Judul: The Utilization of Kemiri Sunan Fruit Peel as Catalyst in the Conversion Process of Crude Oil into Biodiesel
Abstrak: Pemanfaatan buah kemiri sunan sebagai bahan baku pembuatan biodiesel akan menghasilkan limbah berupa kulit buah. Bila tidak dikelola dengan baik, maka dapat mencemari lingkungan. Kandungan senyawa kalium yang terdapat pada kulit buah kemiri sunan berpotensi untuk dimanfaatkan sebagai katalis heterogen dalam proses transesterefikasi pembuatan biodiesel. Penelitian ini bertujuan mengetahui pengaruh waktu transesterifikasi dan konsentrasi katalis kulit kemiri sunan dalam pembuatan biodiesel. Katalis yang terdapat pada kulit buah kemiri sunan diaktivasi terlebih dahulu melalui proses kalsinasi dengan suhu 800 oC 4 jam. Proses pembuatan biodiesel dilakukan menggunakan hotplate dengan suhu 60 oC dengan perbandingan mol metanol 1:6 dengan waktu reaksi transesterifikasi selama 1 dan 2 jam dengan kecepatan pengadukan 500 rpm. Konsentrasi katalis yang digunakan yaitu 1,5%, 1,75%, 2% dan 2,25%. Rancangan percobaan yang digunakan pada penelitian ini yaitu rancangan acak lengkap faktorial dua faktor dan dianalisis dengan ANOVA (α=0,05). Parameter penentu kondisi terbaik adalah rendemen, viskositas, densitas, dan angka asam biodiesel. Hasil rendemen terbaik yang didapatkan sebesar 78,22% dalam waktu transesterifikasi 60 menit dengan konsentrasi katalis 1,5%. Dari hasil penelitian ini didapatkan hasil biodiesel yang sesuai SK Dirjen EBTKE No. 189/2019 dengan nilai rendemen sebesar 70,89% – 78,22%, nilai densitas sebesar 0,869 – 0,875 g/m3, nilai viskositas sebesar 3,07 – 3,22 cSt. Angka asam dengan nilai 0,44 – 0,78 tidak sesuai dengan standar dengan nilai maksimal 0,4., The utilization of Kemiri Sunan candlenut fruit as a feedstock for biodiesel production generates waste in the form of fruit peels. If not managed properly, this waste can pollute the environment. The presence of potassium compounds in sunan candlenut fruit peels has the potential to be utilized as a heterogeneous catalyst in the transesterification process of biodiesel production. This research aims to investigate the influence of transesterification time and the concentration of sunan candlenut fruit peel catalyst in biodiesel production. The catalyst in sunan candlenut fruit peels is first activated through a calcination process at a temperature of 800 °C for 4 hours. The biodiesel production process is carried out using a hotplate at a temperature of 60 °C with a methanol-to-oil mole ratio of 1:6, and transesterification reaction times of 1 and 2 hours, with a stirring speed of 500 rpm. The concentrations of catalyst used are 1.5%, 1.75%, 2%, and 2.25%. The experimental design used in this study is a two-factor completely randomized factorial design, and the data are analyzed using ANOVA (α=0.05). The key parameters for determining the optimal conditions are yield, viscosity, density, and acid value of the biodiesel. The best yield obtained is 78.22% at a transesterification time of 60 minutes with a 1.5% catalyst concentration. The results of this study yield biodiesel that complies with the Directorate General of New and Renewable Energy and Energy Conservation (DG EBTKE) Regulation No. 189/2019, with a yield ranging from 70.89% to 78.22%, density values ranging from 0.869 to 0.875 g/m3, and viscosity values ranging from 3.07 to 3.22 cSt. However, the acid value, with a range of 0.44 to 0.78, does not meet the standard, which has a maximum value of 0.4.
Keyword: biodiesel, kalsinasi, katalis heterogen, konsentrasi, calcination, concentration, heterogeneous catalyst

Judul: The Utilization of Kemiri Sunan Fruit Peel as Heterogeneous Catalyst in Biodiesel Production through Trans-esterification Reaction
Abstrak: Penggunaan buah kemiri sunan sebagai bahan baku pembuatan biodiesel dapat menghasilkan limbah berupa kulit buah yang dapat mencemari lingkungan dan mengganggu estetika lingkungan. Kulit buah kemiri sunan tersebut berpotensi dimanfaatkan sebagai katalis heterogen dalam proses transesterifikasi pada produksi biodiesel. Katalis kalium oksida (K2O) yang terdapat pada kulit buah kemiri sunan dapat diaktivasi melalui proses kalsinasi, dengan berbagai suhu yaitu 650 oC, 800 oC dan 950 oC selama 4 jam. Proses pembuatan biodiesel dilakukan menggunakan hotplate dengan suhu 60 oC dengan perbandingan mol metanol 1:6 dengan waktu reaksi transesterifikasi selama 2 jam. Konsentrasi katalis yang digunakan yaitu 2%, 2,5% dan 3%. Hasil rendemen terbaik yaitu 82,67%. Selain rendemen, penelitian ini juga menganalisis viskositas, densitas, angka asam dan stabilitas oksidasi. Rancangan percobaan yang digunakan pada penelitian ini yaitu rancangan acak lengkap faktorial dua faktor dan dianalisis dengan ANOVA (α=0,05) serta uji duncan. Penelitian ini dapat disimpulkan bahwa suhu kalsinasi dan konsentrasi katalis sangat mempengaruhi proses pembuatan biodiesel., The use of Kemiri Sunan as raw material for biodiesel production can produce waste in the form of fruit peel, which pollute the environment and can impair the aesthetics of the environment. The fruit peel of the Kemiri Sunan has the potential to act as a heterogeneous catalyst in the trans-esterification process in biodiesel production. The potassium oxide (K2O) catalyst contained in the fruit peel of the kemiri sunan can be activated by the calcination process at different temperatures, namely 650 oC, 800 oC and 950 oC for 4 hours. The process of producing biodiesel was carried out using a hot plate with a temperature of 60 oC with a mole ratio of 1:6 methanol with a trans-esterification reaction time of 2 hours. The concentration of the catalyst used was 2%, 2.5% and 3%. The best yield was 82.67%. In addition to the yield, the viscosity, density, acid number and oxidation stability were also analyzed in this study. The experimental design used in this study was a fully randomized two-factorial factorial design and was analyzed by ANOVA (α=0.05) and Duncan's test. From these investigations it can be concluded that the calcination temperature and catalyst concentration have a major influence on the production process of biodiesel.
Keyword: biodiesel, heterogeneous catalyst, K2O, calcination, concentration

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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