木薯淀粉接枝共聚物对钢、铝的缓蚀性能及机理研究

Yunnan province is rich in cassava resources, and there is a good opportunity and surroundings of cassava starch industry. In this project, cassava starch graft copolymer (CSGC) was prepared by grafting vinyl monomers onto cassava starch. The inhibition action and mechanism of CSGC on the corrosion of steel and aluminium in various solutions (acid, alkaline, neutral) are studied by weight loss method, electrochemical technique, advanced instrumental analyst, quantum chemical calculation and molecular dynamic simulation. It is aimed to develop a preparation routine with low-cost and good reproducibility of preparing CSGC. The new data of the inhibition action of CSGC on steel and aluminium are accumulated. It is also aimed to reveal the effects of preparation CSGC condition, inhibitor concentration, media concentration, temperature and corrosion immersion time on the inhibitive performance. The adsorption isotherm of inhibitor on metal surface can be obtained via fitting with the experimental data. The adsorption thermodynamic parameters and corrosion kinetic parameters are calculated. It is to elucidate the adsorption behavior of CSGC on metal surface and the electrochemical mechanism. The micro-topography and chemical composition of the adsorption film of inhibitor on metal surface are characterized by advanced analystic instruments. Also, it is to study the relationship between molecular structure and inhibition ability using quantum chemical calculation, and the adsorption mode of inhibitor molecule on metal surface by molecular dynamic simulation. The reasonable inhibitive mechanism is proposed. It is hoped to provide the academic foundation in search of CSGC inhibitor with low-cost, high inhibition efficiency, non-toxicity and safety for steel and aluminium, and then directs the exploitation of the corrosion inhibitor using cassava starch.

依托云南丰富的木薯资源，结合云南木薯淀粉产业发展的大好机遇。本项目采用木薯淀粉与烯类单体接枝共聚合成制备出木薯淀粉接枝共聚物，用失重法、电化学法、仪器分析测试、量子化学计算和分子动力学模拟研究木薯淀粉接枝共聚物在各类溶液（酸性、碱性、中性）介质中对钢、铝的缓蚀性能和作用机理。建立一条成本低廉的木薯淀粉接枝共聚物缓蚀剂制备路线；积累木薯淀粉接枝共聚物对钢、铝缓蚀性能的新数据；揭示合成条件、缓蚀剂浓度、介质浓度、温度、腐蚀浸泡时间对缓蚀性能的影响规律；拟合木薯淀粉接枝共聚物的吸附等温式，计算出吸附热力学和腐蚀动力学参数；阐明接枝共聚物在钢、铝表面的吸附行为及电化学作用机理；表征吸附膜层的微观形貌和成分；阐释缓蚀剂分子的构效关系及其在金属表面的吸附方式；提出合理的缓蚀机理；为寻求钢和铝价廉、高效、无毒、使用安全的木薯淀粉接枝共聚物缓蚀剂提供理论依据，为木薯淀粉资源作为缓蚀剂的开发利用奠定基础。

天然高分子产物缓蚀剂具有持久、高效、环保等优点，已成为当前缓蚀剂领域的研究热点之一。本项目依托云南丰富的木薯资源，将木薯淀粉与烯类单体接枝共聚制备出木薯淀粉接枝共聚物，系统深入研究了木薯淀粉接枝共聚物在各类溶液（酸性、碱性、中性）介质中对钢、铝的缓蚀性能和作用机理，取得如下重要结果：. （1）建立了木薯淀粉接枝共聚物缓蚀剂的制备方法——氧化还原引发接枝共聚改性，实验筛选得出较佳合成条件：温度40-45 oC；引发剂过硫酸盐（K2S2O8）用量为4.0 - 4.5 mmol/L；烯类单体的用量为85 -90 mg/L；反应时间为 3-3.5 h。. （2）积累了大量的实验原创数据，得到了缓蚀剂浓度、温度、介质浓度、腐蚀时间对缓蚀性能的影响规律。木薯淀粉接枝共聚物缓蚀剂对钢和铝在酸中均具有良好的缓蚀作用，在碱性介质中的缓蚀作用较差，当缓蚀剂浓度用量为2.0 g/L时，缓蚀率不超过60%。三元接枝共聚物和阳离子接枝共聚物的缓蚀性能优于二元接枝共聚物。. （3）木薯淀粉接枝共聚物在钢、铝表面的吸附服从Langmuir吸附等温式，对钢在酸中为混合抑制型缓蚀剂，作用机理为“几何覆盖效应”；对铝在HCl介质中为阴极抑制型缓蚀剂；在强碱NaOH溶液中则为混合抑制型缓蚀剂；在H3PO4和HNO3溶液介质中为抑制阳极为主的混合抑制型缓蚀剂。. （4）SEM、AFM、接触角测试、XPS、XRD等研究得出木薯淀粉接枝共聚物缓蚀钢、铝表面腐蚀程度大为减缓，主要由腐蚀产物及缓蚀剂吸附膜层组成，且疏水性急剧上升。. （5）木薯淀粉接枝共聚物的吸附活性中心为烯类单体，淀粉骨架基本平行吸附于金属表面上，且吸附能明显高于木薯淀粉和烯类单体。缓蚀作用机理为烯类单体优先吸附在金属表面，而淀粉聚合物分子则有效屏蔽了溶液介质对金属表面的腐蚀。. 项目执行期内，发表学术论文12篇，其中3篇被SCI收录；授权国家发明专利2项，荣获云南省科学技术奖。项目负责人李向红入选云南省中青年学术和技术带头人后备人才、云南省“万人计划”青年拔尖人才、云南省享受省政府特殊津贴人员。