Abstract
In this work, the adsorption isotherm, Kinetic and thermodynamic of removal of Fe3+, Cu2+, Pb2+ and Zn2+) ions by activated carbon produced from rice husk were studied. The results shown that the Freundlich isotherm model achieved best fit with the equilibrium adsorption data for adsorption of (Fe3+, Cu2+ and Pb2+) ions, it is indicates to multilayer adsorption nature of these metal ions on RHAC. The adsorption capacity (Kf) of the adsorbent have a value of (312.1, 628.93 and 162.66 mg/g) for (Fe3+, Cu2+ and Pb2+), respectively. The Langmuir isotherm model gives best fit with the equilibrium adsorption data, it is instated to monolayer adsorption nature of (Zn2+) ions on RHAC. The monolayer adsorption capacity (Q) have a value of (714.285 mg/g). The adsorption kinetics were followed the pseudo-second-order model, this model gives the best- fit to experimental data for all heavy metal ions which studied in this work. which have highest correlation coefficient values of (0.988 ,0.996 ,0.999 and 0.9232) for (Cu2+, Fe3+, Pb2+ and Zn2+), respectively. Also, the adsorption thermodynamic showed that the adsorption of heavy metal ions becomes more feasibility with increasing in temperature due to negative values of ΔG. The adsorption process is endothermicdue to positive values of ΔH.
Highlights
The contamination of water by heavy metal ions has increased over the last few decades due to industrial processes such as petroleum refinery process and the development of new technology in refining of petroleum (Ambursa et al, 2011)
The results shown that the Freundlich isotherm model achieved best fit with the equilibrium adsorption data for adsorption of (Fe3+, Cu2+ and Pb2+) ions, it is indicates to multilayer adsorption nature of these metal ions on RHAC
Adsorption equilibrium is the set of conditions at which the number of molecules arriving on the surface of the adsorbent equals the number of molecules that are leaving
Summary
The contamination of water by heavy metal ions has increased over the last few decades due to industrial processes such as petroleum refinery process and the development of new technology in refining of petroleum (Ambursa et al, 2011). Some in place treatment technologies available for the removal of heavy metal ions from aqueous solutions are chemical precipitation, ion exchange, coagulation, and bioremediation and sorption/ adsorption. Of all these techniques adsorption at solid substrate is preferred because of its high efficiency, easy handling and cost effectiveness as well as availability of different adsorbents (Baskaranet al., 2010). Several kinetic models are used to explain the mechanism of the adsorption processes (Mohammadi et al, 2010).it is important to be able to predict the rate at which pollutant is removed from aqueous solutions in order to design appropriate adsorption treatment plants. The Langmuir (Safa & Bhatti, 2011), the Freundlich (Kumagai et al, 2010), Temkin (Dada et al, 2012) and the D-R (Katal et al, 2012), isotherm equations were used to describe the experimental data
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