In
this study we examined the adsorption, kinetics and thermodynamics of
heavy metals of used engine oil that come during engine operation and
forsaw the possibility of polluting soil and ground water. the effect of
temperature on adsorption
was investigated in the range (15 – 45o C) and results showed that
maximum removal occurred at 45C. Effect of pH indicated that maximum
removal of both Zn and Pb was at pH =13. Increasing adsorbent (soil)
dosage from 0.5 to 3g showed that maximum adsorption of both Zn and Pb
onto soil occurred with 3 g of soil. Equilibrium concentration happened
at 90 minutes. Lanqmuir and Freiundlich models were used to study
adsorption process at equilibrium and the results
showed that Frenundlich is better for Zn while Lanqmuir fits better
with Pb. In order to investigate adsorption behavior of Zn and Pb on
soil, three kinetic models applied; Pseudo-first order, Pseudo-second
order and intra- particle diffusion models were applied to fit kinetics
data. The rate constants and correlation coefficients were determined
for the three models. Thermodynamic parameters such as Gibbs free
energy, standard enthalpy and standard entropy change were calculated
for both zinc and lead.
Iron oxide nanoadsorbents are cost-effective adsorbents that provide high adsorption capacity, rapid adsorption rate and simple separation and regeneration. In this study, Fe3O4 nanoadsorbents have been employed for the removal of Pb(II) ions from aqueous solutions by a batch-adsorption technique. The effects of contact time, initial concentration of Pb(II) ions, temperature, solution pH and coexisting ions on the amount of Pb(II) adsorbed have been investigated. Pb(II) adsorption was fast, and equilibrium was achieved within 30 min. The amount of Pb(II) adsorbed increased as temperature increased, suggesting an endothermic adsorption. The optimal pH value for Pb(II) adsorption was around 5.5. Furthermore, the addition of coexisting cations such as Ca2+, Ni2+, Co2+, and Cd2+ has no remarkable influence on Pb(II) removal efficiency. The adsorption equilibrium data fitted very well to Langmuir and Freundlich adsorption isotherm models. The thermodynamics of Pb(II) adsorption onto the Fe3O4 nanoadsorbents indicated that the adsorption was spontaneous, endothermic and physical in nature. The desorption and regeneration studies have proven that Fe3O4 nanoadsorbents can be employed repeatedly without impacting its adsorption capacity.
Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, Alberta, Canada
Current Affiliation:
Department of Chemical Engineering, An-Najah National University, P.O. Box 7, Nablus, Palestine
Preferred Abstract (Original):
The presence of dyestuffs in wastewater poses an environmental concern since these organic contaminants are toxic to aquatic and non-aquatic life. In addition, these contaminants are difficult to remove or biodegrade, which poses a challenge to the conventional wastewater treatment techniques. In this work, the adsorption of acid red dye 27 (AR27) onto γ-Fe2O3 nanoadsorbents was studied for the removal of red dye from aqueous solutions by the batch-adsorption technique. The experiments were carried out at different conditions of contact time, initial AR27 concentration, temperature, co-existing ions, and solution pH. It was found that the adsorption was a rapid process, and equilibrium was achieved in less than 4 minutes. The removal of AR27 decreased with the increase in solution pH and temperature. Furthermore, the addition of chloride and nitrate anions has no remarkable influence on AR27 removal efficiency. On the other hand, the effects of sulfate and bicarbonate anions on the removal of AR27 were significant. The adsorption equilibrium data fitted very well using Langmuir and Freundlich adsorption isotherm models. The data obtained from adsorption isotherms at different temperatures were used to calculate thermodynamic quantities of adsorption, such as standard Gibbs free energy change, enthalpy change , and entropy change . The adsorption process was found to be spontaneous, exothermic and physical in nature. The results indicate that γ-Fe2O3 nanoadsorbents could be employed for the removal of dyes from wastewater.