Judul: Adsorben Berbasis Limbah Padat Agar-Agar sebagai Penjerap Zat Warna Indigosol dan Zat Warna Limbah Industri Batik
Abstrak: This study aimed to compare adsorption capacityof solid waste of agar and its carbonization results for indygosol dyes and to compare coagulation-flocculation using adsorpstion process to reduce batik industry waste dyes. The waste after treatment by netralization and coagulation-flocculation using alum reduced chemical oxygen demand (COD) and dyes percent by 45 % and 57.78 % at 50 and 150 ppm alum. Solid waste of agar contained 69.68 % crude fiber which indicates high carbon content in the sample. Solid waste of agar after carbonization had adsorption capacity and efficiency of 6.2394 mg/g and 83.38% for indigosol dyes, and could reduce dyes and COD in the batik industrial waste decreased by 59.81% and 22.19%. Solid waste of agar without carbonization resulted adsorption capacity and efficiency of 3.0644 mg/g and 40.87% for indygosol dyes, and could reduced dyes and COD of the waste by 52.78% and 18.13%.
Keyword: solid waste of agar, indigoso, coagulation-flocculation, carbonization, adsorption

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: 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