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: Baggase as cibacron red reactive dye adsorbent.
Abstrak: Cibacron Red is one of reactive dye types which is widely used by textile industry. But, reactive dye waste from textile industrial process causes many environment problems. Lots of waste treatment efforts are conducted; one of which is to make use of agricultural side products that are potential to be utilized as adsorbent. This research utilizes baggase as Cibacron Red reactive dye adsorbent. Baggase was divided in two categories, unmodified adsorbent and concentrated-sulphuric-acid-modified adsorbent. As a comparison, activated carbon that originated from coconut shell, which is commercially-used adsorbent, was used. Adsorption was carried out by varying adsorption times, adsorbent weights, and initial concentrations of Cibacron Red reactive dye; where then the results were applied to textile industrial waste. The optimum adsorption time, adsorbent weight, and initial concentration for unmodified adsorbent were 45 minutes, 1 g, and 150 ppm, respectively. On the other hand, the optimum conditions for acid-modified adsorbent were 53.5 minutes, 2.5 g, and 150 ppm. The optimum conditions for activated carbon, as comparison, were 60 minutes, 3 gram, and 150 ppm. In single solution tests of Cibacron Red, adsorption capacity for unmodified adsorbent, acid-modified adsorbent, and activated carbon were 788.7, 5669.6, dan 3827.5 μg/g adsorbent; with adsorption efficiency were 6.2, 94.1, dan 75.6% correspondingly. Application of three types of adsorbent toward textile industrial waste showed adsorption efficiency were 1.3, 97.6, and 51.7% in that order. Isotherm type for all types of adsorbent 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