Nuri Öztürk

Adsorption of Cr(VI) from Aqueous Solutions Onto Raw and Acid-Activated Reşadiye and Hançılı Clays

ABSTRACT The adsorption of Cr(VI) from aqueous solutions onto raw and acid-activated clays—namely, Reşadiye region clay (R, raw Reşadiye region clay; R-H2SO4, acid-activated with H2SO4 Reşadiye region clay; R-HCl, acid-activated with HCl Reşadiye region clay) and Hançılı region clay (H, raw Hançılı region clay; H-H2SO4, acid-activated with H2SO4 Hançılı region clay; H-HCl, acid-activated with HCl Hançılı region clay)—was studied in a batch system. For optimization of the Cr(VI) adsorption on raw clays and acid-activated clays, the effect of pH, temperature, initial Cr(VI) concentration, time, and adsorbent dosage were investigated. X-ray diffraction analyses of raw and acid-activated clays were used to determine the effects of acid-activating on the layer structure of the clays. The surface characterizations of clays and modified clays were performed by using FT-IR spectroscopy. The Langmuir and Freundlich adsorption models were employed to describe the equilibrium isotherms, and thus the isotherm constants were determined. The data obtained from our investigations were well described by the Langmuir model. The adsorption capacity of the adsorbents Reşadiye and Hançılı clays were found to be 0.0269, 0.0144, and 0.0170 mmol/g for H, H-HCl, and H-H2SO4 and 0.0356, 0.0276, and 0.0422 mmol/g for R, R-HCl, and R-H2SO4, respectively. The results show that the adsorption was strongly dependent on pH of the medium, initial Cr(VI) concentration and temperature. The removal of Cr(VI) reached saturation in about 120 min, and the adsorption process of Cr(VI) was observed as exothermic. A maximum removal of 73% was noted at 1.0 × 10−4 M concentration of Cr(VI) in solution for H-HCl. Furthermore the enhancement of removal of Cr(VI) was observed from pH 3 to 4. The results are discussed to highlight the influence of acid activation on Cr(VI) adsorption characteristics of the clays.

Experimental (FT-IR, NMR and UV) and theoretical (M06-2X and DFT) investigation, and frequency estimation analyses on (E)-3-(4-bromo-5-methylthiophen-2-yl)acrylonitrile.

The spectroscopic properties of (E)-3-(4-bromo-5-methylthiophen-2-yl)acrylonitrile have been investigated by FT-IR, UV, (1)H and (13)C NMR techniques. The theoretical vibrational frequencies and optimized geometric parameters (bond lengths and angles) have been calculated using density functional theory (DFT/B3LYP: Becke, 3-parameter, Lee-Yang-Parr) and DFT/M06-2X (the highly parameterized, empirical exchange correlation function) quantum chemical methods with 6-311++G(d,p) basis set by Gaussian 03 software, for the first time. The assignments of the vibrational frequencies have been carried out by potential energy distribution (PED) analysis by using VEDA 4 software. The theoretical optimized geometric parameters and vibrational frequencies were in good agreement with the corresponding experimental data, and with the results in the literature. (1)H and (13)C NMR chemical shifts were calculated by using the gauge-invariant atomic orbital (GIAO) method. The electronic properties, such as excitation energies, oscillator strength wavelengths were performed by B3LYP methods. In addition, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies and the other related molecular energy values have been calculated and depicted.

FT-IR Spectroscopic Study of 1,5-Pentanedithiol and 1,6-Hexanedithiol Adsorbed on NaA, CaA and NaY Zeolites

The adsorption of 1,5-pentanedithiol (1,5-PDT) and 1,6-hexanedithiol (1,6-HDT) in liquid phases on NaA (or 4A-type), CaA (or 5A-type) and NaY zeolites has been studied by using infrared spectroscopy. From the IR spectra it is found that the peak positions of the symmetric as well as the antisymmetric modes of the methylene (CH2) groups are observed at almost the same band values for the title dithiolates adsorbed on the A-type and NaY zeolites. On the other hand, the weak SH stretching vibration, observed for all samples, can be attributed to the sulphure atoms of 1,5-PDT and 1,6-HDT coordinatively adsorbed on cationic sites of the zeolites.

FT-IR Spectroscopic Study of 1,3-Diaminopropane Adsorbed on Type A, X and Y Zeolites

The IR spectra of 1,3-diaminopropane adsorbed on NaA (type 4A), CaA (type 5A), NaX (type 13X) and NaY zeolites are reported. From the IR spectral data it can easily be stated that the characteristic NH vibration bands of aliphatic amine groups play an important role in the adsorptions of 1,3-diaminopropane on the mentioned zeolites.

Experimental (FT-IR, Laser-Raman and NMR) and Theoretical Spectroscopic Analysis of 3-[(N-methylanilino)methyl]-5-(thiophen-2-yl)-1,3,4-oxadiazole-2(3H)-thione

The structure of a potential bioactive agent namely, 3-[(N-methylanilino)methyl]-5-(thiophen-2-yl)-1,3,4-oxadiazole-2(3H)-thione was characterized by proton and carbon-13 nuclear magnetic resonance...