Constructing porous aromatic frameworks with controllable hierarchical pores to investigate their effect on the...

Adsorption activity serves as a key indicator to assess the applicability of materials in micro-pollutant adsorption. Nevertheless, the current understanding of the relationship between hierarchical pores and adsorption activity remains highly ambiguous and insufficient to guide the design and synthesis of porous materials for efficient adsorption of micropollutants. Herein, we report a novel type of sulfonated porous aromatic frameworks (PAFs) with tunable hierarchical pores (especially macropores and micropores) to systematically investigate the relationship between porous structure and micro-pollutant adsorption activity. The hierarchical pores were finely designed and regulated by controlling the amount of water in the aqueous phase and adjusting the porogen-to-monomer volume ratio in the oil phase during high internal phase emulsions (HIPE) polymerization, respectively. The water amount in the aqueous phase helped to optimize porosity and macropore size, and the volume ratio of porogen-to-monomer could modulate the micropore volume and specific surface area of PAF materials. The adsorption data of methylene blue (MB) and tetracycline (TC) suggested that the adsorption rate was independent of specific surface area and micropore volume but increased with increasing macropore size of PAF materials. In contrast, the adsorption capacity was governed by micropore structure rather than macropore size. Moreover, the removal efficiencies of MB and TC exceeded 99% within 10 s, with k ₂ values of 2.09 g mg^-1 min^-1 and 1.53 g mg^-1 min^-1, respectively, which are almost 10-100 times higher than those of other porous adsorbents. This work introduces a straightforward and viable approach to prepare sulfonated POPs materials with breakneck adsorption rate. More importantly, it reveals the inherent relationship between hierarchical pores and the adsorption activity of micro-pollutants.