枸杞中甜菜碱的提取及其缓蚀性能研究

Study on Extraction and Corrosion Inhibition of Betaine in Lycium Barbarum

为了开发一种环保型天然缓蚀剂,采用纤维素酶酶解法提取枸杞中的甜菜碱,在单因素实验的基础上,采用响应面实验优化提取工艺,并研究了甜菜碱粗提液和粗提液与聚天冬氨酸复配物对Q235碳钢在硫酸溶液的缓蚀作用及其机理。结果表明,枸杞中甜菜碱的最佳提取工艺条件为:酶解时间为59 min,酶解温度为46℃,酶解pH值为3,纤维素酶用量为3 mg/g,液料比为25∶1 mL/g,甲醇体积分数为80%。在最优工艺参数下,枸杞中甜菜碱的提取率为20.34%,与模型预测值20.45%吻合良好。缓蚀实验表明,枸杞甜菜碱粗提液在硫酸介质中对碳钢具有良好的缓蚀效果,缓蚀效率随粗提液浓度的增大而升高,30℃下,当甜菜碱粗提液的浓度达到250 mg/L时,缓蚀效率可达到90%以上;与聚天冬氨酸复配后,缓蚀效率明显提高。甜菜碱粗提液及其复配物均为混合型缓蚀剂,可有效吸附在碳钢表面形成一层保护膜,吸附过程遵循Langmuir等温方程式,二者在碳钢表面的吸附均属于自发过程,属于以物理吸附为主的物理吸附和化学吸附共同作用的过程。

In order to develop an environment⁃friendly natural corrosion inhibitor,betaines in Lycium barbarum were extracted using cellulose.On the basis of single factor experiment,the extraction process was optimized by response surface methodology,and the inhibitory performance and mechanism of betaine crude extracting solution and its compound with polyaspartic acid for Q235 carbon steel in H 2 SO 4 solution were stud⁃ied.Results showed that the best conditions for the extraction of betaines from Lycium barbarum were an enzymolysis time of 59 min,an enzy⁃molysis temperature of 46℃,an enzymolysis pH value of 3,a cellulose dosage of 3 mg/g,a liquid⁃solid ratio of 25∶1(mL/g)and a metha⁃nol concentration of 80%(volume fraction).Under these conditions,the extraction rate of betaines was 20.34%,which was consistent with the predicted extraction rate 20.45%.The corrosion inhibition experiments exhibited that the betaine crude extracting solution of Lycium barbarum had good corrosion inhibition performance for carbon steel in sulfuric acid,and its inhibition efficiency increased with the rise of the concentra⁃tion of betaine crude extracting solution.The inhibition efficiency reached more than 90%at 30℃when the concentration of betaine crude ex⁃tracting solution reached 250 mg/L.After being combined with polyaspartic acid,the inhibition efficiency was enhanced obviously.Besides,both the betaine crude extracting solution and its complex were mixed⁃type inhibitors,which could be adsorbed on the surface of carbon steel to form a protective film.The adsorption process could be well described with Langmuir adsorption isolliemi equation.The adsorptions of betaine crude extractive and its complex on carbon steel surface were both spontaneous process dominated by physical adsorption in association with chemical adsorption.