Synthesis and Characterization of Forward Osmosis Membrane for Removal of Praseodymium Rare Earth Element

ABSTRACT

This study investigates the removal of praseodymium ions (Pr ^{3 +} ), a rare earth element (REE), from synthetic wastewater using forward osmosis (FO) technology. FO is considered a more environmentally friendly alternative to conventional treatment methods such as solvent extraction and chemical precipitation, which typically require high energy consumption and generate secondary waste, particularly when recovering REEs at low concentrations. Thin‐film composite (TFC) FO membranes were fabricated via interfacial polymerisation (IP) using different concentrations of m ‐phenylenediamine (MPD) (0.5%, 1%, and 2%) and varying reaction times (30, 60, and 120 s). Characterization through field‐emission scanning electron microscopy, Fourier‐transform infrared spectroscopy, and contact angle measurements confirmed the successful formation of a dense polyamide (PA) selective layer. Increasing MPD concentration and IP reaction time enhanced membrane selectivity and surface hydrophilicity. FO performance tests showed that all fabricated membranes achieved Pr ^{3 +} removal efficiencies exceeding 95%, with the highest removal efficiency of 98.96% obtained using a membrane prepared with 2% MPD and a 120 s IP reaction time. However, the formation of a thicker PA layer led to a reduction in water flux as MPD concentration and IP time increased. Overall, the results demonstrate the potential of FO membrane technology for the efficient recovery of praseodymium from aqueous solutions and provide valuable insights into membrane fabrication and operational optimisation for REE treatment applications.