共混改性聚醚砜超滤膜的制备及其性能研究
发布时间：2019-01-21 09:05
【摘要】：膜技术作为高效的分离新技术,在水处理中有着很好的发展前景,受到越来越多的关注,但膜技术尚不成熟,其面临的一个主要问题是由膜的亲水性不足带来的易受污染,清洗频率增加进而导致膜寿命降低,成本上升。所以,如何提高膜的亲水性及耐污染性,成为现阶段研究的重要方向。本论文利用载银羟基磷灰石HAP/Ag作为改性材料,以共混法制备改性聚醚砜超滤膜,探索了制备时适宜的各材料添加比例,表征及测试了制备后的改性膜性能,并对改性膜的阻力变化进行了分析。主要结论如下:(1)负载银纳米羟基磷灰石材料(HAP/Ag)在结构特征、尺寸大小、晶型结构和特征官能团等方面均与羟基磷灰石(HAP)相似性很高,表明HAP/Ag材料很好地维持了HAP材料原本的结构和性质;(2)随着改性材料HAP/Ag的添加,聚醚砜树脂(PES)膜的水通量、截留率和接触角有所改变:在添加量为2%时改性膜的水通量达到最大值,较原膜通量提高了397%;当添加量为5%时,截留率达到了最大值97%,高于原始膜64%的截留效果;当添加量为3%时,接触角最小,较原始膜的接触角下降了19.27%,表现出很好的亲水性能;另外,改性超滤膜的弹性形变量增大,最大拉力也逐渐增加;(3)添加改性材料后制备的所有PES超滤膜周围均产生了直径大小不一的抑菌圈,浓度接触实验进一步验证随着HAP/Ag添加量的不同,抑菌效果有所差异;银离子浸出量大小及速率实验验证得出材料中银离子具有初期快速溶出,后期缓慢释放的特性;(4)通过正交分析,铸膜液配比的优化条件为:PES18%,聚乙烯基吡咯烷酮(PVP)6%,HAP/Ag 2%;优化后的改性PES超滤膜其纯水通量为205.88 L·m-2·h-1,截留率为98.94%,水通量衰减系数为0.31,抗污性能良好。(5)优化的PES改性膜对COD的去除率达到了54.5%,对浊度的去除率为90.3%,与未改性的PES超滤膜相比,其去除率分别提高了1.20倍和1.93倍;两者有相同的阻力变化趋势,其中内部污染阻力和膜的固有阻力是导致两组膜在超滤过程中通量衰减的主要因素,而优化后的PES改性膜其阻力值一直低于未改性的PES膜,表明改性后的膜较原始膜,有更强的抗污能力。
[Abstract]:Membrane technology, as a new separation technology with high efficiency, has a good prospect in water treatment and has attracted more and more attention. However, the membrane technology is still immature, and one of the main problems it faces is the vulnerability to contamination caused by the lack of hydrophilicity of membrane. The increase of cleaning frequency leads to the decrease of membrane life and the increase of cost. Therefore, how to improve the hydrophilicity and pollution resistance of the membrane has become an important research direction at this stage. In this paper, the modified polyethersulfone ultrafiltration membrane was prepared by blending with silver loaded hydroxyapatite (HAP/Ag) as the modified material. The suitable proportion of each material was explored, and the properties of the modified membrane were characterized and tested. The change of resistance of the modified membrane was analyzed. The main conclusions are as follows: (1) the silver loaded nano-hydroxyapatite (HAP/Ag) is similar to hydroxyapatite (HAP) in structure, size, crystal structure and functional groups. The results show that the structure and properties of HAP materials are well maintained by HAP/Ag materials. (2) with the addition of the modified material HAP/Ag, the water flux, rejection rate and contact angle of the (PES) membrane were changed: the water flux of the modified membrane reached the maximum value when the addition amount was 2, and the flux of the modified membrane was increased by 397% compared with the original membrane flux; When the addition amount is 5, the rejection rate reaches the maximum 97, which is higher than 64% of the original membrane, and when the addition is 3, the contact angle is the smallest, which is 19.27 lower than that of the original membrane, showing good hydrophilicity. In addition, the elastic shape of the modified ultrafiltration membrane increases, and the maximum tensile force increases gradually. (3) all the PES ultrafiltration membranes prepared by adding modified materials produced different diameter bacteriostasis circles. The concentration contact experiment further verified that the bacteriostatic effect was different with the amount of HAP/Ag added; The experimental results of silver ion leaching amount and rate show that the silver ion has the characteristics of rapid dissolution in the initial stage and slow release in the later stage. (4) by orthogonal analysis, the optimum conditions of casting liquid ratio are as follows: PES18%, polyvinylpyrrolidone (PVP) 6 and HAP / Ag _ (2); The optimized modified PES ultrafiltration membrane has a pure water flux of 205.88 L m ~ (-2) h-1, a rejection rate of 98.94 and a water flux attenuation coefficient of 0.31. (5) the removal rate of COD by optimized PES modified membrane was 54.5%, and the turbidity removal rate was 90.30.The removal rate was 1.20 times and 1.93 times higher than that of unmodified PES ultrafiltration membrane, respectively. The internal fouling resistance and the intrinsic resistance of the two groups of membranes were the main factors leading to the flux attenuation of the two groups of membranes during ultrafiltration, while the optimized PES modified membrane had a lower resistance value than the unmodified PES membrane. The results showed that the modified membrane had stronger antifouling ability than the original membrane.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703
[Abstract]:Membrane technology, as a new separation technology with high efficiency, has a good prospect in water treatment and has attracted more and more attention. However, the membrane technology is still immature, and one of the main problems it faces is the vulnerability to contamination caused by the lack of hydrophilicity of membrane. The increase of cleaning frequency leads to the decrease of membrane life and the increase of cost. Therefore, how to improve the hydrophilicity and pollution resistance of the membrane has become an important research direction at this stage. In this paper, the modified polyethersulfone ultrafiltration membrane was prepared by blending with silver loaded hydroxyapatite (HAP/Ag) as the modified material. The suitable proportion of each material was explored, and the properties of the modified membrane were characterized and tested. The change of resistance of the modified membrane was analyzed. The main conclusions are as follows: (1) the silver loaded nano-hydroxyapatite (HAP/Ag) is similar to hydroxyapatite (HAP) in structure, size, crystal structure and functional groups. The results show that the structure and properties of HAP materials are well maintained by HAP/Ag materials. (2) with the addition of the modified material HAP/Ag, the water flux, rejection rate and contact angle of the (PES) membrane were changed: the water flux of the modified membrane reached the maximum value when the addition amount was 2, and the flux of the modified membrane was increased by 397% compared with the original membrane flux; When the addition amount is 5, the rejection rate reaches the maximum 97, which is higher than 64% of the original membrane, and when the addition is 3, the contact angle is the smallest, which is 19.27 lower than that of the original membrane, showing good hydrophilicity. In addition, the elastic shape of the modified ultrafiltration membrane increases, and the maximum tensile force increases gradually. (3) all the PES ultrafiltration membranes prepared by adding modified materials produced different diameter bacteriostasis circles. The concentration contact experiment further verified that the bacteriostatic effect was different with the amount of HAP/Ag added; The experimental results of silver ion leaching amount and rate show that the silver ion has the characteristics of rapid dissolution in the initial stage and slow release in the later stage. (4) by orthogonal analysis, the optimum conditions of casting liquid ratio are as follows: PES18%, polyvinylpyrrolidone (PVP) 6 and HAP / Ag _ (2); The optimized modified PES ultrafiltration membrane has a pure water flux of 205.88 L m ~ (-2) h-1, a rejection rate of 98.94 and a water flux attenuation coefficient of 0.31. (5) the removal rate of COD by optimized PES modified membrane was 54.5%, and the turbidity removal rate was 90.30.The removal rate was 1.20 times and 1.93 times higher than that of unmodified PES ultrafiltration membrane, respectively. The internal fouling resistance and the intrinsic resistance of the two groups of membranes were the main factors leading to the flux attenuation of the two groups of membranes during ultrafiltration, while the optimized PES modified membrane had a lower resistance value than the unmodified PES membrane. The results showed that the modified membrane had stronger antifouling ability than the original membrane.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703
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