Abstract
Fe-Al-Zr ternary mixed oxides composite was synthesized via co-precipitation method for the removal Pb(II), Cd(II) and Cr(VI) ions from aqueous solutions. The as-synthesized materials were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscope hyphenated with energy dispersive X-ray diffraction (SEM-EDX) and Fourier transform infrared (FTIR) techniques. The pH at the point of zero charge (pHpzc) of the sorbent and effect of ionic strength on sorption were also determined. The batch tests were conducted to optimize the various sorption parameters such as pH, adsorbent dose, contact time, speed of agitation and initial metal concentration. The experimental results showed that the adsorbed amounts of Pb(II), Cd(II) and Cr(VI) tend to decrease with increase in pH. Freundlich isotherm model fits better the equilibrium data for the adsorbent. Kinetic data correlated better with both pseudo first order and pseudo second order kinetic models. The spontaneous nature of the adsorption process was also confirmed from thermodynamic grounds. The nanosized adsorbent exhibited an adsorption efficiency of 96.65%, 96.55% and 97.2% for Cd(II), Cr(VI) and Pb(II), respectively, at optimum condition. Experimental results showed that the nanocomposite was effective for the removal of the title heavy metals from aqueous solution.
 
 Bull. Chem. Soc. Ethiop. 2020, 34(1), 105-121.
 DOI: https://dx.doi.org/10.4314/bcse.v34i1.10
Highlights
Heavy metals pollution to the environment is a consequence of several activities like chemical manufacturing, painting and coating, tanning, mining, extractive metallurgy, nuclear and other industries [1]
X-ray diffraction (XRD) is one of the most important non-destructive tools to analyze all kinds of matter-ranging from fluids, to powders and crystals
This could due to absence of calcinations making the material predominantly amorphous. Crystallized alumina such as γ-Al2O3 and α-Al2O3 could be expected under thermal treatment with temperature at 800 oC and 1000 oC respectively [30], where as monoclinic or tetragonal phases are expected in the temperature range from 600– 800 oC [45]
Summary
Heavy metals pollution to the environment is a consequence of several activities like chemical manufacturing, painting and coating, tanning, mining, extractive metallurgy, nuclear and other industries [1]. These metals exert a deleterious effect on fauna and flora of lakes and streams [2]. Various treatment techniques are practiced for removal of toxic heavy metals from water and wastewaters. The principal types of adsorbents include activated carbon [12], synthetic polymers [13] and silica-based adsorbents [14] These adsorbents are not often used for wastewater adsorption because of their high cost.
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