Study on functional group, oil adsorption process, and the effect of chemical wash on lignite and sub-bituminous coal

Abstract

Abstract This study was to determine the characteristics of Indonesia’s low-grade coal, which was sub-bituminous taken from Samarinda coal mine and lignite taken from Palembang coal mine. Experiment was conducted using Fourier Transform Infrared (FTIR) spectroscopy to analyze the functional group of the coal. Inherent moisture was 2. 16 g in 5 g lignite coal, and 1. 42 g in 5 g sub-bituminous coal. Soaking coal with liquid smoke reduced the percentage of residual (volatile matter and ash content) combustion and increased fixed carbon. Adsorption of oil by coal was measured by the change of free fatty acid (FFA) in the oil, in which lignite coal was decreased about 0.1 % and sub-bituminous coal was decreased about 0.07 %. In contrast, by heating adsorption 100 °C, FFA change in the oil was increased about 0.28 % for lignite coal and increased about 0.46 % for sub-bituminous coal, by heating adsorption 125 °C, the increase was about 0.44 %for lignite coal and was about 0.59 % for sub-bituminous coal, and by heating adsorption 150 °C, FFA was increased about 0.41 % for lignite coal and about 0.46 % for sub-bituminous coal.