Materials Science Forum Vol. 964

Abstract: The aim of this research is to synthesize mesoporous silica directly from the bottom ash waste through the melting method using alkali at high temperatures. The resulting mesoporous silica will be used as CH₄ gas adsorbent. The bottom ash waste was firstly separated by Fe and Ca using 37% HCl followed by melting at high temperatures and producing silica extract. The extract will be used as the basic material for making mesoporous silica which impregnation with PEG 4000. The resulting solids will then be characterized using XRD and BET. The result of mesoporous silica was then carried out by measuring CH₄ gas adsorption capacity by gravimetric method with interval temperature of 30, 40, and 50 °C and pressure of 1, 3, and 5 atm.

Abstract: The kinetics of crystallization of magnesium carbonate (nesquehonite) at room temperature (27°C) has been examined using an electrical conductivity method during process of nucleation. Magnesium carbonate hydrate from a reaction of magnesium chloride (MgCl₂) and sodium carbonate (Na₂CO₃) in supersaturated condition was analyzed. Variations of batch reactor experimental are magnesium chloride initial concentration (500-3.000 mg/L) and operating pH (8-14). In this paper, we studied the crystallization kinetics of magnesium carbonate via an electrical conductivity method, a concentration monitoring method. By monitoring electrical conductivity during the solution reaction process, changes in [Mg²⁺] can be measured and an induction period of nucleation could be determined. Crystal has been formed was confirmed with powder X-ray Diffractometer (XRD) analyses. The results show that magnesium carbonate is formed during operating condition pH 10 with magnesium chloride initial concentration 3.000 mg/L. The nucleation process of magnesium carbonate crystallization can be represented by second-order reaction equation with R² is 0.8. The induction period of magnesium carbonate crystallization is 50 second.

Abstract: In this study the effect of mixed culture of Zymomonas mobilis and Pichia stipitis to produce bioethanol from Solid Waste Arenga pinnata (SWAP) was investigated. The fermentation liquid substrate was resulted from an integrated process of pretreatment and enzymatic hydrolysis. Combination of diluted acid and ethanol organosolv pretreatment was used to increase the SWAP lignin removal. Raw pretreatment was used to decrease the SWAP particle size to 200 mesh. Acid pretreatment was done using 5% (v/v) diluted sulfate acid. Acid pretreated SWAP was treated for 65 min with organosolv pretreatment. Enzymatic hydrolysis by a combination of cellulase and xylanase was done for 48 h to convert cellulose into reducing sugar. The surfactants (Tween 80) addition was done to increase the sugar yield of the hydrolysis process. Fermentation variable consist of single culture of Z. mobilis as the control and mixed culture of Z. mobilis and P. stipitis, the microorganisms used to convert glucose and xylose into ethanol. The number of inoculum used in this experiment was more than 1.4 billion cells and the duration of fermentation process was 72 h. The delignification process decreased 95.43% lignin in SWAP. X-ray Diffraction (XRD) analysis assay showed an increase of crystallinity index of SWAP with pretreatment combination to 37.87%. Enzymatic hydrolysis by a combination of cellulase and xylanase with the addition of Tween 80 produced 9.16 gr glucose/L reducing sugar concentration. The highest ethanol resulted by fermentation process using mixed culture of Z. mobilis and P. stipitis with 0.33% (v/v) ethanol concentration and 0.57 (g ethanol/g reducing sugar) ethanol yield. Fermentation process using single culture Z. mobilis resulted 0.28% (v/v) ethanol concentration, and 0.48 (g ethanol/g reducing sugar) ethanol yield. The mixed culture fermentation with Z. mobilis and P. stipitis resulted ethanol yield 19 % higher than the single culture fermentation using Z. mobilis.

Abstract: The utilization of empty bunches (EFB) as biomass still limited. EFB is used as additional fuel in palm oil mills where the combustion process is directly used. This process has deficiencies due to the characteristics of empty bunches which tend to have high water content. To achieve good combustion results, EFB required pre-treatment technique. In this study, experimental studies of EFB pre-treatment is proposed by torrefaction to improve EFB energy quality. Torrefaction of EFB is performed in several temperature variations with a range between 150-300 °C (150,200,250,300) and a certain duration (15,20,25,30,45 minutes). An investigation is done by using a calorimetric bomb, proximate analysis to find the moisture and ash content and ultimate analysis, which determined the chemical properties of the pre-treatment process. The physical properties of EFB, which fibrous and tough makes EFB size reduction difficult to reach homogenous state. Mass yield of torrefied EFB decreased with increasing temperature as well as with increasing times of torrefaction. Fundamentally, the study has highlighted the effects of torrefaction on solid fuel properties of EFB and its potential as a solid fuel for future thermal applications.

Abstract: Nanocellulose composites are very potential to be applied as automotive component materials.The purpose of this research is to analyze the influence of nanocellulose fraction of the silicon rubber composite material to morphology, sound absorption coefficient, density, thermal stability, and thermal conductivity. The nanocellulose of the composites were isolated from oil palm empty fruit bunch, while the matrix was silicone rubber. Tests conducted in this research included sound absorption coefficient, SEM, TGA, density, and thermal conductivity. Sound absorption coefficient had a value between 0,33 to 0.42 for a frequency of 500 Hz to 4000 Hz. This sound absorption coefficient had a wide band sound absorption tendency and was developed for sound absorption material of mufflers.

Abstract: The study aimed to synthesize alginate hydrogel-based composites which could be injected for medical purpose and can be cured in situ gelling after the injection process. The effect of reduced graphene oxide (r-GO) addition on Alginate /poly (vinyl alcohol) (PVA) hydrogel to physical properties were evaluated. Synthesis of hydrogel Alginate/PVA/r-GO composite was previously performed by production of r-GO using Hummer method. The composition of r-GO used in composite hydrogel was 0.4, 0.8, 1.2 and 1.6% wt. The sample was then characterized using XRD, FTIR, and analyzed perform with its curing time, injectable performance, swelling ratio, and water content.

Abstract: An alternative sensor that can be used to monitor Nitrogen Oxide (NOx) levels in the air is an electrochemical sensor type such as Sodium Super Ionic Conductor (NASICON). In this study titanium doping on zirconium was carried out to improve the electrical conductivity of NASICON. This material was synthesized using the solid state method by mixing sodium carbonate, silicon dioxide, zirconium oxide, ammonium dihydrogen phosphate, titanium dioxide and some anhydrous ethanol into the Ballmill for 12 hours, dried at 80 °C for 12 hours then calcined at 1125 °C for 12 hours with heating rate of 2 °C.min^-1. Then the material was pressed at 160 MPa to produce pellets with diameter of 10 mm and the sintering process was carried out at 1175 °C for 12 hours at a speed of 1 °C.min^-1. The doping of Titanium was varied from 0 to 6 mol%. The XRD characterization results indicate that the formed material phase was monoclinic phase and rhombohedral phase. The most optimal electrical conductivity of 5.897x10^-5 S.cm^-1 was obtained by Titanium doping of 6 mol%.

Abstract: The growth of the textile industry in Indonesia has resulted in increased textile dye waste production. Rhodamine B is one of the dyes that are often used in the textile industry. The use of these dyes will cause serious environmental and biological problems, even able to induce irritation of the skin and eyes. Thus, it is necessary to filter dyes from the textile industry waste in Indonesia. Some conventional methods for removing Rhodamine B are carried out by biochemical and physical-chemical methods, such as liquid membranes, ozonation and adsorption, but this method requires expensive and not very effective costs. One alternative method that can be applied in Indonesia is photocatalysts. Photocatalytics are processes where light and catalyst are simultaneously used to accelerate chemical reactions. In this study, the photocatalyst used was semiconductor material ZnO and TiO₂ with the addition of rGO. rGO synthesis was carried out using the Hummer method, for the synthesis of ZnO using Zinc powder as a precursor, and the synthesis of TiO₂ using precursor of TiCl₃. This study was conducted to analyze the effect of adding 5%, 10%, and 15% rGO to the photocatalytic properties of ZnO / rGO / TiO₂ composites for degradation of Rhodamine B. The characterization process carried out in this study included XRD, SEM & EDX, FTIR, and photocatalytic testing. Photocatalyst materials ZnO / rGO / TiO₂ with variations in the amount of rGO were synthesized as evidenced by XRD testing, where there was a peak for all three component, SEM, shows the morphology of Zn in the form of hexagonal nano rod, rGO in the form of transparent sheets and TiO₂ in the form of agglomerated balls. From FTIR testing, rGO and TiO₂ functional groups were seen. The highest efficiency for degradation of Rhodamine-B was obtained for the addition of 15% rGO with a 5-hour irradiation time, ie its efficiency reached 96.92% in degradation of Rhodamine B.

Abstract: Rice straw waste in Indonesia is abundant and not yet used optimally. The composition of rice straw is 40% cellulose, 30% hemicellulose, 15% silica and 15% lignin so it is potentially to be a raw material of active carbon and supercapasitor electrode. Many efforts has been done to increase the value of capacitance of electrode like increase the surface area with activation and milling process. In this research used the variation of activator substance and the variation of milling velocity, they are H₃PO₄ 450 rpm, H₃PO₄ 600 rpm, and KOH 450 rpm. The purposes of this research are identify and characterize the rice straw charcoal material as nanocarbon and also knowing the nanocarbon quality of rice straw charcoal material as supercapacitor electrode. The methods are carbonization, activation, and solid state reaction. The result of this research shows the value of capacitance at H₃PO₄ 450 rpm, H₃PO₄ 600 rpm, and KOH 450 rpm are 28,96 F/g; 30,89 F/g; dan 19,31 F/g. From this research, we can conclude that activator substance and milling velocity affect the value of capacitance that is produced. The result of SEM-EDX test is comparable with the result of cyclic voltammetry test, the higher number of pores the higher value of capacitances produced.

Abstract: The abundant of nickel ore resources in Indonesia and the regulations of Law of Coals and Minerals No. 4 year 2009 cause the development of nickel ore processing technology. One of the proven nickel ore processing technology is Mini Blast Furnace (MBF). When, the raw materials were fed to the MBF, there is a charging system to ensure good distribution of raw materials in MBF. The double bell charging system has an important role on the distribution of burden material in MBF. By optimizing the distribution and layers of the material burden, it will increase the stability and efficiency of the MBF process. Therefore, this study focused on analyzing the effect of large bell angle on the distribution of burden material in MBF using discrete element method. After analyzed, large bell angle differences produce different burden material distribution. For particle distribution, particles of small density (coal and dolomitee) tend to be concentrated in the center zone and particles of large density (ore) tend to be concentrated in the intermediate and peripheral zone. The larger angle of the large bell will increase particle falling velocity and the kinetic energy of the burden material. The most stable layer in MBF was obtained when using 65^o bell angle. The MBF with 65^o large bell angle is the best bell angle for MBF with capacity of 250 ton/day due to the greatest possibility of central working furnace operation.