【正文】 一種新型系列自組裝非離子型兩親 Schiff堿被合成，它們的化學(xué)結(jié)構(gòu)用元素分析法確定，紅外光譜和核磁共振氫譜。表面 狀況數(shù)據(jù) 和熱力學(xué)數(shù)據(jù)顯示它們對(duì)在界面吸附有較大的傾向 。 1. Introduction Ferrous, nonferrous metals and their alloys are extensively used in industry. To remove unwanted scale and salt deposits or mill scales formed during manufacture, metals are immersed in acid solutions, which are known as an acid pickling bath. After the scale is removed, the metal may be subjected to attack by the acids. In order to reduce the degree of metal attack and rate of consumption of the acid, corrosion inhibitors are added to the pickling solutions Hydrochloric and sulphuric acids are the most monly used acids in the pickling bath [1,2]. Most mercial inhibitor formulations include aldehydes and amines in their structure [3,4]. The choice of the inhibitors is based on two considerations: first, they could be synthesized conventionally from relatively cheap raw materials。為了降低金屬受腐蝕的程度和酸液的消耗速率，我們需要在酸洗液中添加緩蝕劑。 這些物質(zhì)通常 能 有效地吸附在金屬表面。 實(shí)驗(yàn)結(jié)果發(fā)現(xiàn)， 結(jié)果發(fā)現(xiàn)， 含有雜原子化合物 的致密 自組裝單層 能 有效阻止某些電化學(xué)過程，從而 能夠作為有效的緩蝕 劑 。 2. Experimental procedures . Synthesis of Schiff bases mol of anisaldehyde was condensed with mol of paminobenzoic acid in the presence of 250 mL of ethyl alcohol as a solvent. The reaction mixture was refluxed for 6 h and then left overnight until the product was precipitated. The product was washed by petroleum ether and recrystallized from ethanol. The final product was dried under vacuum at 40 ?C [15]. The produced Schiff base was denoted as SB and the chemical structure was represented in Scheme 1. Scheme 1. Chemical structure of the synthesized Schiff base. Scheme 2. Chemical structure of the synthesized nonionic Schiff base. 茴香醛 和 250mL的無水乙醇做溶劑。合成的席夫堿記為 SB，化學(xué)結(jié)構(gòu)式 如 方案 1表示。真空蒸餾除去未反應(yīng)的物料和溶劑，方案 2 .記非離子型席夫堿產(chǎn)物為 SBPEG鏈烷酸（ R），列在表 1中。此外，界面張力測量在緩蝕劑 油的體系中進(jìn)行 [17]。測試的樣品用蒸餾水和乙醇洗滌后，干燥，稱重。 . Hydrogen gas evolution technique In the gas evolution measurement, the corrosion rates of aluminum were investigated by the hydrogen evolution rate with the inhibitors concentrations of 400, 200, 100, 50, 25 and 10ppm and 4N HCl solution without inhibitors. The hydrogen evolved is a function of the corrosion reaction and it displaced the fluid in the gasometeric setup, which is read directly. Experiments performed without inhibitors recorded the highest volume of hydrogen gas evolved [19]. The percentage efficiency was calculated as %Efficiency =[Vb ? V / Vb ] where Vb and V are the volumes of hydrogen evolved without and with inhibitors, respectively. . 析氫技術(shù) 在氣體 析出 實(shí)驗(yàn)測試中， 用氣體的變化速率考察鋁在含加有濃度為 400,200,100,50,25 和 10 ppm緩蝕劑以及沒加緩蝕劑的 4N HCl溶液中的腐蝕速率。 3. Results and discussion . The surface activity . Effect of hydrophobic chain length (nonpolar chain) Fig. 1 represents the relation between the surface tension and ?log concentration of the synthesized nonionic Schiff base amphiphiles containing similar polyethylene glycol content (n=45 EO units) at 25 ?C. It is clear that the surface tension profile has the characteristics of the nonionic surfactants. That appeared in the relatively higher surface tension values. Also, it could be observed that increasing the number of methylene groups along the hydrophobic chains from 10 to 18 units decreases the critical micelle concentrations gradually [17]. That effect was explained in a previous work [20,21] due to the repulsion occurred between the hydrophobic chains (nonpolar phase) and the water phase (polar phase), which forced the molecules to adsorb at the air– water interface and to micellize in the bulk of their solutions in order to decrease that repulsion. While, the lowest critical micelle concentration was found at base containing PEO2020 and the hydrophobic chains is oleate (Table 2), which referred to the above reasons and also to the unsaturation sites in the oleate chain which increases the repulsion extent. The effectiveness (π cmc) values showed gradual decrease by increasing the hydrophobic chain length indicating the increasing of accumulated surfactant molecules at the interface. The maximum accumulation was indicated by the lowest surface tension depression at the critical micelle concentration and was recorded for SB2020oleate molecules at 44 mN/m . The effectiveness values as well as the maximum surface excess considered as a clear description for the accumulation extent of amphiphiles molecules at the air– water interface. The calculated values of the maximum surface excess showed increasing trend from SB2020decanoate to SB2020oleate as represented from the slope of preCMC region of surface tension profile (Fig. 1). The maximum surface excess values were increased from decanoate to oleate derivatives indicating higher surface concentration and increasing number of surfactant molecules at the interface. Values of the minimum surface area occupied by the nonionic Schiff base amphiphiles at the interface (Amin) were calculated according to the equation: