In situ synthetic hierarchical porous MIL-53(Cr) as an efficient adsorbent for mesopores-controlled adsorption of tetracycline

Significant concerns have been raised over the adsorption of tetracyclines from aquatic environments. In this paper, hierarchically porous MIL-53(Cr) was synthesized by in situ synthesis for the first time and the influence of mesopores on tetracycline adsorption was investigated. Benefiting from the high mesoporous volume, more TC molecular could enter the channel to interact with adsorption sites, and the adsorption capacity of 20-AA-MIL-53(Cr) for TC increased twelvefold, up to 148.5 mg/g. In addition, various kinetic models have also been used to investigate the adsorption process of tetracycline. Particularly, considering the molecular size of TC about 12.9 Å×7.4 Å, Elovich and intraparticle diffusion kinetic models were used to testify that the external mass transfer of TC on 20-AA-MIL-53(Cr) was much higher than that on MIL-53(Cr) when the pore size was expanded to 2–3 nm. What's more, the results of water stability test revealed the excellent water stability of 20-AA-MIL-53(Cr) for over 5 days. This study described a simple method for the preparation of hierarchical porous MIL-53(Cr) and explored the effect of mesopores on the adsorption of TC, so as to propose that hierarchical porous MIL-53(Cr) can be used as a potential adsorbent in water adsorption treatment. • Hierarchical porous x-AA-MIL-53(Cr) was prepared by in situ synthesis for the first time. • 20-AA-MIL-53(Cr) had the highest surface area (2249 m 2 /g) and mesoporous volume (0.62 cm 3 /g). • The adsorption capacity of tetracycline by hierarchical porous MIL-53(Cr) increased twelvefold. • The presence of mesopores allowed more tetracycline molecules to contact the adsorption sites.