Adi Darmawan

Iron Oxide Silica Derived from Sol-Gel Synthesis

In this work we investigate the effect of iron oxide embedded in silica matrices as a function of Fe/Si molar ratio and sol pH. To achieve homogeneous dispersion of iron oxide particles, iron nitrate nonahydrate was dissolved in hydrogen peroxide and was mixed with tetraethyl orthosilicate and ethanol in a sol-gel synthesis method. Increasing the calcination temperature led to a reduction in surface area, although the average pore radius remained almost constant at about 10 Å, independent of the Fe/Si molar ratio or sol pH. Hence, the densification of the matrix was accompanied by similar reduction in pore volume. However, calcination at 700 °C resulted in samples with similar surface area though the iron oxide content increased from 5% to 50% Fe/Si molar ratio. As metal oxide particles have lower surface area than polymeric silica structures, these results strongly suggest that the iron oxides opposed the silica structure collapse. The effect of sol pH was found to be less significant than the Fe/Si molar ratio in the formation of molecular sieve structures derived from iron oxide silica.

Interlayer free - nickel doped silica membranes for desalination

This work shows for the first time the potential of nickel oxide silica membranes for desalination applications. Nickel oxide silica xerogels were synthesised via a sol-gel method including TEOS, nickel nitrate with and without addition of hydrogen peroxide. The effects of nickel addition (5% - 50 mol %) on the structure-property relationship of the silica materials were systematically studied. The membrane performance were tested as a function of feed salt concentration (0.3-3.5 wt% NaCl) and temperature (27-60 °C). The membranes which were prepared using equal sol-gel conditions to the xerogel samples showed the raised feed temperatures resulted in increased water fluxes, whilst increasing the salt concentration resulted in decreased water fluxes. The membranes with addition of hydrogen peroxide exhibited better performances than their HO absence counterpart. The salt rejection was in excess of 90% and the maximum flux observed was 7.3 kg m h at 60°C for a 0.3 wt% NaCl feed concentration.

DEALUMINASI ZEOLIT ALAM CIPATUJAH MELALUI PENAMBAHAN ASAM DAN OKSIDATOR

Sampai saat ini zeolit tetap menjadi primadona sebagai bahan penapis molekuler atau adsorben. Umumnya zeolit alam perlu diberi perlakuan tertentu bila akan digunakan sebagai adsorben, karena rasio Si/Al rendah dan mengandung unsur-unsur pengotor yang harus diminimalkan pengaruhnya. Oleh karena itu perlu dilakukan dealuminasi. Salah satu metode dealuminasi adalah pengasaman dan untuk memaksimalkannya ditambah dengan oksidator KMnO 4 . Prosedur kerja penelitian ini meliputi dealuminasi zeolit alam Cipatujah menggunakan H 2 SO 4 dan HCl serta ditambah dengan oksidator KMnO 4 . Selanjutnya dilakukan karakterisasi terhadap zeolit sebelum dan sesudah perlakuan dealuminasi menggunakan spektrofotometer inframerah (IR), difraktometer sinar-x (XRD) dan spektroskopi serapan atom (AAS). Dari hasil interpretasi terhadap data spektra inframerah maupun difraktogram XRD menunjukkan bahwa zeolit alam yang digunakan termasuk jenis mordenit. Dari data penentuan kadar unsur menggunakan AAS diperoleh hasil bahwa pada dealuminasi menggunakan H 2 SO 4 dan KMnO 4 mampu menaikkan rasio Si/Al dari 2,852 menjadi 11-12. sedangkan dengan menggunakan HCl rasio Si/Al naik menjadi 9,945.