A systematic study on anti-corrosion and anti-fouling effect of hydrophobic Langmuir-Blodgett and self-assembled molecular layers deposited on metal surfaces, as well as anti-microbial adhesion properties of coatings with biocide is presented. Both types of efficiencies produced by LB films are enhanced by Fe 3þ ions built in the molecular film. The quaternary ammonium type biocide embedded into the cross-linked gelatin decreased significantly the microbial adhesion, the biofilm formation.

No abstract

Langmuir-Blodgett films (LB) of hydroxamic amphiphiles were used as coating barriers on metal surface against corrosion. Two long-chain hydroxamic acids [CH3(CH2)16CONHOH] monolayers in the presence of some divalent cations (Ca2+, Mg2+, and Cu2+) have been studied at different pH of the subphase. The monolayer was characterized by surface pressure-area isotherms and visualized by Brewster angle microscope (BAM). Compact Langmuir layers were deposited on copper surface, where the modified surfaces were characterized by contact angle measurement as well as by electrochemical techniques. The morphology of LB coated copper surface was visualized by atomic force microscopy (AFM). The coated copper surfaces were tested in corrosive media at acidic and neutral pH. The results show that the multi-molecular LB films of hydroxamic acid salts form good barriers against copper corrosion. The comparison of these results with copper coated by LB layers without divalent cations shows that the presence of divalent cations in the subphase increases the copper corrosion inhibition. The octadecanoyl hydroxamic acid (C18N) results in better and more stable monolayer with cations in the subphase.

Free of ions of Octadecanoyl monohydroxamic acid (C18N) and in the presence of Fe3+ ion multilayers were deposited on the copper surface as Langmuir-Blodgett (LB) films. Their inhibiting effect on copper corrosion was investigated in 0.1 M sodium sulfate solution by different techniques such as potentiodynamic polarization and by electrochemical impedance spectroscopy (EIS). As well as that, the copper surfaces were visualized using a Scanning electron microscope (SEM). The results showed that the highest inhibition efficiency (92%) was achieved by LB film of 5 monomolecular layers of C18N/Fe3+. The LB films work as a cathodic inhibitor which inhibits the cathodic reaction. The presence of Fe3+ ions significantly improves the inhibition efficiency through the formation of a more compact dense layer of C18N/Fe3+ complex that blocks the flux of aggressive ions to the metal surface. The effect of immersion time on the inhibiting characteristics of LB films on the copper surfaces was studied.

The kenics static mixer (KMS) has been profoundly used in water and wastewater treatment processes, essentially in water ozonation for oxidation and disinfection purposes. since higher concentration of ozone is required, new contactors which operate efficiently at low gas/liquid ratio has been developed. The Kenics static mixer can fulfil these demands which lead to increase in the ozone mass transfer rate [1]. The main purpose of this paper is to use the steady state back flow cell model (BFCM) developed by Tizaoui and Zhang [1] so as to estimate the concentration profile of ozone in the liquid and the gas phases along the KMS.  The study also aim to develop a Matlab code for the BFCM of the static mixer.  Moreover, this research studied the effect of the main operating parameters: volumetric liquid mass transfer coefficient  ,the length of the Kenics static mixer, flow rate of water , and gas flow rate , back flow ratio and the temperature on ozone concentration profile in the gas and liquid phases  and  respectively along the height of the Kenics static mixer.

No abstract