L-半胱氨酸改性聚环氧琥珀酸的合成及其阻垢缓蚀性能

Synthesis of L-cysteine modified polyepoxysuccinic acid and evaluation of its inhibition on scale deposition and corrosion

以L-半胱氨酸(LCY)为改性剂改性聚环氧琥珀酸(PESA)得到了一种聚环氧琥珀酸衍生物L-半胱氨酸改性聚环氧琥珀酸(LCY-PESA),用红外光谱和核磁共振谱表征了LCY-PESA的物质结构,用红外光谱、X射线衍射光谱和扫描电镜研究了钙垢的晶型(形),探讨了LCY-PESA的静态阻垢、动态阻垢、静态缓蚀、分散氧化铁和生物降解等性能,通过量子化学计算方法研究了LCY-PESA的缓蚀机理。静态阻垢结果表明,在c(Ca2+)为400mg·L?1、c(3HCO?)为800 mg·L?1的实验介质中,LCY-PESA投放量为6 mg·L?1,阻垢率即可达到94.6%;当c(Ca2+)为150 mg·L?1、c(Fe2+)为10 mg·L?1、LCY-PESA投放量为15 mg·L?1时,最小透光率为61.5%。动态阻垢测试显示:随着加药量的增加,动态污垢热阻减小,当加药量为1 mg·L?1时LCY-PESA的动态阻垢率比PESA提高了约15%。红外光谱、X射线衍射光谱和扫描电镜结果表明,LCY-PESA对钙垢有明显的晶格扭曲作用,把方解石变为球霰石,表现出良好的阻垢分散性能。该衍生物还表现出了优良的可生物降解性能。量子化学计算表明:LCY-PESA分子中的S原子和N原子对HOMO轨道的电荷密度影响较大,导致LCY-PESA的HOMO轨道和LUMO轨道的能隙差值小于PESA分子的能隙差值,因此LCY-PESA分子抑制金属腐蚀的效果好于PESA。

A polyepoxysuccinic acid derivative（LCY-PESA） was synthesized from polyepoxysuccinic acid（PESA） and L-cysteine（LCY） as well as characterized by infrared（IR） and nuclear magnetic resonance（NMR） spectroscopy. The new LCY-PESA polymer was evaluated on inhibition of static and dynamic scale deposition, static corrosion inhibition, iron oxide dispersion, and biodegradation. The mechanism of corrosion inhibition was further explored theoretically by quantum chemistry modeling on molecular orbitals of the LCY-PESA polymer. In a medium containing Ca2＋ at 400 mg·L-1 and 3HCO- at 800 mg·L-1, the inhibition on static scale deposition reached up to 94.6% with addition of LCY-PESA at 6 mg·L-1. The minimum light transmittance was 61.5% when 15 mg·L-1 LCY-PESA was introduced to a clear medium of Ca2＋ at 150 mg·L-1 and Fe2＋ at 10 mg·L-1. The heat resistance of dynamic scale deposition decreased upon LCY-PESA addition to medium. At concentration of 1.0 mg·L-1, LCY-PESA had about 15% higher inhibition on dynamic scale deposition than PESA. Analysis on crystal structure of calcium carbonate scale deposits by infrared spectroscopy（IR）, X-ray diffraction（XRD）, and scanning electron microscopy（SEM） indicated that LCY-PESA could significantly distort calcium carbonate crystals such that the steady calcite was transformed to vaterite. Further experimental results showed that the new polymer had good scale dispersion and biodegradability. Molecular simulation showed that the sulfur and nitrogen atoms of LCY moiety strongly alter electron density of the highest occupied molecular orbital（HOMO） of the LCY-PESA molecule so that the energy gap（ΔE） between HOMO and LUMO（the lowest unoccupied molecular orbital） of LCY-PESA is less than that of PESA, which could improve corrosion inhibition of LCY-PESA polymer.