Optimization of Excess Magnesium Addition and Heating Rate on Silicon Dioxide and Silicon Extraction Based Rice Husk

Abstract

Indonesia is an agricultural country that produces rice sufficiently large. According to Central Agency on Statistics (BPS 2013) data, in 2012 rice production in Indonesia amounted to 69.05 million tonnes of milled rice, an increase of 3.29 million tonnes (5.00%) compared to 2011. Each tonne of rice containing 72% rice, 5% -8% bran and 20% - 22% husk (Muthadhi 2007). Seeing these data would appear a lot of agricultural waste,one of them is rice husk waste . Waste destruction process naturally progresses slowly (Nugraha and Setiawati 2006). Rice husk generated from most of the countries that produce rice just burned and disposed of as waste (Azadi et al. 2010). Rice husk, a waste product of the rice industry is rich in silica. (Kalapathy et al. 2000). Utilization of rice husk stove developed by IPB from 2007, produces another form of waste (Irzaman et al 2007). Rice husk charcoal from rice husk stove IPB, can be used to produce silica. The Silica resulting from the incineration process can be used as a source of silicon (Rohaeti et al.2010). This research is aimed to optimize of the speed of temperature increase (0.5 0C/menit and 1.5 0C/menit) to obtain high-purity silicon dioxide and optimization of addition of excess magnesium by chemical reduction method by comparing the amount of magnesium and silica (49: 60) to obtain high-purity silicon . Silicon dioxide and silicon obtained will be analyzed using Energy Dispersive X-ray (EDX) and FTIR Spectroscopy. Preparation of silicon through three (3) phases, husk charcoal, silica / silicon dioxide and silicon. Making husk charcoal through several stages. At first the rice husk is dried with the aid of sunlight with the aim of accelerating the combustion process. Then the rice husks were weighed at 4000 grams, entered into a husk stove and continued with the combustion process (Ahmad 2012), rice husk and then weighed. In this process produced husk charcoal at 1370 grams (34.25%). Rice husk charcoal as much as 60 grams put in of porcelain bowls and burned in a furnace at a temperature of 400 °C initially for 2 hours, subsequent heating to a temperature of 950 °C for 1 hour with a temperature increase rate setting of 0.5 ° C / min and 1.5 °C / min. After the ash obtained by burning weighed, then washed rice husk ash by using hydrochloric acid (HCl) 3% technical (12 mL 3% HCl technical for 1 gram of rice husk ash), and then heated over a hotplate with a temperature setting of 200 °C and stirred with a magnetic stirrer at a speed of 240 rpm for 2 hours. Subsequently washed with hot distilled water (temperature around 100 °C) repeatedly until the free acid (tested with litmus paper), and then filtered through ash-free paper. Screening results (residues separated from the filter paper) included in the of porcelain bowls and then heated in a furnace at temperatures of 1000 °C for 1 hour with the temperature rise and 5 oC/menit 1 oC/menit remaining until the white silica. The samples were cooled in the furnace and weighed, then the results are tested EDX and FTIR Spectroscopy. The next process to obtain silicon, silica mixed with reducing agents, namely magnesium powder with a ratio 49:60. Once mixed, the sample is heated in a furnace for 1 hour at a temperature of 650 oC. Once heated, the mixture obtained is weighed, then washed with 75 mL of 3% HCl technical. Then heated on a hotplate with a temperature setting of 200 °C and stirred with a magnetic stirrer at a speed of 240 rpm for 2 hours. Then the samples were washed again with 3% HCl technical 300 mL, 1 hour, 240 rpm (Hikmawati 2010). Samples were filtered and washed with hot distilled water (temperature around 100 °C) repeatedly so that the free acid, and then dried in a furnace at 110 °C for 12 hours (Hikmawati 2010, Ahmad 2012 and Otto 2013). The results of EDX analysis, produces silicon dioxide with a purity of 99.15% (for a heating rate of 0.5 ° C / min) and 78.96% (for a heating rate of 1.5 ° C / min). Chemical reduction of silica with magnesium excess magnesium and silica in the ratio 49: 60 has resulted in silicon with a purity of 44.03%. Characterization of silicon dioxide using FTIR spectroscopy showed siloxane functional groups. Peaks of FTIR spectra showed specific peaks associated with silicon dioxide at wave number 1110 cm-1 to 467 cm-1.