Preparation, characterization, and theoretical studies of azelaic acid derived from oleic acid by use of a novel ozonolysis method

Environmentally friendly manufacture of organic compounds has been intensively reexamined in recent years. Many excellent methods have been devised to produce organic compounds from renewable resources. Azelaic acid has been produced by ozonolysis of oleic acid. The reaction was performed in a Bach bubbling reactor, with fine bubbles, at high temperature (150 °C) without utilizing any catalyst or any solvent. Yield of the reaction was 20% after 2 h. Production of azelaic acid was confirmed by use of FT-IR and ¹H NMR spectroscopic data and high-performance liquid chromatography of both synthesized and reference azelaic acid. A theoretical study was performed to obtain quantum chemical data for azelaic acid and to optimize the molecule’s geometry.     

Enhancement of 2-chlorophenol photocatalytic degradation in the presence Co<Superscript>2+</Superscript>-doped ZnO nanoparticles under direct solar radiation

The performance of Co²⁺-doped ZnO nanoparticles, prepared using the sol–gel method, for 2-chlorophenol degradation under direct solar radiation was investigated. Various parameters were investigated during the degradation process, namely solar intensity, Co²⁺ ion concentration, loading concentrations of Co²⁺-doped ZnO, and pH. The photocatalytic degradation efficiency increased when the initial concentration of 2-chlorophenol decreased; the optimum concentration was 50 mg/L under similar experimental conditions. Moreover, optimum values, established on a sunny day, were 0.75 wt% of Co²⁺, a 1 g/L loading concentration, and a pH of 6.0, respectively. The highest degradation efficiency observed was 95 %, after only 90 min of solar light irradiation. The mechanism of visible photocatalytic degradation using Co²⁺-doped ZnO was explained as a strong electronic interaction between Co²⁺, Co³⁺ and ZnO, and a promotion in the charge separation, which enhanced the degradation performance. The fragmentation of 2-chlorophenol under the optimal conditions was investigated using HPLC, comparing standards of all intermediate compounds. The pathway of the fragmentation was proposed as involving hydroxyhydroquinone, catechol, and phenol formation, which were then converted to non-toxic compounds such as oxalic acid and acetic acid with further decomposition to CO₂ and H₂O.     

Antimicrobial and antioxidant activities of new metal complexes derived from 3-aminocoumarin

3-Aminocoumarin (L) has been synthesized and used as a ligand for the formation of Cr(III), Ni(II), and Cu(II) complexes. The chemical structures were characterized using different spectroscopic methods. The elemental analyses revealed that the complexes where M=Ni(II) and Cu(II) have the general formulae [ML(2)Cl(2)], while the Cr(III) complex has the formula [CrL(2)Cl(2)]Cl. The molar conductance data reveal that all the metal chelates, except the Cr(III) one, are non-electrolytes. From the magnetic and UV-Visible spectra, it is found that these complexes have octahedral structures. The stability for the prepared complexes was studied theoretically using Density Function Theory. The total energy for the complexes was calculated and it was shown that the copper complex is the most stable one. Complexes were tested against selected types of microbial organisms and showed significant activities. The free radical scavenging activity of metal complexes have been determined by measuring their interaction with the stable free radical DPPH and all the compounds have shown encouraging antioxidant activities.     

Size and shape controlled of α-Fe2O3 nanoparticles prepared via sol–gel technique and their photocatalytic activity

Journal of Sol-Gel Science and Technology - Haematite (α-Fe2O3) nanoparticles (NPs) of different sizes and morphologies were prepared from two different iron precursors (iron acetate (A) and...     

The role of 4-amino-5-phenyl-4H-1,2,4-triazole-3-thiol in the inhibition of nickel–aluminum bronze alloy corrosion: electrochemical and DFT studies

Inhibition of corrosion of nickel–aluminum bronze alloy (NAB) by use of 4-amino-5-phenyl-4H-1,2,4-triazole-3-thiol (APTT) was investigated by monitoring weight loss and open-circuit potentials (OCP), and by use of electrochemical impedance spectroscopy (EIS). Quantum chemical data were calculated by use of the density functional theory (DFT) model. Results showed that APTT inhibits corrosion of NAB alloy fairly well. The efficiency of inhibition increases with increasing concentration of APTT, and adsorption of the inhibitor obeys the Langmuir adsorption isotherm model. Negative values of adsorption free energy indicate chemical adsorption is spontaneous. The theoretical study showed that sulfur and nitrogen atoms (S, N7 and N8) were the reactive sites.     

Photocatalytic degradation of chlorophenols under direct solar radiation in the presence of ZnO catalyst

The photocatalytic degradation of chlorophenols was evaluated under direct solar radiation using commercial ZnO catalyst. Effects of several parameters such as a catalyst loading, pH of solution and initial concentration on the degradation process have been investigated. The photocatalytic degradation efficiency of chlorophenols at the optimum value of the parameters was compared under similar experimental conditions. The results of efficiency and mineralization showed the degradation of 2-chlorophenol and 2,4-dichlorophenol compound with the first order kinetic rate and the rate constant decreases as the initial concentration of the chlorophenols increase. However, the rate constant was strongly affected by type of chlorophenols compound present either 2-chlorophenol or 2,4-dichlorophenol. The highest removal of chlorophenols was obtained after 120 min and the final intermediate compounds of chlorophenols degradation are lower molecular weight compound consisting of acetic acid which was analyzed through the HPLC.     

Corrosion Inhibition of Mild Steel in Hydrochloric Acid Environment Using Terephthaldehyde Based on Schiff Base: Gravimetric,Thermodynamic, and Computational Studies

Using traditional weight-loss tests, as well as different electrochemical techniques (potentiodynamic polarization and electrochemical impedance spectroscopy), we investigated the corrosion-inhibition performance of 2,2′-(1,4-phenylenebis(methanylylidene)) bis(N-(3-methoxyphenyl) hydrazinecarbothioamide) (PMBMH) as an inhibitor for mild steel in a 1 M hydrochloric acid solution. The maximum protection efficacy of 0.0005 M of PMBMH was 95%. Due to the creation of a protective adsorption layer instead of the adsorbed H₂O molecules and acidic chloride ions, the existence of the investigated inhibitor reduced the corrosion rate and increased the inhibitory efficacy. The inhibition efficiency increased as the inhibitor concentration increased, but it decreased as the temperature increased. The PMBMH adsorption mode followed the Langmuir adsorption isotherm, with high adsorption-inhibition activity. Furthermore, the value of the ∆Gadso indicated that PMBMH contributed to the physical and chemical adsorption onto the mild-steel surface. Moreover, density functional theory (DFT) helped in the calculation of the quantum chemical parameters for finding the correlation between the inhibition activity and the molecular structure. The experimental and theoretical findings in this investigation are in good agreement.