Biomimetic sol-gel synthesis was used to prepare new FeO(OH) zeolite (clinoptilolite tuff) adsorbent effective for antimony removal. The product was compared with other on the market accessible natural or commercial adsorption materials like granulated ferric hydroxide GEH, powder of zero valent iron (ZVI)- nanofer and the new synthesized oxi(hydr)oxide FeO(OH) and characterized by XRD, XPS, Raman, FT IR, TG, DTA, DTG, TEM and SEM techniques. Based upon the SEM analysis, the oxidized nanofer sample revealed the existence of hematite and goethite and morphology of FeO(OH) dopant confirmed the presence of ferrihydrite, in less extent also magnetite and hematite. Recorded exothermic maxima on DTA curves for powdered FeO(OH) zeolite at 460 °C and for pure component FeO(OH) at 560 °C indicated an 100 °C shifted exothermic effect, which characterized strong chemical interaction of FeO(OH) with zeolite structure. Based upon the XPS analyses, also the difference between Fe species in the raw and FeO(OH) doped zeolite was found in increasing Si/Al ratio, however only at the surface below app. 5 nm, measured as 3.94 for raw and 5.38 for sample treated with alkalic solution. The plotting of adsorption isotherms in the system studied clearly showed the increasing uptake capacity of the adsorbents towards antimony with the increased S(BET) data (GEH ˃FeO(OH)˃FeO(OH) zeolite˃nanofer)

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Using a laboratory set-up, sorption of chromate and arsenate from aqueous solutions with the octadecylammonium acetate (ODA)-modified clinoptilolite was examined. In the experiments, a natural montmorillonite was compared with organically, i.e. surfactant-loaded clinoptilolite and with some inorganically substituted (Ag, Pb)-monoforms. The arrangements of the surface-attached ODA chains have been an important factor for the difference in the adsorption states of the guest species (oxyanions). A novel nanostructure inorganic-organic composite prepared has been investigated using SEM, thermogravimetry, UV-VIS diffuse reflectance and powder XRD spectral analytical methods. Finally, adsorption isotherms for the system studied have been measured. An approach for regeneration of exhausted surfactant-immobilized clinoptilolite with inorganic salt solutions under dynamic regime has been proposed.

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