Extraction of iron (III) ions by core-shell microgel for in situ formation of iron nanoparticles to reduce harmful pollutants from water

Abstract

Since the most transition metal ions and organic dyes are hazardous, it is crucial to remove them from water. For this purpose, various systems are reported for removal of only transition metal ions or organic dyes. I have introduced a new system which is suitable for removal of both metal ions and organic dyes. The free radical precipitation polymerization method was used to create the spherical system of silica surrounded by poly(N-vinylcaprolactam-acrylic acid) S@P(NVCP-AA) core shell microgels and then characterized by using FTIR, DLS, XRD, and STEM. The S@P(NVCP-AA) microgel system was applied as adsorbent to extract iron (III) ions from water under various concentrations of S@P(NVCP-AA), iron (III) ions content, pH, and agitation time. The adsorption process of iron (III) ions on S@P(NVCP-AA) microgels was investigated by different adsorption isotherms. The kinetics of adsorption of iron (III) ions on S@P(NVCP-AA) microgel system was also examined by intra-particle diffusion model (InPDM), pseudo-1st order (P1O), pseudo-2nd order (P2O) and Elovich model (EM). Iron nanoparticles were formed by in-situ reduction of iron (III) ions that had been adsorbed in the P(NVCP-AA) shell region of the S@P(NVCP-AA) microgel. The organic pollutants and toxic transition metal ions like 4-nitrophenol (4NiP), methyl red (MeR), methylene blue (MeB) and chromium (VI) ions (CMI) were reduced from an aqueous medium by using the iron nanoparticles loaded in S@P(NVCP-AA) microgels. The pseudo 1st order rate constant values for the catalytic reduction of 4NiP, MeR, MeB and CMI were found to be 0.778 min−1, 0.928 min−1, 0.943 min−1 and 0.142 min−1 respectively. The resulting S@Fe-P(NVCP-AA) system can act as an efficient catalyst for a wide range of additional organic transformations.