In situ preparation of Tricholoma mushroom polysaccharide-g-poly(N,N-dimethyl acrylamide-co-acrylic acid)–CuO composite nanoparticles for highly sensitive and selective sensing of Th4+ in aqueous medium
Herein, we report for the first time the highly sensitive and selective sensing of Th4+ in aqueous solution, using mushroom polysaccharide-based graft copolymer–CuO composite nanoparticles (TMP–CuO NPs), by optical, colorimetric and electrochemical methods. The graft copolymer was prepared in water by a solution phase radical polymerization technique using Tricholoma mushroom polysaccharide (TMP) with a mixture of N,N-dimethyl acrylamide (DMA) and acrylic acid (AA) in the presence of potassium peroxydisulphate (K2S2O8) as the radical initiator. The graft copolymer was characterized by 1H NMR and FTIR spectroscopy, and FESEM analysis. The TMP–CuO NPs were characterized by UV-visible and FTIR spectroscopy, XRD, EDAX, HRTEM, FESEM, and DLS analyses. The prepared TMP–CuO NPs have unique properties for the sensing of Th4+ in water medium, which were investigated by optical, colorimetric and electrochemical methods. The UV-absorption spectra showed a significant redshift of the localized surface plasmon (LSPR) band (λmax) with a gradual decrease in the absorption intensity upon each addition of Th4+ into the TMP–CuO NPs medium. Also, the reddish brown colour of the TMP–CuO NPs solution changed to colourless after the addition of a certain concentration of Th4+ ions. Electrochemical studies for the sensing of Th4+ by cyclic voltammetry showed a clear reduction peak at 1.009 V. The selective detection of Th4+ in water medium was also investigated in the presence of some environmentally relevant metal ions by using optical and colorimetric analysis. The morphological changes of TMP–CuO NPs in the presence of trace amounts of Th4+via the formation of the CuO–Th amalgam was confirmed by XPS, XRD, FTIR, FESEM, and EDAX analysis.