Chemistry / Kimya
Permanent URI for this collectionhttps://hdl.handle.net/11147/4072
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Article Citation - WoS: 87Citation - Scopus: 108Synthesis and Characterization of Bentonite/Iron Nanoparticles and Their Application as Adsorbent of Cobalt Ions(Elsevier Ltd., 2010) Shahwan, Talal; Üzüm, Çağrı; Eroğlu, Ahmet Emin; Lieberwirth, IngoThis study reports the synthesis and characterization of iron nanoparticles in the presence of K10 bentonite. Introducing K10 during synthesis of iron nanoparticles resulted in a partial decrease in the aggregation of the nanoparticles. The dispersed nanoparticles showed a typical core–shell structure and were predominantly within the 10–60 nm size range. The composite adsorbent was tested for the removal of Co2+ ions in aqueous solution at various contact times, concentrations, pH, and repetitive loadings. The rate of adsorption was evaluated using first and second order rate equations. The adsorption was described by the Freundlich model. The adsorbent showed effective removal after re-use and the adsorption increased with increasing initial pH.Article Citation - WoS: 83Citation - Scopus: 97Characterization of the Uptake of Aqueous Ni2+ Ions on Nanoparticles of Zero-Valent Iron (nzvi)(Elsevier Ltd., 2009) Efecan, Nazlı; Shahwan, Talal; Eroğlu, Ahmet Emin; Lieberwirth, IngoThis study investigates the fixation of aqueous Ni2+ ions by nanoparticles of zero-valent iron (nZVI) prepared using the borohydride reduction method. The uptake of Ni2+ was tested under various experimental conditions like initial concentration, time, pH, and repetitive application of nZVI. Part of the experiments was devoted to comparing the extent of uptake of Ni2+ ions with those of Cu2+, Cd2+, Zn2+, and Sr2+ ions, which belong to a wide range of standard reduction potentials. Particle size analysis of nZVI in aqueous solution indicated that the material suffered extensive aggregation, much above the extent of aggregation known for dry nZVI. Nevertheless, nZVI showed fast uptake kinetics and very high uptake capacity. The overall results demonstrated the high fixation capability of nZVI towards the studied transition metal ions in aqueous solution. The same conclusion is, however, not valid for the removal of Sr2+ ions.Article Citation - WoS: 306Citation - Scopus: 345Synthesis and Characterization of Kaolinite-Supported Zero-Valent Iron Nanoparticles and Their Application for the Removal of Aqueous Cu2+ and Co2+ Ions(Elsevier Ltd., 2009) Üzüm, Çağrı; Shahwan, Talal; Eroğlu, Ahmet Emin; Hallam, Keith R.; Scott, Thomas B.; Lieberwirth, IngoThis study reports the synthesis and characterization of nano-scale zero-valent iron in the presence of kaolinite clay (nZVI-kaol). The adsorbent, nZVI-kaol, was produced at initial Fe:kaolinite mass ratios of 1:1, 0.5:1, and 0.2:1. The presence of kaolinite resulted in decreased aggregation of iron nanoparticles, yielding composites with iso-electric points (IEPs) around 6.7–7.0. The reduction in Fe2+ precursor concentration appeared to decrease further the extent of aggregation and the size of individual nZVI particles. The synthesized nZVI-kaol materials were then tested for the removal of aqueous Cu2+ and Co2+ ions. The investigated parameters in the uptake experiments included volume/mass (V/M) ratio, initial concentrations of Cu2+ and Co2+ ions, contact time, pH, and repetitive application of the adsorbent. The adsorbents demonstrated high removal abilities towards both cations under the investigated conditions. Repetitive loading tests showed that significant removal could still be achieved at small concentrations by samples reused several times. X-ray photoelectron spectroscopy (XPS) analysis showed that while Co2+ was mainly fixed by the oxyhydroxyl groups of iron nanoparticles, Cu2+ ions were fixed by a redox mechanism, leading to the formation of Cu2O and Cu0.Article Citation - WoS: 163Citation - Scopus: 187Application of Zero-Valent Iron Nanoparticles for the Removal of Aqueous Co2+ Ions Under Various Experimental Conditions(Elsevier Ltd., 2008) Üzüm, Çağrı; Shahwan, Talal; Eroğlu, Ahmet Emin; Lieberwirth, Ingo; Scott, Thomas B.; Hallam, Keith R.Nanosized zero-valent iron (nZVI) is increasingly gaining interest as an efficient sorbent for various types of aqueous pollutants. In this study, nZVI was synthesised by the borohydride reduction method, characterised and then examined for the removal of aqueous Co2+ ions over a wide range of concentrations, from 1 to 1000 mg/L. The size of nZVI particles was predominantly within the range of 20–80 nm, and only limited oxidation was observed in samples aged for a period of 2 months. The experiments investigated the effects of V/m ratio, concentration, contact time, repetitive loading, pH and aging on the extent of retardation of Co2+ ions. Iron nanoparticles demonstrated very rapid uptake and large capacity for the removal of Co2+ ions. Effective uptake was observed even after a number of repetitive trials. The extent of Co2+ uptake increased with the increasing pH. X-ray photoelectron spectroscopy (XPS) indicate that the fixation of Co2+ ions takes place through the interaction of these ions with the oxohydroxyl groups on the iron nanoparticle surfaces in addition to spontaneous precipitate formation at high loadings.