Iron(III) (hydr)oxide loaded anion exchange hybrid polymers obtained via tetrachloroferrate ionic form—Synthesis optimization and characterization

Abstract

This study focused on the synthesis optimization and characterization of hybrid ion exchangers (HIX) containing iron(III) (hydr)oxide, in which commercially available strongly alkaline anion exchange resins of both macroreticular (Amberlite IRA 900) and gel-type structure (Amberlite IRA 402) were used as the supporting materials. The inorganic deposit was introduced into the anion exchangers in two steps conducted batchwise at ambient temperature. First, the functional groups were quantitatively transformed from the Cl− into the FeCl4− form using 5moldm−3 HCl solution with added FeCl3. Then, the vacuum-filtered intermediate products were contacted with NaOH/NaCl solution to precipitate hydrate ferric oxides (HFO) into the grains. The matrix structure of the anion exchanger significantly affected the kinetics of the ion exchange reaction. The final products contained about 12.6% Fe. The distribution of the inorganic deposit in the two products was different (SEM, EDS analysis). Freeze drying was tried as a post-processing method to prevent the collapse of the structure of the macroreticular HIX. It was demonstrated that the way of drying (thermal drying or freeze drying) of the macroreticular anion exchanger and the HIX of the same polymeric structure had an effect on the results of the surface area and porosity measurement of both materials (determined by N2 adsorption-desorption method and mercury intrusion porosimetry). The obtained materials will be used as sorbents for treating contaminated waters. Moreover, the results of this work will be helpful in the synthesis of HIX containing nanostructured binary metal oxides to obtain sorbents with enhanced sorption properties.