From plastic bottle waste to functional adsorbent: a nanostructured bimetallic Al/Cd-BDC MOF for enhanced methylene blue removal

The dual environmental crises of industrial water pollution and plastic waste accumulation necessitate the development of sustainable, high-performance materials derived from waste streams. In this work, a novel bimetallic metal-organic framework (MOF), designated as Al/Cd-BDC, was successfully synthesized through an innovative “waste-to-value” strategy, using terephthalic acid (TPA) derived from the chemical upcycling of post-consumer PET plastic waste. Morphological investigation unveiled spherical microstructures composed of needle-shaped nanocrystals, creating an urchin-like hierarchical architecture. This structure provides substantial porosity and a high specific surface area of 650.8 m2g–1, which enhances mass transport and creates highly accessible active sites. The synthesized Al/Cd-BDC demonstrated exceptional and rapid performance in the removal of methylene blue (MB) from aqueous solutions. Under optimized conditions (pH: 7; adsorbent dose: 0.6 g L–1; t: 30min), it achieved a removal efficiency of 98.97%, with a theoretical maximum adsorption capacity (Qm, cal.) of 352.2 mg g–1. This superior performance is attributed to the synergistic effects of the bimetallic centers and the hierarchical nanostructure. Furthermore, the MOF exhibited excellent stability and reusability, maintaining over 97% removal efficiency after five consecutive cycles. These findings underscore the potential of Al/Cd-BDC as a robust and sustainable adsorbent for industrial wastewater treatment.