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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, Yogyakarta 55281, Indonesia

Author-ID : 3960054

Chemical Engineering, Chemistry & Bioengineering Chemistry

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Synthesis of Fulvic Acid-Coated Magnetite (Fe3O4–FA) and Its Application for the Reductive Adsorption of [AuCl4]– Philip Anggo Krisbiantoro; Sri Juari Santosa; Eko Sri Kunarti
Indonesian Journal of Chemistry Vol 17, No 3 (2017)
Publisher : Universitas Gadjah Mada

Fulvic acid-coated magnetite (Fe3O4–FA) has been synthesized through coprecipitation method using NH4OH. Synthesis conducted by cheap and environmentally friendly preparation used iron salts and extracted fulvic acid (FA) from Peat soil of Rawa Pening, Central Java, Indonesia. Characterization using FT–IR indicated that the coating of FA on Fe3O4 occurred through the formation of chemical bond between iron of Fe3O4 and carboxyl group of FA. The XRD measurement indicated that coated Fe3O4 successfully dispersed in smaller size than uncoated Fe3O4, i.e. from 16.67 to 14.84 nm for Fe3O4 and Fe3O4–FA, respectively. Synthesized Fe3O4–FA has pHPZC 6.37 and stable at pH > 3.0. The extracted FA has total acidity 866.61 cmol kg–1, –COOH content 229.77 cmol kg–1 and –OH content 636.84 cmol kg–1. Fe3O4–FA has total acidity 494.86 cmol kg–1, –COOH content 67.80 cmol kg–1 and –OH content 427.06 cmol kg–1. The adsorption rate constant (k) of [AuCl4]– on Fe3O4–A according to the Ho kinetic model was 8006.53 g mol–1 min–1. The adsorption capacity (qmax) according to Langmuir isotherm model was 1.24 × 10–4 mol g–1. The presence of reduction towards the adsorbed [AuCl4]– was shown by the appearance of peaks at 2θ: 37.41; 43.66; 64.25, and 76.67° in the XRD diffractogram.

Preparation of Water Repellent Layer on Glass Using Hydrophobic Compound Modified Rice Hull Ash Silica Alfa Akustia Widati; Nuryono Nuryono; Dessy Puspa Aryanti; Madjid Arie Wibowo; Eko Sri Kunarti; Indriana Kartini; Bambang Rusdiarso
Indonesian Journal of Chemistry Vol 18, No 4 (2018)
Publisher : Universitas Gadjah Mada

In this study water repellent layered glass has been prepared by coating silica (SiO2) combined with a hydrophobic silane compound. SiO2 was extracted from rice hull ash and two silane compounds, namely hexadecyltrimethoxysilane (HDTMS) and trimethylchlorosilane (TMCS) were used. Coating was performed through two deposition techniques, i.e. one step (mono-layer) and layer by layer (LBL, multi-layer). The effect of silane to SiO2 mole ratio, silane type and layer number on the glass characters was evaluated. Characterization included hydrophobicity, transparency, surface roughness and stability of coating. Results showed that increasing the mole ratio of silane to SiO2 and the layer number increased the hydrophobicity of the glass surface. The optimum mole ratio was 5:1 and the significant increase of contact angle occurred at lower mole ratio, but the stability tends to be increased at higher mole ratio. For HDTMS-SiO2 layer, the technique of LBL technique produced a coating with higher hydrophobicity and transparency than single-stage one. The LBL technique produced the highest water contact angle of 103.7° with transmittance of 96%, while for TMCS-SiO2 layer the one stage technique produced hydrophobic layer with higher water contact angle of 108.0° and transparency about 94.52%. The prepared hydrophobic glasses were relatively stable in polar and non-polar solvents, but unstable to ambient conditions.

Short Time Synthesis of Titania Nanotubes: Effect of Pre-Mixing Prior Hydrothermal Indriana Kartini; Ira Nur Arba’atul Jannah; Fitri Rizki Amalia; Salim Mustofa; Eko Sri Kunarti; Respati Tri Swasono
Indonesian Journal of Chemistry Vol 19, No 1 (2019)
Publisher : Universitas Gadjah Mada

The effect of pre-mixing by mechanical stirring before hydrothermal and hydrothermal time on the crystalline phases and morphology of titania has been studied. It was shown that nanotubes titania can be obtained after 5 h hydrothermal at 150 °C. The XRD patterns and Raman spectra of the produced powders showed the existence of anatase and titanate crystalline phases. At the longest stirring, TiO2 (B) was observed. High textural coefficient for [200] plane of anatase (TC200) confirmed oriented growth of one-dimensional anatase along [200]. All powders resulted at various stirring time were nanotubes, as confirmed by Transmission Electron Microscope (TEM). It was found that the longer the stirring, the higher the surface area of the nanotubes. All powders showed type-IV isotherm for nitrogen gas adsorption/desorption, indicating the existence of mesoporous materials. However, long hydrothermal induced the nanospheres formation, hence reducing the surface area. The band-gap of the resulted titania nanotubes were ranging from 3.11–3.16 eV. The photocatalytic performance toward the degradation of methylene blue of the titania nanotubes was higher (~50%) compared to the bulk TiO2 (~5%) under visible-light and was comparable under UV-light (~60%). These results pave a way of producing visible-sensitive TiO2 photocatalyst by altering the morphology.

Synthesis and Photoactivity of Fe3O4/TiO2-Co as a Magnetically Separable Visible Light Responsive Photocatalyst Eko Sri Kunarti; Indriana Kartini; Akhmad Syoufian; Karolina Martha Widyandari
Indonesian Journal of Chemistry Vol 18, No 3 (2018)
Publisher : Universitas Gadjah Mada

Synthesis of magnetic photocatalyst, Fe3O4/TiO2-Co, with characterization and photoactivity examination have been conducted. The synthesis was initiated by preparation of Fe3O4 particles using coprecipitation method. The Fe3O4 particles were then coated with TiO2-Co at a various ratio of Fe3O4:TiO2 and concentration of Co(II) dopant. The Fe3O4/TiO2-Co was characterized by FTIR, XRD, TEM, SEM-EDX, VSM, and SR UV-visible methods. Photoactivity of the Fe3O4/TiO2-Co was carried out using methylene blue as a target molecule in degradation reaction within a batch system. By using optimum conditions, the degradation of methylene blue solution was performed under exposure to UV, visible light and dark condition. Results showed that the Fe3O4/TiO2-Co formation was confirmed by the presence of Fe3O4 and anatase diffraction peaks in the X-ray diffractogram. SR UV-Vis spectra indicated that the Fe3O4/TiO2-Co was responsive to visible light. Band gap energy of the Fe3O4/TiO2-Co with dopant concentration of 1; 5; 10 and 15% were 3.22; 3.12; 3.09 and 2.81 eV, respectively. The methylene blue solution can be well photodegraded at a pH of 10 for 210 min. The Fe3O4/TiO2-Co has the highest ability to methylene blue photodegradation with dopant concentration of 10% gave degradation yield of 80.51 and 95.38% under UV and visible irradiation, respectively.

Synthesis of Gold Nanoparticles Using p-Aminobenzoic Acid and p-Aminosalicylic Acid as Reducing Agent Abdul Aji; Eko Sri Kunarti; Sri Juari Santosa
Indonesian Journal of Chemistry Vol 19, No 1 (2019)
Publisher : Universitas Gadjah Mada

Synthesis of gold nanoparticles (AuNPs) by reduction of HAuCl4 with p-aminobenzoic acid and p-aminosalicylic acid as a reducing agent was investigated. This work was conducted in order to determine the optimum condition of AuNPs synthesis and examine the effect of the hydroxyl group in p-aminosalicylic acid towards the size, shape, and stability of the synthesized gold nanoparticles (AuNPs). The optimum condition of the gold nanoparticles synthesis was determined by UV/Vis spectrophotometer, the shape and size of gold nanoparticles were measured by Transmission Electron Microscope (TEM). The synthesis process was started by reacting HAuCl4 and the reducing agents in an aqueous solution at 86 ºC. The initial gold concentration, reducing agents concentration and pH were varied in order to obtain the optimum condition. In the optimum condition, the results showed that p-aminosalicylic acid containing both hydroxyl and amino groups performed higher reduction ability compared to p-aminobenzoic acid that only containing an amino group. Reducing agents which have a hydroxyl group (p-aminosalicylic acid) could produce AuNPs with a smaller concentration of HAuCl4 than p-aminobenzoic acid. Gold nanoparticles that were synthesized with p-aminosalicylic acid were more stable and had a smaller particle size compared to its counterpart that is synthesized with p-aminobenzoic acid.

Superparamagnetic Nanocomposite of Magnetite-Chitosan Using Oleic Acid as Anti Agglomeration and Glutaraldehyde as Crosslinkage Agent Suyanta Suyanta; Sutarno Sutarno; Nuryono Nuryono; Bambang Rusdiarso; Eko Sri Kunarti; Hesti Kusumastuti; Lia Kurnia
Indonesian Journal of Chemistry Vol 19, No 1 (2019)
Publisher : Universitas Gadjah Mada

In this research magnetite was synthesized by coprecipitation method, in which solution of NH4OH was added into the solution containing a mixture of Fe2+/Fe3+ (molar ratio 1:2) until pH 11 under strong ultrasonic agitation for 30 min. The black sediment of magnetite was filtered, washed and dried. The product was then modified by using oleic acid to prevent agglomeration. Chitosan was prepared by deacetilization of chitin, whereas chitin was extracted from shrimp shell. In the synthesis of nanocomposite, 0.5 g of chitosan and 1.5 g of oleic acid modified magnetite were introduced into 100 mL of 2% acetic acid solution, followed by sonication treatment for 10 min and magnetic stirring for 20 min. In order to perform the cross-linkage reaction, solution of 2% glutaraldehyde was added into the mixture at temperature of 40 °C for 3 h. The composite was collected by magnetic separation, followed by washing with distilled water and ethanol in a row. The product was dried and characterized by XRD, FTIR, TEM and VSM methods. The result showed that the composite had good crystal structure with a cubic inverse spinel structure, monodisperse and quasi sphere in shape with diameter of 20–25 nm. It had high saturation magnetization (43.4 emu/g) and superparamagnetic property.

The Synthesis and Stability Study of Silver Nanoparticles Prepared by Using p-Aminobenzoic Acid as Reducing and Stabilizing Agent Dian Susanthy; Sri Juari Santosa; Eko Sri Kunarti
Indonesian Journal of Chemistry Vol 18, No 3 (2018)
Publisher : Universitas Gadjah Mada

A study to examine the performance of p-aminobenzoic acid as both reducing agent for silver nitrate to silver nanoparticles (AgNPs) and stabilizing agent for the formed AgNPs has been done. The synthesis of AgNPs was performed by mixing silver nitrate solution as precursor with p-aminobenzoic acid solution and heating it in a boiling water bath. After the solution turned to yellow, the reaction stopped by cooling it in tap water. The formed AgNPs were analyzed by using UV-Vis spectrophotometry to evaluate their SPR absorption in wavelength range of 400–500 nm. The synthesis process was highly depend on the pH, reaction time, and mole ratios of the reactants. The synthesis only occur in pH 11 and at reaction time 30 min, the particle size of the formed AgNPs was 12 ± 7 nm. Longer reaction time increased the reducing performance of p-aminobenzoic acid in AgNPs synthesis but decreased its stabilizing performance. The increase of silver nitrate amount relative to p-aminobenzoic acid in the synthesis increased the reducing and stabilizing performance of p-aminobenzoic acid and the optimum mole ratio between AgNO3 and p-aminobenzoic acid was 5:100 (AgNO3 to p-aminobenzoic acid).

Synthesis of Citrate-Capped Gold Nanoparticles from Reduced [AuCl4]– on Ascorbic Acid-Immobilized Mg/Al Hydrotalcite Agustina Sus Andreani; Suyanta Suyanta; Eko Sri Kunarti; Sri Juari Santosa
Indonesian Journal of Chemistry Vol 18, No 3 (2018)
Publisher : Universitas Gadjah Mada

Reductive adsorption of [AuCl4]-– by using ascorbic acid immobilized on Mg/Al hydrotalcite (Mg/Al HT) and synthesis of gold nanoparticles (AuNPs) from the reduced gold using sodium citrate have been conducted. Mg/Al HT was synthesized by co-precipitation method at pH 10 with molar ratio of Mg(II) and Al(III) 2:1. Ascorbic acid (AA) was then immobilized on Mg/Al HT to form hybrid of AA and Mg/Al HT (Mg/Al HT-AA). Mg/Al HT-AA was used to reductively adsorb [AuCl4]– and the formed Au(0) was extracted by using sodium citrate to form citrate-capped AuNPs. The formation of AuNPs from 100 mg/L [AuCl4]– solution removed by 60 mg Mg/Al HT-AA was optimum at pH 5.0, by using 70 mM sodium citrate and 2 h sonication time. This optimum condition was successfully applied to synthesize AuNPs from [AuCl4]– as the leaching product of gold from PCB using aquaregia.

Effect of Reaction Time and Stability Properties of Gold Nanoparticles Synthesized by p-Aminobenzoic Acid and p-Aminosalicylic Acid Abdul Aji; Sri Juari Santosa; Eko Sri Kunarti
Indonesian Journal of Chemistry Vol 20, No 2 (2020)
Publisher : Universitas Gadjah Mada

In this work, we determined the influenced of the reaction time at the synthesis of gold nanoparticles (AuNPs) by p-aminosalicylic acid and p-aminobenzoic acid as reducing agent. Besides working as a reducing agent, the p-aminobenzoic acid and p-aminosalicylic acid also simultaneously played a role as a capping agent/stabilizing agent. Gold ion was first mixed with the pH adjusted p-aminobenzoic acid and p-aminosalicylic acid. The mixture then heated in boiling water at 86 °C. The formation of AuNPs was indicated by the appearance of red color and analyzed with UV/Vis spectrophotometry to evaluate their surface plasmon resonance (SPR) absorption in the wavelength range 400–800 nm. The reducing ability of the reducing agents was affected by its structure. Gold nanoparticles that were synthesized with p-aminosalicylic acid were more stable, faster and had a smaller size than its counterpart that is synthesized with p-aminobenzoic acid. The stability test over a periods 5 months showed that AuNPs were relatively stable.

Silver Nanoparticles Capped with p-Hydroxybenzoic Acid as a Colorimetric Sensor for the Determination of Paraquat Gusrizal Gusrizal; Sri Juari Santosa; Eko Sri Kunarti; Bambang Rusdiarso
Indonesian Journal of Chemistry Vol 20, No 3 (2020)
Publisher : Universitas Gadjah Mada

Highly stable silver nanoparticles capped with p-hydroxybenzoic acid were synthesized by reducing silver ion with p-hydroxybenzoic acid and used for the detection of paraquat. The synthesized silver nanoparticles, which are yellow, exhibited an absorption peak at 420 nm when measured with a UV-visible spectrophotometer due to the surface plasmon resonance. In the presence of paraquat, the color of silver nanoparticles changed from yellow to purple accompanied by the appearance of a new peak at 580 nm in addition to the peak at 420 nm. In order to obtain optimum experimental conditions, temperature, and time of reaction were optimized, and the ratio of absorbance obtained at 580 nm and 420 nm (A580/A420) were monitored. The A580/A420 is proportional to the concentration of paraquat. Under the most favorable condition, the calibration curve showed a high level of linearity ranging from 6.0 × 10–4 to 1.0 × 10–3 M, and the detection limit was found to be 8.30 × 10–6 M. Silver nanoparticles capped with p-hydroxybenzoic acid was found to be useful for the colorimetric determination of paraquat in the aqueous medium.

Co-Authors Adhitasari Suratman Agus Kuncaka Agustina Sus Andreani Aji, Abdul Akhmad Syoufian Alfa Akustia Widati Annisa Afra Martha Bambang Rusdiarso Defia Indah Permatasari Dessy Puspa Aryanti Dewi Agustiningsih Dian Susanthy Dwi Ratih Purwaningsih Elma Retna Dewi Faathir Al Faath Rachmawati Feri Mukhayani Fitri Rizki Amalia Gusrizal Gusrizal Hesti Kusumastuti Indriana Kartini Ira Nur Arba’atul Jannah Karolina Martha Widyandari Leny Yuliatun Lia Kurnia Madjid Arie Wibowo Nikho Asyoka Wijaya Nuryono Nuryono Philip Anggo Krisbiantoro Respati Tri Swasono Salim Mustofa Sri Juari Santosa Sutarno Sutarno Suyanta Suyanta W. Widjijono Yuichi Kamiya

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