Preparation of pitch-based activated carbon fibers with high specific surface area and excellent adsorption properties

Activated carbon fibers (ACFs), as the third generation of activated carbon materials, are promising adsorbents due to their rich surface functional groups, high porosity and remarkable adsorption capacity. Exploring low-cost raw materials especially available industrial by-products and agricultural waste has always been the focus of ACFs research and application. Herein, pitch-based ACFs are prepared from low-cost coal tar pitch via spray melt spinning, stabilization, carbonization and KOH activation process. The activated temperature significantly affects the structure, surface function groups, specific surface area and pore structure. The as-prepared ACFs possess abundant oxygen functional groups, larger surface area and narrow pore size distribution in the range of 0.7–4.0 nm, correspondingly showing highlighted absorption capacities for iodine, methylene blue and cadmium ions (Cd2+). Cd2+ with the diameter of far less than 1 nm can enter the narrow pores and combine with oxygen-containing functional groups violently, which well follows the Langmuir isotherm model (R2 = 0.9921) and exhibits secondary kinetic characteristics. These results distinctly demonstrate that pitch-based ACFs are promising candidates for polluted water treatment, especially to remove small organic molecules, dyes and heavy metal ions.