固定化酶在柴油泄漏下循环冷却水中的应用研究

发布时间：2018-06-02 16:18

本文选题：循环冷却水 + 油品泄漏　；参考：《中国石油大学(华东)》2015年硕士论文

【摘要】：在我国石油炼化企业中,由于密封技术落后、换热器质量差、管线老化和操作不当等原因,普遍存在着油品泄漏问题。泄漏的油品在装置中与循环冷却水混合,不仅影响了循环冷却水的换热性能,而且加剧了设备的腐蚀。因此,开发可应用于油品泄漏情况下循环冷却水中的水处理剂是当务之急,有利于提高循环冷却水水质,保证循环冷却水系统的正常运行,是节约淡水资源和合理使用水资源的有效途径。本论文重点研究了固定化生物酶在油品泄漏情况下循环冷却水系统中的应用。(1)合成固定化载体:采用溶胶-凝胶法合成介孔SiO_2微球,并利用TEM、BET、FT-IR等对其进行表征。(2)以合成的介孔SiO_2微球为载体,分别固定化漆酶、溶菌酶、脂肪酶,考察3种固定化酶的酶学特性,并且分析它们的缓蚀效果。(3)采用物理吸附法共固定化溶菌酶和脂肪酶,利用Design Expert软件优化固定双酶的最佳条件。(4)将固定化双酶应用于循环冷却水模拟系统装置中,分析其对柴油泄漏下循环冷却水的作用效果。实验表明:(1)溶胶-凝胶法合成介孔SiO_2微球的介孔孔径均匀,比表面积为1088.9m2/g,孔径分布在2-3 nm之间,平均孔径为2.55 nm,且孔径均匀。(2)以制得的介孔SiO_2微球为载体,先吸附戊二醛,再通过共价结合固定化漆酶。最佳固定条件是戊二醛浓度为0.75%(v/v),作用时间为8h,给酶量为0.04L/L,固定化时间为10h。向柴油浓度为80mg/L的循环冷却水中投加0.8g/L的固定化漆酶时,缓蚀率达到最高,为49.23%。(3)用物理吸附法固定化溶菌酶的最佳给酶量为0.8g/L,最佳固定化时间为10h,最佳固定化pH为6.5,最佳缓冲液离子浓度为50mmol/L。向80mg/L柴油浓度的循环冷却水中投加0.7g/L固定化溶菌酶,缓蚀率可达到78.21%。(4)固定化脂肪酶的最佳固定化条件:脂肪酶给酶量为1.5g/L,固定化时间为8h,固定化pH为8,固定化缓冲溶液离子强度为25mmol/L。当向80mg/L柴油浓度的循环冷却水中投加0.8g/L的固定化脂肪酶时,缓蚀率可达到61.7%。(5)在单因素实验的基础上,考察以溶菌酶浓度、溶菌酶固定化时间、脂肪酶浓度、脂肪酶固定化时间4个因素为自变量,在酶活力最佳时候的水平值为中心点,缓蚀率为响应值,采用Box-Behnken法进行4因素3水平响应面分析优化。共固定化溶菌酶和脂肪酶的最佳条件为:溶菌酶浓度为0.88g/L,溶菌酶固定化时间为11.81h,脂肪酶浓度为2.07g/L,脂肪酶固定化时间为9.22h,此时预测缓蚀率最高为86.10%。(6)共固定化酶与活性炭1:2的体积配比制成混合滤料,过滤出水中柴油的浓度可降为2.1mg/L,除油率可达97%。混合滤料过滤后的出水对碳钢的腐蚀速率有明显的下降,从0.2106mm/a降至0.0818mm/a,即缓蚀率达到61.16%。
[Abstract]:In the petroleum refining and chemical enterprises of our country, due to the backward sealing technology, poor quality of heat exchangers, aging of pipelines and improper operation, oil leakage is common. The leaking oil mixed with the circulating cooling water not only affects the heat transfer performance of the circulating cooling water, but also intensifies the corrosion of the equipment. Therefore, it is urgent to develop the water treatment agent that can be used in circulating cooling water in the case of oil leakage, which is helpful to improve the quality of circulating cooling water and ensure the normal operation of the circulating cooling water system. It is an effective way to save fresh water resources and make rational use of water resources. In this paper, the application of immobilized biological enzymes in circulating cooling water system under oil leakage was studied. The immobilized carrier was synthesized by sol-gel method, and the mesoporous SiO_2 microspheres were synthesized by sol-gel method. The immobilized laccase, lysozyme and lipase were immobilized on the mesoporous SiO_2 microspheres. The inhibition effect of the two enzymes was analyzed. The physical adsorption method was used to co-immobilize lysozyme and lipase, and the optimal conditions for immobilization of double enzymes were optimized by Design Expert software. 4) the immobilized double enzymes were applied in the system of circulating cooling water simulation. Its effect on circulating cooling water under diesel oil leakage is analyzed. The experimental results show that the mesoporous SiO_2 microspheres synthesized by the sol-gel method have homogeneous mesoporous pore size, a specific surface area of 1088.9m2 / g, pore size distribution between 2-3 nm and an average pore size of 2.55 nm, and an average pore diameter of 2.55 nm. Then the immobilized laccase was immobilized by covalent binding. The optimal immobilization conditions were as follows: glutaraldehyde concentration was 0.75g / v / v, the time of action was 8h, the amount of enzyme was 0.04L / L, and the immobilization time was 10h. When the immobilized laccase of 0.8g/L was added to the circulating cooling water with diesel fuel concentration of 80mg/L, the corrosion inhibition rate reached the highest. The optimum amount of immobilized lysozyme was 0.8 g / L, the best immobilization time was 10 h, the best pH was 6.5, and the best buffer ion concentration was 50 mmol / L. 0.7g/L immobilized lysozyme was added to circulating cooling water containing 80mg/L diesel fuel. The optimum conditions for immobilization of lipase were as follows: the amount of lipase was 1.5 g / L, the immobilization time was 8 h, the pH of immobilization was 8, and the ionic strength of immobilized buffer solution was 25 mmol / L. When the immobilized lipase of 0.8g/L was added to the circulating cooling water of 80mg/L diesel fuel concentration, the inhibition rate could reach 61.7%. On the basis of single factor experiment, the concentration of lysozyme, the immobilization time of lysozyme and the concentration of lipase were investigated. Four factors of lipase immobilization time were independent variables, the level of lipase activity at the best time was the center point, the inhibition rate was the response value, and the Box-Behnken method was used to optimize the level response surface analysis of 4 factors and 3 levels. The optimum conditions for co-immobilization of lysozyme and lipase are as follows: lysozyme concentration is 0.88 g / L, lysozyme immobilization time is 11.81 h, lipase concentration is 2.07 g / L, lipase immobilization time is 9.22 h, and the highest inhibition rate is 86.10% and live enzyme is predicted. The mixture of carbon at 1:2 volume ratio is made into a mixed filter material. The concentration of diesel oil in filtered water can be reduced to 2.1 mg / L, and the oil removal rate can reach 97%. The corrosion rate of carbon steel was obviously decreased from 0.2106mm/a to 0.0818mm / a, that is, the corrosion inhibition rate reached 61.16 mm / a.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：Q814.2;TQ085.4;TE62

【参考文献】