PELAPISAN MAGNETIT DENGAN SILIKA TERMODIFIKASI MERKAPTO

NUR MUTIA ROSIATI, Prof. Dr. Nuryono, MS

2013 | Skripsi | KIMIA

Dalam penelitian ini telah dilakukan pelapisan magnetit dengan silika termodifikasi merkapto menggunakan larutan natrium silikat dari abu sekam padi sebagai sumber silika dan 3-merkaptopropiltrimetoksisilan (MPTMS) sebagai sumber merkapto. Magnetit diperoleh melalui kopresipitasi campuran garam Fe 2+ /Fe 3+ menggunakan larutan NH4OH sebagai pengendap. Efektivitas teknik pengadukan mekanik dan ultrasonik dibandingkan. Pelapisan dilakukan melalui proses sol-gel dengan mencampur magnetit, larutan natrium silikat dan MPTMS pada berbagai variasi perbandingan mol silika dan MPTMS (100:0, 75:25, 50:50, 25:75 dan 0:100). Campuran tersebut diatur hingga tercapai pH 7 dengan penambahan larutan HCl atau larutan NH4OH. Magnetit terlapis dikarakterisasi dengan spektrofotometer Fourier Transform Infrared (FTIR), difraktometer sinar-X (XRD), Transmission Electron Micrograph (TEM), Gas Sorption Analyzer (GSA) metode BET, Vibrating Sample Magnetometer (VSM) dan uji kestabilan terhadap asam. Hasil penelitian menunjukkan bahwa kristalinitas magnetit hasil sintesis pengadukan ultrasonik lebih tinggi daripada pengadukan mekanik. Pelapisan pada magnetit dapat meningkatkan ukuran partikel dan kestabilan terhadap asam namun mengakibatkan berkurangnya sifat kemagnetan.

In this research magnetite has been coated with mercapto modificated silica using sodium silicate solution extracted from rice husk ash as silica source and 3- mercaptopropiltrimethoxysilane (MPTMS) as mercapto source. Magnetite obtained through Fe 2+ /Fe 3+ salts mixture co-precipitation using NH4OH as precipitating solution. Effectiveness of mechanical and ultrasonic stirring techniques were compared. Coating was done through the sol-gel process by mixing magnetite, sodium silicate and MPTMS at various mole ratio of silica and MTPMS (100:0, 75:25, 50:50, 25:75 and 0:100). The mixture was adjusted to pH 7 using HCl or NH4OH solution. Coated magnetite was characterized by Fourier Transform Infrared Spectrophotometer (FTIR), X-ray Diffraction (XRD), Transmission Electron Micrograph (TEM), Gas Sorption Analyzer (GSA) by BET method, Vibrating Sample Magnetometer (VSM) and stability test to acidic condition. The results showed that the crystallinity of synthesized magnetite by ultrasonic stirring was higher than that of mechanical stirring. Magnetite coating could increase the particle size and stability to acid but reduce the magnetic properties.

Kata Kunci : magnetit, pelapisan, silika, MPTMS