Papers by Keyword: Salicylic Acid

Abstract: This research has prepared Fe₃O₄/SiO₂/TiO₂-S composite materials as magnetic photocatalysts. Detailed characterization of the composite materials was undertaken using FTIR, XRD, TEM, VSM and DRUV. The photocatalytic activity of composite materials was conducted through salicylic acid degradation under visible light illumination. The result based on the infrared spectra and XRD diffractogram revealed the appearance of the characteristic peak of Fe₃O₄, SiO₂, and S-TiO₂. The sulfur doping causes an absorption edge shifts toward a higher wavelength. Fe₃O₄/SiO₂/TiO₂-S 3% composite material had the narrowest band gap energy of 2.77 eV and presented good photocatalytic activity with a percentage degradation of 91.6% under visible light during 60 minutes of illumination time. The composite exhibited recoverable efficiency due to its magnetic properties.

Abstract: The electrospinning technique is being widely used in the fabrication of micro and nanofibers, with a myriad of biomedical applications such as drug inoculation, tissue regeneration and scaffold production. In the present article, nanofibers based on polyvinyl alcohol (PVA), chitosan (C) and salicylic acid (SA) were developed experimentally. Solutions at 18% w/w of PVA and 3% w/w of C and SA were prepared using always distilled water as solvent. Solution with C and SA (labelled as CSA solution) had the same amount of both substances in it. Then, mixtures at 100/0, 98/2, 96/4, 93/7 and 90/10 in PVA/CSA weight ratio were prepared. The rheological behavior of the solutions was evaluated and they were subsequently electrospun. The samples were characterized by scanning electron microscopy, differential scanning calorimetry and Fourier transform infrared spectroscopy in attenuated total reflection mode.

Abstract: The in situ chemical deposition of polypyrrole (Ppy) in presence of different concentrations of salicylic acid (SA) directly at copper 99.9% surface in ethanol solution using hydrogen peroxide as catalyst was studied. In all the concentrations, 50.0, 25.0, 12.5 and 6.25 mmol L^-1 the polymerization was possible. The layer formed on the copper surface showed to be adherent and homogeneous. Its morphology presented as compact microspheres. The polarization curves showed a positive displacement in the corrosion potential of copper with undoped Ppy when compared to the polished copper surface. Copper surfaces containing doped Ppy-SA also showed an increase to the positive direction in the corrosion potential and the corrosion current density decreases more sharply in the presence of SA as dopant. These results indicated that Ppy+SA can act as a protective layer on copper surface and improve the corrosion protection. The protection efficiency of the coating was Cu surface < Cu+Ppy < Cu+Ppy+SA 50.0 < Cu+Ppy+SA 25.0 < Cu+Ppy+SA 12.5 < Cu+Ppy+SA 6.25 mmol L^-1.

Abstract: Molecular and lattice vibration frequencies of solid-state salicylic acid were studied in the Terahertz (THz) and Mid-Infrared (Mid-IR) ranges. The calculation of the THz and Mid-IR spectra of salicylic acid which was based on the solid-state density functional theory (DFT) was carried out. Experimental studies were conducted by THz absorbance spectroscopy and Fourier transform infrared spectroscopy (FTIR) methods. Vibrations revealed in “finger-print” spectrum of salicylic acid were compared with the typical vibrations of groups of atoms that make up organic molecules.

Abstract: Plant growth is impressed by biotic and abiotic stress inversely. There are many reports about proteins change level in salinity stress. Leaves fill up more soluble sugar of glucose, fructose and proline with treatment of salicylic acid. In this study, Citrullus lanatus seeds planted in pots containing perlite were put in a growth chamber under controlled conditions of 30 ±2 °Cand 14 ±2 °Ctemperature, 14h lightness and 10h darkness; NaCl concentration of 0,4,8,12 ds/m and salicylic acid concentration of 0,1,2,4 mM were used in the form of factorial experiment in a complete randomized design (CRD). The results demonstrated that increasing of proline and sugars due to osmotic slope in plants lead to increasing of tolerance against dehydrations of leave content and acceleration of plant developments in stress conditions.

Abstract: The effect of salicylic acid/ethanol as a coupling agent on the tensile properties and thermal stability of recycled high density polyethylene/wood fiber (rHDPE/WF) composites were studied. Both composites rHDPE/WF and rHDPE/WF_M (treatment with salicylic acid) were prepared using Brabender Plasticorder at temperature of 160°C and rotor speed of 50 rpm. The result indicated that rHDPE/WF_M composites with salicylic acid exhibit higher tensile strength and modulus of elasticity and lower elongation at break than rHDPE/WF composites. It was also found that the addition of salicylic acid/ethanol shows better thermal stability in rHDPE/WF_M composites than rHDPE/WF composites.

Abstract: The present work reports on complexation of hydroxypropyl-β-cyclodextrin (HP-β-CD) with salicylic acid (SA) by vacuum evaporation and inclusion behavior confirmed by FT-IR, OM and SEM. Complex stoichiometry, release mechanism and skin sensitivity were evaluated. The results showed that SA could be encapsulated into cyclodextrin at the ratio of 1:1. Negative values of Gibbs free energy, enthalpy and entropy changes indicated a feasible, spontaneous and exothermic process. Release studies evidenced a burst release in first 2 h, followed by a sustained release and the release rate was temperature-dependent. Furthermore, an improved water solubility and significant reduced irritation effect of SA could be obtained by HP-β-CD.

Abstract: The effect of salicylic acid as a coupling agent on the tensile properties, and morphology analysis of recycled high density polyethylene/wood fiber (rHDPE/WF) composites were studied. Both composites rHDPE/WF and rHDPE/WF_M (treatment with salicylic acid) were prepared using Brabender Plasticorder at temperature of 160°C and rotor speed of 50 rpm. The result indicated that rHDPE/WF_M composites with salicylic acid exhibit higher tensile strength and modulus of elasticity but lower elongation at break than rHDPE/WF composites. The SEM micrographs showed that the wood fiber was more widely dispersed in the rHDPE matrix with addition of ethyl salicylate than rHDPE/WF_M.

Abstract: In the paper the results of control drug release from different forms of carriers are presented. Dibutyrylchitin, chitosan, polylactid acid and polycaprolactone have been used as matrices for delivery of therapeutic substances (ibuprofen and salicylic acid). Two configurations of matrices for drug delivery have been found. Flat drug delivery systems (films) and spherical matrices (beads) were tested in the aim of control drug transport. To control the drug release, matrices have been modified. The release of active substances from films has been tested in buffer solution of pH 5.5. Spherical matrices have been tested in buffer solutions of pH 1.4 and pH 7.2. To experimental data First order and two stage models were fitted.

Abstract: Fe³⁺ doped Bi₂MoO₆ photocatalyst was successfully synthesized via a hydrothermal process using Bi (NO₃)₃ and (NH₄)₆ Mo₇O₂₄4H₂O as starting materials. XRD, SEM and UV-Vis absorption spectrum techniques were employed to characterize the phase composition and spectrum properties of the as-synthesized samples. Salicylic acid was selected as a model pollutant to investigate the effect Fe³⁺ doping on the photocatalytic activity of as-synthesized Bi₂MoO₆. The experimental results indicated that Fe³⁺ element doping can enhance the photocatalytic activity of Bi₂MoO₆ photocatalyst. When the amount of Fe³⁺ doped in Bi₂MoO₆ is 0.5%, the photocatalyst exhibits the best photocatalytica activity. The doped Fe³⁺ doped into the crystal lattice of Bi₂MoO₆ photocatalyst act as the electron traps and facilitates the separation of the separation of photogenerated electron-hole pairs due to its electron deficient. Thus, Fe³⁺ doping improve the photocatalytic with great efficiency.