Adsorption of Iron (Fe) Heavy Metal in Acid Mine Drainage from Coal Mining

Abstract

Adsorption is one of effective method to overcome acid mine drainage issue because of its economy and abundant availability of adsorbents. The research aimed to analyze the adsorption effectiveness and capacity of composite as the iron adsorbent in acid mine drainage. Composite consists of claystone from coal overburden, zeolite, and activated carbon from coconut shell. This study used experimental approaches in laboratory. Types of mineral contained in adsorbent materials (claystone, zeolite, and activated carbon) were: kaolinite, mordenite, and cristobalite. Composites were constructed with the following ratios: 50:25:25, 25:25:50, and 25:50:25 (Claystone[C] : Zeolite[Z] : Activated carbon[A]). The composite with a ratio of 25:25:50 had the greatest surface area of 62.44 m2/g, according to the results of the surface area analyzer test. Adsorption was performed in a batch system with a hot plate stirrer and composite mass of 2.5, 5, and 7.5 grams, for contact time variations of 30, 60, 90, 120, and 150 minutes. The adsorption test revealed that the composite was successful in increasing the pH of acid mine drainage to neutral (7.0) and lowering the Fe concentration to meet the quality standard. The best effectiveness of iron lowering was 99,35% with composite mass of 5 grams. However, the 2.5 grams composite mass is more efficient in terms of efficiency because it can lower the Fe concentration to 0.1484 mg/l with only 30 minutes contact time, ensuring that the Fe concentration fulfills the quality standard. The composite with a mass of 2.5 grams has the best adsorption capacity (1,286 mg/g).