Abstract. The objective of this research was to study a kinetic model of biodiesel production from waste cooking oil assisted by ultrasound power. The model considered the biodiesel production process as a 2nd order reversible reaction, while its kinetic parameters were estimated using MATLAB, based on data extracted from Hingu, et al. [1]. The data represented experiments under low-frequency ultrasonic wave (20 kHz) and variations of temperature, power, catalyst concentration, and alcohol-oil molar ratio. Statistical analysis showed that the proposed model fits well to the experimental data with a determination coefficient (R 2 ) higher than 0.9.

Beberapa impuritis yang terkandung dalam gas alam  harus dibersihkan terlebih dahulu. Kontaminan yang paling banyak dijumpai yaitu gas hydrogen sulfida (H2S) dan gas karbondioksida (CO2). Gas H2S merupakan senyawa asam yang sangat berbahaya bagi kesehatan dan lingkungan sedangkan  gas CO2  bisa memperkecil nilai kalor pada gas alam dan membuat korosi pada perpipaan sehingga harus dihilangkan. Proses absorpsi dengan memakai solven alkanolamine merupakan salah satu teknologi penghilangan gas H2S dan CO2 yang sering dipakai. Pada penelitian ini solven yang dikaji adalah metildietanolamina (MDEA). Pada simulator komersial seperti Aspen Hysys terdapat proses absorpsi kimia. Tujuan dari penelitian ini untuk mengetahui pengaruh suhu solven dan konsentrasi solven terhadap komposisi CO2/H2S serta loading CO2/H2S  pada sweet gas.  Penelitian ini memperlihatkan simulasi absorbsi gas CO2/H2S menggunakan solven MDEA. Semakin besar temperatur operasi maka loading CO2/ H2S makin besar tetapi  komposisi CO2/ H2S di sweet gas makin rendah.

Biodiesel merupakan sumber energi alternatif dan terbarukan karena biodiesel bisa diproduksi dari lemak hewani, minyak nabati, maupun minyak jelantah. Pada umumnya, biodiesel disintesis melalui proses transesterifikasi, yakni reaksi trigliserida dengan alkohol untuk menghasilkan gliserol dan FAMEberbantukan katalis basa. Sintesis biodiesel ini dipakai material minyak goreng bekas  yang  diambil  dari  asrama vyatra PEM Akamigas di Wilayah Cepu, Kabupaten Blora, Jawa Tengah dengan kandungan FFA yang dihasilkan yaitu 1,0 % sehingga bisa dijalankan langsung reaksi  transesterifikasi dengan cara elektrolisis. Pengerjaan penelitian ini dengan mencampurkan 50 gram minyak goreng bekas dan metanol berbantukan katalis NaOH 1% sertacampuran aquadest (2 %wt) dan Aseton (10 wt%). Reaksi transesterifikasi ini ditentukan variasi parameter tegangan listrik yakni 5 V, 10 V, 20 V dan 30 Vbeserta variasi rasio molar  methanol : minyak jelantah  4, 5, 6, 7, dan 8. Penelitian ini menghasilkan  yield biodiesel optimum pada variasi tegangan listrik 30 Vdan rasio  molar methanol : minyak 6 yaitu sebesar 95,1 %.

As we know, proven oil reserves in the world have decreased, as well as in Indonesia. Currently, proven oil reserves in Indonesia is about 2.483,97 MMSTB in 2019. Assuming a constant production without the discovery of new reserves, then in the next 10 to 11 years Indonesia will not be able to produce petroleum anymore. On the other hand, compared to proven petroleum reserves in Indonesia, proven natural gas reserves in Indonesia are quite large. It is around 49,74 TSCF in 2019. And the reserve to production is about 34 years since 2009 to 2018. Therefore, in this work, a syngas to synfuel plant has been prepared as a contribution for preparation of a shifting from producing fuel with petroleum as raw material, to fuel with natural gas as raw material. Particularly for eastern Indonesia, where access to several areas is difficult to reach so that the distribution of gas products is less relevant.

Biodiesel is an alternative fuel for diesel machines. Used cooking oil is blended with diesel with a certain volume ratio to improve the characteristics. The characteristics of biodiesel can not be fully used by diesel engines because it doesn’t meet the standards so that its characteristics need to be improved. As for utilizing it, it must be blended with diesel oil. The purpose of this study is to improve the physical and chemical properties of biodiesel, knowing the percentage of biodiesel volume from used cooking oil with diesel oil so that it can be known the optimal ratio of biodiesel with diesel oil which is close to diesel fuel specifications. Characteristics as variables in this paper are density, kinematic viscosity, pour point, and flash point of the specified mixture. The results show that the kinematic viscosity and density of the biodiesel-diesel mixture increase as the biodiesel mixture increases. Mixtures with higher biodiesel content have higher flash points. Mixing diesel with used cooking oil biodiesel may be of no use compared to diesel, but it can help in adjusting the viscosity, density, pour point, and flash point values according to applicable regulations.