SYNTHESIS, CHARACTERIZATION AND STUDY ON THE SORPTION PROPERTY OF Fe3O4/Al2O3/ZrO2 NANOCOMPOSITES TOWARD THE REMOVAL OF CADMIUM, LEAD AND CHROMIUM IONS FROM AQUEOUS SOLUTION

Abstract

The pollution caused by heavy metals is one of the major environmental problems that is imperative to be solved. Fe-Al-Zr ternary mixed oxides nanocomposite was Synthesized by using ferric chloride hexa hydrate, ferrous chloride tetrahydrate, aluminum nitrate nanohydrate and zirconyl chloride octahydrate via co-precipitate method. The crystallinity, surface area and functional group of the material were investigated by means of X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and Fourier transform infrared (FTIR) techniques. The pH of point zero charge and ion strength of the selected adsorbent was also determined. The sorption kinetics and thermodynamics, the influence of some factors such as pH, adsorbent dose, contact time, speed of agitation and initial metal concentration on sorption were also investigated. The sorption properties of the adsorbent are also described. The results of batch sorption experiments in the determination of Pb(II), Cd(II) and Cr(VI) metal ion sorption behaviors and sorption mechanisms were presented and discussed. The effects of each of the above mentioned parameters on the adsorption of Pb(II), Cd(II) and Cr(VI) were determined to be pH = 6, dose = 1g, contact time = 12 h, agitation speed = 120 rpm with initial concentration of 20 ppm for Cd(II); pH = 4, dose = 0.1 g, contact time = 12 h, agitation speed = 120 rpm with initial concentration of 20 ppm for Cr(VI) and also pH = 6, dose = 0.5 g, contact time = 6 h, agitation speed = 100 rpm with initial concentration of 20 ppm for Pb(II) by Fe-Al-Zr. The experimental results showed that the adsorbed amounts of Pb(II), Cd(II) and Cr(VI) tend to decrease with increase in pH. Desorbabilty of Cd(II), Cr(VI) and Pb(II) was investigated and found to be increased with increasing pH. Freundlich isotherm models fit the equilibrium data well on the adsorbent. Kinetic data correlated well with the pseudo second order kinetic model, suggesting that more of the adsorption process might be chemical sorption. Since the value of the thermodynamics parameter (∆G) appeared to be negative, the spontaneous nature of theadsorption process was confirmed. It has been found that, having all parameters optimized, the nanosized adsorbent entitled to have an adsorption efficiency of 96.65%, 96.55% and 97.2% for Cd(II), Cr(VI) and Pb(II), respectively. The effect of interfering cations on the adsorption of Cd(II), Cr(VI) and Pb(II) these also studied. Experimental results show that the nanocomposite was effective for the removal of the title heavy metals from aqueous solution.