Indonesian Physical Review Volume 07 Issue 02, May 2024 P-ISSN: 2615-1278, E-ISSN: 2614-7904 281 Synthesis and Characterization of Activated Carbon Prepared from Rice Husk by Physics-Chemical Activation Anak Agung Gde Suyoga Wiguna 1* , Ida Bagus Putu Mardana 1* , Putu Artawan 1* 1 Physics and Science Teaching Department, Faculty of Mathematics and Natural Science, Ganesha University of Education, Indonesia Corresponding Authors E-mail: anak.agung.gde@undiksha.ac.id, putu.mardana@undiksha.ac.id, artawan.putu@undiksha.ac.id, Article Info Abstract Article info: Received: 16-02-2024 Revised: 16-05-2024 Accepted: 22-05-2024 Keywords: Synthesis; characterization; activated carbon; Rice husk How To Cite: A. A. G. S. Wiguna, I. B. P. Mardana, P. Artawan, “Synthesis and characterization of rice husk activated carbon by HCl activation,” Indonesian Physical Review, vol. 7, no. 2, p 281-290, 2024. DOI: https://doi.org/10.29303/ip r.v7i2.311 Activated carbon is an amorphous carbon material predominantly composed of free carbon atoms with high adsorption capacity. The amorphous structure in activated carbon affects its adsorption capacity; the higher the percentage of amorphous carbon, the greater the adsorption capacity of the activated carbon. Activated carbon can be obtained from rice husk waste, which contains 30-40% C in cellulose, hemicellulose, and lignin. Therefore, this study was conducted to observe activated carbon's phases, morphology, elemental composition, and particle size. Activated carbon was synthesized using a physics-chemical activation method, which began with washing the rice husk samples, followed by air drying, carbonizing into charcoal, and grinding it finely. The rice husk charcoal powder was then physically activated at a temperature of 500℃. The physically activated product was then chemically activated using 6M HCl with a charcoal-to-activator ratio of 1:10 (m/V), stirred at 250 rpm for 1 hour, and then allowed to settle for 24 hours. It was then washed and dried to produce activated carbon powder. XRD test results showed diffraction peaks at 2θ = 22.23° without sharp or pointed peaks, indicating that the activated carbon has an amorphous structure. SEM test results showed the morphology of rice husk- activated carbon with spherical particle shapes and a particle size distribution of 20-70 nm. EDX test results showed that the rice husk activated carbon is predominantly composed of C, O, and Si with respective percentages of 54.31%, 40.04%, and 2.49%. Copyright © 2024 Authors. All rights reserved. Introduction One sector that plays a crucial role in Indonesia's economic growth is industry. The industrial sector produces various products for human needs and exports. Adequate resources must support the sustainability of the sector in Indonesia. One abundant resource in Indonesia is its natural resources. Indonesia is an agricultural country where 40% of its population is involved in farming. One of the leading agricultural products in Indonesia is rice. This is because rice is a crucial commodity as a staple food for Indonesians. Based on data from the Central Statistics