Identifikasi silika amorf dari sekam padi

Abstract

Rice husk is an agriculture by product derived from rice milling, which is produced in a large quantity. Up to present time, rice husk is utilized for limited uses, such as for a fuel in brick production, processed to a charcoal planting medium, and burnt to ash for cleansing powder. With a certain technique, however, rice husk can be processed to produce amourphous silica. This research was aimed to find out characteristics of rice husk ash derived from incineration at different temperatures and oxidation by H2O2. This research consisted of two main steps, i.e. combustion of rice husk and identification of silica of the combustion product. Combustion of rice husk was done with both incineration and oxidation by H2O2. Incineration was run at 400°C, 500°C, 600°C, 700°C and 900°C for 5 hours. The oxidation of rice husk was run with added H2O2 30% until the entire organic compound disappeared (do not effervesce again). Identification of silica was carried out using polarization microscope, refractometer, DTA, FT-IR and XRD. In addition, identification of silica was also done for rice husk ash from common incineration, quartzsand from Pangkalanbun (Kalimantan) and for standard quartz. Chemical characteristics of rice husk, including SiO2, Al2O3, K2O, MnO, MgO, CaO, and total C was done as well. Identification with DTA showed that the silica derived from incineration of rice husk at 400°C, 500°C, 600°C, and from oxidation of rice husk with H2O2 have DTA curve that reflecting amourphous silica. In the contrary, the DTA curve of silica in the ash from incineration at 700 °C and 900°C are much more reflect DTA curve of crystallin silica. The results of identification using FT-IR and XRD showed that only silica in the ash from incineration at 900 °C showing characteristics of crystalline silica. The results revealed that incineration of rice husk at 400°C seem to be the optimum temperature to produce amourphous silica from rice husk for use as absorbent.