Yuni K. Krisnandi

ETS-10 as a photocatalyst

ETS-10 is a microporous titanosilicate zeolite with a framework containing linear Ti− O −Ti− O− chains. This paper describes an investigation of the photoreactivity of ETS-10 with the particular objective of evaluating the potential of this novel material as a zeolitic photocatalyst. The photoreactivity and photocat- alytic activity of ETS-10 are strongly influenced by defects in the structure. A relatively defect free material catalyses photo-polymerisation of ethene, and in the presence of oxygen catalyses the partial oxidation of ethene to acetic acid and acetaldehyde, which remain strongly adsorbed in the pores. A more defective material is photoreduced when irradiated in the presence of adsorbed ethene, and catalyses the complete oxidation of ethene to carbon dioxide and water in the presence of oxygen. These differences are attributed to differences in the concentrations of exposed titanium sites associated with defects in the ETS-10 structure.

Photoreactivity of ETS-10

Irradiation of H-ETS-10 in the presence of adsorbed methanol or ethene causes photoreduction of Ti(IV) to Ti(III); photoreduction does not occur for Na, K-ETS-10, but a photoinduced polymerization of ethene is observed.

Preparation and Characterization of Magnetite-Silica Nano-Composite as Adsorbents for Removal of Methylene Blue Dyes from Environmental Water Samples

Magnetite-silica nanocomposites (Fe3O4/SiO2) have been synthesized and characterized and were used as an effective sorbent material for dyes removal from environmental water samples. They were prepared by a simple procedure via a co precipitation of iron (II) and iron (III) ion mixture in ammonium hydroxide and then was impregnated by a sodium silicate. The prepared samples were characterized using Zeta potential, XRD, VSM, TEM, EDS, and porosity analysis. The result of characterization showed that Fe3O4 nanoparticles have been coated by silica. The composite have been superparamagnetic behaviour at room temperature and contain both meso-and microporosity system. Mesoporosity contributes dominantly to the pore volume. Adsorption performance of magnetic-silica nanoparticles were examined its ability to adsorp methylene blue dye in aqueous solution. The 20 mg/L of initial concentration of methelene blue, 1 gr/L adsorbent in solution and under shakker for 5 hour, the remain of methylene blue in solution was 13,3% for Fe3O4/SiO2 (3:1), 30,2% for Fe3O4/SiO2 (2:1) and 24,2 % for Fe3O4/SiO2 (1:1). The composite was effective to adsorb dyes in water and can be easily recovered from treated water with helping of magnetic bar.

Photo-electro-catalytic performance of highly ordered nitrogen doped TiO2 nanotubes array photoanode

Highly ordered nitrogen doped TiO2 nanotube arrays (N-TNTAs) were synthesized via a one step anodization method at 40 V for 1 hour, in the electrolyte containing ammonium fluoride (NH4F), water and triethylamine solution, followed calcination under N2 atmosphere at 450oC for 3 h. The obtained samples were characterized by means of FE-SEM image showed that the N-TNTs are in a highly ordered array, having inner diameters, wall thickness, tube length of 65 nm, 30 nm and 900 nm, respectively. The X-ray diffraction (XRD) patterns of N-TNTAs and undoped TiO2 nanotubes arrays (TNTAs) are identical consists of anatase phase, which suggests that the doping of N does not affect the crystalline structure. X-ray photoelectron spectroscopy (XPS), revealed that N atom was incorporated into the lattice of a TiO2 nanotube array film. The infrared spectra, showed a new peak at 1240 cm-1 may indicate the incorporation of N into the lattice of TiO2 through substituting O atoms, in the form of ~N-Ti-O~. A red shift of the absorption edge toward the visible region of N-TNTAs are observed by diffuse reflectance spectroscopy (DRS), which is corresponding to a band gap of 2.8 eV. The photo-electro-catalytic (PEC) degradation efficiency toward methylene blue solution under visible light illumination of the N-TNTAs electrode was 89%, in which the rate constant of N-TNTAs electrode was 8 times better compared to that the undoped TNTAs photo-electrode.

Modification of hybrid NaY/ZSM-5/IDC zeolite composite with exchanged Cu2+ and its application as ammonia gas sensor

A Modified NaY/ZSM-5/IDC zeolite composite with Cu2+ has been succsessfully prepared on the surface of quartz based Interdigitated Capacitor (IDC). The ZSM-5 was synthesized with double template using hydrothermal method and NaY zeolite was synthesized using sol-gel method. Powder XRD patterns confirmed that structures were ZSM-5 and NaY zeolites. Surface area analysis using BET method are 472,27 m2/g with pore size 2,32 nm for mesoporous ZSM-5 and 392,81 m2/g with pore size 1,6 nm for microporous NaY zeolite. NaY/ZSM-5/IDC and Cu/NaY/ZSM-5/IDC prior ammonia gas sensor testing using Electrochemical Impedance Spectroscopy (EIS) method. The composite has different sensitivity in range concentration of ammonia 0-300 ppm. The Cu/NaY/ZSM5/IDC has higher sensitivity compared to NaY/ZSM5/IDC.

Synthesis of ZSM-5 zeolite from coal fly ash and rice husk: characterization and application for partial oxidation of methane to methanol

Indonesian fly ash (SiO2/Al2O3 mole ratio = 3.59) was used together with rice husk (SiO2 92%) as raw material for mesoporous ZSM-5 zeolite synthesis. Prior being used, coal fly ash and rice husk were subjected to pre-treatment in order to extract silicate (SiO4 4-) and aluminate (AlO4 5-) and to remove the impurities. Then the ZSM-5 zeolite were synthesized through hydrothermal treatment using two types of templates (TPAOH and PDDA). The as-synthesized ZSM-5 was characterized using FTIR, XRD, SEM-EDX, and BET. The result of FTIR showed peaks at 1250-950 cm-1 (v asymetric T-O), 820-650 cm-1 (v symetric T-O), and at 650-500 cm-1 confirming the presence of the five number ring of the pentasil structure. The result of XRD showed the appearance of certain peaks in the position 2 theta between 7-9° and 22-25° indicative of ZSM-5 structure, but also showed the pattern of low intensity magnetite and hematite. The SEM image showed the rough surface of hexagonal crystals from ZSM-5 structure, indicative of mesoporosity in the structure. EDX result showed Si/Al ratio of 20, while surface area analysis gave SA of 43.16. The ZSM-5 zeolites then was modified with cobalt oxide through impregnation method. The catalytic activity as heterogeneous catalysts in partial oxidation of methane was tested. The result showed that hence the catalytic activity of ZSM-5 and Co/ZSM-5 from fly ash and rice husk were still inferior compared to the pro-analysis sourced-counterpart, they were potential to be used as catalyst in the partial oxidation of methane to methanol.

Synthesis of porous activated carbon from petroleum sludge using mesoporous silica template

Porous activated carbon (PAC) was synthesized using hard template method from petroleum sludge waste categorized as toxic waste, using mesoporous MCM-41 as silica template. This sludge waste consists of very high carbon content due to the processing and separation’s by-product of crude oil and natural gas from the flowing fluids released from the reservoir. The properties of sludge waste was characterized by FTIR to identify the functional group, XRD to determine the crystal structure, SEM-EDX and CS analyzer to perform elemental analysis, as well as determination of moisture content and ash content. The properties of PAC were studied by analyzing the pore size and volume using BET method, and elemental analysis using SEM-EDX and CS analyzer. The elemental analysis results showed that sludge waste consists of 47.10% carbon, indicated it is potential to be converted into activated carbon. The functional group analysis results indicated that sludge waste consists of some functional groups such as hydroxyl, ...

Modification of natural zeolite from Bayat with tandem acid-base treatments and cobalt (II) impregnation

Natural zeolite was modified using tandem acid-based treaments in order to create a mesoporous zeolite. Themesoporous zeolite was then characterized using XRD, FTIR, EDX, and AAS. The XRD patterns showed that the structure of zeolite mostly was clinoptilolite. After subjected to the tandem treatment, no significant change in the XRD patterns wasobserved. This indicates that the structure of zeolite is intact. However, the FTIR analysis shows that the wave number of functional groups in the zeolite were shifted after subjected to tandem acid-base treatment, compared to the one of the raw material. However the main functional groups of zeolites still exist after tandem acid-base treatment.The EDX analysis showed that the Si/Al ratio was increased after acid treatments (in average, approximately 1.5 times). In contrast, the Si/Al ratio was decreased from 4.50 to 4.13 after basic treatment. The mesoporous zeolite then was modified further with cobalt (II)-impregnation using incipient wetness method with varia...

PHOTOCURRENT ENHANCEMENT OF CdS QUANTUM DOT SENSITIZED TiO2 ELECTRODE IN THE PRESENCE OF GOLD NANO PARTICLES

PHOTOCURRENT ENHANCEMENT OF CdS QUANTUM DOT SENSITIZED TiO 2 ELECTRODE IN THE PRESENCE OF GOLD NANO PARTICLES . Photo current enhancement of CdS Quantum Dot (CdS-QD) sensitized TiO 2 electrode in the presence of gold nano particles had been investigated. CdS quantum dots were prepared by successive ionic layer adsorption and reaction (SILAR) method, in which solution containing Cd(CH 3 COO) 2 and Na 2 S were used as a precursor. Where as, gold nano particles was synthesized using solution containing HAuCl 4 as a precursor, NaBH 4 as a reducing agent and polyvinyl pyrrolydone (PVP) as a stabilizer. The film of CdS quantum dots and Au nano particles were characterized by UV-Vis spectrophotometer, Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), and electro chemical working station. Photo electrochemical study revealed that CdS-sensitized TiO 2 electrode with gold nanoparticles have been able to increase photocurrent of 54 A/cm 2 to 68 A/cm 2 , so the photocurrent enhancement of approximately 25% was observed. This observation indicates that the gold nanoparticles is potentially applicable to enhance photocurrent in a CdS-QD sensitized TiO 2 electrode, which may lead to the development of more efficient solar cell.

Study of CO2 adsorption capacity of mesoporous carbon and activated carbon modified by triethylenetetramine (TETA)

Mesoporous carbon was synthesized by soft template method using phloroglucinol and formaldehyde as a carbon source; and Pluronic F-127 as a mesoporous template. The synthesized mesoporous carbon and commercial activated carbon were modified with triethylenetetramine (TETA) to increase CO2 adsorption capacity. Based on FTIR characterization, the synthesized mesoporous carbon and the activated carbon without modification process has similarity pattern. After the modification, both of them showed absorption peaks in the area around 1580 to 1650 cm-1 which is known as N-H bending vibration and absorption peaks in the area around 3150 to 3380 cm-1 which is known as N-H stretching vibration. The XRD results showed two peaks at 2θ = 24.21° and 2θ = 43.85°, according to JCPDS index No. 75-1621 those peak are the typical peaks for hexagonal graphite carbon. In BET analysis, the synthesized mesoporous carbon and activated carbon modified TETA have surface area, pore volume and pore diameter lower than without modification process. In carbon dioxide adsorption testing, the synthesized mesoporous carbon showed better performance than the commercial activated carbon for CO2 adsorption both without modification and by modification. The synthesized mesoporous carbon obtained CO2 adsorption of 9.916 mmol/g and the activated carbon of 3.84 mmol/g for on 3.5 hours of adsorption. It is three times better than activated carbon for adsorption of carbon dioxide. The modified mesoporous carbon has the best performance for adsorption of gas CO2 if compared by unmodified.