Kinetic Study of Humic Acid Extraction from Oxidized Low Rank Coal: Shrinking Core Model
Daniel Timotius*, Alit Istiani, Aldian Fahrialam, Hatta Muzaffar Arifin, Annisa Rizky Ramadhanty, Aditya Kurniawan, Himawan Tri Bayu Murti Petrus, Ferian Anggara,Yuni Kusumastuti, Mochammad Prahastomi

Chemical Engineering Department, Faculty of Industrial Engineering, Universitas Pembangunan Nasional Veteran Yogyakarta, Jl. SWK 104, Yogyakarta 55283, Indonesia
Chemical Engineering Department, Faculty of Engineering, Universitas Gadjah Mada, Jl Grafika 2 Yogyakarta 55281, Indonesia
Department of Geological Engineering, Gadjah Mada University, Jl Grafika 2 Yogyakarta 55281, Indonesia
Department of Geological Engineering, Universitas Pembangunan Nasional Veteran Yogyakarta, Jl. SWK 104, Yogyakarta 55283, Indonesia

Abstract

Humic acid is a complex mixture of partially decomposed organic materials found in soil, peat, and coal, known for its high molecular weight and heterogeneous composition. It plays a crucial role in soil fertility and plant growth by improving soil structure, enhancing nutrient availability, and aiding in water retention. In the current study, humic acid is extracted from oxidized low-rank coal. The oxidation and extraction are conducted using H2O2 and KOH solution, respectively. The kinetics is evaluated using shrinking core model. The shrinking core model in solid-liquid extraction describes a process where a solid particle reacts with a liquid, causing the reaction to progress inward from the outer surface, forming a shrinking unreacted core of solid. As the reaction proceeds, the reacted layer of the solid dissolves or diffuses into the liquid, while the unreacted core becomes progressively smaller until it is completely consumed. The result shows that the kinetics follow ash diffusion model. The obtained Activation energy and Arrhenius constant are 25.87 kJ/mol/K and 6.91 min-1.

Keywords: Extraction, humic acid, kinetics, shrinking core model

Topic: Engineering