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The corrosion behavior of zinc in 0.2 M hydrochloric acid solution by Azadirachta indica(AI-Neem) was investigated using mass loss, electrochemical polarization and impedance methods. Inhibition efficiency depends on the concentration of AI-Neem and it reaches maximum value at 1,000 ppm. The shape of polarization profile indicated that AI-Neem is a mixed type inhibitor with predominant cathodic effect. Adsorption of AI-Neem on the zinc surface follows Temkin adsorption isotherm. The surface morphology of zinc was studied by using scanning electron microscope images.

The corrosion inhibition efficiencies of four compounds namely N-[(1E)-(2-chloroquinolin-3-yl) methylene]-N-phenylamine(CQMA), N-(1E)-(2-chloroquinolin-3-yl) methylene]-N-(4-fluorophenyl) amine (CQMFA), N-(4-chloro phenyl)-N-[(1E)-(2-chloroquinolin-3-yl) methylene] amine (CQMCA), and N-(4-bromo phenyl)-N-[(1E)-(2-chloroquinolin-3-yl) methylene]amine (CQMBA) on mild steel corrosion in hydrochloric acid media were investigated using mass loss, potentiodynamic polarization and electrochemical impedance spectroscopy. For all the studied inhibitors the inhibition efficiency values were found to increase with increasing concentration up to 5.00 × 10−4mol · dm−3. Scanning electron microscopic technique showed the formation of a thick film on the steel surface in the presence of inhibitors.

Nanoparticles of zinc oxide were synthesized by a simple and low-cost method using gelatin as organic precursor. Techniques of X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to characterize the structure and property of the zinc oxide. The results show that the ZnO nanoparticles with high crystallinity can be obtained using this simple method. Gelatin plays an important role in the formation of the ZnO nanoparticles. Moreover, the composite film was prepared by synthesized ZnO nanoparticles, multi wall carbon nanotube (MWNT) and polycaprolactone (PCL) on glassy carbon electrode (ZnO–MWNT–PCL–GCE). The porous ZnO–MWNT–PCL film was used as a supporting matrix to immobilize Co(ii) ions. Immobilized Co ions exhibit excellent electrocatalytic activities to glucose oxidation. The sensor responded linearly to glucose in the concentration of 5.0 × 10−5to 6.0 × 10−3M with detection limit of 1.6 × 10−5M at 3σusing cyclic voltammetry (CV). Moreover, the studied biosensor exhibited good reproducibility and long-term stability. Furthermore, the fabricated electrode displayed voltammetry response to the glucose in human blood serum and the results were matched with referenced values obtained by the standard technique.

The liquid phase acetylation of anisole by acetic anhydride (anisole:acetic anhydride in a molar ratio of 2:1) using zeolite HBEA (Si/Al=11) as catalyst was carried out in a batch reactor at 90°C, without and with addition of the product, p-methoxyacetophenone (p-MOAP) (molar ratio anisole/p-MOAP=3 and 6). As expected, acetic acid and p-MOAP are produced in equal amounts during the initial stages of the reaction but acetic acid is consumed at long reaction time and high conversion. Partial zeolite dealumination of the used catalyst was evidenced by 27Al MAS NMR spectroscopy and the regenerated catalyst showed a lower activity agreeing with its reduced Al content, i.e., acidity. Without added p-MOAP, acetylation occurs rapidly at low conversion but deactivation becomes important as conversion increases. The reaction rate is largely decreased when p-MOAP is added to the reaction mixture, indicating inhibition of the reaction by p-MOAP. A detailed kinetic analysis using a Langmuir–Hinshelwood model was performed to quantify the nature and extent of the reaction inhibition by p-MOAP. It shows that the adsorption equilibrium constant for p-MOAP exceeds by a factor of at least 6 the adsorption equilibrium constant for any of the reactants and that the occupancy of the intracrystalline volume of the zeolite by p-MOAP increases rapidly with conversion, thereby reducing the access of the reactants to the catalytic sites. Comparison of our results with literature data enabled us to derive an approximate activation energy for this reaction, i.e., ca. 11 kcal mol−1. A good agreement is observed between the calculated and experimental reaction rates as a function of conversion. It is concluded that the deactivation of the catalyst as conversion increases is mainly due to product inhibition, i.e., the competitive adsorption of the reactants and products in the zeolite intracrystalline volume which can be rationalized in terms of the zeolite acting as a solid solvent. Our work suggests that the application of zeolites and other microporous solids as catalysts to fine chemicals synthesis would be better performed using catalytic reactor configurations minimizing the role played by competitive adsorption effects.

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