Azo‐Functionalized Zr‐MOF and Its Mixed Matrix Membrane for High‐Capacity Adsorption of Organic Dyes in Water

The efficient removal of toxic organic dyes from wastewater is of great significance in water pollution remediation. In this work, an azo-functionalized Zr-MOF (UiO-67-BCDC) was successfully designed and synthesized. The successful modification of azo groups enables the formation of broader π-conjugated electron systems, thereby strengthening the π-π interactions between the MOF and dye molecules consisting of π-rich conjugated aromatic systems. UiO-67-BCDC achieves over 90% removal efficiency for small molecule dyes within 10 min. Under aqueous conditions at 313 K and pH = 7, optimal adsorption performance was achieved at an adsorbent dosage of 0.50 g/L, resulting in an adsorption capacity of 710.27 mg/g for Basic Blue 3 (BB-3). The maximum adsorption capacity of UiO-67-BCDC toward BB-3 is 621.68 mg/g at 303 K, approximately 1.2 times that of UiO-67. To prevent agglomeration and loss of powdery MOFs, the UiO-67-BCDC@SA membrane was made with sodium alginate (SA), achieving a BB-3 adsorption capacity of 507.04 mg/g. This study demonstrates an effective strategy for dye removal by azo functionalization and membranization, producing a high-capacity adsorbent with exceptional performance.