CHELATING AGENT FREE SOLID PHASE EXTRACTION (CAF SPE) OF FLUORIDE AND PHOSPHATE BY Fe-Al-Zr TERNARY MIXED OXIDE NANOCOMPOSITE

Abstract

Synthesis of Fe-Al-Zr ternary mixed oxides nanocomposite was performed by using ferric nitrate nona hydrate, aluminum nitrate nona hydrate and zirconium oxide via impregnation method. X-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET) analytical techniques were used to characterize the features of the synthesized mixed nanocomposite. From X-ray analysis it was observed that the mixed oxides nanocomposite was crystalline in nature and the crystallinity increased when the mixed oxy-hydroxide was calcined at 700oC for 3h. Fourier transform-infrared (FTIR) spectroscopy was employed to measure the IR spectra of the synthesized adsorbent before and after phosphate and fluoride adsorption. The pH of point of zero charge of the selected adsorbent was also determined. The method was based on the adsorption of fluoride and phosphate ions in the column packed with Fe-Al-Zr mixed oxide nanocomposite. Elution was performed with 0.5 M HCl and subsequent determination of concentration of the respective ions was made by UV- Vis for phosphate and ion selective electrode for fluoride. The effects of different experimental variables such as pH, eluent type, flow rate and interfering ions on the recovery of the analytes were investigated and optimum conditions were established. The adsorption of fluoride and phosphate on the mixed oxides nanocomposite was investigated for different parameters and the adsorption capacities were evaluated using the Langmuir and Freundlich isotherm models. The mixed oxide nanocomposite prepared by sintering the mixed oxy-hydroxide at 400oC showed a very high adsorption capacity of fluoride and phosphate. Thus, these nanocomposites can be used as good adsorbents and for the preconcentration of fluoride and phosphate ions from ground water, lake water and river water systems.