Key Engineering Materials Vol. 872

Abstract: This study focuses on the biosynthesis of silver nanoparticles using Banana Raja (Musa Paradisiaca Var. Raja) peel extract. The aim is to determine the effect of concentration differences of silver nitrate (AgNO₃) as the precursor on the production of silver nanoparticles. In this study, banana peel extract (BPE) was reacted with AgNO₃ solution at several concentrations of silver nitrate solution i.e. 0.125; 0.1; 0.075 and 0.05 M at temperature of 50 °C. The ratio of banana peel extract and AgNO₃ solution used was 5:500 (v/v). The stirring was done by using a magnetic stirrer. The reaction took place when the color of the mixture (extract and AgNO₃) changed until the color of the mixture became constant. The results of the colloidal silver nanoparticles were characterized using UV-Vis Spectrometer, while the functional groups of the banana extract was analyzed using a Fourier Transform Infra-Red (FT-IR) apparatus. Whereas, the morphology of the silver nanoparticles was studied using a Scanning Electron Microscopy (SEM). The UV-Vis Spectrometer result show that the concentration of AgNO₃ which gave the highest absorbance value was at 0.1 M. The SEM micrographs could not clearly show the difference in the morphology of silver nanoparticles samples at different concentrations of AgNO₃ solution.

Abstract: The objectives of this study are to obtain essential oil from Sedap Malam (Tuberose) flower via extraction method and to characterize the physical and chemical properties of the essential oil produced, such as density, rendement, and chemical composition. The extraction process was carried out by using methanol solvent. The ratio between Sedap Malam flower and the methanol solvent was 1:5. After the extraction process of the essential oil finished, the essential oil and the solvent were separated via a simple distillation process. The collected essential oil was then characterized using Gas Chromatography-Mass Spectrophotometry (GC-MS) apparatus and Fourier Transform Infra-Red (FT-IR) analysis to investigate the content of the essential oil extracted from Sedap Malam flower. The physical characterization results showed that the essential oil has average rendement value of 12.605 % and density value of 1.0905 g/mL. Additionally, organoleptic test was carried to test the response of respondents toward the color and odor/fragrance of the essential oil extracted from Sedap Malam flower. Most of the responses were included in categories of “Like” and “Really like”. Additionally, for the fragrance, most of response of the respondents for all the four samples of essential oil were in category of “Really like”.

Abstract: The aim of this study was to characterize the fatigue life of the SAE 1541 carbon steel. The fatigue life was predicted based on the strain-life approach through the application of constant and variable strain data with negative, zero, and positive mean values. Each strain data was developed at amplitude range of 200 με, 400 με, 600 με, 800 με, 1,000 με, 1,200 με, 1,400 με, 1,600 με, 1,800 με, and 2,000 με. The results showed there was no significant difference in the fatigue life for negative, zero, and positive mean strain amplitudes using the Coffin-Manson model. This is due to the non-consideration of the mean strain effect by the Coffin-Manson model. However, according to the Morrow and SWT models, negative mean strain data gave a longer fatigue life while positive mean strain data gave a shorter life. In addition, variable strain data gave a longer fatigue life since they contain low and high amplitudes, with the low amplitudes contributing to minimum fatigue damage.

Abstract: To develop a sustainable concrete and to minimize the depletion of the natural resources, an attempt was made to develop sustainable concrete mixtures benefiting from the geopolymer technology and the use of recycled aggregate in self-compacting geopolymer concrete (SCGC). This study aim to examine the effects of sodium hydroxide (SH) molarity and sodium silicate (Na2SiO3)/ sodium hydroxide (SS/SH) ration the fresh properties of SCGC mixtures containing recycled coarse aggregates (RCA) Mixes were prepared with three different molarity (8M, 10M and 12M) of) and four SS/SH ratios (1.5, 2.0, 2.5 and 3.0). Six mixes were examined in this study. The results were compared with the EFNARC limits for self-compacting concrete (SCC). It was found that the SS/SH ratio and the molarity of SH affect the fresh properties of (SCGC). However, the results showed that, SCGC mixtures containing RCA can be developed and satisfy the requirements of EFNARC for fresh state of SCC.

Abstract: Understanding the origin of the high activity of Na₂O promotion on the χ-Fe₅C₂(2 0 0) surface during CO₂ hydrogenation is imperative. In this work, we revealed how Na₂O promoted the catalytic performance of χ-Fe₅C₂ during CO₂ hydrogenation. Detailed analyses confirmed that Na₂O addition facilitated the adsorption of CO₂ and promoted the desorption of product (C₂H₄). Electronic structure calculations suggested that the electron donating ability of Na could enhance the dissociation of CO₂, which is essential for producing hydrocarbons from CO₂.

Abstract: The problem associated with biodiesel production is economic feasibility. The biodiesel cost will reduce when the low cost feedstock was used. Kapok seed oil (KSO) is a promising candidate as raw material for biodiesel synthesis. In this research, the investigation of biodiesel synthesis from KSO was studied using Indonesia Natural Zeolite as heterogeneous catalysts. The catalyst was tested to synthesize biodiesel from KSO. The reaction temperatures, KSO to methanol mole ratio, and catalyst amount were varied to examine their effects on biodiesel synthesis. The highest biodiesel yield of 84% were obtained at 65°C of reaction temperature, 1:16 of KSO to methanol mole ratio, and 10% of catalyst amount.