Enhanced adsorption of volatile organic compounds on anthracite-based activated carbon: Effects of ash reduction and coal tar coating

초록

As demand for Korean anthracite declines, converting anthracite into high-value-added materials has become increasingly important. Anthracite-based activated carbon can be a possible candidate. This study aimed to reduce the high ash content of Korean anthracite and facilitate pore development via coal tar coating. First, under optimized froth flotation conditions, the ash content was effectively reduced from approximately 33 wt% to below 9 wt%. Three coal tar samples labeled CT1, CT2 and CT3 were employed for coating. Prior to coating application for preparing activated carbons, three coal tar samples were analyzed to characterize their molecular properties using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS). Results showed that the average DBE values decreased in the order of CT3 > CT2 > CT1, confirming that CT3 possessed the most complex molecular structure and the highest degree of unsaturation. Following coal tar coating, carbonization, and steam activation, the activated carbon reached a specific surface area of 774.83 m(2)/g (CT3). In adsorption tests, the activated carbon demonstrated superior performance for nonpolar VOCs, especially toluene, achieving an adsorption capacity of 201.25 mg/g, higher than that for acetone (56.26 mg/g). While previous studies employing coal tar for activated carbon production have mainly focused on monolithic activated carbon using coal tar as a binder, few have explored powdered activated carbon coated with coal tar. This study presents a differentiated approach through flotation and assessing the performance of coal-tar-coated activated carbon through VOC adsorption experiments. We also discuss pore development and specific surface area variations as the functions of coal tar DBE (double bond equivalent) and viscosity.

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