Judul: Studi Kinetika Adsorpsi Asam Lemak Bebas pada Pemurnian Minyak Ikan Lemuru (Sardinella sp.)
Abstrak: Fish oil can be produced from by-product industry, but the fish oil have uninteresting color and high free fatty acids so it needs to be purified. The purpose of this research is to study fatty acid profile of fish oil, study of adsorption kinetics free fatty acid, and fish oil clarity. Result of second-order rate (k2) was 0.0344 g mg-1min-1 for attapulgite, 0.0222 g mg-1min-1 for bentonite, and 0.0460 g mg-1min-1 for chitosan. The adsorption capacity saturation (qs) was 56.53 mg/gram for attapulgite, 42.40 mg/gram for bentonite, and 47.11 mg/gram for chitosan. The external film mass-transfer coefficient (KsA) was 0.0018 mL/s for attapulgite, 0.0015 mL/s for chitosan, and 0.0013 mL/s for bentonite. The intraparticular diffusion coefficients (Kw) for attapulgite were 0.1542 mg mL-1 min-0.5, chitosan 0.1285 mg mL-1 min-0.5, and bentonite 0.1156 mg mL-1 min-0.5. Clarity for all adsorbents increase with increasing adsorption time until the 60th minute. Results indicated that attapulgite was the best adsorbent than chitosan and bentonite for FFA removal from sardine fish oil.
Keyword: free fatty acid, adsorption kinetics, purification, sardine fish oil

Judul: Pemurnian Minyak Ikan Sardin (Sardinella sp.): Sentrifugasi dan Adsorben Bentonit
Abstrak: Centrifugation and purification using adsorbents is one example of a fish oil refining techniques applied to reduce impurities of fish oil. The study aimed to determine the sardine oil quality before treatment, to determine yield of fish oil after centrifugation treatment, to determine the influence of centrifugation speed and bentonite concentration on sardine oil quality. Level of free fatty acids and peroxide value before purification was 35.53% and 170 meq/kg. Yield of fish oil after centrifugation treatment has been ranged from 17.42±3.56 to 76.33±0.21%. The best treatment which could reduce the peroxide value and total oxidation was a treatment with centrifugation speed at 6500 rpm and bentonite concentration at 3%. Peroxide value and total oxidation of its treatment was 25.00±0.00 meq/kg and 51.43±0.01 meq/kg. The lowest value of p-anisidine was 1.29±0.05 meq/kg and its value could be found in a treatment with centrifugation speed at 4500 rpm and bentonite concentration at 5%. The level of free fatty acids after purification process was ranged from 27.35 to 34.69%. Oil clarity tended to increase with the increase of speed centrifugation and adsorbent concentration.
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Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf