Judul: Adsorben berbasis limbah padat tapioka
Abstrak: The use of agroindustrial waste and clay mineral have been studied as alternative adsorbents for dyes, such as cibacron blue. In this research, tapioca solid waste, kaolin, bentonite, and the mixture of tapioca solid waste and kaolinite or bentonite were used as adsorbents for cibacron blue. Acid and base treatments were carried out to activate the adsorbents. Adsorption was varied with adsorption times and adsorbent weight. The result showed that acid activated tapioca solid waste had the highest adsorption capacity. The optimum adsorption time and adsorbent tapioca solid waste weight was 75 minutes and 1 g. The cibacron blue concentration decrease from 50 mg/L to 11.12 mg/L. On the other hand, the optimum condition for commercially activated carbon were 30 minutes and 0.5 g with concentration decreasing from 50 mg/L to 19.44 mg/L. The adsorption capacity for acid activated tapioca solid waste and activated carbon were 1.94 mg/g and 3.05 mg/g adsorbent respectively. With adsorption efficiency were 77.75% and 61.11%. Acid activated tapioca solid waste were followed Freundlich isotherm.
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Judul: Adsorpsi asam lemak bebas dan zat warna menggunakan campuran kaolin-limbah padat tapioka
Abstrak: Adsorption of free fatty acids in used cooking oil and methylene blue dye is studied. The results showed that the mixture of kaolin and tapioca solid waste is a potential adsorbent for the adsorption free fatty acids and dyes. The effect of kaolin activation treatment, such as heating temperature and the use of acid is also studied. The best activation results for the kaolin activation used in the free fatty acid adsorption was heating treatment at 750 °C followed by treatment with H2SO4 30%, whereas for methylene blue adsorption by acid treatment only. Activation of tapioca solid waste was using 30% H3PO4 treatment. Optimum conditions for adsorption, adsorption capacity, and adsorption efficiency of a mixture of kaolin and tapioca solid waste showed different results and specific for each type of sample used. For the same amount of adsorbent, free fatty acid adsorption was reached in 90 minutes using the ratio of activated kaolin and tapioca solid waste of 25:75 (1:3). Meanwhile, methylene blue adsorption was achieved at 30 minutes with the ratio of activated kaolin and tapioca solid waste of 75:25 (3:1). The results showed that the type of adsorption isotherm for free fatty acids was Freundlich isotherm, whereas for methylene blue adsorption was Langmuir isotherm.
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Judul: Identifikasi Westerly Wind Bursts Dan Hubungannya Dengan Kejadian El Niño
Abstrak: Westerly Wind Burst (WWBs) didefiniskan sebagai gangguan atmosfer berskala sinoptik yang ditandai dengan angin baratan kuat dengan kecepatan lebih dari 5 m/s disekitar ekuator yang terjadi selama lebih dari 2 hari. WWBs diyakini sebagai salah satu gangguan yang berperan dalam proses fisis kejadian El Niño, sehingga perlu dilakukan penelitian untuk melihat bagaimana karakteristik WWBs dan hubungannya dengan kejadian El Niño. Data yang digunakan adalah angin zonal & meridional, suhu permukaan laut (SPL), dan data Oceanic Nino Index (ONI) selama tahun 1981-2015. Selama periode 1981-2015, terdeteksi WWBs sebanyak 173 kejadian dengan kecepatan angin berkisar antara 5-10 m/s yang tersebar dari Samudra Hindia hingga Samudra Pasifik. Kejadian WWBs terbanyak terdeteksi di Samudra Pasifik timur dan tengah (wilayah Nino 3.4) masing-masing sebanyak 102 dan 64 kejadian, sedangkan WWBs di Samudra Pasifik barat dan Samudra Hindia masing-masing hanya 4 dan 3 kejadian. WWBs yang terdeteksi pada umumnya diikuti oleh kejadian El Niño, frekuensi kejadian WWBs akan meningkat ketika El Niño menguat. Hasil analisis komposit angin zonal dan SPL pada kejadian El Niño (1982-1983, 1991-1992, dan 1997-1998) menunjukkan bahwa WWBs mulai terdeteksi 3-4 bulan sebelum kejadian El Niño dan mencapai puncaknya pada Bulan November-Januari di tahun berikutnya seiring dengan fase puncak kejadian El Niño. Hasil analisis korelasi antara frekuensi kejadian WWBs dan ONI adalah 0.51 yang signifikan pada selang kepercayaan 99%. Hal ini menunjukkan bahwa kejadian WWBs dan El Niño memiliki hubungan yang searah. Ketika frekuensi WWBs meningkat, kejadian El Niño juga akan mengalami penguatan.
Keyword: Westerly Wind Burst, Angin Zonal, SPL, El Niño, GrADS