Tailored Thin-Film Poly(Piperazine-Amide) Composite Membrane for Fluoride Separation from Water

Water pollution due to fluoride (F⁻) is a significant threat worldwide. Fluoride contamination affects many life forms (both plants and humans) when they enter the food chain. Poly(piperazine-amide) membranes have a promising role in nanofiltration activities. However, piperazine, as a cyclic secondary aliphatic amine, reacts with 1,3,5-trimesoyl chloride (TMC) in the interfacial polymerization. The physical characterization of the membranes was performed through different analytical tools like Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle analyzer. The selectivity in separating bivalent and monovalent salts is well observed in this composite membrane. The composite membranes show their potentiality in defluoridation. The rejection profile is ~ 84% for the feed water (pH 6.5) having 10 mg/L fluoride at pressure 1.034 MPa. The influencing parameters (viz. pH, concentration, applied pressure, nature of water matrix) on separation performances are studied.