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A ceramic membrane has been produced from a natural zeolite. A series of samples has been sintered at range temperature from room temperaure to 900°C. The influence of the sintering temperature on the specific surface area, pore diameter, and surface roughness has been investigated. It has been found that a decrease for value of the specific surface area and average pore diameter from 300°C to 900°C was attributed to a change of the crystalline structure of tridimite from partially to fully crystallized samples. The fabricated membrane has been used successfully to evaluate the separation performance during the treatment of coconut sap. The membranes have a steady state flux from 0.12 to 0.22 mL/min.cm2 at an applied pressure of 1 bar.

In this paper, we present the synthesis procedure and the results of an investigation of a novel silica xerogel (SX) glass ceramic developed from an amorphous SX derived from sago waste ash that incorporates TiO2 as an additive. The studied compositions have been prepared by adding of either 20% or 80 wt% of TiO2 into SX, respectively. The samples have been dry pressed and sintered in the temperature range between 900°C and 1500°C. Their properties have been characterized on the basis of the experimental data obtained using X-ray diffraction (XRD), Fourier transform infrared (FTIR), and ultraviolet-visible (UV-Vis) spectroscopy. It has been found that an increase of the content of SX in the composition leads to an increase of the shift of the bandgap energy of TiO2. The analysis based on the interpretation of both XRD patterns and FTIR spectrum allows one to explain the shift in the bandgap energy by an enlargement of the crystallite size of TiO2 and by forming of more Si–O–Ti bonds in the samples with a smaller loading of TiO2.

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Penelitian pembangkit listrik terus berkembang seiring meningkatnya kebutuhan energi listrik. Pemanfaatan sumber energi terbarukan seperti tenaga angin, tenaga air, tenaga gelombang laut serta tenaga arus laut memerlukan generator listrik putaran rendah tanpa eksitasi tambahan untuk dapat menghasilkan energi listrik. Generator sinkron magnet permanen (PMSG) merupakan generator yang medan eksitasinya dihasilkan oleh medan magnet permanen. Generator ini memiliki keunggulan dapat beroperasi pada putaran rendah serta tinggi memiliki tingkatan efisiensi yang lebih baik dibanding dengan generator induksi. Penggunaan PMSG bisa didapat dengan memanfaatkan motor BLDC mesin cuci bekas tipe satu tabung. Spesifikasi motor BLDC tipe outer rotor memiliki kumparan stator berbentuk roda gigi berinti besi berjumlah 36 coil dengan wiring 1 x 12 coil 3 fasa, terdiri 90 lilitan tiap coil dengan diameter penampang kawat 0,8 mm, berbahan alumunium dengan jenis belitan concentrated. Rotor memiliki 12 batang magnet permanen berbahan Barium ferrite (BaO 6Fe2O3). Secara konstruksi motor BLDC dan PMSG memiliki sebuah kemiripan dimana pada bagian rotornya terdapat magnet permanen, sehingga motor BLDC dapat dipertimbangkan untuk diaplikasikan sebagai generator. Hasil pengujian generator dari BLDC dapat membangkitkan daya listrik sebesar 855 VA pada kecepatan putar 1300 RPM, tegangan kerja generator sebesar 200 VAC fasa-netral, 350 VAC fasa-fasa dengan efisiensi sebesar 68,2 % .