摘要
本文以两种不同分子量的壳聚糖为原材制备了一系列不同分子量不同羧甲基取代度的羧甲基壳聚糖(CMCS),通过静态阻垢法、扫描电子显微镜(SEM)、X射线衍射(XRD)、失重法、极化曲线法、电化学阻抗法等技术详细考察了CMCS内部结构因素(分子量、羧甲基取代度等)与外部环境因素(药剂投加量、温度等)对碳酸钙的阻垢以及对碳钢的缓蚀性能影响.结果表明CMCS具有较好的缓蚀阻垢效果.CMCS的阻垢与缓蚀性能均随着羧甲基取代度的增加而增强;在相似羧甲基取代度条件下,分子量低的壳聚糖制得的CMCS的阻垢及缓蚀效果更佳.SEM和XRD结果分析表明,CMCS作为阻垢剂对CaCO_(3)的阻垢作用是晶格畸变、螯合作用和分散增容作用等多种效应共同作用的结果.在CMCS缓蚀机制研究中,失重法及电化学法结果大体一致,CMCS是一种混合型缓蚀剂,能同时抑制阴极和阳极反应;抑制机理主要是CMCS上羟基、氨基及羧基等活性功能基团上孤对电子易与Fe外层空轨道有效配位形成单分子层保护膜,从而隔绝腐蚀介质达到对碳钢缓蚀的目的.综上,CMCS具有较好的阻垢缓蚀效果,其作为一种绿色环保的水处理剂材料,具有广阔的应用前景.
A series of carboxymethyl chitosan(CMCS) with various degrees of carboxymethyl substitution was prepared from two chitosan samples with different molecular weights. Static scale inhibition method, scanning electron microscope(SEM), X-ray diffraction(XRD), weight-loss method, and electrochemical measurements were taken to study the effects of internal structural factors(molecular weight, degree of carboxymethyl substitution, etc.) and external environmental factors(dosage, temperature, etc.) of CMCS on the inhibition of CaCO_(3) scale and the corrosion on carbon steel, respectively. The results showed that CMCS had good scale and corrosion inhibition effects. Under the similar degree of carboxymethyl substitution, the scale and corrosion inhibition efficiencies of CMCS with low molecular weight were higher than that with high molecular weight;and the higher the degree of carboxymethyl substitution was,the better scale and corrosion inhibition effects it had. SEM and XRD results indicated that the scale-inhibition mechanisms of CMCS were mainly ascribed to its notable chelation and complexation with Ca^(2+), dispersion effect on CaCO_(3) microcrystal, and the distortion of the CaCO_(3) lattice, which caused the formation of unstable vaterite and aragonite structures. The results of electrochemical method showed that CMCS was a kind of mixed-type corrosion inhibitors, which could inhibit both cathode and anode reactions. The corrosion inhibition mechanisms were mainly ascribed to that the active functional groups such as hydroxyl, amino and carboxyl groups of CMCS were easy to chelate with Fe to form a monolayer protective film, so as to isolate the corrosion media and achieve the purpose of corrosion inhibition for carbon steel. In short, CMCS, as a green and environmental-friendly water treatment agent, has good scale and corrosion inhibition effect, and a wide application potential.
作者
宋荻
余伟
杨琥
Di Song;Wei Yu;Hu Yang(State Key Laboratory of Pollution Control and Resource Reuse,School of the Environment,Nanjing University,Nanjing 210023,China)
出处
《中国科学：化学》
CAS
CSCD
北大核心
2021年第5期566-580,共15页
SCIENTIA SINICA Chimica
基金
国家自然科学基金(编号:51778279)资助项目。
关键词
羧甲基壳聚糖
阻垢
缓蚀
羧甲基取代度
阻垢缓蚀机制
carboxymethyl chitosan
scale inhibition
corrosion inhibition
degree of carboxymethyl substitution
mechanisms of scale and corrosion inhibition
