Determination of adsorptive properties of a Turkish Sepiolite for removal of Reactive Blue 15 anionic dye from aqueous solutions

WOS: 000262292400067PubMed ID: 18534746Reactive Blue 15 (RB 15) adsorption on the Turkish Sepiolite was carried out by batch equilibrium technique. IR spectrum and surface area measurement of the composite of dye-sepiolite (Turkish) pointed out that dye species replaced partly the zeolitic water to form hydrogen bond with bound water and adsorbed to the channels sites. The effects of temperature, pH and ionic strength on adsorption of dye molecules were investigated and the nature of adsorption process was determined by calculating Delta H, Delta S and Delta G values. The adsorbed amount increased with increase in temperature, but that for high pH values decreased for the adsorption of reactive dye. (C) 2008 Elsevier B.V. All rights reserved

Structural analysis of naproxen-intercalated bentonite (Unye)

The difference in the basal spacing (8.79Å) and a higher mass loss (6.2%) in the temperature range of 200-750°C of naproxen-bentonite (N-bentonite) comparing to that of Unye bentonite (UB) signified the existence of thermally stable organic species in the interlamellar space of the bentonite clay. The asymmetric OCO- stretching band (1607cm-1) of N-bentonite became stronger in the temperature interval of 100-400°C as a result of binding via the CO group of the ligand to exchangeable cation and/or water molecule whereas the OH bending peak of water (1633cm-1) and the CC stretching vibration of aromatic ring (1531cm-1) became weaker on thermal treatment. The effect of ionic strength on the desorption of naproxen species and the related kinetic data revealed that the release mechanism at pH=7.4 is unrestricted diffusion controlled and governed by the repulsive interactions between the bentonite surface and the negatively charged species. The pore structure characteristics of the bentonite samples corresponding to the surface area, pore volume and pore size were determined by using the conventional analysis of the nitrogen adsorption-desorption isotherms. © 2011 Elsevier B.V

The spectral, structral and thermal characterizations of dimethyl sulphoxide, pyridine, ethanolamine and N-methyl formamide intercalated kaolinites

The intercalation of dimethyl sulphoxide (DMSO), pyridine (Py), ethanolamine (Ea), and Nmethyl formamide (NMF) molecules into the kaolinite interlayers led to an appreciable decrease of 3697 cm-1 of the hydroxyl band. The appearance of the peaks at 3662, 3541, and 3504 cm-1 proved that the DMSO species are intercalated between the kaolinite layers through forming H-bonds with internal-surface hydroxyl groups. The intensities of the 942 and 796 cm-1 bending peaks arising from inner-surface hydroxyls decreased and new vibrational features appeared due to the intercalation of the guest species. The d001 value of pure kaolinite was found at 7.18 Å, and the d001 values were seen at 11.26, 11.62, 10.77, and 10.67 Å for kaolinite-dimethyl sulphoxide (K-DMSO), kaolinite-pyridine (K-Py), kaolinite-ethanolamine (K-EA), and kaolinite-N-methyl formamide (K-NMF) composites, respectively. The endothermic differential thermal analysis (DTA) peaks at a temperature of 108 - 334°C reflected the changes in the physicochemical properties of the intercalated species. The thermal stability increase followed the order of K-Py<K-NMF<K-Ea<K-DMSO. Based on the thermal analysis data, the intercalation ratios of the composites above were determined as 80.0, 40.0, 81.6, and 82.0%, respectively. The specific surface areas are affected by the intercalation geometry of the composites within the gallery spacing. The surface areas of the K-DMSO, K-Py, and K-EA complexes increased whereas the surface area of K-NMF decreased with respect to that of untreated kaolinite. © 2010 Verlag der Zeitschrift für Naturforschung, Tübingen

Adsorption of Reactive Red 120 from aqueous solutions by cetylpyridinium-bentonite

BACKGROUND: The removal of Reactive Red 120 (RR 120) from aqueous solutions using cetylpyridinium modified Resadiye bentonite (CP-bentonite) prepared by ion exchange was investigated with particular reference to the effects of temperature, pH and ionic strength on adsorption. RESULTS: Fourier transform infrared (FTIR) and thermal analysis (TG-DTG/DTA) techniques revealed that the anionic dye (RR 120) molecules replaced partly cationic surfactant species on interacting with CP-bentonite. The positive surface charge originating from the cationic surfactant species located on the external surface of the modified bentonite sample increased at low pH values. The significant amount of dye removal by CP-bentonite at high pH values proved the importance of ? and van der Waals interactions other than the electrostatic attraction in the duration of the adsorption process. The adsorption isotherms and the kinetic data were well described by the Langmuir and pseudo-second-order kinetic model, respectively. The Gibbs energy (?G), enthalpy (?H) and entropy (?S) changes in the temperature range 25-65 °C pointed out that the RR 120 uptake increased in parallel with the temperature. CONCLUSION: This study showed that the structural arrangement of cetylpyridinium ions in the CP-bentonite sample aswell as the pH, temperature and ionic strength of the bulk solution influenced the adsorption of RR 120 dye from aqueous solutions by CP-bentonite. © 2010 Society of Chemical Industry