Generation of Eroded Nanoplastics from Real World Wastes and Their Capacity for Heavy Metal Adsorption

Our study investigates the generation of nanoplastics (NPs) from real-world plastic waste and their capacity to adsorb heavy metal (HM) ions. NPs, synthesized from polyethylene terephthalate (PET), polystyrene (PS), and polypropylene (PP) using a milling method, were characterized using dynamic light scattering (DLS) and scanning electron microscopy (SEM), confirming particle sizes below 200 nm. Manganese (Mn²⁺), cobalt (Co²⁺), zinc (Zn²⁺), cadmium (Cd²⁺), and lead (Pb²⁺) at concentrations ranging from 50.0 parts per billion (ppb) to 2.0 ppm (ppm) were exposed to the NPs. Residual HM concentrations were measured using inductively coupled plasma mass spectrometry (ICP-MS). PP exhibited the highest adsorption capacities, with Langmuir maximum adsorption capacity (q_m) values of 90.91 μg per gram (μg/g) for Mn²⁺, 114.94 μg/g for Co²⁺, 101.01 μg/g for Zn²⁺, and 107.53 μg/g for Cd²⁺. Pb²⁺ showed rapid adsorption, with over 99% adsorption within 5 min, with a capacity of 396.1 μg/g on PP, 390.6 μg/g on PET, and 393.2 μg/g on PS. Adsorption kinetics followed a pseudo-second-order model, suggesting chemisorption, while Langmuir and Freundlich isotherms supported monolayer adsorption.