Modification of palygorskite surface by organofunctionalization for application in immobilization of H3PW12O40

Modified palygorskite with 3-aminopropyltriethoxysilane (KH550) and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (KH792) were used as adsorbent supports for adsorption of 12-phosphotungstic acid (H₃PW₁₂O₄₀, HPW). The effect of some factors, such as adsorbent dosage, contact time, initial HPW concentration and temperature, was investigated. The experimental data were well fitted with the pseudo-second-order kinetic model and the Langmuir adsorption isotherm model at all studied temperatures. The physicochemical properties of the solids were characterized by using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis-simultaneous differential thermal analysis (TGA-SDTA), and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy analysis techniques. The characteristic results indicated that silylated-Pa was a suitable support for adsorption of HPW; and HPW was finely and effectively distributed on silylated-Pa and retained partly strong Bronsted acidity.