Fabrication of Microporous Water Filter Using Titanium Dioxide Particles, Silica Particles, and Polyethylene Glycol

We report the fabrication of microporous filter for use in filtering both inorganic and organic substances from liquid materials. Titania (TiO 2) anatase was used as the main material for this filter. Polyethylene glycol (PEG) with average molecular weight of 20,000 was also used as additive to control the formation of pores, especially pore sizes. The mixture of titania and PEG was pressed into cylindrical tablet shape at room temperature and then simply heated inside a furnace up to temperature where the PEG decomposed into gas to leave only connected titania particles. The use of titania as base material for the filter allows the organic substances that trapped inside the filter pores to be easily removed by heating up the used filter at above decomposition temperature of the trapped organics. We also made other filter by adding small amount of silica (SiO2) particles to reduce the size of the pores as well as to improve the mechanical strength. We observed that filters containing silica particles, with smaller in size compared to titania, resulted in better mechanical strength, smaller in pore sizes and better filtering results in term of turbidity and dissolved oxygen (DO) content. This method is potential for development of larger scale and cheaper water filters for use in various applications

Effect of Polystyrene Latex Addition on Size and Pore Volume of Porous Calcium Oxide Particles Prepared by Spray-Pyrolysis Method and Its Ability for SO2 Retention

In this study, the effects of polystyrene (PS) latex addition on the particle morphology and the pore content of calcium oxide (CaO) were investigated. The CaO particles were prepared using an ultrasonic nebulizer-assisted spray-pyrolysis method with variation of the PS/Ca(NO3)2·4H2O mass ratio in the precursor. Good crystallinity of CaO was obtained at 825°C of synthesis temperature under 2 l/min of nitrogen gas flow, which was confirmed by Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). According to scanning electron microscope (SEM) characterization, the CaO particles synthesized with 0 and 25 wt% PS addition had an almost spherical shape with an average size of 1.58 and 1.48 µm, respectively. In addition, macropores were formed in the CaO particles prepared with 25 wt% PS addition that had an average pore diameter of 583.26 nm. Meanwhile, the CaO particles prepared with 75 wt% PS addition had a random shape and an average size of 1.41 µm. The mesopore content was investigated by Barret-Joyner-Halenda (BJH) analysis, which showed improvement of the pore size from 3.45 nm to 5.42 nm for 0 and 25 wt% PS addition, respectively, which is proportional to the pore volume, pore surface area, and the capacity of SO2 retention

Sintesis Nanoserat Poli(vinil Alkohol) Dalam Bentuk Lembaran Dengan Pemintal Elektrik Multi Nozel Dan Kolektor Drum

Electrospinning system with single needle and planar collector has the disadvantage of a low productivity. To overcome this problem drum collector and multi-nozzle system were employed. The multi-nozzle system was used to improve the production rate, while the drum collector was used for maintaining the uniformity of the size. The purposes of this study were to examine the influence of electric field in the electrospinning process and to control the morphology of the obtained poly(vinyl alcohol)/PVA nanofibers by changing the solution flow rate. The obtained results were: (1) PVA nanofibers membrane have been successfully produced stacked on the drum collector, (2) distortion of the electric field at the tip of the needle was occurred, which results in inhomogeneous thickness of the stacked nanofibers, and (3) the morphology of the obtained nanofibers at the flow rates of 0.4 and 0.6 ml/hour have many beads while at 0.8 ml/hour the number of beads decreased

The Effect of Nonwoven Microfiber Substrate Polypropylene Thickness to Air Filtration Performance of Polyacrilonitrille Nanofiber

Since a nanofiber medium on itself is soft and fragile and cannot be used alone as air filters. Coating nanofiber on a rigid substrate to form a composite that can be handled readily is necessary. Beside can improve the filtration efficiency, adding the substrate will also save the use of nanofibers mat itself. The aim of this study is to evaluate the effect of substrate thickness on the performance of nanofibers mat in aerosol filtration in order to find the optimum thickness of substrate that can increase the quality of nanofiber filter. The substrate used was a low cost microfiber non-woven fabric made from polypropylene (PP). The nanofibers mat was composed of electrospun polyacrylonitrile (PAN) with concentration of 9 wt.% which dissolved at N,N dimethylformamide (DMF). Five variations of PP different in thickness was used as substrate. From the SEM image, it was found that there is increasing fiber diameter of PAN after electrospun into PP substrate. From the porosity estimation of each nanofiber, it was found that the porosity decreased with increasing the substrate thickness. For test the performance of nanofiber filter, the particles of polystyrene latex (PSL) which generated by atomizer was used as the aerosol particle. In addition, to evaluate the performance filter in PM2.5 filtration, the experiment was carried out with generate the smoke from burning incense. Air filtration performance of all variations is obtained by comparison the results of measurement including: pressure drop, efficiency and quality factor. From the results, there is limitation on the substrates thickness based on the value of the quality factor obtained. Overall, PP nonwoven as the substrates gives the great contribution on the efficiency of PAN nanofiber. Keywords: substrate, polypropylene, thickness, nanofiber, air filtration

Optimasi Parameter Pemintalan Elektrik Menggunakan Teknik Algoritma Genetika: Tegangan Listrik dan Jarak Nozzle-Kolektor

Studi optimasi dua parameter pemintalan elektrik, yaitu tegangan listrik dan jarak nozzle-kolektor, telah dilakukan dengan teknik algoritma genetika dalam domain [1,60] kV dan [5,25] cm serta jumlah populasi 100 buah, peluang pindah silang (pc) 0,7 dan peluang mutasi (pm) 0,5. Jejari serat seukuran 155 nm diperoleh dari hasil subsitusi nilai optimum tegangan listrik 1,83 kV dan jarak nozzle-kolektor 23,50 cm pada simulasi pemintalan elektrik yang dimodelkan oleh Reneker, dkk. Hasil optimasi ini diharapkan dapat membantu eksperimen di laboratorium

Penumbuhan Lapisan Tipis Material Sensor Giant Magnetoresistance Berstruktur Sandwich dengan Metode Sputtering

Material giant magnetoresistance (GMR) menjanjikan untuk diterapkan dalam bidang teknologi penting, salah satunya sebagai sensor medan magnet lemah. Sensor GMR memiliki kelebihan, yakni ukuran yang kecil, daya dan harga yang relatif rendah dibandingkan sensor-sensor magnetik lainnya serta sifat-sifat magnetik dan elektriknya dapat divariasikan dalam rentangan yang sangat lebar. Tujuan dari penelitian ini adalah untuk melihat efek giant magnetoresistance dari lapisan tipis sandwich NiCoFe/Cu/NiCoFe yang ditumbuhkan di atas substrat Si (100) dengan metoda dc-Opposed Target Magnetron Sputtering (dc-OTMS). Parameter penumbuhan yakni; suhu 1000C, laju aliran gas argon sebesar 100 sccm, tekanan 0,52 mTorr, dan tegangan dc 600 volt. Dalam paper ini, akan dibahas pengaruh ketebalan lapisan feromagnetik (NiCoFe) dan ketebalan lapisan non magnetik (Cu) terhadap sifat giant magnetoresistance dari sandwich NiCoFe/Cu/NiCoFe. Hasil pengukuran rasio magnetoresistance memperlihatkan bahwa ketebalan lapisan NiCoFe mempengaruhi nilai rasio GMR, serta makin tebal lapisan NiCoFe, makin kecil medan saturasi, yang ditandai dengan kurva rasio GMR yang makin runcing. Dalam struktur sandwich, kecilnya nilai rasio GMR saat ketebalan NiCoFe rendah, kemungkinan disebabkan oleh hamburan pada permukaan luar seperti antarmuka substrat-film atau buffer layer. Hamburan ini mempengaruhi nilai GMR saat ketebalan lapisan feromagnet lebih kecil dibanding panjang lintasan bebas rata-rata yang berhubungan dengan elektron ber-spin ke atas dan spin ke bawah. Demikian pula halnya dengan ketebalan lapisan non magnetik Cu juga mempengaruhi rasio GMR, dimana rasio GMR semakin berkurang dengan bertambahnya ketebalan lapisan Cu. Hal ini kemungkinan terjadi akibat peningkatan hamburan elektron konduksi yang melintasi lapisan pemisah non magnetik, yang mengurangi aliran elektron diantara lapisan-lapisan feromagnetik dan meningkatkan arus shunting, sehingga mengurangi nilai rasio GMR

Luminescence Nanopartikelemisi Cahayatampak Sebagai Tintapengaman

LUMINESCENCE NANOPARTIKELEMISI CAHAYATAMPAK SEBAGAI TINTAPENGAMAN. Nanopartikel ZnO disintesis dengan metode sol-gel dengan menggunakan LiOH sebagai agen hidrolisisnya. Hasil sintesis dikarakterisasi dengan difraksi sinar X (XRD) untuk mengkaji kristalinitas dan UV Vis untuk menentukan lebar celah pita energi. Koloid nanopartikel yang dihasilkan memiliki ukuran sekitar 3 nm yang menghasilkan celah pita energi sekitar 3,53 eV. Kristalinitas nanopartikel dipengaruhi oleh konsentrasi LiOH yang digunakan. ZnO berukuran 3 nm dapat menghasilkan luminescence cahaya biru jika disinari ultraviolet. Pembesaran ukuran partikel menyebabkan pergeseran luminescence ke arah merah. Luminescence cahaya tampak pada koloid dimanfaatkan sebagai tinta pengaman. Pada penelitian ini juga dilaporkan uji tinta menggunakan nanopartikel dengan memvariasikan sejumlah parameter seperti jenis kertas, warna kertas dan komposisi tinta

Klinostat Tiga Dimensi sebagai Simulator Mikrogravitasi untuk Berbagai Eksperimen tanpa Bobot

Sebuah klinostat tiga dimensi (3-D) telah dirancang untuk menyediakan sebuah lingkungan dengan gravitasi sangat kecil (mikrogravitasi) bagi berbagai percobaan tanpa bobot. Besarnya gravitasi berhubungan dengan kecepatan sudut dari perputaran klinostat tersebut. Dua buah rangka berbentuk segi empat diputar pada sumbu rotasi y-z dengan menggunakan dua motor DC dan kecepatannya diatur oleh mikrokontroler AT89S52 dengan menggunakan prinsip pulse width modulation (PWM). Alat ini telah diuji selama 8 jam tanpa henti untuk berbagai kecepatan sudut di bawah 17 rpm (rotation per minute). Telah didapatkan bahwa alat ini berfungsi dengan baik

Alat Ukur Curah Hujan Tipping-Bucket Sederhana dan Murah Berbasis Mikrokontroler

Telah dirancang dan dibangun alat pengukur curah hujan tipe tipping-bucket (TB) berbasis mikrokontroler AT89S8252. Alat ini menghasilkan tetesan 0,21 mm untuk daerah tabung kecil terpancang sebagai penerima tetesan (tipping-bucket/TB) dari kerucut penampung air hujan seluas 2837,54 mm2. Untuk mencacah TB-nya, sensor tipe reed switch digunakan dan dibaca oleh data logger berbasis mikrokontroler AT89S8252. Data logger tersebut dilengkapi sebuah real time clock dan komunikasi serial agar dapat mengirimkan data ke komputer. Curah hujan maksimum yang bisa diukur adalah 914,4 mm/jam