STUDI PEMANFAATAN SILIKA DARI ABU JERAMI PADI SEBAGAI BAHAN TAMBAHAN UNTUK MENINGKATKAN KUALITAS SIFAT FISIS GERABAH

Oleh :
M. SONY MUGHOFIR - M0303035 -

ABSTRACT M. Sony Mughofir. 2008. A STUDY OF SILICA UTILIZATION FROM RICE STRAW ASH AS AN ADDITIVE MATERIAL FOR INCREASING THE EARTHENWARE PHYSICAL PROPERTIES QUALITY. Thesis. Departement of Chemistry. Mathematic and Science Faculty. Sebelas Maret University. A silica from rice straw ash had been used as an additive material for increase the earthenware quality. Rice straw ash was chosen for their advantages such as capable of producing ashes with high percentage of SiO2 , available to be obtained all year and as renewable natural resources. Rice straw was burned at 350o C and then calcined at 500; 600; 700 and 800o C for 4 hours. To reduce impurities, the ashes were washed by HCl 1M. The forms of silica then are determined by the X-Ray Diffraction (XRD) analysis and its concentration by Atomic Absorbtion Spectroscopy (AAS). Earthenware mixture was made from clay and rice straw ash by 0; 3; 5 and 10% over the total amount of the mixture. The calcined temperature was set up to 900o C with heating rate of 135o C/hour and held it in 3 hours then cooled until room temperature. The earthenware characteristic was determined by frying shrinkage test, firing shrinkage tes, density test, porosity test and bending strength test. XRD analysis shows that the amorphous silica was formed at 500-600o C, and the crystalline at 700-800o C. AAS analysis shows that silica concentration in rice straw ash is 76,69 + 2,07%. The best frying shrinkage, density and bending strength points are found from the mixture containing 10% adding of ashes at the temperature of 500o C, there were 6,01 + 0,14%, 2,493 + 0.044 g/cm3 and 941,25 N/cm2 . The best firing shrinkage 0,45 + 0,02%, is found from 10% ashes of mixture upon 800o C, while the best porosity point is found from the mixture without the adding of ashes. In general, the optimum earthenware characteristic is found from the mixture containing 10% adding of ashes at the temperature of 500o C. Keyword: Rice straw ash, silica, earthenware characteristic