Novel one step preparation of a 3D alginate based MOF hydrogel for water treatment

Growing efforts have been focused on processing MOF particles into hydrogels. We propose a novel one-step method for the preparation of a novel 3D alginate based MOF hydrogel and use it for tetracycline removal. Rather than the formation of ZIF-67-alginate hydrogel (AM-M) using Co-alginate as the precursor, the Co2+ chelates with alginate and 2-methylimidazolate simultaneously and forms into a different MOF hydrogel (MA-M). The microstructure of the material turns from a smooth surface similar to the alginate hydrogel into a uniform particle-like one, indicating the AM-M has a polymer skeleton while the MA-M has a whole MOF structure. In tetracycline adsorption, the MA-M reaches equilibrium faster than AM-M. The maximum adsorption capacity of tetracycline adsorption on MA-M is 364.89 mg g(-1), which is higher than that of AM-M (302.32 mg g(-1)). The MA-M has good regeneration properties after 10 cycles. The results pave a new way for the preparation of novel polymer based MOF hydrogels with great potential for water treatment.