SYNTHESIS OF MAGNESIUM HYDROXIDE FOR FLAME RETARDANT MATERIAL BY LEACHING OF DOLOMITE IN SULFURIC ACID AND CHEMICAL PRESIPITATION USING SODIUM HYDROXIDE

• Main Author: RIO ZULFAHMI (NIM : 12513029), MUHAMMAD
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/29323
• Institution: Institut Teknologi Bandung

The use of plastic, polymer and textile-based materials in this modern era is increasing such as in building materials and construction, automotive, electrical and electronic. The use of this material has several advantages such as its lightweight and corrosion resistant, but it has the disadvantage of having flammable vulnerability especially at high temperatures. Therefore, the use of such kinds of materials needs a flame retardant material. According to Global Industry Perspective, Comprehensive Analysis, and Forecast 2014 2020 data, flame retardant demand reaches 2.5 million tons in 2014 and is expected to increase until 2020. Compared with other flame retardant material such as Al(OH)3, Mg(OH)2 has a higher decomposition temperature, namely 330°C. This magnesium hydroxide can be synthesized from high magnesium-containing minerals, such as dolomite. The potential for high dolomite reserves in Indonesia is still not utilized optimally. This study investigated the dolomite mineral leaching behavior with sulfuric acid and precipitation of Mg(OH) by chemical neutralization of pregnant leach solution using NaOH to obtain Mg(OH)2 precipitate used for flame retardant material. <br /> <br /> <br /> The synthesis of Mg(OH)2 was began by extracting magnesium through a leaching process in a solution of sulfuric acid which can dissolve magnesium simultaneously. Measurements of dissolved magnesium and calcium concentrations were done by using Atomic Absorption Spectroscopy (AAS). A series of leaching experiments was conducted to study the effect of sulfuric acid concentration, temperature, solid/liquid ratio (S/L), dolomite particle size, and leach time on extraction percentage of magnesium. Dissolved magnesium was then precipitated by neutralization of pregnant leach solution by using NaOH to obtain Mg(OH)2 precipitate with certain purity. The precipitation experiment was performed on 200 ml of pregnant leach solution produced by leaching of dolomite ini 2M sulfuric acid under variations of pH, temperature, and ultrasonic treatment to study the effect of these variables on the precipitation percentage of Mg(OH)2. Characterization of the Mg(OH)2 precipitate was carried out to determine the chemical composition, particle size, and morphology of the precipitate as well as <br /> <br /> its suitability for flame retardant material. <br /> <br /> <br /> The experimental results showed that the best magnesium extraction percentage of 98.8% was obtained by leaching with 4M H2SO4, temperature 25°C, S/L ratio of 100 (g/L) and stirring speed of 300 rpm within 10 minutes. The highest Mg(OH)2 precipitation of 97.63% was obtained by the addition of 50 mL 16M NaOH, temperature 25°C and stirring speed 1000 rpm. The contents of magnesium and calcium in precipitates were 96.97% and 0.08%, respectively. The main impurity in Mg(OH)2 precipitate is sodium sulfate salt with a content of 2.87%. The result of precipitate analysis using X-Ray Diffraction (XRD) identified Mg(OH)2 as the main compound in precipitate. The precipitate has not met the purity requirement to be used as flame retardant material. <br />