Adsorption of methylene blue by biochar produced through torrefaction and slow pyrolysis from switchgrass

The present work involves a study of sorption of methylene blue (MB) by charcoal samples produced through torrefaction and pyrolysis processes from switchgrass (Panicum virgatum). The adsorption of MB was determined using the spectrometric analysis method at various pH, temperature values and MB concentrations. The heat treatment temperature during biochar production significantly influenced the surface chemistry of biochars indicating that biochar samples, based on their thermal history alone, can behave significantly differently in the rhizosphere or in their ability to adsorb pollutants. The pH of the solution containing MB significantly affected its adsorption by biochars but trends were markedly different. The concentration of MB was also affected adsorption behavior of the two charcoals. The results indicate that biochars can be produced with desired properties to solve specific agricultural or environmental needs

Specific vapor sorption properties of phosphorus-containing dendrimers

Specific combination of guest sorption properties was observed for phosphorus-containing dendrimers, which distinguish them from ordinary polymers and clathrate-forming hosts. The sorption capacity for 30 volatile guests, binding reversibility, guest desorption kinetics and guest exchange, glass transition behavior and ability to be plasticized with guest were studied for phosphorus dendrimers of different generations (G1-G4 and G9) using quartz crystal microbalance sensor, FTIR microspectroscopy, atomic force microscopy, simultaneous thermogravimetry and differential scanning calorimetry combined with mass-spectrometry of evolved vapors. The dendrimers were found to have a different selectivity for different homological series of guests, high glass transition points without plasticization with guest even at high temperatures and saturation levels, moderate guest-binding irreversibility and ability both for effective guest exchange and independent guest sorption. These properties constitute an advantage of the studied dendrimers as receptor materials in various applications. © 2011 Elsevier Inc

IR and NMR spectra, intramolecular hydrogen bonding and conformations of para-tert-butyl-aminothiacalix[4]arene in solid state and chloroform solution

It is demonstrated that dissolution of aminothiacalix[4]arene in chloroform results in transformation of 1,3-alternate conformation, adopted in single-crystal and bulk polycrystalline solids, to the pinched-cone form. This conformer is stabilised by the intramolecular hydrogen bonds of two distal amino-groups acting as H-donors with another two amino moieties that appear as H-acceptors. The H-bonds cause quite small (ca. 10-20 cm-1) red shift of the IR bands of the NH2 stretching vibrations, which suggests rather weak NH⋯N hydrogen bonding. This latter is sufficient to stabilize the pinched-cone conformation in the chloroform solution, but the energy gap between the pinched-cone and other conformations is small, and solid-state intermolecular forces easily overcome it, leading to realisation of the 1,3-alternate conformer. The comparison of the DFT computed and experimental vibrational and NMR spectra demonstrates good quality of present quantum-chemical computations, allows complete interpretation of the spectra and reveals simple IR and NMR spectroscopic markers of the conformers of aminothiacalix[4]arenes. © 2009 Elsevier B.V. All rights reserved

Novel Azo-Dyes-Modified Isatin Derivatives: Synthesis, UV/VIS Spectroscopic, and Electrochemical Study

© 2016 Wiley-VHCA AG, ZürichA high-yield and simple synthesis of certain aminomethylisatins bearing dye fragments via the Mannich reaction of isatin with amino-containing azobenzenes was reported. It was found that the absence of electron-donating groups in azo-dye molecule prevents aminomethylation of isatin. The effect of the incorporation of an isatin moiety with an azobenzene dye in one molecule on its absorption and electrochemical behavior was studied using UV spectroscopy and cyclic voltammetry

Crystal Growth, Dynamic and Charge Transfer Properties of New Coronene Charge Transfer Complexes

© 2015 American Chemical Society. Two new coronene charge transfer complexes with F4-TCNQ of 2:1 and 1:1:1 (solvate with acetonitrile, MeCN) stoichiometry were obtained using crystal growth procedures from the solution and vapor phase. It was shown that mobility of coronene molecules in crystals is more affected by the asymmetry of its surrounding than by the composition and degree of charge transfer and interstack interactions. The combination of X-ray diffraction and electrochemistry in the solid state and a time-resolved one in solution allowed us to clarify the nucleation in solution showing that the formation of 2:1 coronene/F4-TCNQ complexes is thermodynamically preferable. The X-ray single crystal data for pristine coronene showed the crystal structure to be the same as at ambient temperature, raising doubt about the previously reported phase transitions at 140-180 K

Adsorption of methylene blue by biochar produced through torrefaction and slow pyrolysis from switchgrass

The present work involves a study of sorption of methylene blue (MB) by charcoal samples produced through torrefaction and pyrolysis processes from switchgrass (Panicum virgatum). The adsorption of MB was determined using the spectrometric analysis method at various pH, temperature values and MB concentrations. The heat treatment temperature during biochar production significantly influenced the surface chemistry of biochars indicating that biochar samples, based on their thermal history alone, can behave significantly differently in the rhizosphere or in their ability to adsorb pollutants. The pH of the solution containing MB significantly affected its adsorption by biochars but trends were markedly different. The concentration of MB was also affected adsorption behavior of the two charcoals. The results indicate that biochars can be produced with desired properties to solve specific agricultural or environmental needs

Adsorption of methylene blue by biochar produced through torrefaction and slow pyrolysis from switchgrass

The present work involves a study of sorption of methylene blue (MB) by charcoal samples produced through torrefaction and pyrolysis processes from switchgrass (Panicum virgatum). The adsorption of MB was determined using the spectrometric analysis method at various pH, temperature values and MB concentrations. The heat treatment temperature during biochar production significantly influenced the surface chemistry of biochars indicating that biochar samples, based on their thermal history alone, can behave significantly differently in the rhizosphere or in their ability to adsorb pollutants. The pH of the solution containing MB significantly affected its adsorption by biochars but trends were markedly different. The concentration of MB was also affected adsorption behavior of the two charcoals. The results indicate that biochars can be produced with desired properties to solve specific agricultural or environmental needs

Specific vapor sorption properties of phosphorus-containing dendrimers

Specific combination of guest sorption properties was observed for phosphorus-containing dendrimers, which distinguish them from ordinary polymers and clathrate-forming hosts. The sorption capacity for 30 volatile guests, binding reversibility, guest desorption kinetics and guest exchange, glass transition behavior and ability to be plasticized with guest were studied for phosphorus dendrimers of different generations (G1-G4 and G9) using quartz crystal microbalance sensor, FTIR microspectroscopy, atomic force microscopy, simultaneous thermogravimetry and differential scanning calorimetry combined with mass-spectrometry of evolved vapors. The dendrimers were found to have a different selectivity for different homological series of guests, high glass transition points without plasticization with guest even at high temperatures and saturation levels, moderate guest-binding irreversibility and ability both for effective guest exchange and independent guest sorption. These properties constitute an advantage of the studied dendrimers as receptor materials in various applications. © 2011 Elsevier Inc

Vibrational spectra of p-carboxylate and p-sulfonate azocalix[4]arene

The vibrational spectra of calixarenes with azobenzene units having sulfonate (p-SAC) and carboxylate (p-CAC) groups in the para position were recorded and analyzed. The optimization of the structure and analysis of normal vibration for calixarenes were performed using the DFT method. The calculated geometric parameters, the frequencies of the harmonic oscillations, the band intensities in the IR spectra, and the Raman scattering activity of the calixarenes are consistent with the experimental data. The p-CAC and p-SAC calix[4]arene molecules are in conical conformation due to the ring system of H-bonds along the low rim. The H-bond is weaker in the p-SAC molecule. The orientation of the aromatic moieties depends on the type of terminal functional groups. The energy differences between the E-and Z-forms of azobenzene groups in p-CAC and p-SAC are 60.8 and 62.6 kcal/mol, respectively. The experimental vibrational spectra of the calixarenes were interpreted using the potential energy distribution. Bands characteristic of trans and cis conformations of azobenzene fragments have been assigned. The HOMO and LUMO frontal molecular orbitals of the calixarene molecules are localized. The studied calixarenes can be used as antioxidants for thermal and light stabilization of polymer building materials

FT-IR and FT-Raman study of p-sulfonatocalix [8]arene

© 2019 Elsevier B.V. Spectral study indicates that the hydroxyl groups of calixarene are involved in the formation of intramolecular hydrogen bonds which stabilize the conformation of the pleated loop. Spectral characteristics, charge distribution, and reactivity of calix [8]arenes with tert-butyl (TB8) or sulfonate groups (SC8) were determined. From the IR data of SC8 and TB8, it follows that both substances have practically equal strong cooperative H-bonding. The torsion angles characterizing the conformation of the TB8 and SC8 molecules change. For the SC8 molecule, the pleated loop conformation is by 8.3 kcal/mol more stable than the double cone conformation. The substitution of tert-butyl groups for sulfonyl groups in calixarenes is accompanied by an increase in ionization energy, electronic affinity, chemical potential and dipole moment