Key Engineering Materials Vol. 849

Abstract: Plastic shopping bags are easy to obtain for free or at low prices, hence contribute as the highest quantity among plastic waste. The plastic shopping bags waste has no economic value. Usually they are just thrown away. An alternative solution is by utilizing them to produce paving block by mixing with sands. The objective of this experiment is to evaluate the best ratio composition of plastic shopping bags waste and sand, followed by evaluation of the physical-mechanical properties of this particular paving block. Several different mixture ratios of weights of plastic shopping bag and sand were evaluated to obtain the best physical-mechanical properties of the paving block. The mixture ratios of weight of plastic shopping bags waste and sand were 1:1, 1:2, 1:3, 1:4 and 1:5, respectively. The shopping plastic bags waste was melted before mixed with sand. The different mixture ratios were mixed with same pressure. The paving block mixture with ratio of 1:4 exhibited the best physical-mechanical properties as revealed by no defect, no crack and fine surface. The compressive strength of 17.4 MPa, friction resistance of 0.138 mm/sec and water absorption of 2.518% can be achieved, which is suitable for parking area construction.

Abstract: Several Indonesian paper mills utilize used paper as feedstock as the price is much cheaper and abundant availability, but the strength of the paper product tends to decrease. Xylan which is extracted from corncobs is a potential additive for upgrading the quality by modifying the fibre surface. This research studies the effect of sodium hydroxide concentration for extraction to produce an acceptable strength of paper product. The extraction process is at temperature of 90°C for 2 hours in a stirred tank reactor and the xylan product is deposited with 10 N acetic acid at pH of 4.5 - 5.0. Using 16% of NaOH concentration, the extraction produces 21.82% yield of xylan. With addition of this xylan product at mass ratio between xylan and corncobs of 5% increases 30.1% of the tensile strength and 31.83% of the tire strength. The optimum concentration of the use of NaOH in xylan extraction was at 16% NaOH with the largest xylan yield obtained at 21.82%.

Abstract: Synthesizing materials can be attempted by utilizing alternative sources such as wastes or disposed/by-products of certain activities. In this article, exploration of silica from agricultural waste and from geothermal sludgefor production of silica catalysts, are presented. The first silica catalyst was synthesized from rice husk. The husk was initially heated until silica ashes could be formed. After immersion in acidic solution, impregnation with nickel and molybdenum were conducted to introduce active metal of nickel (Ni) and molybdenum (Mo) in the support structure. The catalyst formed, Ni-Mo/SiO₂ was applied to convert crude palm oil into biofuels. The other silica catalyst was obtained from geothermal sludge. After washing, the catalyst was soaked in sulphuric acid solution to form acidic silica solid catalyst. The catalyst was applied in hydrolysis of seaweed-industry solid waste to produce glucose. The catalyst was relatively successful to facilitate 19-20% glucose yield, or up to 21% glucose selectivity from waste material.

Abstract: The main components of artificial leather were polymer, plasticizer, stabilizer, and filler. Silica is one of the commons reinforcing filler for many composites. Meanwhile, amorphous silica is usually precipitate in geothermal power plants and become solid waste in large amounts. The aim of this study is to evaluate the mechanical properties of PVC-based artificial leather by utilizing geothermal silica as reinforcing filler. The plastisol was prepared by mixing the PVC, plasticizer, co-plasticizer, stabilizer, and filler with the amount of 100, 60, 3, 0.5 and 25 phr respectively. Commercial-calcium carbonate and geothermal-silica were used as filler for each sample formulation, then the non-filler plastisol also prepared as a reference. Artificial leather made by coating the release paper using the plastisol then heated at 190°C. The mechanical properties were investigated using a universal testing machine for the elongation, tensile strength and separation force. The surface morphology of each sample were analyzed using SEM. The results show us that the geothermal silica filled artificial leather has better elongation, tensile strength, and separation force compared to the calcium carbonate since there are stronger filler-polymer bonds formed. Therefore geothermal silica has high potential as filler for artificial leather, thus gives an alternative solution for the solid waste problem in geothermal power plant and also provide low-cost source of reinforcing fillers for artificial leather industries.

Abstract: Polystyrene is a type of plastic that is widely used in daily life. It is applied for decoration, food packaging, and electronic packaging process. However, the use of polystyrene has become a problem for the environments because its properties are difficult to be degraded by nature. Pyrolysis method can be regarded as one of the environmentally friendly methods for recycling polystyrene waste. This research aims to investigate the effect of bentonite and natural zeolite catalyst on the pyrolysis of polystyrene. The experiment was carried out in a batch process. The pyrolysis process consists of a cylindrical reactor with electrical heater, a condenser, and a liquid product container. About 100 grams of polystyrene material was pyrolysis per batch. Catalysts used in the variation of 0%, 10%, 15%, 20%, and 25% of polystyrene. The liquid product was collected in 60 minutes and weighed. The composition of the liquid product was determined by gas chromatography. Polystyrene pyrolysis utilizes bentonite and natural zeolite as the catalyst. It produces benzene, toluene, ethylbenzene, styrene, and isopropyl benzene as the liquid product, and polystyrene residue as a solid product. Among the catalyst studied, bentonite is found to be the most efficient and increase the styrene selectivity (30.28 wt%) significantly at a reaction temperature of 400°C in comparison to the natural zeolite catalyst.

Abstract: The government tries to anticipate the needs of fuel in Indonesia. Efforts to develop new fuels have also been done. New fuels and renewable energy that has been developed are water, wind, bioenergy, solar, ocean, and geothermal. Bioenergy which now widely developed is biodiesel. The development of biodiesel industry which has increased rapidly, was accompanied by government policies that are written in the blueprint of the national energy management, make the biodiesel production grow rapidly. Glycerol as a by-product of the biodiesel industry is available abundantly, so it is necessary to study alternative uses. One alternative is to process glycerol into triacetin which can be used as bio-additive. The reaction between glycerol and acetic acid using a batch reactor was done ​​on the mole ratio of catalyst/glycerol of 3.0%, the mole ratio of acetic acid/glycerol of 3/1, reaction temperature of 80-110°C and reaction time of 60 minutes. The optimum condition is achieved when the batch reaction was run with catalyst Amberlyst-15 at temperature of 110°C with conversion of 97.52% and selectivity triacetin of 89.74%.

Abstract: Biocomposite based tapioca starch (TS) and sugarcane bagasse cellulose nanofibers (SBCN) was made through casting method. SBCN was prepared by chemical and ultrasonication process. It was successfully displayed by transmission electron microscope (TEM) in range 20 - 45 nm. Meanwhile, particle size analysis (PSA) also supported the distribution diameter of SBCN for 59.75 ± 10.84 nm. SBCN and glycerol were used as reinforcement and plasticizer, respectively. The amount concentration of SBCN was varied from 0 to 8 wt%. Biocomposite was characterized by using scanning electron microscopy (SEM) and tensile test. SEM image displays SBCN is in good interfacial bonding with the matrix. The highest tensile strength of biocomposite was in TS/4SBCN sample for 20.84 MPa. These results showed that SBCN fiber become potential candidate as reinforcement in biocomposite application.

Abstract: Indonesia coal ash is predicted to reach 10.8 million tons in the year 2020 but its utilization is still limited. In the last decade, coal ash has become a promising REY source candidate. To determine the potency of REY in Indonesia coal ash, information about element concentration and mineralogy of the ash is essential. In this study, coal ash samples were taken from Paiton-2, Pacitan, Rembang, and Tanjung Jati coal-fired power plants. Element content and mineralogy were analyzed using Inductive Couple Plasma Mass Spectroscopy/Atomic Emission Spectroscopy (ICP-MS/AES), X-Ray Diffractometer (XRD) and petrographic. The results showed that coal fly ash and bottom ash contains critical REY in the range of 38% to 41% with C_outlook larger than one. XRD analysis showed that both fly ash and bottom ash have similar mineral phases with slightly different concentrations. The mineral phase is dominated by amorphous glass, quartz, Fe-bearing minerals, and unburned carbon. The amorphous glass phase in fly ash is in the range of 23 to 34% while in bottom ash between 14 and 34%. Unburned carbon content in fly ash and bottom ashes are 7-13% and 7-19%, respectively. Fe-bearing mineral content in fly ash is 15-20% and bottom ash is 13-20%. In addition, Indonesia coal ash has a higher Heavy-REY enrichment factor than Light-REY. The Enrichment Factor of HREY in fly ash is as much as 1.3 times (in average) of the bottom ash.

Abstract: Indonesia coal ash is predicted to reach 10.8 million tons in the year 2020 but its utilization is still limited. In the last decade, coal ash has become a promising REY source candidate. To determine the potency of REY in Indonesia coal ash, information about element concentration and mineralogy of the ash is essential. In this study, coal ash samples were taken from Paiton-2, Pacitan, Rembang, and Tanjung Jati coal-fired power plants. Element content and mineralogy were analyzed using Inductive Couple Plasma Mass Spectroscopy/Atomic Emission Spectroscopy (ICP-MS/AES), X-Ray Diffractometer (XRD) and petrographic. The results showed that coal fly ash and bottom ash contains critical REY in the range of 38% to 41% with C_outlook larger than one. XRD analysis showed that both fly ash and bottom ash have similar mineral phases with slightly different concentrations. The mineral phase is dominated by amorphous glass, quartz, Fe-bearing minerals, and unburned carbon. The amorphous glass phase in fly ash is in the range of 23 to 34% while in bottom ash between 14 and 34%. Unburned carbon content in fly ash and bottom ashes are 7-13% and 7-19%, respectively. Fe-bearing mineral content in fly ash is 15-20% and bottom ash is 13-20%. In addition, Indonesia coal ash has a higher Heavy-REY enrichment factor than Light-REY. The Enrichment Factor of HREY in fly ash is as much as 1.3 times (in average) of the bottom ash.

Abstract: The purpose of this study is to characterize Lampung iron sand and to conduct preliminary experiments on the TiO₂ synthesis which can be used for the manufacturing of functional food packaging. The iron sand from South Lampung Regency, Lampung Province that will be utilized as raw material. The experiment was initiated by sieving the iron sand on 80, 100, 150, 200 and 325 mesh sieves. Analysis using X-Ray Fluorescence (XRF) to determine the element content and X-Ray Diffraction (XRD) to observe the mineralization of the iron sand was conducted. The experiment was carried out through the stages of leaching, precipitation, and calcination. Roasting was applied firstly by putting the iron sand into the muffle furnace for 5 hours at a temperature of 700°C. Followed by leaching using HCl for 48 hours and heated at 105°C with a stirring speed of 300 rpm. The leaching solution was filtered with filtrate and solid residue as products. The solid residue was then leached using 10% H₂O₂ solution. The leached filtrate was heated at 105°C for 40 minutes resulting TiO₂ precipitates (powder). Further, the powder was calcined and characterized. Characterization of raw material using XRF shows the major elements of Fe, Ti, Mg, Si, Al and Ca. The highest Ti content is found in mesh 200 with 9.6%, while iron content is about 80.7%. While from the XRD analysis, it shows five mineral types namely magnetite (Fe₃O₄), Rhodonite (Mn, Fe, Mg, Ca) SiO₃, Quart (SiO₂), Ilmenite (FeOTiO₂) and Rutile (TiO₂). The preliminary experiment showed that the Ti content in the synthesized TiO₂ powder is 21.2%. The purity of TiO₂ is low due to the presence of Fe metal which is dissolved during leaching, so that prior to precipitation purification is needed to remove impurities such as iron and other metals.