Conversion of waste PET bottles into supported ionic liquid membranes for heavy metal separation from wastewater

Plastic waste poses a significant and persistent environmental challenge, creating a division between producers and consumers. Addressing this issue requires exploring various techniques, including thermal processing, landfilling, and recycling. Plastic waste recycling, a complex approach, depends on particle size, location, and source material. This study focuses on recycling plastic waste bottles made of polyethylene terephthalate (PET). The phase inversion method converts discarded PET bottles into polymeric membranes. Subsequently, the performance of the membrane is enhanced by infusing ionic liquid into its pores. The modified membrane, referred to as a supported ionic liquid membrane (SILM), was subsequently employed for the removal of heavy metal contaminants, specifically Pb (II), Cd (II), and As (V), within a specially designed H-cell system. The H-cell setup includes feed and stripping phase compartments, separated by the modified membrane. Metal ion separation efficiency is evaluated under varying operating conditions, including carrier concentration, feed phase concentration, stripping phase concentration, stirring rate, and temperature. Removal efficiency is optimized using the Box-Behnken design in response surface methodology. After optimizing the parameters of the modified plastic waste membrane, exceptional removal efficiencies are attained, with removal rates exceeding 95% for Pb (II), 88% for Cd (II), and 78% for As (V). This study highlights the potential of recycled PET plastic waste as a valuable resource for developing highly efficient and sustainable membranes for heavy metal removal.