Investigations on characteristics of polyurethane foam impregnated with nanochitosan and nanosilver/silver oxide and its effectiveness in phosphate removal.

A novel potential adsorbent, produced with chitosan nanoparticles and silver/silver oxide nanoparticles impregnated on polyurethane foam (PFCA), is developed for phosphate removal in aqueous solutions. The ultraviolet-visible (UV-Vis) spectroscopy uncovered the emergence of nanoparticles. The field emission scanning electron microscopy (FESEM) provided the mean size of chitosan nanoparticles between 56 and 112 nm and that of silver-silver oxide nanoparticles between 44 and 75 nm. Energy dispersive X-ray (EDX) spectroscopy determined the presence of specific elements (C, O, P and Ag) in the adsorbent before and after treatment. Fourier transform infrared (FTIR) spectroscopy revealed the interplay between the N-H bond of amino group in PFCA and phosphate ions during adsorption. X-ray diffraction (XRD) analysis of PFCA showed nearly the same pattern before and after treatment, indicating the stability of PFCA. The silver ion concentration in the effluent from inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis was found to be very less and below the drinking water limits. The surface area estimated by Brunauer-Emmett-Teller (BET) studies was found to be 2.17 m2/g. The experimental studies showed that PFCA can remove 61.24% of phosphate from an influent phosphate phosphorus concentration of 50 mg P/L, at its propitious condition. Even after 7 cycles of reuse, PFCA proved to be effective in removing 20.58% of phosphate. Hence, PFCA can be considered to be a potential sorbent for removing phosphate from surface water. Graphical abstract.