TY - GEN CY - UNIVERSITAS LAMPUNG ID - eprints61977 UR - http://digilib.unila.ac.id/61977/ A1 - Nurul Rosadinah, 1757011010 Y1 - 2021/// N2 - Pada industri minyak dan gas sering dijumpai permasalahan pada pipa seperti terjadinya pengendapan garam yang disebut dengan kerak. Salah satu kerak yang terbentuk pada pipa-pipa industri adalah kalsium sulfat (CaSO4). Kerak pada pipa- pipa industri akan mengakibatkan aliran fluida terhambat baik dalam pipa maupun alat penukar panas. Untuk mengatasi hal tersebut, pada penelitian ini digunakan limbah cair tempe sebagai inhibitor kerak kalsium sulfat (CaSO4) dengan metode penambahan bibit kristal (seeded experiment) pada suhu 90 °C dengan variasi konsentrasi larutan pertumbuhan 0,1; 0,15; dan 0,2 M serta variasi inhibitor 5, 15, 25, 35, dan 45%. Untuk melihat waktu simpan inhibitor, inhibitor disimpan selama 1, 3, dan 7 hari. Limbah cair tempe dengan waku simpan 1 hari digunakan sebagai inhibitor. Nilai persen efektivitas paling efektif diperoleh pada konsentrasi larutan pertumbuhan 0,15 M dan konsentrasi inhibitor 45% sebesar 89,76%. Berdasarkan hasil analisis menggunakan spectophotometer infra red (IR) limbah cair tempe mengandung gugus O?H dan C=O. Pada analisis high performance liquid chromatography (HPLC) limbah cair tempe mengandung asam laktat sebesar 5%. Hasil analisis scanning electron microscopy (SEM) dan x-ray diffraction (XRD) menunjukkan kerak CaSO4 tanpa penambahan inhibitor terdiri dari kristal fasa gipsum dan basanit, sedangkan setelah penambahan inhibitor terdiri dari kristal fasa gipsum, basanit, dan sedikit anhidrit. Analisis kuantitatif menggunakan particle size analyzer (PSA) menunjukan bahwa distribusi ukuran partikel kerak CaSO4 menjadi lebih kecil dengan adanya penambahan inhibitor berdasarkan nilai rata-rata (mean) yaitu dari 20,82 menjadi 9,571 ?m dan nilai tengah (median) yaitu dari 17,46 menjadi 8,438 ?m. Kata kunci : CaSO4, inhibitor, kerak, limbah cair tempe In the oil and gas industry, pipe problems are often encountered, for example salt deposition, which is known as scale. One of the scale formed in industrial pipes is calcium sulfate (CaSO4). The scale on industrial pipes will cause an obstructed fluid flow both in the pipe and in the heat exchanger. To overcome this problem, this study uses tempeh?s liquid waste as a scale inhibitor of calcium sulfate (CaSO4) by using a method of adding crystals seed (seeded experiment) at a temperature of 90 °C with variations in the growth solution concentration 0,1; 0,15; and 0,2 M and inhibitor variations of 5, 15, 25, 35, and 45%. To see the shelf-life of the inhibitor, it was stored for 1, 3, and 7 days. Tempeh?s liquid waste with a storage time of 1 day is used as an inhibitor. The most effective percentage value of effectiveness is obtained at 0.15 M growth solution concentration and 45% inhibitor concentration at 89.76%. Based on the analysis of the use of infra red (IR) spectophotometer, tempeh?s liquid waste contains O?H and C=O. In the high performance liquid chromatography (HPLC) analysis, tempeh?s liquid waste contains 5% lactic acid. Analysis result of scanning electron microscopy (SEM) and x-ray diffraction (XRD) show that the CaSO4 scale without the addition of an inhibitor consisted of gypsum and bassanite crystals, while after the addition of inhibitors it consisted of gypsum, bassanite, and a little anhydrite crystal. Gypsum is a type of hardscale crystal, while bassanite and anhydrite are the type of softscale crystal. The quantitative analysis using particle size analyzer (PSA) showed that the particle size distribution of CaSO4 scale became smaller with the addition of inhibitors based on the average score (mean) from 20.82 to 9.571 ?m and the median score from 17.46 to 8.438 ?m. Key words : CaSO4, inhibitor, scale, tempeh?s liquid waste PB - FAKULTAS MATEMATIKA DAN ILMU PENGETAHUAN ALAM TI - STUDI PENAMBAHAN LIMBAH CAIR TEMPE SEBAGAI INHIBITOR KALSIUM SULFAT (CaSO4) MENGGUNAKAN METODE SEEDED EXPERIMENT AV - restricted ER -