A High-Performance Nanofiltration Membrane by Embedding Amino Acid and Ionic Liquids in the Cellulose Acetate for Heavy Metals Separation

Abstract

Water reclamation is necessary to meet the potable water demand. Heavy metals like iron, zinc, lead, and copper, particularly in water, pose significant toxicity risks to humans and other biological life. Over the last few years, the contamination level of these heavy metals in water and soils has increased alarmingly. On the other hand, membrane systems have emerged as a prominent approach to water reclamation. Subsequently, amino acid (AA) and ionic liquids (ILs) incorporated cellulose acetate (CA) membranes, which were fabricated using the phase inversion technique and effectively utilized for these metal separations. The membranes characterization by FTIR, SEM, TGA, and DSC exhibited the presence of various functional groups, change in surface morphologies, and improvement in thermal stabilities due to AA-IL, respectively. The PWF was increased to 98 L/m2 hr at 4 bar pressure due to enhancement of hydrophilicity. Rejection percentage of heavy metal ions for AA‒IL (0.5%) incorporated CA membranes was 94%. The rejection rates for 4 different heavy metal ions present in the industrial effluent were studied, and it was found that the rejection rate was 89,91,84, and 90% for copper, zinc, iron, and lead, respectively. AA‒IL (0.5) incorporated the CA membrane's rejection capacity, which was observed to be the highest for all metals. The AA‒IL incorporated CA membranes are efficient and effective for nanofiltration to treat heavy metal ions solution.