Broadening the pore size of coal-based activated carbon via a washing-free chem-physical activation method for high-capacity dye adsorption.

Aiming to overcome the limitations of the narrow pore size distributions of traditional activated carbon materials and to achieve wide adaptabilities towards large molecules adsorption, we herein demonstrate a new type of activated carbon with a broadened pore size distribution for high-rate and high-capacity aqueous dye molecule (Rhodamine B) adsorption. The preparation of CP-AC is achieved by a facile and one-step mineral-assisted chem-physical activation strategy from Chinese large-reserve Zhundong coal with ZnCl2 and CO2 as the activation agents. The method yields the activated carbon (CP-AC) that has a pore-size broadened hierarchical pore configuration with a high surface area and a large pore volume, favorably enabling a high-capacity Rhodamine B adsorption up to 881 mg g-1, which is among the highest levels of the reported activated carbons. A sonication-assisted adsorption test further demonstrates the high-rate adsorption capability of CP-AC with Rhodamine B adsorption capacity up to 842 mg g-1 within 30 min (96% of the saturation capacity) while microporous activated carbon obtained by solely ZnCl2 activation could just achieve a capacity of 374 mg g-1 within 30 min. In virtue of the low-cost resource materials and washing-free craft, this work offers a simple and green preparation strategy towards high-performance coal based activated carbons, holding great potentials for the industrial production and applications.