Photodegradation is a save and low cost methods to clean water bodies from some organic pollutants. The method has been developed in term of increasing the efficiency of the degradation capacity of photocatalyst. The photocatalyst working under visible light is the most desirable. The preparation of silica supported nickel-copper oxide [(Ni-Cu)Ox@SiO2] catalyst and the use of the catalyst in the photodegradation of methylene blue in the water are reported. The catalyst was prepared by impregnating the silica support into the mixture of nickel and copper salts, followed by calcination at 800○C for 4 hours. A series method of XRD, SEM-EDX, and UV-Vis Diffuse Reflectance has been used to characterize the catalyst. The catalyst adsorption test was undertaken in the dark, and the catalyst activity test for photodegradation of methylene blue was conducted under the sunlight. The XRD diffractogram of as prepared (Ni-Cu)Ox@SiO2 shows a weak-wide peak at 2θ = 21.8° indicating SiO2 tridymite, and has a crystallite size of 10.38 nm. The combination method of SEM and EDX confirms the formation of (Ni-Cu)Ox@SiO2. The (Ni-Cu)Ox@SiO2 catalyst has a relatively low bandgap energy and shows a good activity for photodegradation of blue methylene under sunlight. The adsorption of the methylene blue on the (Ni-Cu)Ox@SiO2 follows the Langmuir isotherm pattern.

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In this article, the synthesis of silver nanoparticles through a reduction reaction process using Salacca zalacca extract is reported. The AgNPs were characterized using X-ray diffraction, transmission electron microscopy, Fourier transform infrared and UV-visible spectrophotometry methods. The AgNPs antibacterial activity was determined against of Gram-positive bacteria (Staphylococcus epidermidis) and Gram-negative bacteria (Escherichia coli). The main functional groups contained in Salacca zalacca extract are carbonyl, hydroxyl and nitrile groups, which are believed to reduce the silver ions to metal. The surface plasmon resonance values of brownish red AgNPs are in the range of 410 nm to 460 nm. The structure of AgNPs is face centered cubic (FCC). The diameter of silver nanoparticles crystallite is 14.2 ± 2.6 nm. The AgNPs growth inhibition zones of Escherichia coli and Staphylococcus epidermidis are 9.6 mm and 9.2 mm, respectively.

A series of Ca1-xCoxTiO3 has been prepared through the ceramic method as polycrystalline powders with x = 0, 0.01, 0.025, 0.05 and 0.1. The structure of resulting materials was refined from a powder X-ray diffraction using the Rietvield method showing the perovskite-type structure isostructural with CaTiO3. The morphology and particle size of Ca1-xCoxTiO3 were studied using SEM/EDX that showed a particle size of around 3.5 nm with non-homogenous particle sphere shapes. The electronic structure of CaxCo1-xTiO3 was studied by UV/ visible spectroscopy method, which showed that the prepared Ca1-xCoxTiO3 having good response in the visible region with the band gap energy (Eg) of around 2.2 eV, which is highly potent as visible light photocatalysts. The adsorption capacity and adsorption equilibrium constant of the oxides to the methylene blue were also studied. The adsorption process in Ca1-xCoxTiO3 materials follows the Langmuir adsorption type as a consequence of homogenous pore structures. The catalytic activity of Ca1-xCoxTiO3 on the methylene blue degradation are also discussed.

Penelitian ini bertujuan untukmensintesis nanosilika dari daun bambu dan mengaplikasikannya sebagai pengemban fotokatalis CuO (0,25% CuOx@SiO2) pada reaksi degradasi congo red. Senyawa SiO2 dihasilkan dari abu daun bambu wulung (Gigantochloa atroviolacea) melalui proses kalsinasi pada suhu 800°C selama 6 jam. Senyawa 0,25% CuOx@SiO2 yang dihasilkan selanjutnya dikarakterisasi dengan UV-Vis diffuse reflectance spectra dan uji aktivitas adsorbsinya pada keadaan gelap, dilanjutkan uji aktivitas fotodegradasi larutan pewarna congo red pada sinar UV dan sinar tampak. Analisis Diffraksi sinar X menunjukkan senyawa SiO2 yang bersifat kristalin yang ditandai dengan puncak tajam pada 2Ø=21,87 (sesuai dengan JCPDS PDF No. 39-1425). Analisis UV-Vis diffuse reflectance menunjukkan bahwa energi celah pita senyawa 0,25% CuOx@SiO2 adalah 4,269 eV. Aktivitas adsorbsi sampel mengikuti pola isoterm adsorbsi Freundlich dengan nilai kapasitas adsorbsi 2011,731425 mol/gram. Aktivitas fotokatalitiknya terhadap degradasi congo red pada sinar UV dan sinar tampak mengikuti laju reaksi orde dua dengan nilai laju reaksi 0, 010464.C2 pada sinar UV dan 0.010481.C2 pada sinar tampak.