Materials Science Forum Vol. 964

Abstract: Iron sand as the largest form of iron ore reserves in Indonesia has not been optimized properly for domestic iron-steel production. In the production chain of pig iron from iron sand, there is a problem that in sponge iron (result of direct reduction) contains many impurities, especially titanium. This research is conducted to determine the effect of additive variation to the Fe content and Fe recovery during sponge iron smelting process into pig iron using electric arc furnace (EAF). Types of additives variation that used in this research are CaCl₂ and CaC₂, as well as smelting without additive as comparison. Briquettes made from sponge iron, coal, flux (SiO₂), and variations of additive are melted in crucible using EAF (16.2 Volt; 180 Ampere) for 6 minutes. Based on EDX and XRD results of pig iron and slag, the optimum process of sponge iron smelting is use the CaCl₂ as additive. It’s shown by the result that the pig iron containing the highest %wt Fe by 90.97% and the highest Fe recovery by 80.41%. The product that used CaC₂ as additive has Fe content of 89.31 %wt and Fe recovery during process of 72.36%. Meanwhile, the results obtained from the smelting without additives only shows that the Fe content in pig iron amounted to 88.90 %wt and 68.76% values for Fe Recovery.

Abstract: The availability (readiness) of a Steam Power Plant (PLTU) is an important factor, since one income from a Power Plant is based on its readiness reflected in the EAF (Equivalent Availibility Factor). Factor opposite to Availibility is Outage. Outage occurs when a unit is out of sync to a network and not in a Reserve Shutdown state.

Abstract: HY-80 is the high yield steel that commonly used for naval ship and submarine. Arc welding operations are critical stage in fabrication of this steel. During welding, the problem may occur in the heat affected zone due to the high temperature makes the microstructure suddenly changes. Coarse grain heat affected zone (CGHAZ) develops close to the fusion line, steel become brittle and the impact toughness decrease. This research investigated the microstructure of HY-80 weldment, impact toughness at sub-zero temperatures, and hardness distribution along cross-section of the welded joint. ER100S welding wire, Ar+10%CO₂ shielding gas mixture and single V-groove butt joint with an angle of 60° were selected prior to welding. 12 mm thick of HY-80 steel plate that used in this experiment was multipass welded by gas metal arc welding (GMAW). Impact toughness at sub-zero temperature, hardness and microstructure evolutions of base metal (BM), heat affected zone (HAZ) and weld metal (WM) were observed. The result shows at a temperature of-80 °C, the lowest impact toughness was measured at WM (61 J) as compared to fusion line (101 J) and BM (217 J). The hardness measurement shows the maximum hardness was measured in CGHAZ followed WM and BM. Vickers hardness test result of weld joint at bottom area are higher than top area. It may caused of the low heat input of back weld compared to other passes. The lower heat input, cooling rate increased and initiate the formation of hard phase. The microstructure of WM shows acicular ferrites and non-metallic inclusions, these inclusions may deteriorate the impact toughness.

Abstract: In this research, the characterization of waste to electric prototype performance using dual fuel diesel engine and multi stage downdraft gasification reactor was conducted. Syn-gas was produced by gasification process using downdraft gasification reactor with municipal solid waste feeding. The gasification system consists of feeding system, gasification reactor, gas refinery unit, dual fuel engine generator set and system control. Before entering the gasification reactor, municipal solid waste undergoes pre-treatment process, which consists of crusher, mixing and compacting into pellets of solid waste municipal. Municipal solid waste downdraft gasifier reactor converted pellets municipal solid waste throught drying, pyrolisis, partial oxidation and reduction processes to raw syn-gas. Using syn gas refinery unit, content dust and particles on raw syn gas was cleaned by water in current mode in water scrubber, where its also acts like a cooler unit. Syn gas is further used as fuel in dual fuel diesel engines with an input mechanism using a ventury mixer. The ventury mixer mechanism was used to manage the ratio of syn gas and combustion air. Yanmar diesel engine was modified with dual fuel that used air gas integration model and coupled with generator to resulted electrical power output. Downdraft gasification reactor resulted syn gas with efficiency to 66 % with gas composition CO, CH₄ and H₂ are 18.01%, 1.12% and 12.55% (vol%) and heating value of 4 MJ/Kg. Multistage mechanism can reduce the tar content until only 60 mg/Nm³. Engine performance on dual fuel mode operation with specific fuel consumption 0,17 kg/kwh of diesel fuel and 8 kg/kwh of msw pellets at 80% engine load. Overall, in this dual fuel system, syn gas from gasification process is able to substitute diesel consumption up to 44%.

Abstract: Rice became the main product of agriculture in agrarian countries including Indonesia. Rice husk is a waste of rice as one of the largest silica producers. Silica from rice husks can be used as a source of silica in the manufacture of sodium silicate as an alternative to the formation of mesoporous silica at a low price. In this research, the characterization of mesoporous silica nanoparticle (MSN) MCM-41 from rice husk (rice husk) with sol-gel method followed by hydrothermal treatment. Silica extraction was performed by titrating sodium silica using HCl method until the gel was formed. The mesoporous synthesis was performed with the addition of CTAB. The titration is then carried out using a solution of acetic acid. XRD shows silica with an amorphous structure. The FTIR results show that extraction silica and MSN MCM-41 contain pure silica displayed with Si-O-Si functional groups in the sample. The SEM results show MSN MCM-41 images such as a coral-like structure of agglomerated silica and the higher temperature hydrothermal treatment then it would be the more large size of particles. The material has a hexagonal pore structure such as a honeycomb as characteristic of MCM-41 with a pore size of 2.535 nm which includes mesoporous material. The result of nitrogen adsorption-desorption isotherms shows lower hydrothermal temperature will increase the specific surface area and decrease average pore size, where the best result with surface area value is 825.365 m²/gr and average pore size is 6.10426 nm obtained from process hydrothermal at 85°C.

Abstract: In-situ transesterification method without catalysts to produce biodiesel (fatty acid ethyl esters, FAEE) from rice bran using subcritical water ethanol mixture has been investigated. This method was found to be efficient since the rice bran oil (RBO) extraction and reaction of RBO into FAEE occur simultaneously. In this process other chemical (ethyl levulinate, EL) was also formed along with FAEE. EL can be used to improve the biodiesel quality by improving the low temperature properties of biodiesel. In this study effect of co-solvent types (without co-solvent, ethyl acetate, chloroform, and n-hexane) and water ethanol ratio (20%, 40%, 50%, 60% and 80%, v/v) on the content and yield of FAEE and EL at subcritical water ethanol mixture (T= 160°C, P= 80 bar, and t= 2 h) were investigated systematically. The content and yield of FAEE and EL obtained was found to be affected by the type of co-solvent. The content of FAEE and EL obtained without co-solvent (ethanol and water polarity index were PI=5.2 and PI=10.2, respectively) and with co-solvent of ethyl acetate (PI= 4.4), chloroform (PI= 4.1) and n-hexane (PI= 0.1) were 55.80% and 3.92%, 68.63% and 1.15%, 65.56% and 2.14%, and 62.00% and 0.93%, respectively. Higher polarity index of co-solvent extracted more RBO, as consequent the yield of FAEE (79.79%) obtained was higher using ethyl acetate as co-solvent. This data also suggested that RBO contains more free fatty acids (FFA= 63.59%) rather than of triglycerides (TG= 24.94%).The content and yield of FAEE and EL decreased with increasing water ethanol ratio. The highest content of FAEE (60.57%) and EL (8.48%) and yield of FAEE (78.03%) and EL (10.92%) were obtained using water ethanol ratio of 20%, v/v.

Abstract: Lipids extraction from wet and unbroken microalgae (Chlorella vulgaris) using subcritical water with aid of co-solvents has been investigated. Lipids extraction from wet and unbroken microalgae has a crucial role in order to eliminate dewatering and drying steps. Subcritical water is able to extract lipids from feedstock with high water content. This work was conducted to study several factors affecting in subcritical water extraction (SWE) from wet and unbroken microalgae. In this study, effect of co-solvent types (without co-solvent, chloroform, methanol, ethanol, ethyl acetate, and n-hexane) under subcritical water (microalgae = 5g (dry weight), moisture content= 94.12%, T= 160°C, P = 80 bar, t= 30 min), extraction time (15 min, 30 min, 1 h, 3 h, and 5 h), and temperature (160^o C, 180^o C and 200^o C) on yield of lipids were investigated orderly. Yield of lipids obtained without co-solvent (water polarity index = 10.2) and with co-solvents of methanol (PI=5.1), ethanol (PI=5.2), chloroform (PI=4.1), ethyl acetate (PI=4.4), and n-hexane (PI=0.1) were 38.73%, 26.47%, 26.12%, 51.93%, 53.40%, and 25.59%, respectively compared to the yield of lipids extracted using Bligh and Dyer method. Ethyl acetate is solvent with moderate PI, therefore can extract more lipids that is also have moderate polarity. Ethyl acetate shows a good performance to extract lipids from wet and unbroken microalgae because ethyl acetate can extract broader range of lipids including neutral and polar lipids. This study also found that increasing of extraction time and temperature to extract lipids in subcritical water condition can increase yield of lipids.

Abstract: High content of free fatty acids (FFA) in crude rice bran oil (CRBO) needs to be separated through deacidification. Generally, deacidification process that is widely used are chemical and physical processes which causes the loss of bioactive compounds (γ-oryzanol) and un-environmentally friendly. The liquid-liquid extraction (LLE) using deep eutectic solvents (DES) to remove FFA and preserve g-oryzanol would be implemented in this study. DES with different hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) with certain molar ratio such as Choline Chloride (ChCl)-Ethylene glycol 1:2 (DES I), ChCl-Glycerol 1:1 (DES II), ChCl-Urea 1:2 (DES III), ChCl-Oxalic acid 1:2 (DES IV), and Betaine Monohydrate-Glycerol 1:8 (NADES) were used as solvent to extract FFA from dewaxed/degummed RBO (DDRBO) for certain extraction time (30, 60, 120, 180, and 240 min) and extraction temperature (30°C, 40°C, 50°C, 60°C, and 70°C) under stirring (200 rpm). Deacidification using DES I for 240 min. and temperature of 50 °C was the optimum solvent to remove FFA (19.03 ± 2.33 %) and preserve g-oryzanol (recovery of g-oryzanol was 51.30 ± 1.77 %). The results also revealed that the longer time of extraction would be increased removal of FFA and decreased recovery of g-oryzanol. The higher temperature of extraction would be increased removal of FFA. In this work, temperature of 50 °C was the best extraction temperature of FFA since DES has highest solubility at this temperature.

Abstract: Plastic waste is majority an organic material that cannot easily decomposed by bacteria, so it needs to be recycled. One of the utilization of plastic waste recycling is become a mixture in the manufacture of building materials such as concrete, paving block, tiles, roof. This experiment purpose to find out the effect of addition of variation of LDPE and PP thermoplastic binder to physical and mechanical properties of LDPE/PP/Sand composite for construction material application. In this experiment are using many tests, such are SEM, FTIR, compression strength, density, water absorbability, and hardness. the result after the test are the best composition of composite PP/LDPE/sand is 70/0/30 because its have compression strength 14,2 MPa, while density value was 1.30 g/cm3, for the water absorbability is 0.073%, and for the highest hardness is 62.3 hardness of shore D. From the results obtained, composite material can be classified into construction materials for mortar application S type with average compression strength is 12.4 MPa.

Abstract: This research is aimed to get a better understanding on the effort of reducing the porosity level in aluminum alloys. The degassing process (2, 5 and 8 minutes) is done to reduce the hydrogen content in liquid aluminum and cooling rate modifications (13 °C / min, 20 °C / min and 26 °C / min) was performed to reduce the porosity by reducing the size of Dendrite Arm Spacing (DAS). The casting method used in this research is sand casting and raw materials were melted using an electric furnace at 720 °C. The microstructural images showed the DAS size are decreased by size from 137.3 μm to 87.58 μm obtained from cooling rates of 13 °C / min and 26 °C / min respectively. In the other hand, the level of porosity is also decreased from 3.58% at 2 min degassing and the cooling rate of 13 °C / min to 1.8% at 5 min degassing and 26 °C / min cooling rate. Furthermore, the tensile test results show that the value of tensile strength increases when the DAS size and porosity level are smaller. The highest ultimate tensile strength value is 105.9 and the lowest is 70,53 MPa.