(464e) Adsorptive Removal of Polystyrene Nanoplastics from Water Using MIL-101(Cr) Metal Organic Framework

Nanoplastics are becoming a serious environmental problem, and their potential to transport co-existing contaminants, making them a real threat to human health. Because of their mobility, size (<1μm), accumulation tendency, and ability to adsorb other toxic pollutants, nanoplastics are toxic for terrestrial and aquatic living organisms along with human beings causing inflammation and oxidative stress. Nanoplastics at low concentrations (less than 20 ppm) may also show these effects, but there has been little research on their removal. In this study, we synthesized MIL-101 via hydrothermal method using chromium nitrate and terephthalic acid for the adsorption of polystyrene nanoplastics (PSNPs) with initial concentrations of 5 ppm and 70 ppm. The characterization of MIL-101 and PSNPs was done by Fourier transform infrared spectroscopy (FTIR), Brunauer Emmett Teller (BET), and scanning electron microscopy (SEM). The isotherm adsorption tests were completed at a pH range of 2-10 and the results showed that pH of the solution govern the adsorption efficiency, with a maximum efficiency (in the range of 94-99%) at pH 5. The adsorption kinetics and isotherm studies for adsorption of PSNPs on MIL-101 followed the pseudo-first-order model and Langmuir model, indicating that physical and monolayer adsorption mechanism was dominant. The regenerated MIL-101 (with NaOH) removed almost 80% PSNPs from water even after the 3^rd cycle. The electrostatic interaction between PSNPs and MIL-101 was the most dominating adsorption mechanism. The results of this study showed that MIL-101 is an efficient adsorbent for the adsorption of PSNPs at different concentration (low:5 ppm, high: 70 ppm) from water at low (100 ppm) adsorbent dosage.