Recycling acid-leaching clay wastewater to synthesize bimetallic metal-organic frameworks for efficient removal of Pb2+ and UO22+

With the increasingly serious problems of resource depletion and environmental pollution, it has become a key path to synthesize low-cost and high-value-added functional materials through recycling waste resources. Inspired by the sustainable development concept of "turning waste into treasure", two bimetallic metal-organic frameworks (BMOFs) of MIL-53(Al, Fe) and NH 2 -MIL-53(Al, Fe) were successfully prepared by a one-pot hydrothermal method using acid-leaching wastewater generated from the whitening process of mixed-dimensional attapulgite clay as the metal ion source and reaction medium. The obtained BMOFs presented excellent crystallinity, acid-base stability, and adsorption performance for Pb 2+ (263.2 and 304.0 mg/g) and UO 2 2+ (497.5 and 704.2 mg/g). The involved adsorption mechanisms were mainly attributed to coordination and electrostatic interactions. This research realized the sustainable utilization of acid-leaching wastewater during fine-processing of non-metallic minerals, and significantly reduced the synthesis cost of MOFs, embodying the sustainable development goal of 3Rs (reduce, reuse and recycle) concept.