In this study the fluoropolymers, poly(ethylene-co-tetrafluoroethylene) (ETFE) and poly(vinylidene fluoride) (PVDF) films, together with the radiation-induced crosslinked polytetrafluoroethylene (cPTFE) film were compared on the basis of their preparation and properties of radiation-grafted polymer electrolyte membranes. The polymer electrolyte membranes were prepared by radiation grafting of styrene into the base films and subsequent sulfonation. The proton conductivity and chemical stability of the three types of membranes with a similar ion exchange capacity (IEC) near 1.0 mmol/g were investigated and are discussed in detail. Although the ETFE-based polymer electrolyte membrane was relatively more stable, its proton conductivity was lower than those of the PVDF-and cPTFEbased membranes. On the other hand, the cPTFE-based membrane showed a significantly higher proton conductivity, but its chemical stability was shorter than that of the ETFE-based membrane. It is considered that the difference in the preparation and properties of the polymer electrolyte membranes was due to the difference in the degree of crystallinity as well as in the chemical structure of the fluoropolymer base films.

T his work investigated the photodegradation of azo dye, methyl orange, without and with the addition of C-N-codoped TiO 2 catalyst using a visible halogen-lamp as a light source. C-Ncodoped TiO 2 was prepared by free-organic solvent peroxo sol-gel method. The effects of initial dye concentration, catalyst dosage, and pH solution on the photodegradation of methyl orange were studied. Photodegradation process for methyl orange solution at acidic condition showed high removal percentage. 5 mg L-1 methyl orange achieved color removal until 94% for 180 min irradiation in photodegradation process with the presence of C-N-codoped TiO 2 catalyst, and approximately 70% TOC removed as the results of mineralization process. The kinetics reaction rate of photodegradation of methyl orange dye with the addition of C-N-codoped TiO2 followed pseudo-first order represented by Langmuir-Hinshelwood model, the kinetics constant of photodegradation became higher by decreasing the initial concentration of methyl orange. Three organic byproducts of methyl orange formed during photodegradation process was identified by LC-MS/MS system then degradation pathway of methyl orange photodegradation in the presence of C-N-codoped TiO 2 catalyst was proposed.

Objective: In this study, the effect of hydrothermal temperature on the synthesis of hydroxyapatite (HAp) from limestone was investigated.Methods: Precursors of limestone (CaCO3) and diammonium hydrogen phosphate ((NH4)2HPO4) with Ca/P ratio of 1.67 was mixed at pH 10 in order to synthesize hydroxyapatite by hydrothermal method. The solution was hydrothermally treated in an autoclave at various temperatures of 120, 160 and 200 °C for 24 h. Nano powder formed was then characterized.Results: The hydroxyapatite obtained by hydrothermal method at various temperatures was characterized. The analysis of Fourier Transform Infrared (FTIR) revealed that HAp had phosphate (PO43-) and hydroxyl (O-H) groups although carbonate (CO32-) group remained. X-Ray Diffraction (XRD) revealed that the size of nanosize crystals was formed and then provided a large surface area. Scanning Electron Microscopy (SEM) results showed that HAp had a spherical shape. There was more agglomeration at 200 °C than at 160 °C. The ratio of the results of Energy Dispersive X-ray (EDX) analysis in 160 °C was 1.95 and at 200 °C was 1.71Conclusion: The hydroxyapatite prepared at a temperature of 200 °C had smaller crystal size than the hydroxyapatite prepared at the temperatures of 120 and 160 °C. SEM pictures showed that the nanoparticle hydroxyapatite had a spherical shape.

AbstrakZat warna direct red-23 merupakan pewarna sintetik dengan struktur senyawa organik yang bersifat nonbiodegradable. Zat warna direct red-23 mengandung senyawa azo dan bersifat karsinogenik. Zat warna direct red-23 didegradasi secara fotolisis menggunakan sinar UV (ultraviolet), sinar matahari, tanpa dan dengan penambahan katalis C-N-codoped TiO2. Larutan zat warna direct red-23setelah dan sebelum didegradasi diukur dengan spektrofotometer UV-Vis pada panjang gelombang 400-800 nm. Penentuan berat optimum katalis C-Ncodoped TiO2 dilakukan dengan metode fotolisis sinar UV dan didapatkan berat optimum 15 mg. Persen degradasi zat warna direct red-23 secara fotolisis sinar UV dan sinar matahari tanpa katalis C-N-codoped TiO2 27.47% dan 13.74%. Persen degradasi meningkat menjadi 68.68% dan 28.57% dengan penambahan 15 mg katalis C-N-codoped selama 120 menit fotolisis. Dari penelitian dapat disimpulkan metode fotolisis dengan sinar UV lebih efisien dibandingkan dengan sinar matahari.Kata kunci: Direct red-23, sinar UV, sinar matahari, C-N-codoped TiO2. AbstractDirect red-23 dye is a synthetic dye that is widely used in textile industry. Wastes generated from textile industrial processes are generally non-biodegradable organic compounds containing azo compounds and carcinogenic. Direct red-23 dye was degraded by photolysis UV Light method, solar irradiation, without and addition of C-N-codoped TiO2 catalyst. The results degradation of direct red-23 were measured with a UV-Vis spectrophotometer at wavelength of 400-800 nm. Determination of optimum weight of the C-N-codoped TiO2 catalyst was performed by photolysisUV Light method and the optimum C-N-codoped TiO2 catalyst is obtained 15 mg. Percent degradation of direct red-23 dye by photolysis of UV light and solar irradiation without C-Ncodoped TiO2 to 27.47% and 13.74%. Percent degradation increased to 68.68% and 28.57% by adding C-Ncodoped TiO2 catalyst was adding 120 menutes of photolysis. From the research it can be concluded by photolysis with UV Light methodis more efficient compared to solar radiation.

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