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Hydroxyapatite (HA) has been deposited on silica (SiO2) particles to produce HA-SiO2 composite that will be used as the powder component of calcium phosphate cement. HA was expected to be on the composite surface to maintain its bioactivity. SiO2 was made by the sol-gel method, in which silicate solution was extracted from rice husk ash with NaOH solution. Deposition of HA on SiO2 was carried out by wet chemical deposition method at various Ca/Si molar ratio (in a range of 5–25) followed by calcination at 600 °C for 2 h. Results showed that HA was successfully deposited on SiO2 particles. The cell parameters of the HA crystals were slightly distorted by the presence of SiO2 and HA in the composite had a bigger cell volume than pure HA. The crystallite size of HA in the composites increased with the increase of the Ca/Si ratio but the values were smaller than pure HA. SiO2 acted as a morphology directing agent. At low Ca/Si ratio, the HA-SiO2 particles were in a form of short rod-like particles with sizes of < 50 nm, while at high Ca/Si ratio, a mixture of short and long rod-like particles with the size of < 100 nm was obtained. The zeta potential of composites was almost similar to pure HA. These properties indicated that HA-SiO2 composites support the bioactivity of injectable calcium phosphate cement.

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ABSTRAKTelah dilakukan penelitian tentang preparasi katalis zeolit alam asam sebagai katalis dalam proses pirolisis katalitik polietilena. Katalis zeolit alam asam dibuat melalui aktivasi dan kalsinasi zeolit alam Wonosari yang meliputi perendaman dalam larutan HF 1%, perlakuan HCl, perendaman dalam larutan NH4Cl dan kalsinasi dengan dan tanpa gas N2. Proses kalsinasi dilakukan pada temperatur 500 C. Karakter katalis yang meliputi rasio Si/Al, keasaman, luas permukaan, volume pori dan rerata jejari pori, masing-masing ditentukan dengan Spektroskopi Serapan Atom (AAS), metode adsorpsi NH3 dan alat penganalisis luas permukaan. Hasilnya adalah preparasi telah meningkatkan keasaman zeolit sebesar 132,5%, rasio Si/Al sebesar 146,9%, luas permukaan sebesar 748%, volume pori sebesar 98% dan menurunkan rerata jejari pori sebesar 76%. Proses pirolisis dan proses pirolisis katalitik dilakukan dengan reactor bach dan produk cair dianalisis dengan GC dan GC-MS serta FTIR. Produk proses pirolisis polietilena adalah olefin C9-C15 sedangkan produk pirolisis dengan katalis zeolit alam asam adalah olefin C5-C12. ABSTRACTStudy of the preparation of acidic natural zeolite catalyst as a catalyst in catalytic process of polyetilene has been conducted. The acidic natural zeolite catalyst was prepared by: activation and calcination of natural zeolite from Wonosari. The activation of the zeolite was carried out by HF (1%) and HCl treatment, followed by immersing in the NH4Cl solution and calcination with and without N2 gas. The calcination process were conducted at 500 C. The catalysts characters included Si/Al ratio, acidity, surface area, pore volume and average pore were analyzed by Atomic Adsorption Spectroscopy (AAS), NH3 adsorption method and Surface Area Analyzer, respectively. The results showed that the preparation process has been increased the zeolite acidity of 132.5%, Si/Al ratio of 146.9%, surface area of 748%, pore volume of 98% and has been decreased the average pore of 76%. Pyrolisis and catalityc pyrolisis were done by using batch reactor and the liquid product was analyzed by GC, GC-MS and FTIR. Product of pyrolisis process are olefines C9-C15 and product of catalytic process are olefines C5-C12.