Judul: Delignifikasi Kulit Singkong sebagai Bahan Baku Bioetanol dengan Metode Alkali dan Pemanasan Microwave
Abstrak: Indonesia menduduki peringkat keempat sebagai negara produsen singkong terbesar dengan jumlah produksi sebesar 20 juta ton per tahun. Sebanyak 15-20% per kilogram singkong merupakan limbah berupa kulit singkong yang mengandung pati dan memungkingkan untuk dikonversi menjadi alternatif energi seperti bioetanol. Proses produksi bioetanol dilakukan melalui tahap pretreatment/delignifikasi, hidrolisis, fermentasi, dan pemurnian. Proses pretreatment dilakukan untuk mendapatkan kandungan selulosa yang akan digunakan dalam proses hidrolisis. Pretreatment dapat dikombinasi seperti penggabungan metode secara fisika (pemanasan microwave) dan kimia (larutan alkali). Penggunaan metode alkali dan pemanasan microwave akan meningkatkan kadar selulosa dan menurunkan kadar lignin yang lebih baik dibandingkan dengan metode yang lain. Larutan alkali yang digunakan yaitu NaOH karena memiliki sifat yang sesuai apabila dikombinasikan dengan pemanasan microwave. Delignifikasi dilakukan dengan memberikan variasi konsentrasi NaOH 0,5 M, 0,75 M, dan 1 M dan variasi lama waktu paparan panas microwave 5, 10, dan 15 menit. Hasil variasi pretreatment diuji secara statistik menggunakan rancangan acak lengkap. Secara statistik, peningkatan konsentrasi larutan NaOH dan lama waktu paparan panas microwave memberikan pengaruh nyata untuk kandungan selulosa dan lignin. Konsentrasi NaOH dan waktu paparan microwave terbaik adalah 1 M dan 15 menit. Perbandingan data sebelum dan setelah pretreatment menunjukkan bahwa metode tersebut memenuhi syarat pretreatment lignoselulosa., Indonesia is the fourth-largest producer of cassava with a total production of 20 million tonnes per year. Up to 15-20% per kilogram of cassava is waste in the form of cassava peel, which contains starch and allows it to be converted into alternative energy such as bioethanol. The process of bioethanol production is carried out by stages of pretreatment/delignification, hydrolysis, fermentation, and purification. The pretreatment process is carried out to obtain the cellulose content that will be used in the hydrolysis process. Pretreatment can be combined, for example by combining physical (microwave heating) and chemical (alkaline solution) methods. Using alkaline methods and microwave heating will increase cellulose content and reduce lignin content which is better than other methods. The alkaline solution used is NaOH because it has suitable properties when combined with microwave heating. The delignification was carried out by varying the concentration of 0,5 M, 0,75 M and 1 M NaOH and the exposure time to microwave heat was 5, 10 and 15 minutes. The results of the pretreatment variation were tested statistically using a complete block design. Statistically, the increase in the concentration of the NaOH solution and the duration of exposure to microwave heat had a significant effect on the cellulose and lignin content. The best NaOH concentration and microwave exposure time were 1 M and 15 minutes. Comparison of the data before and after pretreatment shows that the method meets the requirements of lignocellulosic pretreatment.
Keyword: alkaline, bioethanol, cassava peel, delignification, microwave heating

Judul: Delignification of Cacao Pods Husk as a Raw Material for Bioethanol using Alkaline and Microwave Heating Methods
Abstrak: Sebagai negara produsen dan eksportir kakao terbesar di dunia, Indonesia memproduksi kakao sebanyak 720,66 ribu ton per tahun atau 14,34% dari produksi kakao dunia. Sebanyak 74% buah kakao merupakan limbah kulit kakao yang mengandung lignoselulosa dan berpotensi diolah menjadi bioetanol. Dalam memproduksi bioetanol ada beberapa tahapan, seperti pretreatment atau delignifikasi, hidrolisis, fermentasi, dan pemurnian. Tahap pretreatment dilakukan untuk mendapatkan kandungan selulosa/gula yang diproses lebih lanjut pada tahap hidrolisis. Pretreatment dapat dikombinasi seperti penggabungan metode secara fisika dan kimia. Penggunaan metode alkali dan pemanasan microwave merupakan bentuk penggabungan metode fisika dan kimia yang berguna untuk meningkatkan kandungan selulosa dan menurunkan kandungan lignin. Metode ini merupakan metode terbaik yang sudah dilakukan jika dibandingkan dengan metode lain. Larutan alkali yang digunakan yaitu NaOH karena memiliki sifat yang mampu mendegradasi lignin tanpa merusak struktur selulosa. Delignifikasi dilakukan dengan memberikan variasi konsentrasi NaOH 0,75 M; 1 M; dan 1,5 M dan variasi lama waktu paparan panas microwave 5; 7,5; dan 10 menit. Hasil variasi pretreatment diuji secara statistik menggunakan rancangan acak lengkap. Secara statistik, peningkatan konsentrasi larutan NaOH dan lama waktu paparan panas microwave memberikan pengaruh nyata untuk kandungan lignin dan selulosa. Konsentrasi NaOH dan waktu paparan microwave terbaik adalah 1 M dan 7,5 menit., As the largest producer and exporter of cocoa in the world, Indonesia produces approximately 720,66 thousand tons of cocoa per year, which accounts for 14,34% of global cocoa production. About 74% of cocoa fruits consist of cocoa husks, which contain lignocellulose and have the potential to be processed into bioethanol. The production of bioethanol involves several stages, such as pretreatment/delignification, hydrolysis, fermentation, and purification. The pretreatment stage is conducted to obtain cellulose/sugar content that will be further processed in the hydrolysis stage. Pretreatment can be done by combining physical and chemical methods. The use of alkaline methods and microwave heating is a form of combining physical and chemical methods, which is useful for increasing cellulose content and reducing lignin content. This method has been proven to be the best compared to other methods. Alkali solutions, such as NaOH, are used because it can degrade lignin without damaging the cellulose structure. Delignification is carried out by varying the concentration of NaOH at 0,75 M, 1 M, and 1,5 M, and the exposure time to microwave heating at 5; 7,5; and 10 min. The results of the pretreatment variations are statistically tested using a completely randomized design. Statistically, increasing the concentration of NaOH solution and the duration of microwave heating significantly affect the lignin and cellulose content. The optimal NaOH concentration and microwave exposure time are 1 M and 7,5 min.
Keyword: alkaline, bioethanol, cacao pods husk, delignification, microwave heating

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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