A chitosan/MOF hybrid monolith with improved stability and enhanced adsorption performances via a pre-frozen...

In wastewater remediation by adsorption, three-dimensional porous MOF (metal-organic frame)/polymer hybrid monoliths have been demonstrated to be promising absorbents with effective adsorption and recovery capacities. However, MOF/polymer monoliths often suffer from obvious decrease of porous structures due to large shrinkage during dry at room temperature, weakening the accessibility of active sites for adsorption. Here, a so-called pre-frozen crosslinking process is employed for fabrication of a chitosan/UiO-66 monolith, of which shrinkage is restrained markedly during drying in the air, and the shape of the monolith can be kept intact in 6.3 M acetic acid (CH₃COOH), deionized water and 1 M sodium hydroxide (NaOH) for 60 days. Furthermore, the monolith achieves an adsorption capacity of 55.50 mg g^-1 for methylchlorophenoxypropionic acid (MCPP) from its aqueous solution, increasing by 55.6% compared with UiO-66 particles, and the maximum adsorption capacity is 256.41 mg g^-1.