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AbstrakProses produksi biodiesel dari dedak padi dengan memanfaatkan microwave secara in situ telah berhasil dilakukan. Pengaruh jumlah metanol dan waktu reaksi terhadap kandungan FAMEs dalam produk dipelajari dalam penelitian ini. Dedak padi , metanol dan katalis basa berupa NaOH 0.6 w% dimasukkan ke dalam labu alas datar dilengkapi dengan kondensor dan dimasukkan ke dalam reaktor microwave yang telah dimodifikasi.  Produk reaksi yang berupa campuran FAMEs, gliserol, reaktan yang tidak bereaksi dan komponen lainnya kemudian dicuci menggunakan n- heksana dan dilanjut dilakukan proses distilasi. Hasil penelitian menunjukan bahwa dengan menggunakan reaktor microwave, kandungan FAMEs lebih tinggi diperoleh dengan waktu reaksi yang lebih singkat. Gelombang mikro berhasil mempercepat terjadinya reaksi transesterifikasi. Kandungan FAMEs tertinggi yaitu 6.2036 % diperoleh pada waktu reaksi 10 menit, metanol 60 ml dan suhu reaksi 60oC.  Kata kunci : Biodiesel, In situ, Microwave, Dedak padi AbstractThe process of biodiesel production from rice bran using in situ microwaves has been successfully carried out. The effect of the amount of methanol and reaction time on the FAMEs content in the product was studied in this study. Rice bran, methanol and alkaline catalyst in the form of 0.6 w% NaOH are put into a flat bottom flask equipped with a condenser and put into a modified microwave reactor. The reaction product in the form of a mixture of FAMEs, glycerol, unreacted reactants and other components is then washed using n-hexane and contuining with the distillation process. The results showed that by using a microwave reactor, a higher FAMEs content was obtained with a shorter reaction time. Microwaves successfully accelerate the transesterification reaction. The highest FAMEs content of 6.2036% was obtained at a reaction time of 10 minutes, methanol 60 ml and reaction temperature 60oC.Keywords: Biodiesel, In situ, Microwave, Rice bran

Microwave heating treatment was the one type of pretreatment process used in the manufacture bioethanol because it can be applied singly or in combination with other chemicals. The purpose of this study was to determine the effect of microwave heating on the pretreatment process using acid and alkaline solvents. The research was carried out in two stages, namely the preparation of raw materials and pretreatment with microwave. At the stage of preparation of raw materials, bagasse was dried for 2 days and then crushed to a size of 50 mesh to uniform the size of the raw materials. The raw materials that have been prepared are then subjected to a pretreatment process. The pretreatment process was carried out using a modified microwave with temperature settings and the addition of a stirrer. 5 grams of bagasse powder and 200 ml of a solution of H2SO4 or NaOH (0.2 M, 0.4 M, and 1 M) were put into a round tool flask and then put into the microwave. Pretreatment was carried out at 180°C with time variables of 10, 15, 20, 25, and 30 minutes. Then the solution was separated from the residual solid by filtration and the solution was neutralized with 1 M HCl. The results showed that the use of acidic and alkaline solvents, high concentrations of solvents can lead to smaller the acquisition of reducing sugars in the liquid product phase. The highest percentage of reducing sugar obtained is 0.559% when using an acid solvent with a concentration of 0.1 M for 20 minutes.

Penggunaan silika sering digunakan dalam berbagai industri. Tujuan penelitian ini adalah untuk mengetahui kadar silika pada tanah vertisol di desa Bringinbendo. Penelitian ini dimulai dengan perendaman tanah pada aquadest, kemudian dicuci sebanyak 3 kali dan dikeringkan pada 110°C selama 24 jam. Selanjutnya dihaluskan hingga ukuran 250 mesh. Tahapan kedua yaitu sintesis silika dengan metode ekstraksi alkali dan diikuti presipitasi asam. 20 gram serbuk tanah diekstraksi dalam 100 ml NaOH (3, 5, dan 7M) sambil diaduk dan dipanaskan pada 80°C. Selanjutnya ditambahkan aquadest sebanyak 250 ml dan disaring menggunakan kertas Whatman. Filtrat dititrasi dengan HCl 5M sambil diaduk hingga pH mencapai 7. Suspensi dipertahankan pada temperatur kamar selama 24 jam, disaring, dan dicuci sebanyak 5 kali dengan aquadest kemudian dikeringkan. Hasil dari penelitian yaitu massa silika paling besar terdapat pada konsentrasi NaOH 7M pada waktu 1 jam yaitu 2,59 gram dan tanah vertisol di Desa Bringinbendo memiliki kadar silika dalam kategori sedang dengan persentase sebesar 77,7%.Silica is widely used in industry. The aim of this study was to determine the silica content in vertisol soil in Bringinbendo village. This research was started by soaking the soil in aquadest, then washed 3 times and dried it at 110 ° C for 24 hours. Furthermore, smoothed to 250 mesh size. The second stage is the synthesis of silica using the alkaline extraction method and the treatment of acids. 20 grams of soil powder were extracted in 100 ml NaOH (3, 5, dan 7M) while stirring and heated at 80 ° C. Next, 250 ml of aquadest was added and filtered using Whatman paper. The filtrate was titrated with 5M HCl while stirring until the pH reached 7. The suspension was maintained at room temperature for 24 hours, filtered, and 5 times with aquadest then dried. The results of the mass study were that the greatest silica was found in 7M NaOH concentration at 1 hour, namely 2.59 grams and vertisol soil in Bringinbendo Village had silica content in the medium category with a proportion of 77.7%.

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