Green inhibitors are inhibitors that utilize secondary metabolites of plant to reduce the rate of corrosion. Secondary metabolites with heteroatom content phosphate, nitrogen, oxygen and sulfur function as ligands and adsorption centers to bind metals. These metabolites compounds include alkaloids, flavonoids, and tannins. Tristaniopsis merguensis Griff. is a local plant of Bangka Belitung which contains alkaloid, flavonoids and tannins. The focus of this research is to analyze the effect of T. merguensis leaf extract on corrosion rate of stainless steel. T. merguensis extract was obtained by maceration for 3 x 24 hours using ethanol solvent. Determination of corrosion rate using the mass reduction method. Then, functional group analysis contained in extract uses the Fourier Transform Infrared (FT-IR) at wavenumber region 4000–400 cm−1. The results obtained that at the highest concentration of 1000 mg/L the extract of T. merguensis was able to inhibit the corrosion rate of stainless steel until the corrosion rate was 0.3826 mmpy equal to inhibition efficiency 85.27%. This inhibiting ability is more likely because T. merguensis leaf extract containing phenolic compounds. Therefor T. merguensis extract can be used as a green inhibitor.

AbstrakTurbin air adalah suatu mesin yang menghasilkan energi mekanik berupa putaran poros dengan memanfaatkan energi potensial air. Energi ini selanjutnya diubah menjadi bentuk energi lain seperti energi listrik. Turbin air yang digunakan di Indonesia sebagian besar adalah turbin aliran silang (cross flow). Turbin cross flow memiliki kontruksi yang sederhana dan memberikan biaya operasional kecil. Pentingnya dilakukan penelitian ini adalah untuk mengetahui pengaruh debit air dan variasi sudut serang nosel terhadap unjuk kerja turbin cross flow. Penelitian ini dilakukan menggunakan instalasi penelitian yang tersusun atas beberapa peralatan utama. Diantaranya runner (piringan dan sudu), nosel, rotameter, tachometer, dan neraca pegas.

Penelitian ini tentang pemanfaatan kulit pisang kepok menjadi bubuk minuman kopi. Kulit pisang ini umumnya dihaluskan dengan menggunakan blender, namun kelemahannya adalah kapasitas produksinya lebih rendah, sehingga untuk memproduksi dalam jumlah banyak harus dilakukan proses berulang. Berdasarkan hal tersebut, maka dibuatlah sebuah mesin penghalus kulit pisang hingga menjadi bubuk dengan tingkat kehalusan bubuk kopi pada umumnya. Kulit pisang yang digunakan yaitu kulit pisang kepok matang. Proses penghalusan kulit pisang menggunakan mesin dengan menggunakan motor listrik sebesar ½ HP, dengan putaran pada poros penghalus yaitu 1050 rpm. Hasil pengujian dengan bahan uji dengan massa 500 gram yaitu dalam waktu 1 menit menghasilkan 215 gram, waktu 2 menit menghasilkan 225,7 gram, waktu 3 menit menghasilkan   250,7 gram.

Indonesia has quite extensive multi-purpose reservoir waters, one of which was built for the first time is the Ir. H. Djuanda reservoir or better known as Jatiluhur reservoir. The activities carried out in the Jatiluhur reservoir are varied, such as fisheries, transportation,water sources as well as power generation as secondary functions of the reservoir. If managed properly, the reservoir will give a real contribution to the economy and welfare of the community without disrupting the sustainability of the ecosystems and its functions. In Indonesia, problems that often occur in all aquatic ecosystems are eutrophication (nutrient enrichment), sedimentation, and pollution. Water hyacinth (Eichorniacrassipes) is a type of aquatic plant that is generally considered as a weed. The study aims to formulate a water hyacinth management strategyusing the SWOT method with ten respondents.The selection of respondents using purposive sampling method.The results showed that all stakeholders, government, and communities must work together in utilizing and managing reservoirs and watersheds that enter the reservoir waters so that the quality status of reservoir becomes better and the growth of water hyacinth does not increase rapidly. Water hyacinth can also be used as fertilizer or crafts and not just a weed.

This research is about the savonius wind turbine which was made in the form of a prototype as a simple student learning media. The goal is the students understand the process of converting wind energy into mechanical energy. The turbine model used is helical savonius rotor with U, S, and L profile on three blades and four blades. Tests carried out using wind tunnels. The test results show that helical savonius rotor with three blades provides better performance than four blades. The best turbine power is obtained in the L profile with three blades which is equal to 1, 62 watts. While the best power coefficient is obtained from the S profile with 3 blades with a power coefficient value of 0.122.