Judul: Karbon Aktif dari Tempurung Inti Sawit sebagai Adsorben Zat Warna.
Abstrak: Proses adsorpsi menggunakan karbon aktif merupakan cara yang mudah, efektif, dan efisien untuk mengolah limbah zat warna. Limbah pertanian berupa tempurung inti sawit dapat digunakan sebagai bahan dasar dalam pembuatan karbon aktif. Metode yang digunakan untuk menyiapkan karbon aktif berupa aktivasi secara kimia. Bahan dasar berupa limbah tempurung dicampur dengan H3PO4 dengan nisbah (b/v) 1:1, serta dicampur dengan pelambat nyala dengan nisbah 1:8, 1:16, dan 1:24. Pelambat nyala dan H3PO4 dapat menghambat proses pembakaran dan meningkatkan rendemen produk. Rendemen tertinggi ialah produk dengan tambahan pelambat nyala dengan nisbah 1:24, sedangkan kapasitas adsorpsi tertinggi ialah dengan tambahan H3PO4. Isoterm adsorpsi dari karbon aktif yang dihasilkan mengikuti isoterm Langmuir.
Keyword: adsorpsi, H3PO4, isoterm, karbon aktif, pelambat nyala

Judul: Pemanfaatan Karbon Aktif dengan Aktivator H3PO4 dari Limbah Padat Agar sebagai Penjerap pada Limbah Cair Industri Penyamakan Kulit
Abstrak: Agar solid waste can be used as an adsorbent in the form of activated carbon. The study aims were to determine the best concentration of H3PO4 and activation time on the processing of activated carbon and the effectiveness of activated carbon as an adsorbent in the tanning industry wastewater. The activation step of activated carbon was carried out with H3PO4 concentration of 10; 20; 30% and the time activation of 15; 20; 25 hours. The best activation treatment was obtained on 10% H3PO4 concentration and 15 hours activation time with activated carbons yield of 93.42%, moisture content of 10.59%, ash content of 65.91%, absorption of iodine of 1090.80 mg/g, volatile matter of 21.60% dan fixed carbon of 12.35%. The best activated carbon was applied to the tanning industry wastewater with contact time of 0.5; 1; 1.5; 2 hours and activated carbon concentrations of 0; 1; 2; 3%. Application treatment with contact time of 0.5 hours and 3% activated carbon concentration decreased the value of Cr from 4371.21 ppm to 3572.76 ppm, treatment with contact time of 1 hours and 3% activated carbon concentration decreased the value of BOD, COD from 1216.10 mg/L, 17753.33 mg/L to 438.21 mg/L, 11770.00 mg/L respectively, however it did not affect the pH value.
Keyword: adsorbent, agar solid waste, wastewater, activated carbon, H3PO4

Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model