Removal of Ni and Cd Ions from Aqueous Solution Using Iron Dust-zeolite Composite： Analysis by Thermodynamic, Kinetic and Isotherm Studies

To examine the effectiveness of iron dust-zeolite composite as an adsorbent for the removal of heavymetal ions from aqueous solutions, the adsorption isotherms, the kinetic, thermodynamic and optimum conditions,such as initial concentration, pH, contact time, adsorbent dosage and competitive adsorption conditions of heavymetals were investigated. The characterization of the composite was characterized via FTIR, SEM, XRF and XRDmethods. Kinetic results on the removal of heavy metal ions from aqueous solutions have been well described by thepseudo-second-order model. The adsorption data for Cd and Ni ions were fitted well with the Langmuir and Fretm-dlich isotherm models, respectively. The maximum adsorption capacities of iron dust-zeolite for Cd and Ni ions wereequal to 78.125 and 76.33 mg/g, respectively. The thermodynamic parameters such as enthalpy, entropy and freeenergy of adsorption of metal ions were determined. It was found that the process is endothermic, favorable andspontaneous. The competitive adsorption ability of heavy metal ions in the binary system on the composite showedthat Cd ions had a synergistic effect on the adsorotion of Ni and Ni ions had the negative effect on Cd adsorption.

Applied Mineralogical Studies on Iranian Titanium Deposits

Qara-aghaj and Skandian as hard rock titanium deposit and Kahnooj one as a placer deposit were investigated from applied mineralogical point of view. The mineralogical studies were carried out using XRD, XRF, optical microscopy, scanning electron microscopy and microprobe analysis. These studies indicated that ilmenite and magnetite are main valuable minerals in the studied ores. Pyroxene, olivine and plagioclase are the main gangue minerals in Qara-aghaj ore while chlorite and plagioclase are the major gangue minerals in Skandian ore. Plagioclase, clinopyroxene, amphibole, feldspate and some quartz are the important gangue minerals in kahnooj deposit. In all three ores ilmenite is mainly in the form of ilmenite grains but some lamellae of ilmenite with thickness between 0.1 to 20 μm have been occurred as exsolution textures inside magnetite grains, where the magnetite here can be referred to as ilmenomagnetite. In the hard rock ores some fine ilmenites have been disseminated in silicate minerals. The liberation degree of granular ilmenite was determined 150, 140 and 200 μm for Qara-aghaj, Skandian and Kahnooj, respectively. So, only the granular form of ilmenite is recoverable by physical methods. Some sphene and rutile as titanium containing minerals were observed mainly inside ilmenite phase in kahnooj ore. Some fine rutile was also found inside Skandian ilmenite while there were not any other titanium minerals inside Qara-aghaj ilmenite. Apatite is another valuable mineral which was found only in Qara-aghaj ore. Using SEM and microprobe analysis it was found that there are different amounts of exsolved fine lamellae of hematite inside ilmenite in Qara-aghaj and Kahnooj ores while it was not observed in Sckandian one. The average contents of TiO2 in the lattice of Qara-aghaj, Skandian and Kahnooj ilmenite were determined 51.13, 50.9% and 52.02%, respectively. FeO content of ilmenite lattice for all three samples is clearly lower than the theoretical content. This is due to the substitution of Mg and Mn for some Fe2+ ions in the ilmenite lattice. V2O3 content of magnetite lattice is up to 1%. So, magnetite can be a suitable source for production of vanadium as a by-product in all three deposits.