Kinetics and thermodynamics of cadmium ion removal by adsorption onto nano zerovalent iron particles
ABSTRACT Nano zerovalent iron (nZVI) is an effective adsorbent for removing various organic and inorganic contaminants. In this study, nZVI particles were used to investigate the removal of Cd2+ in the concentration range of 25–450 mg L−1. The effect of temperature on kinetics and equilibrium of cadmium sorption on nZVI particles was thoroughly examined. Consistent with an endothermic reaction, an increase in the temperature resulted in increasing cadmium adsorption rate. The adsorption kinetics well fitted using a pseudo second-order kinetic model. The calculated activation energy for adsorption was 54.8 kJ mol−1, indicating the adsorption process to be chemisorption. The intraparticle diffusion model described that the intraparticle diffusion was not the only rate-limiting step. The adsorption isotherm data could be well described by the Langmuir as well as Temkin equations. The maximum adsorption capacity of nZVI for Cd2+ was found to be 769.2 mg g−1 at 297 K. Thermodynamic parameters (i.e., change in the free energy (ΔGo), the enthalpy (ΔHo), and the entropy (ΔSo)) were also evaluated. The overall adsorption process was endothermic and spontaneous in nature. EDX analysis indicated the presence of cadmium ions on the nZVI surface. These results suggest that nZVI could be employed as an efficient adsorbent for the removal of cadmium from contaminated water sources.
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ABSTRACT: Disinfection process by chlorine has been applying effectively in drinking water treatment processes; nevertheless it causes the formation of THMs which are thought to be carcinogen. Restrictions of THMs had been imposed by organizations in most of the countries. In Istanbul, these limit values were not exceeded in present time, but organic content of drinking water supplies is accreted by the increment pollution on occasion of population growth. This will lead to investigate and apply an extra treatment unit for THM removals. In this study, application of nanoparticle was researched in THM removal from tap water. Nanoparticle used in the process was sintered into zeolite in coin form. The results were promising. It was observed that unsintered form was more effective on removal of THMs than sintered form of α-Fe2O3. Furthermore, nanoparticles in zeolite form advanced the adsorption capacity of zeolite.Journal of Clean Energy Technologies. 03/2013; 1(2):120-123.
Article: Preparation and Characterization of Activated carbon – nFe3O4, Activated carbon – nSiO2 and Activated carbon – nZnO Hybrid Materials[show abstract] [hide abstract]
ABSTRACT: The preparation and physicochemical characterization of activated carbon, nano metal oxides, and activated carbon – nFe3O4, activated carbon – nSiO2 and activated carbon – nZnO hybrid materials has been undertaken. The materials have been characterized by scanning and transmission electron microscopy, x-ray diffraction, CNH analysis and Fourier transform infrared spectroscopy. Surface area and porosity, ash content, pH, and point of zero charge were also measured. The results showed that the surfaces of activated carbon, nSiO2, activated carbon - nFe3O4, activated carbon – nSiO2 and activated carbon – nZnO are suitable for the sorption of cationic complexes while the surfaces of nFe3O4 and nZnO are favourable to the sorption of anionic complexes of heavy metals. Results also showed that the composition of the activated carbon and nano metal oxides increased the surface and micropore areas of nano metal oxides due to the large number of micropores and crevices on the surface of the hybrid materials.Particle and Particle Systems Characterization 05/2012; · 0.49 Impact Factor