Nyamplung (Calophyllum inophyllum L.) is one of the most potential plants for biodiesel feedstock because of its high oil content. Mechanical extraction using screw press is one method to get oil from nyamplung seed. Result of the extraction is affected by the seed's condition, such as moisture content and particle size. The paper presents experimental results that estimate the vegetable oil production potential of C. inophyllum. The results show the effect of C. inophyllum seed moisture content and particle size on oil yield, andthe characteristics of C. inophyllum oil.The seed moisture contents used in this experiment are 0%, 1.2%, and 20%, whereas the average seed particle size used are 0.81, 2.90, and 8.60 mm. The C. inophyllum fruits were obtained from Cipatujah Sub-district, Tasikmalaya Regency. The methods used include fruit and seed preparation, seed moisture content and particle size conditioning, mechanical extraction, oil characteristics analysis, and C. inophyllum oil production potential calculation. The optimum seed moisture content to obtain high oil yield is 1.2% which yields 33.39%oil, while the optimum seed particle size to obtain high oil yield is 8.60 mm which yields 33.46% oil. The bigger the particle size will affect on higher oil yield. From this research, it can be concluded that the trees in Cipatujahhave potential to produce C. inophyllum oil up to 5.13 L/tree/year. C. inophyllum oil yield is effected by seed moisture content and particle size, and it has characteristics that support its utilization as biodiesel feedstock.

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Abundant availability and large silica content in rice husk black ash (RHBA) make the use of it very interesting to study. Many works only deal with lab‐scale rice husk ash extraction while the studies on bench‐scale RHBA extraction are still limited. This study, hence, presents the influence of pretreatment, extraction variables, and posttreatment on bench‐scale RHBA processing to bio‐silica. The pretreatment through acid leaching was carried out using HCl. The extraction was implemented under varying process variables such as alkaline‐to‐feed ratio (RA/F), extraction duration, and acid precipitation agent. According to this study, the highest extraction yield up to 98% was gained under RA/F 6 g/g and 1‐h extraction. The amorphous bio‐silica had an asymmetric siloxane bond and white appearance with a purity exceeding 95% and surface area up to 406.98 m2/g. Meanwhile, precipitation under HCl and H2SO4 had little impact on product purity and surface area. This study exhibits that acid leaching is executed to release mineral impurities but is still not sufficient to remove the remaining carbon content in bio‐silica. However, the contribution of refining process is able to do so. Moreover, the produced bio‐silica is suitable for adsorbent purposes which could adsorb up to 83.5% of 3‐monochloropropanediol compound.

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The huge amount of rice hull biomass available in Indonesia can be utilized as raw material for bio-silica production. This study investigated the production of high-purity bio-silica from rice hull ash through an alkaline extraction process. A full factorial design (FFD) was used to screen for significant effects of the observed variables. Three operating variables – acid concentration, solvent to feed ratio (RS/F), and extraction time – were investigated with the purpose of obtaining a high yield and high purity of bio-silica. Yield and purity above 96% were achieved by using pretreatment with 1 mol/L HCl. Employing an RS/F of 5 and a longer extraction time improved the bio-silica yield. The operating variable that enhanced the bio-silica yield and purity most was acid concentration. All variable interactions had an insignificant effect on purity, while two interacting variables had a significant effect on bio-silica yield. Based on the results of this study, rice crop residue can be optimally converted to a bio-silica product in terms of yield and purity by optimizing the most effective operating variables.

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Rice husk has a great potential in its calorific value and silica content in ash which makes its valorization through combustion becomes important and interesting. This study presents the thermodynamics simulation performance of rice husk combustion using a realistic decomposition approach. A non-ideal gas approach and fugacity coefficient were also considered in the calculation. From this study, rice husk is devolatilized to form gases (63.37%), tar (8.69%), char (27.94%), and all of these are then oxidized to form flue gas. The realistic decomposition approach calculated that about 2.6 MJ/kg of specific combustion energy is produced, the maximum combustion temperature is up to 1457 o C for perfect insulation condition, and up to 1400 o C if there is a heat loss.It is found that combustion equipped with larger excess air could quench the heat produced and reduce the combustion efficiency but could maintain the temperature at 700 o C. Furthermore, the thermodynamics simulation expressed that NO emission amount from rice husk combustion is negligible and there is still a probability for CO and H2 to be produced at above 500 o C due to Boudouard reaction and homogeneous water gas shift reaction (WGSR). The study showed that a realistic decomposition approach could predict the rice husk combustion performance with a reasonable and logical result. Supplying excess air of about 180-200% is advantageous to keep the combustion temperature at 700 o C in order to prevent silica crystalline formation which harms human 2 health, as well as suppressing NO emission and reducing CO emission from the simultaneous Boudouard and WGSR.

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