Judul: Sintesis, Pencirian, dan Uji Fotodegradasi Nanokomposit Sodalit/TiO2 Terhadap Zat Warna Biru Metilena.
Abstrak: Kaolin merupakan lempung aluminasilikat. Sintesis zeolit dari bahan dasar kaolin Indonesia belum pernah dilakukan. Pada penelitian ini, digunakan kaolin Bangka Belitung sebagai bahan dasar dalam proses sintesis beberapa jenis zeolit dan nanokomposit sodalit/TiO2 serta aplikasinya untuk mendegradasi biru metilena. Kaolin dikonversi menjadi metakaolin melalui proses kalsinasi pada suhu 550°C dan 700°C selama 3 dan 6 jam. Metakaolin direaksikan dengan NaOH pada kondisi hidrotermal. Nanokomposit sodalit/TiO2 dibuat dengan nisbah metakaolin:TiO2 = 90:10% b/b. Zeolit dan nanokomposit sodalit/TiO2 dicirikan dengan menggunakan difraktometer sinar-X. Nanokomposit diuji kemampuan fotokatalisnya menggunakan lampu UV dengan panjang gelombang 365 nm selama 6 jam. Hasil pencirian menunjukkan bahwa zeolit yang disintesis dominan sodalit. Hasil pengujian fotokatalis pada zat warna menunjukkan bahwa sekitar 74% dari biru metilena didegradasi oleh nanokomposit sodalit/TiO2 setelah diradiasi lampu UV selama 6 jam
Keyword: Kaolin, Metakaolin, Titanium oxide

Judul: Sintesis Nanokomposit Kaolin/TiO2 Teremban Fe2O3 untuk Adsorpsi-Fotodegradasi Biru Metilena
Abstrak: Kaolin is a type of clay mineral that has adsorption capacity. The experiment shows that the adsorption capacity of kaolin was 20.6 mg/g. This value is lower than zeolite adsorption capacity that in general has value above 100 mg/g. Mixing kaolin with other materials to form nanocomposite, may improve its adsorption properties. Nanocomposites that had been synthesized were kaolin/TiO2 nanocomposites with the addition of Fe2O3 using 2 synthetic methods, namely using ball milling and paste methods. The nanocomposite synthesized using ball milling method had higher adsorption capacity value, i.e. 23.6 mg/g. The nanocomposite of kaolin/ TiO2 was able to adsorb and degrade waste dyes in ultraviolet range. Furthermore, addition of Fe2O3 to the kaolin/TiO2 nanocomposite improved the performance of the nanocomposite by reacting under the visible rays. Therefore, the performance of nanocomposite of kaolin/TiO2 added with Fe2O3 was is more effective since visible ray is the major part of the sun light.
Keyword: nanocomposite of kaolin/TiO2/Fe2O3., kaolin, photodegradation, adsorption

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