A non-catalytic in situ process to produce biodiesel from a rice milling by-product using a subcritical water-methanol mixture

A non-catalytic method to produce biodiesel in situ from a rice milling by-product, i.e. rice bran, using subcritical water-methanol mixture has been investigated. The method was found to be unaffected by initial moisture and free fatty acids (FFA) contents in rice bran so that no pretreatment was required. The yield and purity of biodiesel were higher under CO2 atmosphere than those under N atmosphere due the ability of the gas to acidify water-methanol mixture. Oil extraction from the bran was identified as the limiting step and complete oil extraction could be achieved in 3 h at 200oC, 4 MPa (under CO2 atmosphere) and 43.8 wt% methanol concentration. Consequently, the highest biodiesel yield was also achieved at those operating conditions. The experimental data suggested that hydrolysis of rice bran oil into FFA followed by methyl-esterification of FFA into biodiesel could be the preferred reaction path to direct transesterification of oil. Subcritical water-methanol mixture was also able to break down complex carbohydrates in rice bran into simple sugars soluble in aqueous phase so that it could be separated easily from biodiesel

Penggunaan Tanah Vertisol sebagai Bahan Baku Pembuatan Silika

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%