Experimental and theoretical studies of Rhodamine B direct dye sorption onto clay-cellulose composite

Dyes are one of the main water pollutants and many biological and environmental problems are associated with them. Rhodamine B (RhB) is one of the most commonly used dye in the textile, printing, paints, and paper industry. The present work reports the sorptive removal of Rhodamine B direct dye from wastewater onto developed cellulose and clay composites. Sorbent material cellulose (48 g) was extracted from 80 g of bagasse. Then cellulose and two types of acid-activated clays were used to make efficient sorbent namely, composite I and II. Various characterization techniques were used to study the physiochemical properties of the synthesized composites. Different sorption affecting parameters were optimized such as initial dye concentration, time, temperature, pH, and composite dose for the efficient sorption of RhB onto composites. Equilibrium time was 60 min for composite-I and 80 min for composite-II Non-linear equilibrium isotherm and kinetic models demonstrated the fitness of Pseudo-second order and Redlich-Peterson isotherm. Composite-I and II removed 85.9% and 95.6% of RhB at pH 2 in 120 min, respectively. The sorption efficiency was checked, and sorbents were applied to real textile effluent which showed promising removal efficiency of over 90%. To confirm the experimental results, computational optimization and vibrational calculations were carried out using the Gaussian 09 program package with 3–21 G, 6–311 G, and 6–311+G basic sets. Geometric parameters showed the planar geometry. In the case of FTIR spectra, fundamental ring vibrations were observed with C-H and C-C. This study suggests that the developed composites have exceptional sorption ability to remove the dye contents from aqueous media

Experimental and theoretical infrared spectra of famotidine and its interaction with ofloxacin

We present FTIR spectrum of B polymorphic forms of famotidine (fam) that is a powerful histamine H2-receptor antagonist used in the treatment of peptic ulcer. Molecular mechanics and semi empirical AM1, PM3, MNDO and MINDO3 methods have been used to study the molecular geometry, and the harmonic vibrational spectra with the purpose to assist the experimental assignments of famotidine. The calculated geometric parameters have been compared to the corresponding X-ray structure of famotidine and it is found that AM I structure in agreement with the crystal data. We are also investigated the interaction of famotidine with ofloxacin which is a synthetic antimicrobial agent. The changes observed in the some bands (wavenumber, shape) of interacted compound indicated that there is a weak interaction between two molecules. PM3 calculations are also carried out to determine the possible molecular structure of the interacted compound. (c) 2004 Elsevier B.V. All rights reserved

Theoretical Studies of Molecular Structures, Infrared Spectra, NBO and NLO Properties of Some Novel 5-arylazo-6-hydroxy-4-phenyl-3-cyano-2-pyridone Dyes

The optimized geometrical structures, infrared spectra, molecular electrostatic potential, natural bond orbital and nonlinear optical properties of 5-phenylazo-6-hydroxy-4-phenyl-3-cyano-2-pyridoine (1) and 5-(4-bromophenylazo)-6-hydroxy-4-phenyl-3-cyano-2-pyridoine (2) dyes with a detailed study on the azo-hydrazone tautomerism in the ground state have been investigated by density functional theory using B3LYP functional with 6-31G(d,p) basis set. Vibrational modes are assigned with the help of vibrational energy distribution analysis program. Highest occupied molecular orbital and lowest unoccupied molecular orbital energies of the (1) and (2) compounds with azo and hydrazone forms were calculated with the same method and basis set. Molecular parameters like global hardness (η), global softness (σ) and electronegativity (χ) were calculated with the results obtained from the highest occupied and lowest unoccupied molecular orbital energies. Nonlinear optical parameters (mean polarizability (⟨α⟩), the anisotropy of the polarizability (⟨Δα⟩) and the mean first-order hyperpolarizability (⟨β⟩)) of the title compounds were investigated theoretically. The atomic charges, electronic exchange interaction, and charge delocalization of the molecules have been studied by natural bond orbital analysis

Theoretical studies of molecular structures, infrared spectra, NBO and NLO properties of some novel 5-arylazo-6-hydroxy-4-phenyl-3-cyano-2-pyridone dyes

The optimized geometrical structures, infrared spectra, molecular electrostatic potential, natural bond orbital and nonlinear optical properties of 5-phenylazo-6-hydroxy-4-phenyl-3-cyano-2-pyridoine (1) and 5-(4-bromophenylazo)-6-hydroxy-4-phenyl-3-cyano-2-pyridoine (2) dyes with a detailed study on the azo-hydrazone tautomerism in the ground state have been investigated by density functional theory using B3LYP functional with 6-31G(d,p) basis set. Vibrational modes are assigned with the help of vibrational energy distribution analysis program. Highest occupied molecular orbital and lowest unoccupied molecular orbital energies of the (1) and (2) compounds with azo and hydrazone forms were calculated with the same method and basis set. Molecular parameters like global hardness (η), global softness (σ) and electronegativity (χ) were calculated with the results obtained from the highest occupied and lowest unoccupied molecular orbital energies. Nonlinear optical parameters (mean polarizability (⟨α⟩), the anisotropy of the polarizability (⟨Δα⟩) and the mean first-order hyperpolarizability (⟨β⟩)) of the title compounds were investigated theoretically. The atomic charges, electronic exchange interaction, and charge delocalization of the molecules have been studied by natural bond orbital analysis

Spectroscopic studies on the interaction of ofloxacin with metals

Several coordination compounds (1:1) formed between alkaline earth metal cations [Mg(II), Ca(II) and Ba(II)] and transition metal ions [Co(II), Ni(II) and Zn(II)] with oflocaxin were synthesized. The compounds have been characterized using elemental analysis, Fourier transform infrared (FT-IR) spectroscopy and H-1 NMR spectra. The solid state samples of all complexes have been measured within the range 4000-400 cm(-1). Based on normal mode calculations for complexes, the assignments of bands observed in FT-IR spectra of studied compounds have been done. Some significant differences in vibrational structure have been observed and discussed. The frequencies and intensities of some bands of the ofloxacin depend systematically on the second ionization potential of the metals. (C) 2003 Elsevier B.V. All rights reserved