Adsorption capacity of coal-based activated carbon in advanced treatment of drinking water

Activated carbon is the core material in the process of advanced treatment of drinking water. Evaluating the adsorption capacity of activated carbon accurately is the basis of its selection in practical applications. In this study, four typical commercial coal-based activated carbon samples were collected, and a wood-based activated carbon was selected as a comparison. The conventional adsorption performance indexes such as iodine value, methylene blue value, caramel decolorization rate and static adsorption capacity of tannic acid (TA) and humic acid (HA) were determined. Rapid Small-Scale Column Tests (RSSCT) was used to determine the breakthrough curves of activated carbon adsorption on water samples containing TA and HA to evaluate the dynamic adsorption performance of it. The pore structure and surface micro-topography of activated carbons were characterized by N₂ adsorption isotherms and scanning electron microscopy energy dispersive X ray analysis (SEM-EDS). Frenkel-Halsey-Hill model was used to calculate the fractal of activate carbons. The results show that the iodine value, methylene blue value, caramel decolorization rate, tannin acid isothermal adsorption capacity and humic acid isothermal adsorption capacity are obviously correlated with the pore development degree of activated carbon. The anthracite-based activated carbon had the best dynamic adsorption performance in the RSSCT, indicating that the dynamic adsorption performance of activated carbon was less correlated with the pore structure of activated carbon and more correlated with the surface roughness. Therefore, the activated carbon samples can be initially selected by the surface roughness. And then the RSSCT result of the HA is used to select an activated carbon with optimized adsorption capacity under the practical conditions of advanced drinking water treatment.