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Polyaniline-Sn(IV)iodophosphate (PANI-SnIP) nanocomposite cation exchanger was synthesized via the sol-gel approach and its AC and DC electrical conductivity, dielectric properties and optical properties were studied. The characterization of the nanocomposite using FT-IR, UV-Vis spectroscopy, SEM and TEM showed the formation of a nanocomposite with improved physicochemical properties. The AC electrical conductivity was found to increase with the increase in applied frequency and concentration of the Sn(IV)iodophosphate (SnIP) filler content. The optical band gap of the nanocomposite decreased from 3.99 eV for pure polyaniline (PANI) to 3.60 eV for the nanocomposite with 30% SnIP content. The ethanol vapor sensing characteristics were evaluated by the fabrication of a PANI-SnIP nanocomposite as a sensor for ethanol vapor detection. The sensing performance of the nanocomposite was markedly improved with the increase of SnIP concentration. The nanocomposite sensor exhibited a linear response to the variable concentration of ethanol (50, 100, 300, and 500 ppm), a quick response time, and a reproducible and reversible response, which are a clear manifestation of its sensing ability and environmental utility.

A new and novel nanocomposite cation exchanger polyaniline-Sn(IV)iodophosphate (PANI-SnIP) has been synthesized using a sol−gel method by the incorporation of precipitates of Sn(IV)iodophosphate into the matrices of polyaniline. The ion exchange capacity of the composite synthesized at pH 1.0 was found to be 1.2 mequiv g −1 for Na + ion. The characterization of the material using simultaneous thermogravimetry−differential thermal analysis (TGA-DTA), Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) reveals the composite nature of the material with uniform surface morphology and formation of particles of size ranging from 20−25 nm. Study of the various physicochemical properties indicates granulometric nature, fairly good thermal and chemical stability, uniform elution, and bifunctional behavior of the exchanger. The selectivity of the composite for Hg 2+ , Pb 2+ , and Ce 4+ in different solvent media along with their reproducible quantitative separation from binary mixture as well as real samples makes it a potential environmental wastewater detoxicant. The limit of detection (LOD) and limit of quantification (LOQ) for Hg 2+ were found to be 0.53 and 1.9 μg L −1 , respectively. The photocatalytic activity of the nanocomposite has been demonstrated by the photo degradation of Methylene Blue (MB) under solar irradiation.

The poly­aniline-Sn­(IV)­iodo­phosphate nanocomposite (PANI-SnIP) has been synthesized, and its various kinetic and thermo­dynamic parameters for alkaline earth and heavy metal ion exchange were evaluated. Above 0.03 M solution of metal ions, the particle diffusion controlled phenomenon is found to be predominant (R 2 > 0.98). The kinetic and thermo­dynamic parameters like diffusion coefficient (D o), energy of activation (E a), enthalpy of activation (ΔH*), entropy of activation (ΔS*), and free energy of activation (ΔG*) were evaluated under particle diffusion controlled phenomenon. The fractional attainment of equilibrium was faster at an elevated temperature, and the rate of exchange is predominated by Hg­(II) ions in the case of multi­component systems. The positive values of the standard enthalpy change (ΔH*) indicate the endothermic nature of the ion exchange process. The ion exchange follows an associative mechanism as indicated by ΔS* < −130 J mol–1 K–1. The comparatively fast kinetics of ion exchange by the nanocomposite depicts its applicability for environmental remediation.

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