Agus Kuncaka
Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Sekip Utara PO BOX BLS 21 Yogyakarta 55281

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IMPREGNASI BASAH Fe3+ KE DALAM SILIKAT MESOPORI MCM-41-TERSILILASI. ., Suyanta; Kuncaka, Agus
Jurnal Iptek Nuklir Ganendra Vol 16, No 1 (2013)
Publisher : BATAN

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Dalam penelitian ini dilakukan impregnasi basah (wet impregnation) Fe3+ ke dalam MCM-41-tersililasi dengan optimasi konsentrasi Fe3+, waktu dan temperatur. Analisis kristalinitas inang didasarkan pada intensitas puncak bidang [100] difraktogram, analisis kuantitatif Fe dalam MCM-41-tersililasi dilakukan dengan metode AAS, sedang karakterisasi Fe-MCM-41-tersililasi dilakukan dengan metode-metode spektroskopi DRUV-Vis, spektroskopi EPR, dan FTIR. Diperoleh kesimpulan bahwa semakin besar konsentrasi Fe3+ dalam larutan prekursor cenderung meningkatkan kandungan Fe dalam Fe-MCM-41-tersililasi, namun jika digunakan larutan prekursor dengan konsentrasi Fe3+ ≥ 0,1 M berakibat terjadinya kerusakan struktur heksagonal MCM-41-tersililasi. Waktu kontak optimal adalah 8 jam, sedang temperatur optimalnya 40 ºC. Impregnasi basah Fe3+ ke dalam MCM-41-tersililasi dapat mengakibatkan substitusi isomorfis Fe3+ menggantikan Si4+ pada jaringan silikat dan juga  menghasilkan nanopartikel oksida besi diluar jaringan silikat, yaitu mengisi sebagian pori MCM-41-tersililasi.
STUDI SPEKTROSKOPI TENTANG PASIVASI DALAM ANODA CuFeS2 + CaCO3 (CHALCOPYCA) PADA PROSES ELEKTRO-EKSTRAKSI TEMBAGA Kuncaka, Agus; Yudhanti, -; Sugiharto, Eko
Berkala Ilmiah MIPA Vol 16, No 3 (2006)
Publisher : FMIPA UGM

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Studi spektroskopi fungsionalisasi anoda campuran padatan CuFeS2 dan CaCO3 (Chalcopyca) telah dilakukan dengan menggunakan Difraksi Sinar-X (XRD) dan FT-IR. Tujuan penelitian ini untuk mempelajari pasivasi pelarutan CuFeS2 secara elektrokimia. CuFeS2 murni diperoleh dari konsentrat tembaga yang dicuci dengan HF 40 % dan kemudian dinetralkan dengan B(OH)3 8,5 x 10-2M. Padatan CuFeS2 dicampur dengan CaCO3 dengan perbandingan 9 : 1. Campuran diambil 3 gram untuk dibuat pellet dengan tekanan 20 kN/cm2, kemudian dijadikan sebagai anoda. Elektrolisis dilakukan dalam medium 50 mL larutan (Na2SO4 0,5 M + H2SO4) 0,01 M) dengan arus tetap 1,5 mA dengan variasi waktu 30, 60, 120 dan 180 menit, kemudian dilakukan anlisis dengan XRD dan FT-IR. Dari hasil penelitian diperoleh bahwa pasivasi proses pelarutan tembaga dari anoda campuran padatan CuFeS2 dengan CaCO3 dipicu oleh terbentuknya Fe2O3 di permukaan anoda. Struktur anoda-dalam, selama elektrolisis tidak mengalami perubahan, sedang struktur anoda-luar (yang bersentuhan dengan elektrolit) mengalami pelarutan melalui oksidasi CuFeS2 menjadi SO42- serta Cu2+ dan Fe2+. Pembentukan Fe2O3 diperkirakan akibat oksidasi kimia Fe2+ oleh oksigen teradorpsi yang terbentuk selama elektrolisis dipermukaan anoda. Kata kunci: anoda, pasivasi, elektrolisis
HYDROTALSIT Zn-Al-EDTA SEBAGAI ADSORBEN UNTUK POLUTAN ION Pb(II) DI LINGKUNGAN Roto, Roto; Indah, Dahlia Rosma; Kuncaka, Agus
Jurnal Manusia dan Lingkungan (Journal of People and Environment) Vol 22, No 2 (2015)
Publisher : Pusat Studi Lingkungan Hidup Universitas Gadjah Mada

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Polusi ion Pb(II) di dalam lingkungan perairan cenderung naik seiring peningkatan jumlah industri smelter dan daur ulang aki bekas. Penelitian ini bertujuan untuk menguji kemampuan hidrotalsit Zn-Al-EDTA sebagai adsorben ion Pb(II) dalam air secara mendalam. Hidrotalsit Zn-Al-NO3 disintesis dengan metode kopresipitasi dan hidrotermal pada temperatur 100 °C selama 15 jam. Hidrotalsit Zn-Al-EDTA diperoleh dengan penukaran ion. Keasaman larutan, kinetika dan kapasitas adsorpsi diteliti. Hidrotalsit Zn-Al-EDTA memiliki d003 sebesar 14,52 Å sementara Zn-Al-NO3 sebesar 8,90 Å. Spektra FTIR menunjukkan keberadaan serapan gugus C=O pada bilangan gelombang 1684,77 cm-1. Kondisi optimum adsorpsi ion Pb(II) terjadi pada pH 4, waktu kontak 60 menit dan kapasitas adsorpsi diperoleh 2,07 mg/g pada konsentrasi awal 10 mg/L dengan berat adsorben 0,100 g. Adsorpsi ion Pb(II) oleh hidrotalsit Zn-Al-EDTA mengikuti reaksi pseudo orde dua dengan tetapan laju adsorpsi sebesar 8,90 g mmol-1min-1. Adsorpsi ion Pb(II) oleh Zn-Al-EDTA terjadi karena  pembentukan khelat Pb-EDTA di dalam struktur hidrotalsit. Hasil ini diharapkan mampu memberikan kontribusi yang lebih luas di dalam pengendalian konsentrasi Pb(II) di lingkungan.
Functionalization of Fe3O4/SiO2 with N-(2-Aminoethyl)-3-aminopropyl for Sorption of [AuCl4]- Nuryono, Nuryono; Syukur, Mighfar; Kuncaka, Agus; Sakti, Satya Candra Wibawa
Indonesian Journal of Chemistry Vol 16, No 2 (2016)
Publisher : Universitas Gadjah Mada

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Synthesis of Fe3O4/SiO2 modified with N-(2-aminoethyl)-3-aminopropyl group (Fe3O4/SiO2/ED) via coating method and its application for adsorption-desorption of anionic gold in aqueous solution have been conducted. The synthesized product was characterized with an X-ray diffractometer (XRD), a Fourier transform infrared (FT-IR) spectrophotometer and a transmission electron microscopy (TEM). Adsorption of Au(III) was conducted in a batch system and the variables included pH, contact time, and initial concentration were investigated. Results showed that magnetite/silica has been successfully functionalized with N-(2-aminoethyl)-3-aminopropyl in a homogeneous system. Kinetics study showed that adsorption of Au(III) followed the pseudo-second order model with rate constant of 0.710 g mmol L-1min-1. Furthermore, the experimental data fitted well with the Langmuir isotherm model with the maximum adsorption capacity for Au(III) of 142.9 mg g-1 and the energy of 25.0 kJ mol-1. Gold loaded on the Fe3O4/SiO2/ED could be easily desorbed with 0.2 mol L-1 HCl containing 2 wt.% of thiourea with recovery of 99.8%. Fe3O4/SiO2/ED was reusable and stable in 5 cycles of adsorption-desorption with recovery more than 90%. Fe3O4/SiO2/ED showed high selectivity towards Au(III) in the multimetal system Au(III)/Cu(II)/Cr(VI) with the coefficient selectivity for αAu-Cu of 227.5and for αAu-Cr of 12.3.
L-Arginine-Modified Silica for Adsorption of Gold(III) Hastuti, Sri; Nuryono, Nuryono; Kuncaka, Agus
Indonesian Journal of Chemistry Vol 15, No 2 (2015)
Publisher : Universitas Gadjah Mada

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In this research, L-arginine-modified silica (SiO2-Arg) with 3-glycidoxypropyl-trimethoxysilane (GPTMS) as the linking agent has been synthesized through sol gel process for adsorption of Au(III) in aqueous solution. Tetraethyl orthosilicate (TEOS) as the silica source precursor, L-arginine solution 0.9 M with various volume ratios and the linking agent were mixed together to form a gel. SiO2-Arg was characterized using Fourier transform infrared (FTIR) spectrophotometer, thermogravimetric analysis (TGA), and an elemental analysis. Adsorption was carried out in a batch system under various experimental conditions including contact time and initial concentration of metal Au(III). The selectivity of adsorbent toward Au(III) was examined in the presence of Cu(II), Fe(III), and Zn(II) ion at various pHs. Results of characterization showed that silica has been successfully modified with L-arginine. The optimum adsorption of Au(III) on SiO2-Arg was obtained at pH of 3.0 and the adsorption isotherm of Au(III) on SiO2-Arg gives the adsorption capacity of 52.79 mg/g. The kinetic study demonstrates that the adsorption of Au(III) ion follows pseudo-second order with the rate constant of 53197 g mol–1 min–1. The selectivity order of Au-Zn = Au-Cu > Au-Fe. This sol-gel preparation is simple and provides prospective application of SiO2-Arg material as an effective adsorbent for metal ions particularly gold(III).
Study on the Interference of Iron, Aluminium and Silicon on the Atomic Absorption Spectrometric Determination of Mangan in Laterite Mineral Saputro, Sulistyo; Hadipranoto, Ngatidjo; Kuncaka, Agus
Indonesian Journal of Chemistry Vol 1, No 2 (2001)
Publisher : Universitas Gadjah Mada

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Interference of iron, aluminum and silicon on the determination of mangan in laterite mineral by atomic absorption spectrometry has been investigated. Dissolution of laterite mineral into solution have been carried out by wet method destruction using combination of 7 mL of aquaregia, 7.5 mL of concentrated perchloric acid and 9 mL of fluoride acid 48% In sealed teflon flask heated at temperature of about 110 °C for 3 hours to determine the content of Mn element in laterite mineral directly. Interference of these three metals were carried out by evaluating the differences of Mn absorbance at wavelength 279.50 nm and slit width 0.2 nm between the solutions containing mangan only and those containing the some amount of mangan together with the interfering elements at those concentration range in laterite mineral. The result showed that both iron at concentration of 100 ppm until 500 ppm and aluminum at concentration at 3 ppm until 15 ppm caused significant and non-linear interference on the determination of Mn 2 ppm. Interference of iron was effectively eliminated by releasing action of aluminum. The signal depression reductional decrease due to 234 ppm of silicon on the determination of Mn 2 ppm can be eliminated by adding 2.30 mL of CaCl2 0.2% (m/v) into these solution. The content of Mn in the laterite mineral after and before adding of CaCl2 into solution were 2407.04 ± 59.26 μg g-1 and 2311.76 ± 23.61 μg g-1, respectively. This result was significantly different at confidence level 95% as shown by the value of tcalculated=4.91 that was higher than ttable=4.30.
ENHANCEMENT OF THE SENSITIVITY AND SELECTIVITY OF THE VOLTAMMETRIC SENSOR FOR URIC ACID USING MOLECULARLY IMPRINTED POLYMER Khasanah, Miratul; Mudasir, Mudasir; Kuncaka, Agus; Sugiharto, Eko; Supriyanto, Ganden; Wafiroh, Siti
Indonesian Journal of Chemistry Vol 10, No 3 (2010)
Publisher : Universitas Gadjah Mada

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The sensitivity and selectivity of voltammetric sensor for uric acid can be improved by modifying the working electrode using a polymer with a molecular template (molecularly imprinted polymer, MIP). Polymer and MIP was synthesized from methacrylic acid (MAA) as monomer, ethylene glycol dimethacrylic acid (EGDMA) as cross-linker, uric acid (UA) as template and the results were characterized by various methods. The poly-MAA formation was identified by a decrease in the intensity of infrared (IR) spectra at ~1540 cm-1 (C=C) and an increase at ~1700 cm-1 (C=O) compared to the IR spectra of the MAA and EGDMA. The SEM analysis showed that the cavity of polymer is small enough (~ 0.1 µm) and homogeneous. Establishment of MIP was carried out by extracting of the uric acid from the polymer network. The IR spectra of MIP exhibited the decrease in intensity at ~1700 cm-1 (C=O) compared to the non imprinted polymer (NIP). The data of BET analysis showed that polymer pore size increase slightly from 37.71 Å to 38.02 Å after the extraction process of uric acid from the polymer network. Its may be due to incomplete extraction of uric acid from the polymer network. Modifications of hanging mercury drop electrode using MIP made from MAA, EGDMA, and UA with a mole ratio of 1:3:1 produced a sensitive and selective voltammetric sensor for uric acid. The sensitivity obtained was 16.405 nA L/µg. The presence of ascorbic acid in equal concentration with uric acid decreased the current response of only 0.08%. Compared to HMDE electrode, the sensitivity and selectivity of the HMDE-MIP sensor enhanced about 100 and 700 times, respectively. The detection limit was found to be 5.94 x10-10 M.
SILVER RECYCLING FROM PHOTO-PROCESSING WASTE USING ELECTRODEPOSITION METHOD Hadiyanto, Mochammad Feri; Kuncaka, Agus
Indonesian Journal of Chemistry Vol 2, No 2 (2002)
Publisher : Universitas Gadjah Mada

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            Silver electrodeposition of photo-processing waste and without addition of KCN 1,0 M has been studied for silver recycling. Photo procesing waste containing silver in form of [Ag(S2O3)2]3- was electrolysed at constant potential and faradic efficiency was determined at various of electrolysis times. Electrolysis of 100 mL photo processing waste without addition of KCN 1,0 M was carried out at constant potential 1.20 Volt, while electrolysis 100 mL photo procesing waste with addition of 10 mL KCN 1,0 M electrolysis was done at 1.30 Volt.The results showed that for silver electrodeposition from photo processing waste with addition of KCN 1,0 M was more favorable with faradic efficiency respectively were 93,16; 87,02; 74,74 and 78,35% for 30; 60; 90 and 120 minutes of electrolysis.   Keywords: Silver extraction, electrodeposition, photo-processing waste
UTILIZATION OF RICE HUSK AS RAW MATERIAL IN SYNTHESIS OF MESOPOROUS SILICATES MCM-41 Suyanta, Suyanta; Kuncaka, Agus
Indonesian Journal of Chemistry Vol 11, No 3 (2011)
Publisher : Universitas Gadjah Mada

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The research about synthesis and characterization of MCM-41 from rice husk has been done. Silica (SiO2) was extracted from rice husk by refluxing with 3M hydrochloric solution at 80 °C for 3 h. The acid-leached rice husk was filtered, washed, dried and calcined at 650 °C for 6 h lead the rough powder of rice husk silica with light brown in color. Characterization was carried out by X-ray diffraction (XRD) and FTIR spectroscopy method. Rice husk silica was dissolved into the sodium hydroxide solution leading to the solution of sodium silicate, and used as silica source for the synthesis of MCM-41. MCM-41 was synthesized by hydrothermal process to the mixture prepared from 29 g of distilled water, 8.67 g of cetyltrimethyl ammonium bromide (CTMAB), 9.31 g of sodium silicate solution, and amount mL of 1 M H2SO4. Hydrothermal process was carried out at 100 °C in a teflon-lined stainless steel autoclave heated in the oven for 36 h. The solid phase was filtered, then washed with deionised water, and dried in the oven at 100 °C for 2 h. The surfactant CTMAB was removed by calcination at 550 °C for 10 h with heating rate 2 °C/min. The as-synthesized and calcined crystals were characterized by using FTIR spectroscopy, X-ray diffraction and N2 physisorption methods. In order to investigate the effect of silica source, the same procedure was carried out by using pure sodium silicate as silica source. It was concluded that silica extracted from rice husk can be used as raw materials in the synthesis of MCM-41, there is no significant difference in crystallinity and pore properties when was compared to material produced from commercial sodium silicate.
EXTRACTION OF COPPER ELECTROLYTICALLY BY USING SOLID MIXTURE OF CuFeS2 AND CaCO3 (CHALCOPYCA) AS ANODE Kuncaka, Agus; Sugiharto, Eko; Nastiti, Yasinta Endah
Indonesian Journal of Chemistry Vol 5, No 3 (2005)
Publisher : Universitas Gadjah Mada

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Study on a new road of copper electroextraction to make use the solid mixture of CuFeS2 and CaCO3 as anode has been done. The aim of these research was to determine reaction kinetic and faradic efficiency of anodic copper dissolution and catodic copper precipitation. A solid mixture of CuFeS2 and CaCO3 at weight ratio 9:1 was functioned as anode. Electrolysis was carried out at 1.5 mA by varying times of 30,60,120, and 240 minutes in Na2SO4 0.5 M + H2SO4 0.01 M electrolyte. The quantity of copper at the electrolyte and cathode was analyzed by Atomic Absorption Spectrophotometer (AAS). The result of these research showed that copper was deposited in the cathode simultaneously with anodic dissolution. The kinetic of copper dissolution follow zero order with rate constant of 5.10-6 mg/second. The faradic efficiency of copper dissolution and precipitation for those various time respectively were 17.31%; 14.00%; 11,16%; 62.31%; and 1.60%; 8.61%; 7.59%; 60.63%. Keywords: electroextraction, faradic efficiency, copper dissolution.