Institutional Repository of Key Laboratory of Marine Environmental Corrosion and Bio-fouling, IOCAS
|Place of Conferral||中国科学院海洋研究所|
|Keyword||Ldhs 纳米银 反相微乳法 缓蚀 抑菌|
层状双氢氧化物（Layered Double Hydroxide，LDHs）独特的离子化二维夹层结构赋予其优异的吸附、修饰、可控递释性能。LDHs质轻环保、廉价易得，集层状结构的稳固性、层板组成的可控性、层板间距的可调性、层间阴离子的可交换性于一体，具备成为分子容器和离子交换平台的天然属性，可进行多元化的结构改造和功能拓展。本论文从LDHs板层阳离子调节和层间阴离子缓蚀剂嵌插两个技术路线入手，制备了兼具缓蚀和抑菌双功能的超分子复合体系，主要通过以下三方面展开：
（1）通过共沉淀法合成硝酸根型LDHs作为前驱体，将缓蚀性能突出的香兰素（Vanillin，Van）以阴离子交换的方式引入层间，再通过银氨反应在LDHs表面沉积纳米银颗粒，获得目标产物Ag/MgAl-Van-LDHs(N)。扫描电子显微镜（SEM）、X射线衍射仪（XRD）、傅立叶红外变换光谱仪（FTIR）、电化学阻抗谱（EIS）和细菌生长曲线测试结果表明：MgAl-NO3--LDHs呈现不规则片层状，片层直径约为1 μm，厚度约为几十纳米，Van插层后，LDHs的形貌无明显变化，但XRD特征峰（003）、（006）向左发生偏移，层间距变大，24 h内缓蚀效率仍维持在86%以上，并体现出优异的抑菌性能，对大肠杆菌和金黄色葡萄球菌的抑制率分别达到99.65 %和99.79 %。
（2）通过分解尿素法合成了碳酸根型LDHs前驱体，由于CO32-作为层间阴离子与LDHs板层结合紧密，难以通过离子交换法进行缓蚀剂插层，故需要将MgAl-CO32--LDHs高温煅烧，去除CO32-，获得产物为混合金属氧化物（Mixed Metal Oxide，MMOs），然后通过再水合法插层Van，产物为MgAl-Van-LDHs(C)，最后通过银氨反应沉积纳米银颗粒到MgAl-Van-LDHs(C)表面，最终产物为Ag/MgAl-Van-LDHs(C)。通过SEM、XRD、FTIR、EIS、细菌生长曲线测试表明：MgAl-CO32--LDHs在SEM下呈规则的正六边形结构，片层尺寸较大，可达5 μm，煅烧后MMOs依然为规则的正六边形，表面出现裂痕。XRD显示MMOs不具备LDHs的典型层状结构，经过再水合法插层Van后，重新测得XRD特征峰（003）、（006），并且向左发生偏移，表明LDHs的层状结构恢复，且层间距变大。EIS显示Ag/MgAl-Van-LDHs(C)具有优异的缓蚀作用，缓蚀效率在24 h内维持在97.63 %，但对大肠杆菌和金黄色葡萄球菌的抑制率仅为43.99 %和17.80 %。
（3）通过反相微乳法制备了ZnTi-LDHs，其优点是可一步合成缓蚀剂插层LDHs。首先向有机溶剂中添加表面活性剂，制备含有微乳胶束单元的混合液，然后将金属盐、缓蚀剂逐步添加到混合液中并充分溶解，再进行高温高压处理，合成ZnTi-LDH以及缓蚀剂插层的ZnTi-Vc-LDHs、ZnTi-Van-LDHs，对其进行SEM、XRD、FT-IR、EIS、细菌生长曲线测试，结果表明：ZnTi-Vc-LDHs，ZnTi-Van-LDHs呈无规则的片状，片层直径在几十纳米到1 μm，缓蚀剂插层后LDHs的晶型特征峰（003）、（006）向高度数偏移，这是由于插层有机物分子量小于ZnTi-LDH原有层间阴离子十二烷基硫酸钠（SDS）造成插层后LDHs层间距变小导致的。EIS显示ZnTi-Vc-LDHs、ZnTi-Van-LDHs缓蚀效率较为突出，在24 h分别为90.47 %和91.97 %，两者对大肠杆菌抑制率分别为93.57 %和92.63 %，对金黄色葡萄球菌的抑制率分别为91.34 %和97.23 %，此外ZnTi-LDH具有更优异的抑菌效果，对大肠杆菌和金黄色葡萄球菌的抑制率分别为100.00 %和99.63 %。
Layered double hydroxides (LDHs), commonly known as hydrotalcites, is a class of two-dimensional layered material with good adsorption and controlled release properties. The LDHs are mainly composed of metal cations and interlayer anions. The metal cations are adjustable and the interlayer anions can be exchanged, which greatly enriches the application range of LDHs. This study is based on the special structural characteristics of LDHs，to prepares the LDHs with dual functions of corrosion inhibition and antimicrobial activities by changing the metal cations and intercalation anions containing different functional groups of corrosion inhibitors, This research is carried out from the following three aspects:
（1）First, Nitrate-type LDHs were synthesized as a precursor by co-precipitation method, and then vanillin (Vanillin, Van) with good corrosion inhibition effect was intercalated into LDHs by ion exchange method. Next, silver nanoparticles were deposited on the surface of LDHs by silver ammonia reaction to prepare Ag/MgAl-Van-LDHs(N). Scanning electron microscopy (SEM), X-ray diffractometer (XRD), Fourier transform infrared spectrometer(FTIR), electrochemical impedance spectroscopy(EIS), bacterial growth curve and other test analysis were performed on Ag/MgAl-Van-LDHs(N). The results showed that MgAl-NO3--LDHs showed irregular lamellar shape by SEM observation. The diameter of the LDHs lamellar layer was about 1 μm and the thickness was about tens of nanometers. After Van intercalation, there was no obvious change in the morphology of LDHs. However, the XRD characteristic peaks (003) and (006) of LDHs shifted to the left, and the interlayer spacing became larger. The EIS test shows that the LDHs have a good corrosion inhibition efficiency, which maintains above 86 % within 24 hours. Bacteriostasis experiments show that Ag/MgAl-Van-LDHs(N) has very good antibacterial performance, and the inhibition rates against E. coli and Staphylococcus aureus reach 99.65 % and 99.79 %, respectively.
（2）Carbonate LDHs were prepared by the decomposition of urea, in order to prepare Ag/MgAl-Van-LDHs(C). CO32- as an interlayer anion is tightly bound to the LDHs plate layer, so it is difficult to intercalate corrosion inhibitor by ion exchange method. Therefore, it is necessary to calcinate MgAl-CO32--LDHs at high temperature to remove CO32-, and then obtain mixed metal oxides (MMOs). Then Van intercalates by rehydration to obtain MgAl-Van-LDHs(C), and finally nano-silver particles are deposited on the surface of MgAl-Van-LDHs(C) by silver ammonia reaction, and the final product is Ag/MgAl-Van-LDHs(C).
Through the analysis of SEM, XRD, FT-IR, EIS, bacterial growth curve test and other characterization methods, it was observed that MgAl-CO32--LDHs showed a regular hexagonal structure under SEM, and the size of the sheet was large, up to 5 μm . After calcination, the MMOs are still regular hexagons with cracks on the surface. At the same time, XRD results show that MMOs do not have the typical layered structure of LDHs. After intercalating Van by hydration, XRD characteristic peaks (003) and (006) were re-measured and shifted to the left, indicating that the layered structure of LDHs was restored and the interlayer spacing became larger. EIS results show that Ag/MgAl-Van-LDHs(C) has good corrosion inhibition performance, and the corrosion inhibition efficiency is maintained at 97.63 % at 24 h. In addition, the results of the antibacterial test showed that the antibacterial effect of Ag/MgAl-Van-LDHs(C) was not obvious, and the inhibition rates against E. coli and Staphylococcus aureus were only 43.99 % and 17.80 %.
（3）ZnTi-LDHs are prepared by reverse phase microemulsion method, which can synthesize corrosion inhibitor intercalation LDHs in one step. First, the active agent is added to the organic solvent to prepare a mixed liquid containing a microemulsion mixing unit. Then the metal salt and corrosion inhibitor are gradually added to the mixed solution and fully dissolved. Then, the mixed solution reacts under high temperature and high pressure conditions. Finally, ZnTi-LDH and ZnTi-Vc-LDHs and ZnTi-Van-LDHs intercalated with corrosion inhibitor were synthesized. ZnTi-LDHs were tested by SEM, XRD, FT-IR, EIS, bacterial growth curve, etc. ZnTi-Vc-LDHs and ZnTi-Van-LDHs show irregularly shaped flakes under SEM, and the diameter of the flakes ranges from tens of nanometers to 1 μm. XRD showed that the characteristic peaks (003) and (006) of LDHs shifted to the height after the corrosion inhibitor intercalation. Because the molecular weight of intercalated organics Van and Vitamin C（Vc）is less than the interlayer anion sodium lauryl sulfate (SDS) of ZnTi-LDH, the interlayer spacing of LDHs becomes smaller after intercalation; At the same time, the EIS results show that the corrosion inhibition efficiency of ZnTi-Vc-LDHs and ZnTi-Van-LDHs is good, which are 90.47 % and 91.97 % respectively at 24 h. After the bacteriostasis test, it was found that ZnTi-Vc-LDHs and ZnTi-Van-LDHs had good bacteriostasis, the inhibition rates against E. coli were 93.57 % and 92.63 % respectively, and the inhibition rates against Staphylococcus aureus were 91.34 % and 97.23%. In addition, ZnTi-LDH has a more excellent antibacterial effect, the inhibition rate of Escherichia coli and Staphylococcus aureus were 100.00 % and 99.63 %, respectively.
|MOST Discipline Catalogue||理学 ; 理学::海洋科学|
|鞠晓丹. 基于层状双氢氧化物的缓蚀抑菌集成体系构建和性能研究[D]. 中国科学院海洋研究所. 中国科学院大学,2020.|
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