Nanoplastics Removal from Water using Metal–Organic Framework: Investigation of Adsorption Mechanisms, Kinetics, and Effective Environmental Parameters

Nanoplastics are becoming a concern for the environment and are gaining significant attention due to their challenging removal process and ability to transport coexisting pollutants. Because of their mobility, small size (<1 μm), and accumulation tendency, nanoplastics are toxic for terrestrial and aquatic living organisms and humans, causing inflammation and oxidative stress. In this study, we investigated the removal of polystyrene nanoplastics (PSNPs) from water using a chromium-based metal–organic framework (Cr-MOF/MIL-101). Cr-MOF was synthesized via a hydrothermal method using chromium nitrate and terephthalic acid and characterized via different analytical approaches. A 96% removal efficiency was achieved with initial concentrations of 5 and 70 ppm and adsorption kinetics followed the pseudo-first-order model. The adsorption isotherm at room temperature was best fitted with the Freundlich adsorption model, and the maximum adsorption capacity of 800 mg/g was achieved. The electrostatic interaction between PSNPs and Cr-MOF was the most dominating mechanism responsible for adsorption. The Cr-MOF showed acceptable regeneration capacity for cyclic removal of PSNPs.