A Comparative Adsorption Study on Low-cost Synthetic, Nano and Doped ZnO for the Removal of Copper Surfactants Urea Complexes: Equilibrium, Kinetics, and Thermodynamics

Abstract

<P>Background: The effective removal of heavy metals from aqueous wastes is among the most important issues for many industrialized countries. Present paper reports about the synthesis of copper neem urea complex (CNU) and its characterization using elemental and spectroscopic techniques such as IR, NMR, and ESR. </P><P> Methods: The NPs of ZnO and doped with SiO₂ which was extracted from industrial ash’s) was synthesized by precipitation method and characterized through UV, SEM-EDX and XRD techniques. Three low cost adsorbents such as synthetic ZnO, nano ZnO and doped ZnO with SiO₂ were chosen for the adsorption of copper surfactant complex of urea from non-aqueous solutions i.e. petroleum ether. Effect of various parameters like contact time, pH, adsorbent dosage, temperature and initial metal concentration on the removal through degradation and adsorption of CNU were investigated and optimized. </P><P> Results: Isothermal studies indicated that the adsorption of CNU followed Langmuir adsorption isotherm. Kinetic studies indicated that removal of the CNU by the three adsorbents followed second order kinetics. With a maximum adsorption capacity of 7.58 mg/g using all three adsorbents showed an effective and efficient removal 95.8% of CNU from non-aqueous solutions by using ZnO doped with SiO₂ compare to synthetic ZnO and nano ZnO. This is the first report of removal of the CNU complex based on the three adsorbents. </P><P> Conclusion: The potential of application for the treatment of solutions containing these complexes in multi-metal solutions is indicated.</P>