Sri Sudiono
Laboratorium Kimia Fisika FMIPA UGM, Sekip Utara, Jogjakarta

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STUDI KAPASITAS ADSORPSI-REDUKSI ION Au(III) PADA ASAM HUMAT HASIL ISOLASI DARI TANAH GAMBUT RAWA PENING

PHARMACIANA Vol 2, No 2: November 2012
Publisher : PHARMACIANA

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Abstract

Isolasi asam humat dan aplikasinya untuk adsorpsi-reduksi ion Au(III) telah dilakukan. Asam humat diisolasi dari tanah gambut yang diambil dari Rawa Pening, Jawa Tengah. Isolasi asam humat dari tanah gambut didasarkan pada metode ekstraksi tradisional basa. Isolasi asam humat dilakukan dengan mengekstraksi asam humat dari tanah gambut dengan 0,1 M NaOH dan mengendapkan dengan 0,1 M HCl kemudian dilakukan pencucian dengan 0,1 M HCl/0,3 M HF 1/1. Asam humat dikarakterisasi dengan spektroskopi Fourier-Transform Infrared (FTIR) kemudian diaplikasikan untuk adsorpsi-reduksi ion Au(III). Kapasitas adsorpsi menggunakan model isoterm adsorpsi terhadap proses adsorpsi reduksi ion Au(III) juga telah dipelajari. Logam Au yang terbentuk dikonfirmasi dengan difraktogram XRD dan foto mikroskop optik. Hasil perhitungan kapasitas adsorpsi dengan model isotherm Langmuir asam humat adalah 192 mg/g. Pembentukan logam Au ditunjukkan oleh munculnya puncak pada 2_ = 38, 44, dan 64 dalam difraktogram XRD.

UTILISASI TiO2-ZEOLIT DAN SINAR UV UNTUK FOTODEGRADASI ZAT WARNA CONGO RED

Berkala Ilmiah MIPA Vol 16, No 3 (2006)
Publisher : FMIPA UGM

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Abstract

An investigation of Congo Red photodegradation using TiO2-zeolite and uv radiation was performed. TiO2-zeolite was prepared by dispersing of pillaring solution (in form oligocations of titanium) into suspension of zeolite. The suspension was stirred and then filtered to separate the solid phase from the filtrate. The solid phase was calcined by microwave oven at 800 Watt for 5 minutes to convert the oligocations into its oxide forms. The calcined product and unmodified zeolite were characterized using x-ray diffractometry, FT-IR spectrophotometry, X-ray fluorescence and gas sorption analysis to determine their physicochemical properties. Photocatalytic activity of TiO2-zeolite was tested on Congo Red using following method: 50 mg of zeolite was dispersed into 25 mL of 10-4 M Congo Red. The dispersion was irradiated using 365 nm uv light at room temperature on various irradiation times, i.e. 10,20,30,40 and 60 minutes. At certain irradiation time, the dispersion was filtered and the filtrate was then analyzed its concentration using uv-vis spectrophotometry method. Characterization results exhibited that the formation of TiO2 on internal as well as external surfaces of zeolite could not be detected with x-ray diffractometry and FT-IR spectrophotometry, however determination of titanium using x-ray fluorescence analysis on the calcined product showed that the concentration of titanium was much higher than zeolite (0.22% on zeolite and 12.08% on TiO2-zeolite). Gas sorption surface area (16,31 m2/g on zeolite and 100,96 m2/g on tiO2-zeolite) as well as total pore volume of calcined product (13,34 mL/A/g on zeolite and 57,54 mL/A/g on TiO2-zeolite). Photocalytic activity test result conducted on that dye showed that ca 99% of Congo Red was degraded by the system TiO2-zeolite after uv irradiation for 60 minutes. Keywords : TiO2-zeolite, Photocatalytic, UV-irradiation, Congo Red

PREPARATION, CHARACTERIZATIONS AND MODIFICATION OF Ni-Pd/NATURAL ZEOLITE CATALYSTS

Indonesian Journal of Chemistry Vol 5, No 1 (2005)
Publisher : Universitas Gadjah Mada

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Abstract

Preparation, and modification of Ni-Pd/natural zeolite as well as their characterizations had been carried out. The aim of this research for the fututure is to prepare the best characters catalyst for the conversion of waste plastics fraction to gasoline fraction (C5-C12 hydrocarbons). The preparation of catalysts was performed by reacting a natural zeolite with the precursor of Ni(NO3)2. 9H2O and PdCl2 in an ammonia solution (25%). The modifications were performed by varying the rasio of Ni/Pd loaded to the zeolite, whereas the Pd was previously loaded and total metal content was 1 wt.% based on the zeolite. The characterization of catalysts included determination of acidity gravimetrically by adsorption of ammonia or pyridine vapour  base method, metal content by Atomic Adsorption Spectrophotometer (AAS) and X-ray Fluoresence (XRF) and crystallinity by X-ray Diffraction (XRD). The treatment of catalysts using Etilene Diamine Tetra Acetic acid  (EDTA) was performed to study the metal distribution on the outer or inner surface of the zeolite. The characterization results showed that the loading of metals to the zeolite increased its acidity and decreased its spesific surface area, however, did not defect its crystallnity.  The metals loaded on the zeolite were distributed inside the pore and at outer surface of the zeolite. For all catalyst samples, the acidities determined using ammonia were higher than those of pyridine, and the acidities determined before the EDTA treatment was lower than those after the treatment.  Metal contents of the zeolite before the EDTA treatment were higher than those after the treatment. The EDTA treatment enhanced the crystallinity of the sampel. The relationship between the metal rasio towards the acidity of the catalyst samples were in variation. Catalyst samples produced in this research have good characters, thus promisingly can be used for conversion process of waste plastics to gasoline fraction.    Keywords: natural zeolite, acidity, metal content, crystallinity, EDTA

STUDY OF THERMAL AND ACID STABILITY OF BENTONITE CLAY

Indonesian Journal of Chemistry Vol 2, No 1 (2002)
Publisher : Universitas Gadjah Mada

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Abstract

The thermal and acid stability of the bentonite clays (Na- and Ca-bentonite) have been tested. The thermal stability testing has been carried out by heating 5 gram of the clays  for five hours at 200, 300 and 500 °C respectively, meanwhile acid stability testing was performed by immersing 5 gram clays into 100 mL sulphuric acid 1M, 2M and 3M for 24 hours. The tested clays, then were characterized by means of X-Ray difractometry and IR-spectroscopy methods. The characterization results showed that upon heating, both Ca- and Na-bentonites indicated same thermal stability. However, upon acid treatment, Na-bentonite was found relatively stabiler and more resistance then Ca-bentonite.   Keywords: bentonite, clay, thermal stability, acid stability.

THERMAL EFFECT OF COCONUT CREAMS ABILITY TO ADSORB CALCIUM(II)

Indonesian Journal of Chemistry Vol 2, No 2 (2002)
Publisher : Universitas Gadjah Mada

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Abstract

Study of thermal effect of coconut creams ability to adsorb Ca (II) has been done at various temperatures of 49 oC,  59 oC and 80 oC. The adsorption study was performed to check capacity, energy and rate of adsorption by varying the number of initial concentration of CaCl2 bounded on coconut protein. This research was also done to determine number of Ca (II) in the coconut protein using the salt addition and elicits reaction methods. The result showed that adsorption ability tends to increased with the increase of temperature). Coconut cream heated at 59 oC adsorb Ca(II) with the highest adsorption capacity of 3.98 mg/g and K = 3.48x104  mol-1. The salt addition method on the coconut cream gives more Ca (II) than elicit reaction method. The first method gives 0.01137 mol/L and the second was 0.02845 mol/L. Based on the energy of adsorption, cream without heating had 20.59 kJ/mol as a physical adsorption and heating effect at temperatures 49 oC, 59 oC and 80 oC had 24.95; 28.87 and 24.87 kJ/mol respectively as a chemical adsoprtion with the rate of adsorptions of 0,0054;  0,0510 dan  0,3. 10-4 minute-1, respectively.   Keywords: coconut cream, adsorption, thermal effect.

The Role of Carboxyl and Hydroxyl Groups of Humic Acid in Removing AuCl4- from Aqueous Solution

Indonesian Journal of Chemistry Vol 17, No 1 (2017)
Publisher : Universitas Gadjah Mada

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Abstract

Humic acid (HA) extracted from peat soil according to the recommended procedure of the International Humic Substances Society (IHSS) has been tested to remove AuCl4- from aqueous solution. The removal was optimum at pH 2.0 and it was mainly dictated by attachment through hydrogen bonding to unionized carboxyl (–COOH) groups and reduction by the action of the hydroxyl (–OH) groups to gold (Au) metal. The removal of AuCl4- improved after HA was purified through repeated immersion and shaking in a mixed solution containing 0.1 M HCl and 0.3 M HF. When the purification led to the sharp decrease in ash content from 39.34 to 0.85% (w/w) and significant increase in both the –COOH and –OH contents from 3240 to 3487 mmol/kg and from 4260 to 4620 mmol/kg, respectively; the removal of AuCl4- improved from 0.105 to 0.133 mmol/g. This improvement of AuCl4- removal by the purified HA was accompanied by higher ability in reduction to Au metal. The attached AuCl4- on –COOH groups of both crude and purified HAs was qualitatively observed by the characterization result of FT-IR spectroscopy, while the presence of Au metal on the surface of those HAs was verified by the characterization result of XRD.

Synthesis of Iron-Doped Zirconium Titanate as a Potential Visible-Light Responsive Photocatalyst

Indonesian Journal of Chemistry Article in press
Publisher : Universitas Gadjah Mada

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Abstract

Synthesis and properties of iron-doped zirconium titanate (ZrTiO4) as a potential visible-light-responsive photocatalyst had been conducted. Various iron dopant concentration and calcination temperature were investigated toward the properties of Fe-doped ZrTiO4. The photocatalyst material was synthesized by sol-gel and impregnation method. Titanium tetraisopropoxide (TTIP) was used as a precursor, embedded on zirconia fine powder. A certain amount of iron (1, 3, 5, 7 and 9 wt.%) was introduced into the photocatalyst system from iron(II) sulfate heptahydrate (FeSO4·7H2O). Photocatalyst with various iron concentration calcined at 500 °C. ZrTiO4 with 5% iron additionally was calcined at 700 and 900 °C. Characterization was performed by using XRD, FT-IR, SR-UV, and SEM-EDX. The presence of iron on the surface of ZrTiO4 was proved by EDX analysis. Fe-doped ZrTiO4 with the lowest bandgap (2.83 eV) is 7% of iron content after calcination at 500 °C.