Papers by Author: Bambang Sunendar

Abstract: Gas sensor performance is strongly influenced by the crystal structure, composition and morphology of the material used. In this paper, structural and morphological analysis of nanocomposite SnO₂-Graphene synthesized by Sol-Gel method with the composition of 1:1, 1:2, 1:3 will be described. Analysis of the morphology and structure of nanocomposite SnO₂-Graphene is investigated using XRD, SEM and TEM with the purpose of obtaining the crystal structure, morphology, composition and size of the resulting particles. The XRD results showed that the formation of the crystalline phase can be recorded at 2θ = 26.64; 34.2; 51.92, where the results of SEM show that the nanomaterial SnO₂ has tetragonal structure while the graphene has hexagonal structure. The nanocomposite SnO₂-Graphene has nanorod pattern. Furthermore, the surface analysis using TEM of nanocomposite SnO₂-Graphene shows that the surface has the rod diameter in the range of 5-8 nm. The unique nanopattern of SnO₂-Graphene will have potential applicability as the sensing material for CO gas sensor.

Abstract: In this paper, we present the synthesis procedure and the results of an investigation of a novel silica xerogel (SX) glass ceramic developed from an amorphous SX derived from sago waste ash that incorporates TiO₂ as an additive. The studied compositions have been prepared by adding of either 20% or 80 wt% of TiO₂ into SX, respectively. The samples have been dry pressed and sintered in the temperature range between 900°C and 1500°C. Their properties have been characterized on the basis of the experimental data obtained using X-ray diffraction (XRD), Fourier transform infrared (FTIR), and ultraviolet-visible (UV-Vis) spectroscopy. It has been found that an increase of the content of SX in the composition leads to an increase of the shift of the bandgap energy of TiO₂. The analysis based on the interpretation of both XRD patterns and FTIR spectrum allows one to explain the shift in the bandgap energy by an enlargement of the crystallite size of TiO₂ and by forming of more Si–O–Ti bonds in the samples with a smaller loading of TiO₂.

Abstract: In this study, new dental composites materials were developed. The two composites systems composed of zirconia (ZrO2), alumina (Al2O3) and silica (SiO2) (composites A) and zirconia (ZrO2), calcium (CaO), and silica (SiO2) (composites B) were synthesized through sol-gel method. These two systems were combined with urethane dimethacrylate and tetraethylene glycol dimethacrylate with 1% chitosan as coupling agent to build up the dental composites material. The resulting composites were subject to evaluation by microvickers hardness test and X-ray diffraction. The microvickers hardness test revealed that the hardness value for composites A and B were 24.48 and 21.9 VHN, respectively. Furthermore, the data were submitted to t-test (α=0,01) and it showed t count of both samples was 0,871 which means between the -t1-½α< t <t1-½α thus showing statistically the same average hardness value of both samples. Eventually, the new dental composites could be anticipated to apply in dental composites filler. The hardness results support the XRD result revealed that tetragonal crystal phase will help the transformation toughening mechanism and cubical crystal phase of zirconium dioxide. Both of the crystal phases were formed to stabilize the zirconia.

Abstract: Geopolymer is an aluminosilicate material that can be prepared from thermal activation of solid material containing alumina and silica as precursor and alkali activator solution. The precursor is an eco-friendly material and has a potency to replace Portland cement (cementless material). In this work, cementless geopolymer mortar was prepared by mixing fly ash as main precursors, red mud, and electric arc furnace dust slag, followed by addition of activator solution containing sodium hydroxide solution and waterglass. X-ray diffraction and Fourier transform infra-red spectroscopy demonstrated the formation of albite in geopolymer mortars, indicating that geopolymer mortars have been successfully formed. The best compressive strength of mortars was 72.80 MPa achieved by using fly ash and red mud with NaOH 12M under ambient curing.

Abstract: Iron foam is a type of material having potential to be used as water or air filter andimplant material. One of the limitations of this material is its high reactivity on corrosion. In thepresent research TiO2 coating on iron foam substrate has been developed by self-assembledmonolayer method. Focus is given on the effect of TiCl4 and chitosan concentration on thecharacteristic of the developed TiO2 layer. Precursor was prepared with HCl concentration of 0.5; 1;1.5 M and chitosan solution concentration of 1% ; 2% ; 4% (w/v). Scanning Electron Microscopy(SEM) and Energy Dispersive Spectroscopy (EDS) characterizations show that TiO2 particles areformed on the iron foam surfaces. It was observed that with the higher TiCl4 concentration moreTiO2 particles obtained on substrate surfaces. On the other hand, SEM results also show the averageTiO2 particles size at around 1 micrometer and in tetragonal shape. It was observed that with thehigher chitosan concentration, the particles shape tend to have tetragonal stucture, while at lowerchitosan concentration (1%), agglomeration of TiO2 particles were observed.

Abstract: Microencapsulation is a new breakthrough in the field of nanotechnology that can be used for various applications, in particular for the application of controlled release material for functional textiles which were added by certain active substances and gave effects when used such as fragrance and anti mosquito textile. In this research, the synthesis of silica-lavender microencapsulation for anti-mosquito textile had been conducted successfully via sol-gel emulsion process. Sodium silicate solution which was emulsified into the lavender oil as an active ingredient acted as oil phase and ethanol solution acted as water phase. The addition of chitosan as surfactant and polymer for encapsulation with starch as soft template affected the rod-structure formation of nanorod. SEM result showed the morphology of silica-lavender. The rod has the average diameter size of 0.042-0.206 μm. The optimum result of rod-structure was obtained by adding 1% (v/v) of chitosan. FTIR analysis indicated the presence of absorbance peaks at wavenumber of 1411.89, 958.62, and 1078.2 cm^-1 respectively for C-H (alkanes), C-H (alkenes) and ester functional groups which indicated the lavender compound in silica-lavender. UV-Vis analysis showed the maximum absorbance at wavelength of lavender at 350 nm. The combination of morphology and chemical properties of silica-lavender modified by chitosan-starch made this material as a candidate material for application in functional textile.

Abstract: Nanocrystalline TiO₂ has been synthesized through non-aqueous sol-gel using acetic acid (HOAc) and hydrochloric acid (HCl) as a catalyst. Titanium isopropoxide (TTIP) as precursor was prepared by reaction between TiCl₄ with isopropyl alcohol (IPA) in concentration of 0.3 M. The sol-gel process employed at around 60°C using tert-butanol as solvent and HOAc was added as ligand to stabilize the reaction. Controlled hydrolysis and condensation reactions were achieved through in-taking of water molecules released from the esterification reaction of HOAc with tert-butanol. In this paper, the influence of acidic catalyst was described at the volume ratio of HOAc:HCl are 0:2 ; 1:1 and 2:0. The crystallinity and crystal phase of the samples were characterized by X-ray Diffraction and nanocrystalline TiO₂ with anatase phase was resulted. The morphology of the TiO₂ powder was analyzed by Scanning Electron Microscopy. Pore size and the BET surface area were determined by Brunauer-Emmett-Teller (BET) analysis. Nanocrystalline TiO₂ produced was applied for photoelectrode of dye-sensitized solar cell. The optical properties of the TiO₂ photoelectrodes were measured using by UV-Vis Spectrophotometer. The performance of the cell was measured using a solar simulator with light at an intensity of 50 mW/cm² generated by a xenon lamp. The best efficiency of 0.5% was achieved for active area of 0.48 cm².

Abstract: Nanotechnology is one of the key technology had been developed since in all fields including textile industries for medical, hygienic, and technical textiles. Particle size with nanohad been indicated in particular for the application of controlled release material for functional textiles. TiO₂ nanopowder has remarkable photo-catalytic and semiconductor as material for various advanced technology fields of application such as UV Protection. In this research the synthesis of TiO₂ nanoparticle and characterization had been conducted successfully by sol-gel method. The starch was used as a template to get nanoparticles structure. TiO₂ sol with narrow particle size distribution using TiCl₄ as the starting material. The sol was prepared by a process where HCl was added to a gel of hydrated titanium oxide to dissolve it. The effect of preparation parameters were investigated, by deionized water : HCl 1 M was slowly added to TiCl₄ at 5 °C. In this study the production of anatase or rutile TiO₂ nanostructured powder by forced hydrolysis of aqueous Ti (IV) chloride solution and concentration from 0,3, 0,5 then 1 M. TiO₂ sphere were fabricated by a facile and low cost stable starch assisted by sol-gel method. Aqueous solution of starch was added and then heated in temperature 80°C and aqueous solution of ammonium hydroxide was added to adjust pH to 8. After aging period of time, the white precipitate was filtered and then calcined in temperature 500⁰ C. The as-obtained samples were characterize,kjnhjd by SEM (Scanning Electron Microscope), UV-vis diffuse reflectance spectroscopy, X-Ray Diffraction (XRD) and Brunauer Emmett Teller (BET) analysis. The particle size is less than 100 nm and if it uses template particle TiO₂ more uniform distribution and spherical shape with particle size 170 200 nm. Crystalinity particle is 4 19 nm and the phase structure of anatase and rutile. The energy band gap semiconductor TiO₂ synthesis is 3.1 to 3.7 eV. Surface area without template starch 40.655 m²/g, with total for volume 0.278 cm³/g and pore size of 27 nm, and used template starch surface area 35.488m²/g with total for volume 0.196 cm³/g and pore size of 22 nm. Based on this research, the best a crystal phase for UV protection application is rutile phase.