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: A Continuous Vaccination Strategy in the SVIR Epidemic Model
Abstrak: Vaccination is conducted to minimize the spread of a disease. The vaccination is usually done several times within a fixed time interval. In the SVIR model, it is assumed that individuals do not get immediate immunity following a vaccination program. So according to process of vaccination on SVIR model, there are two strategies, i.e. the continuous vaccination strategy (CVS) and the pulse vaccination strategy (PVS). In this study, only the CVS strategy in epidemic model SVIR is considered. Results of the study indicate that dynamics of the CVS system depends on the basic reproductive number. If the basic reproductive number is less than one, then the disease-free fixed point is asymptotically stable. It means that the disease will eventually disappear from the population. Conversely, if the basic reproductive number is greater than one, then the endemic fixed point is asymptotically stable, which means that the disease will remain exist in the population. Simulation result shows that the vaccination would minimize the spread of disease by reducing the basic reproductive number. If the time for the vaccinated recipients to obtain the immunity, as well as a possibility of vaccinated recipients to be infected are neglected, then the disease will be eradicated. This condition is called an over-evaluating effect of vaccination.
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