الفهرس 
I. INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
In this work, a series of environmentally friendly Schiff base nonionic surfactants were synthesized throughout the following steps:- 1. Hydrolysis of the Jatropha oil to obtain the corresponding fatty acids and, 2. Reaction of the fatty acids with polyethylene glycols with different molecular weights (400, 600 g/mole), 3. Reaction of the obtained fatty acid polyethylene glycols with aminobenzoic acid to obtain (E400 and E600) 4. Synthesis of the Schiff bases of (E400 and E600) by their reaction with salicyldehyde and vanillin to obtain E400S, E600S, E400V and E600V. The chemical structures of the synthesized compounds were elucidated by infrared spectroscopic analysis, 1HNMR spectroscopy, (UV) ultraviolet spectroscopy . The surface properties of the synthesized compounds including:. Critical micelle concentrations (CMC), the surface tension at the critical micelle concentration (.cmc), the effectiveness (.cmc), the efficiency, Pc20,maximum surface excess, .max, and minimum surface area (Amin) were determined based on the surface tension measurements of their solutions at a wide concentration range. The thermodynamic properties of these compounds also in their solutions were determined including free energy of micellization (.Gmic) and the adsorption free energy (.Gads). The surface properties of the synthesized compounds showed their high activity at the interfaces which can be considered these compounds as good surfactants. Also, the thermodynamic data of adsorption process (.Gads) and the micellization process (.Gmic) showed the tendency of these compounds for adsorption at different interfaces and also toward micellization in the bulk of their solutions. Hydrophilic-lipophilic balance (HLB), Emulsion stability, and foam height were measured for synthesized Schiff base surfactants. The emulsification power is completely dependent on the space chain length. The synthesized surfactants showed different response towards emulsion stabilization. The synthesized surfactants have negligible tendency towards foam formation that enables their usage as useful additives in oilfield applications. Also, the biodegradability of E400V, E400S, E600V and E600S was evaluated using (Die.away test), The biodegradation ratios of the surfactants (Table 4) are ranged between 83.3% and 93.8% after 28 day. The chemical structures of the synthesized compounds were played an important role on their surface activity. Increasing the hydrophobic chain length (nonpolar chains) increases the surface activity and the tendency towards adsorption at the interfaces. The tendency of these compounds towards adsorption at the interfaces facilitated their application as corrosion inhibitors for carbon steel in acidic medium. The synthesized nonionic surfactants were evaluated as corrosion inhibitors against the corrosion of carbon steel in acidic medium (1 N H2SO4). The inhibitors firstly were screened for their efficiency using gravimetrical method (weight loss technique) at different doses: 50, 100, 200 and 400 ppm for different periods: 1, 3, 6 and 24 hours at 25 oC. Then, excessive studies were done for these inhibitors using gravimetrical, potentiodynamic and electrochemical impedance measurements. The results of polarization technique showed that the Tafel lines are shifted to more negative and more positive potentials for the cathodic and the anodic processes, respectively relative to the blank curve. This means that these additives influence both the cathodic and the anodic processes. Also, the same six compounds tested in polarization methods are evaluated by electrochemical impedance methods and the results showed that all techniques were relatively similar which proves the validity of these results. The results of the corrosion inhibition measurements were promising and some synthesized compounds were closely in the inhibition efficiency as the commercial inhibitor and in similar doses. So, these compounds can be used as corrosion inhibitors in petroleum industry because of its high efficiency and environmentally friendly.