectroscopy and Multivariate Data Analysis Yohanes Martono; Suryasatriya Trihandaru; Ferdy Semuel Rondonuwu
Indonesian Journal of Chemistry Vol 18, No 4 (2018)
Publisher : Universitas Gadjah Mada

Rebaudioside A and stevioside are abundant steviol glycoside contained in Stevia rebaudiana leaves. These components are widely used as a natural sweetener. The objective of this study was to develop rapid determination method of stevioside, and rebaudioside A in S. rebaudiana leaves using near infrared trans-reflectance spectroscopy (NIRS) combined with multivariate analysis. The reference method used was HPLC. A prediction model was developed using partial least square (PLS) regression. Calibration parameters were calculated based on a calibration set of various stevioside, rebaudioside A from 23 samples. Performance of PLS model was assessed in term of optimum determination coefficient (R2), and minimum root mean square error of cross-validation (RMSEV). Validation of PLS model was performed using cross-validation and leave one out calibration of PLS component. Rebaudioside A has well PLS model in wavenumber region of 4100–5100 cm-1, and stevioside determination using difference wavenumber region of 4760-5016 cm-1. PLS model for total (sum of stevioside and rebaudioside A content) was exploited in wavenumber region of 4568-4928 cm-1. NIRS in combination with multivariate data analysis of PLSR can be applied as a rapid method for determining rebaudioside A and the total amount of steviol glycosides in S. rebaudiana leaves.

Separation of Inorganic Anions and Phenolic Compounds Using Tetraethylene Oxide-Bonded Stationary Phases in Capillary Liquid Chromatography Roza Linda; Mohamad Rafi; Lee Wah Lim; Toyohide Takeuchi
Indonesian Journal of Chemistry Vol 19, No 1 (2019)
Publisher : Universitas Gadjah Mada

Tetraethylene glycol monomethyl ether (TEGMM) and tetraethylene glycol (TEG) modified silica were synthesized and used in capillary liquid chromatography as stationary phases. The stationary phases were prepared by chemically bonding TEGMM or TEG on silica via reaction with 3-glycidyloxypropyltrimethoxysilane. The present stationary phases were successfully used for the separation of several inorganic anions and phenolic compounds. The TEG-modified silica stationary phase had a better selectivity and higher retention for five anions compared to TEGMM-modified silica stationary phase. The repeatability of retention time for the five anions was satisfactory on both stationary phases. By using 2 mM sodium chloride as eluent, the relative standard deviation values were in ranging from 0.68–3.21 and 2.00–2.16% for analytes in the TEG-and TEGMM-bonded stationary phase, respectively. It was found that the TEG-bonded stationary phase had hydrophilic properties due to the presence of the hydroxyl group at the end of the TEG chains.

Effect of Reducing Agents on Physical and Chemical Properties of Silver Nanoparticles Roto Roto; Hani Prima Rasydta; Adhitasari Suratman; Nurul Hidayat Aprilita
Indonesian Journal of Chemistry Vol 18, No 4 (2018)
Publisher : Universitas Gadjah Mada

Silver nanoparticles having uniform size and shape, a diameter range of 10–50 nm, excellent stability, and high zeta potential are always desirable for many applications. The silver nanoparticles were synthesized by chemical reduction method using some reducing agents in a polyvinyl alcohol solution. This study aims at determining the effect of reducing agents on the chemical and physical properties of silver nanoparticles. Ascorbic acid, sodium borohydride, hydrazine, sodium citrate, and glucose were used as reducing agents. Surface Plasmon Resonance (SPR) absorbance, morphology, zeta potential, crystal system, and stability of the products were studied. The results showed that the chemical and physical properties of the colloidal Ag nanoparticles were dependent on the reducing agents. In general, the produced silver nanoparticles have an fcc crystal system with a unit cell of 4.0906–4.0992 Å. The SPR absorbance of the colloids has the peak in the range of 401–433 nm. We found that the colloid of silver nanoparticles prepared by using ascorbic acid has uniform spherical shape, the diameter of about 20 nm, and zeta potential of -10.4 mV. After being stored for one month, the SPR absorbance of the colloid decreased by only 5%. This type of colloidal Ag nanoparticles prepared by using ascorbic acid is expected to be used for chemical sensors, an antibacterial agent, and so on.

Potency of Stirred Microfiltration Cell in Separation of Fermented Beans as Protein Isolate for Natural Source of Folic Acid Aspiyanto Aspiyanto; Agustine Susilowati; Puspa Dewi Lotulung; Hakiki Melanie; Yati Maryati
Indonesian Journal of Chemistry Vol 19, No 1 (2019)
Publisher : Universitas Gadjah Mada

Protein isolate from soy bean (Glycine soja L.) tempeh, mung bean (Phaseolus radiatus L.) tempeh and kidney bean (Phaseolus vulgaris L.) tempeh are natural source of folic acid with main role in brain smartness. 0.15 µm microfiltration (MF) membrane fitted in dead-end stirred microfiltration cell (SMFC) was able to separate protein isolate from three (3) kinds of tempeh at stirrer rotation speed 400 rpm, room temperature and pressure 40 psia for 30 minutes. The result of experimental work showed that SMFC had potential use in separation of protein isolate affected by kinds of bean and membrane performance on isolate composition in retentate and permeate. SMFC was able to retain better protein isolate in retentate than that passing across permeate. Retentate of protein isolate from soy bean tempeh, mung bean tempeh and kidney bean tempeh had subsequently compositions of folic acid 362.07, 254.07 and 506.07 µg/mL, total solids 5.56, 4.08 and 1.82 %, N-Amino 4.34, 3.36 and 0.56 mg/mL, and dissolved protein 0.79, 0.34 and 0.72 mg/mL. In this process condition, SMFC was able to increase folic acid in protein isolate retentate of soy tempeh of 0.59 times, mung bean tempeh of 1.1 times and kydney bean tempeh of 1.42 times before purification process in retentate. Based on both SMFC performance and efficiency, all the best purification optimization were obtained kidney beans tempeh. Identification of monomer of kidney bean tempeh protein isolate gave monomers of folic acid, glutamic acid and folic acid fractionation with molecular weight of 443.5797, 148.1643 and 221.2132 Da. and relative intensity of 1.28, 50.11 and 7.05 %, respectively.

Selective Hydrogenation of Sucrose into Sugar Alcohols over Supported Raney Nickel-Based Catalysts Rodiansono Rodiansono; Maria Dewi Astuti; Dwi Rasy Mujiyanti; Uripto Trisno Santoso
Indonesian Journal of Chemistry Vol 19, No 1 (2019)
Publisher : Universitas Gadjah Mada

Selective hydrogenation of sugars (e.g. sucrose, cellobiose, glucose, fructose, xylose, arabinose) into sugar alcohols (sorbitol, mannitol, xylitol, arabitol) can be achieved by means of supported Raney Ni-based catalysts. Various supporting materials such as the layered structure of clay (e.g. bentonite, taeniolite, smectite), metal oxides (e.g. Nb2O5, ZrO2, Al2O3), and conventional supports (e.g. carbon, silica, zeolite (JRC-SZ1)) were employed to obtain high performance of supported Raney Ni-based catalysts. The conventional Raney Ni, Raney Ni/AlOH, and Ni-NP with relatively high dispersion exhibited superior catalytic activity compared with the various supported Raney Ni catalysts with the conversion of 100% and hexitols selectivity almost ~99%. The H2 treatment of Raney Ni/SMT at a temperature of 473–773 K caused the increase in Ni(111) crystallite sizes as the conversion of sucrose with compromised decreased of hexitols product. The presence of acidic co-catalyst such as SnO, amberlyst-15, JRC-SZ1, JRC-Z5-9OH1 on Raney Ni/AlOH catalyst significantly enhanced the formation of glycerol product even though the conversion of sucrose compromised decreased owing to the partial leaching of Ni metal into the reaction mixture.

Page 83 of 199 | Total Record : 1981

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