Article Highlights • Broken honeycomb-like perlite structure as catalyst support • Morphological, textural, and structural characteristics of Ni and Mg influence • Correlation between reducibility and hydrogen chemisorption • Evaluation of lowest reduction temperature for catalyst preparation • Catalyst behavior due to Ni and Mg influence in hydrogenation process Abstract Use of broken honeycomb-like expanded perlite as support for magnesium modified nickel catalysts in process of partial hydrogenation of sunflower oil was studied. By the use of the precipitation-deposition method, two groups of precursors were synthesized: different Ni/SiO 2 mole ratios with constant Mg/Ni mole ratio 0.1, and different Mg/Ni mole ratios with constant Ni/SiO 2 mole ratio 0.25. Characterizations of precursors were done (scanning electron microscopy, diffuse reflectance UV-Vis, infrared spectroscopy, N 2-physisorption, temperature programmed reduction (TPR) and He-pycnometry) to determine the material differences, considering the change in morphology, structure, texture and reducibility with overall Ni and Mg content. In addition, TPR and hydrogen chemisorption were performed in order to estimate the temperature reduction range of supported precursors and the dispersion degree of nickel in reduced precursors, respectively. The interaction between Ni 2+ and perlite support was established. Different reducibility and dispersion were obtained as a function of Ni/SiO 2 and Mg/Ni mole ratios. After the precursor's reduction and paraffin oil impregnation, the obtained catalysts were tested in a sunflower oil hydrogenation reaction. Catalyst activity was monitored through the decrease of the refractive index and hydrogen consumption that gave the insight that the influence on catalyst activity represents the accessibility of triacylglycerols and not always the hydrogen determined dispersion degree.
In this paper, macroporous glycidyl methacrylate and ethylene glycol
dimethacrylate copolymer functionalized with diethylene triamine [PGME-deta],
was evaluated as Reactive Black 5 (RB5) sorbent. Batch RB5 removal from
aqueous solution by PGME-deta was investigated by varying pH, contact time,
sorbent dosage, initial dye concentration and temperature. The sorption is pH
sensitive having maximum at pH 2 (dye removal of 85%), decreasing with the
increase of pH (dye removal of 24% at pH=11) after 60 min. Sorption kinetics
was fitted to chemical-reaction and particle-diffusion models
(pseudo-first-order, pseudo-second-order, intraparticle diffusion and Mckay
models). The pseudo-second-order kinetic model accurately predicted the RB5
amount sorbed under all investigated operating conditions, while the
intraparticle diffusion was the dominant rate-limiting mechanism. The
diffusion mechanism was more prevalent with the decrease in temperature and
the increase in concentration. The isotherm data was best fitted with the
Langmuir model, indicating homogeneous distribution of active sites on
PGME-deta and monolayer sorption, with the maximum sorption capacity of 353
mg g-1. The calculated sorption rates improved with increasing temperature
and an activation energy close to 40 kJ mol-1 was determined, suggesting that
chemisorption was also rate-controlling. [Projekat Ministarstva nauke
Republike Srbije, br. III 43009, br. TR 37021 i br. III 45001]
The effect of cyclodextrin (beta-CD) on the solubility and dissolution rate of various paracetamol dispersion powders (1:1 w/w), and tablets was studied. Lower solubility was exhibited by a spray dried solid dispersion made from paracetamol-Ethocel-Macrogol 6000 (95:2:3). The improvement in solubility was influenced by complexation with beta-CD and the crystalline nature of the powder products made by different procedures. The difference in crystallinity was confirmed by X-ray powder diffraction patterns. The dissolution rate of paracetamol from tablets made from the solid dispersions was satisfactory compared with paracetamol alone. The differences between the dissolution rate from the examined paracetamol tablets resulted from the different solubility of each powder and from the structural changes of particles which influenced the consolidation of the tablet mass.
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