Judul: Pemanfaatan Arang Aktif Serbuk Gergaji Kayu Mindi Sebagai Penjerap Warna Reaktif Cibacron Red
Abstrak: Textile wastewater containing dyes can pollute aquatic environment. This study utilized activated carbon from sawdust of mindi woods as adsorbent of Cibacron Red reactive dyes which are widely used in textile industries. The best activated carbon was obtained by maceration in 5% H3PO4 with activation at 650 ºC for 100 minutes. The optimum adsorption condition were obtained under adsorption time of 60 minutes, 3.0 g of adsorbent, and initial concentration of dye solution of 150 ppm. Adsorption capacity of the activated carbon at optimum conditions was 4891.55 μg/g, with adsorption efficiency of 97.87%. The adsorption followed the Freundlich isoterm. Adsorption treatment with activated carbon on textile manufacture waste could decrease the colour intensity after adsorption up to 97.52%, chemical oxygen demand 91.50%, and biochemical oxygen demand 73.17%. Based on these results, sawdust of mindi woods is potentiall as an adsorbent of dyes, thereby reducing the level of pollution of aquatic environment.
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Judul: Penjerapan zat warna rreaktif cibacron red menggunakan adsorben sekam padi
Abstrak: Textile wastewater containing dyes can pollute aquatic environment. This study utilized rice husk as adsorbent for Cibacron Red reactive dyes which are widely used in textile industries. Husks were made into adsorbent without modification (ATM) and acid modified adsorbent (AMA). The optimum condition was obtained under adsorption time of 30 minutes, 1.0 g of adsorbent, and initial concentration of dye solution was 150 ppm. The optimum condition for AMA was obtained under adsorption time of 60 minutes, 2.0 g of adsorbent, and 150 ppm initial concentration of dye solution. The optimum condition of activated charcoal (AA) as a comparison was 30 minute time of adsorption, 3.0 g of adsorbent, and 150 ppm initial concentration dye solution. Adsorption capacity of ATM, AMA, and AA at the optimum conditions was 2879.00, 6898.30, and 2470.00 μg/g, respectively. Adsorption efficiency of ATM, AMA, and AA at the optimum conditions was 19.86, 91.71, and 40.51%, respectively. All three types of adsorbent followed the Freundlich isotherm. Application of the adsorbent on waste of textile manufacture showed a decrease in colour after adsorption by ATM, AMA, and AA, up to 52.05, 98.86 and 48.69%, respectively, with the initial colour intensity of 1485 Pt-Co. Starting with COD of the wastewater which was 7372.0 mg/L, the values decreased after the adsorption with ATM, AMA, and AA were 43.30, 98.56 and 52.58%, respectively. Starting with BOD of 149.09 mg/L, the values decreased after adsorption by ATM, AMA, and AA were 63.41, 76.09, and 72.46%, respectively. Based on these results, rice husk is potentially used as an adsorbent of dyes, thereby reducing the level of pollution of aquatic environment.
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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