银纳米颗粒改性壳聚糖膜的可控降解性能研究

STUDY ON THE TUNABLE DEGRADABILITY OF CHITOSAN MEMBRANES MODIFIED BY SILVER NANOPARTICLES

石述宇

11749209

硕士

环境工程

邓保林

2019-05-28

2019-06-28

哈尔滨工业大学

深圳

膜法水处理技术在水处理领域中的广泛应用大大提升了水处理的效率和出水质量，其中所用的水处理膜多以来源于石油的化学高分子为原料。这些膜在达到使用寿命后，通常会用焚烧和填埋的处理方法，如此以来就会对自然环境造成二次污染且浪费土地资源。而以来源广泛，价格低廉的天然高分子为主要原料的天然高分子水处理膜在达到使用寿命之后可以自然降解，不会对自然环境造成永久影响。壳聚糖是一种天然高分子生物多糖，主要通过广泛存在于虾蟹和其他甲壳动物外骨骼中的几丁质脱乙酰而得到。使用绿色高效的LiOH/KOH/尿素体系溶解壳聚糖，制备出的壳聚糖水处理膜不单单具有良好的生物相容性和亲水性而且在达到使用寿命之后可以被自然降解。但是壳聚糖水处理膜在实际应用中必须要解决的问题就是要确保其在有效使用过程中不被微生物所降解，影响其正常使用。所以本课题对壳聚糖膜的可控性降解，即为达到使壳聚糖膜的使用过程中不被微生物所降解而在使用寿命结束后可以被自然降解的目的进行了相关研究。本课题的目的是以壳聚糖为基制备一种具有可控降解性能的膜材料，通过银纳米颗粒改性壳聚糖，将银纳米颗粒包埋在壳聚糖中，制备出银纳米颗粒改性壳聚糖膜，并研究其抗降解性能。由于银纳米颗粒改性壳聚糖膜中银的释出的速率和总量取决于银纳米颗粒改性壳聚糖膜的制备条件，因此可以通过控制银纳米颗粒改性壳聚糖膜的制备条件，改变膜中银释出持续时间从而控制银纳米颗粒改性壳聚糖膜抗降解性能持续时间。从扫描电子显微镜（SEM）图像和银释出实验结果可以看出，成膜温度对于膜结构和银纳米颗粒改性壳聚糖膜银释出速率和总量有很大的影响，成膜温度分别为20℃和-20℃的银纳米颗粒改性壳聚糖膜中银释出速度达到稳定时分别为0.025μg/cm2/h和0.075μg/cm2/h。根据银纳米颗粒改性壳聚糖膜抗降解性能实验结果，当溶液中银浓度为10μg/L时，溶菌酶对壳聚糖的降解活性为无银对照组的24%，当溶液中银浓度为40μg/L时，溶菌酶对壳聚糖的降解活性仅剩下了不到5%。根据银纳米颗粒改性壳聚糖膜对大肠杆菌的接触抑制和浸没抑制实验结果，银纳米颗粒改性壳聚糖膜对于大肠杆菌细胞活性也有很强的抑制作用。成膜温度分别为20℃和-20℃含银纳米颗粒量为1%的银纳米颗粒改性壳聚糖膜银持续释出时间分别为196h和73h，在银纳米颗粒改性壳聚糖膜中银释出的过程中，银纳米颗粒改性壳聚糖膜具有很强的抗降解性能。

A wide application of membranes for water treatment has greatly improved the water treatment efficiency and water quality. Membranes, mostly made of polymeric materials derived from petroleum, are eventually disposed of to landfill or incinerated after reaching their service life. Improper disposal of used membranes sometime occur, however, which may pollute the natural environment. It is therefore desirable to develop membranes made of natural polymeric materials that are available at low cost and particularly, are subject to degradation in the environment so there is no permanent environmental impact. Chitosan is a polysaccharide that can be easily obtained from chitin shells of shrimp and other crustaceans. Water treatment membrane made of chitosan had been prepared with good biocompatibility and hydrophilicity when LiOH/KOH/ urea system was applied to dissolve chitosan. Chitosan membrane has the desirable property of biodegradability after its service life. A conundrum is how to make sure the membrane is not degraded by microorganisms during its active applications for water treatment. What we need is a membrane that its degradation is controllable, i.e., the membrane is not subject to degradation during the service but could be degradable after its service life. The goal of this work was to develop a membraene with controlable biodegradability using chitosan as a model membrane material. The anti-degradation properties of chitosan membranes were imparted by embedding the silver nanoparticles into the membrane. Since the release time and rates of silver nanoparticles from the membrane depend on the amounts and protocols of silver nanopartilce embedding, we could potentially control the duration of silver release and thus the duration prior to which the biodegradation would have been suppressed. In this study, the release rates of silver nanoparticles from the modified chitosan membrane were controlled by changing the membrane forming temperature and the embedded amount of silver nanoparticles. From the SEM imaging and silver release experiments, we found the membrane forming temperature could significantly influence on the membrane structure and release rates of silver nanoparticles from the chitosan membrane. For the membrane formed at 20 ℃, the stable release rate of silver is 0.025μg/cm2/h; For the membrane formed at - 20 ℃, the stable silver release rate is 0.075μg/cm2/h. The anti-degradation performance of chitosan membrane was assessed by the lysozyme activity for chitosan degradation. When the concentration of silver in the solution was 10μg/L, the lysozyme activity of chitosan degradation was 24% of the control without silver; and when the concentration of silver in the solution was 40μg/L,the lysozyme activity of chitosan degradation was less than 5%. Silver nanoparticles modified chitosan membrane similarly showed a strong inhibitory effect on microbial activity. The duration of anti-degradation of chitosan membrane modified with silver nanoparticles containing 1% silver nanoparticles at 20 ℃ and-20 ℃ was 196 h and 73 h, respectively.

关键词 天然高分子 壳聚糖膜 银纳米颗粒 生物降解

Keywords natural polymer chitosan membrane silver nanoparticles biodegradation

中文

联合培养

南方科技大学

石述宇. 银纳米颗粒改性壳聚糖膜的可控降解性能研究[D]. 深圳. 哈尔滨工业大学,2019.