具有脱硼功能的螯合膜制备与性质研究

发布时间：2018-03-02 15:28

本文选题：接枝改性　切入点：共混改性　出处：《天津工业大学》2017年博士论文　论文类型：学位论文

【摘要】：硼作为一种重要的化学元素,广泛应用于现代工业领域中。适量的硼元素能够促进动植物体的生长发育,而硼含量过高,会导致动植物体出现中毒现象。世界卫生组织(WHO)规定,饮用水中硼浓度不超过2.4 mg/L,灌溉水中硼浓度不超过1 mg/L。而海水中硼的平均浓度为5mg/L,远超WHO所规定,因此海水除硼在海水淡化过程中非常重要。目前,海水除硼技术发展迅速,但很多方法除硼效果并不理想。本课题组的工作表明,螯合膜分离法是一种非常高效的去除水溶液中硼酸的方法。这种方法利用膜表面上邻位羟基聚合物与硼酸发生络合反应,达到过滤过程中除硼的目的,操作简单,便于推广。本文通过表面接枝和共混等方法制备出三种螯合膜材料,用全反射红外光谱(FT-IR)、X-射线光电子能谱(XPS)、水接触角(WCA)、场发射扫描电镜(FESEM)、原子力显微镜(AFM)以及BET(Brunauer-Emmett-Teller)等方法对螯合膜的结构与性能进行表征,考察了螯合膜在不同硼酸溶液初始浓度、pH值和离子强度等条件下对硼酸的吸附性能,并研究了螯合膜的吸附热力学和吸附动力学以及循环再生性能。首先,通过将聚丙烯腈(PAN)膜上的氰基水解和酰胺化作用,在PAN膜表面接枝了具有超支化聚乙烯亚胺(HPEI),再通过氨基与环氧丙烷的开环反应,制备出一系列具有表面接枝超支化多元醇的PAN改性膜材料PAN-g-PG。PAN-g-PG膜具有很高的吸附容量和很快的吸附速率。研究发现,PAN膜表面接枝PG后展现出超亲水性能,且表面粗糙度增加。吸附热力学和吸附动力学分析表明,螯合膜的硼吸附符合Langmuir等温吸附模型和伪一级动力学模型。当硼酸初始浓度为100mg/L时,螯合膜的最大吸附量为3.2mmol/g,达到吸附平衡的时间仅为4 min。通过在盐酸中处理15min,PAN-g-PG膜吸附再生率为100%。螯合膜经过循环10次后,再生率仍接近100%,表现出良好的循环再生性能。其次,为了进一步增加螯合膜的比表面积,增大螯合膜对硼酸的吸附容量,利用静电纺丝技术制备聚酰胺酸(PAA)纳米纤维膜,并在纤维膜表面通过酰胺化反应和环氧开环反应,成功的引入多元醇结构。结果表明,PAA铸膜液固含量为15%时,PAA纳米纤维膜具有均一的形貌和相对窄的纤维直径分布。XPS和FT-IR表征证明,HPEI和环氧丙醇成功的接枝在膜表面上,两步反应的接枝率随着与HPEI接枝反应时间的增加而增加。PAA-g-PG24纳米纤维膜在270 mg/L、pH=9的硼酸溶液中出现最大吸附量,为5.68mmol/g,这是目前文献中报道的最高吸附量。在5mg/L初始硼酸浓度下,PAA-g-PG24纳米纤维膜对硼酸的吸附量为0.82mmol/g,且吸附平衡时间为15min。PAA-g-PG24纳米纤维膜吸附过程符合Langmuir热力学吸附模型和伪一级动力学模型。经过10次循环后,PAA-g-PG24纳米纤维膜的RE值仍保持在93.9%,表现出很好的循环利用性能。最后,为了简化制膜过程,通过相转化法,将具有脱硼功能的特异性吸附树脂(BSR)与聚砜(PSF)共混,用非溶剂相转化法制备了 PSF/BSR混合基质膜。混合基质膜比聚合物树脂具有更快的吸附速率,这使膜对较低浓度的硼酸溶液更具吸附优势。当处理10mL浓度为5mg/L硼酸溶液时,PSF/BSR4共混膜通量为25 L/m2·h,硼去除率为97.6%,循环10次后,恢复率可保持在95.9%。
[Abstract]:Boron is an important chemical element, widely used in modern industrial fields. The amount of boron can promote the growth of animals and plants, and the boron content is too high, will lead to animal and plant poisoning occurs. The WHO (WHO), boron in drinking water was less than 2.4 mg/L, the irrigation water concentration of boron more than 1 mg/L. and the average concentration of boron in seawater was 5mg/L, far exceeding the required WHO, therefore seawater boron removal is very important in the desalination process. At present, seawater boron removal technology is developing rapidly, but many methods of boron removal effect is not ideal. This work shows that the chelating membrane separation method is a very efficient removal of boric acid in aqueous solution. This method uses the membrane surface of ortho hydroxyl polymer with boric acid complexation reaction to filtration process of boron removal, simple operation and easy popularization. This paper through the table Surface grafting and blending method to prepare three kinds of chelating membrane materials by total reflection infrared spectroscopy (FT-IR), X- ray photoelectron spectroscopy (XPS), water contact angle (WCA), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and BET (Brunauer-Emmett-Teller) of structure and characterization the methods of chelating membrane, were investigated at different initial concentrations of boric acid chelating membrane solution, the adsorption properties for boric acid pH value and ionic strength conditions, and studied the chelating membrane adsorption thermodynamics and adsorption kinetics and recycling performance. First, by using polyacrylonitrile (PAN) membrane on the hydrolysis of cyano group and acyl amination, grafted on the surface of PAN film with hyperbranched polyethylenimine (HPEI), and then through the ring opening reaction of amino and epoxy propane, preparation of a series of surface grafted with hyperbranched polyol PAN modified PAN-g-PG.PAN-g-PG membrane with a membrane material High adsorption capacity and fast adsorption rate. The study found that grafted on the surface of PAN film PG exhibit hydrophilic properties, and the surface roughness increases. The adsorption thermodynamics and kinetics analysis showed that the adsorption of boron chelate membrane accords with Langmuir isotherm model and pseudo first order kinetic model. When the initial concentration of boric acid was 100mg/L. The maximum adsorption capacity of the chelating membrane is 3.2mmol/g, the adsorption equilibrium time is only 4 of min. treated by 15min in hydrochloric acid, PAN-g-PG membrane adsorption regeneration rate of 100%. chelating membrane after after 10 cycles, the regeneration rate is close to 100%, showing good performance of regeneration cycle. Secondly, in order to further increase the chelating membrane surface the area, the adsorption capacity increased to boric acid chelating membrane, preparation of polyamic acid by electrospinning (PAA) nano fiber membrane, and the membrane surface by amidation reaction and epoxy ring opening reaction into The introduction of the polyols power. The results show that the PAA casting solution when solid content is 15%, and the relatively narrow fiber morphology of PAA nano fiber film with uniform diameter distribution of.XPS and FT-IR indicated that HPEI and glycidol successfully grafted onto the membrane surface, increase the grafting reaction of the two step rate with HPEI the grafting reaction time and increase of.PAA-g-PG24 nano fiber membrane at 270 mg/L, the maximum adsorption capacity, appear boric acid solution pH=9 for 5.68mmol/g, which is the highest adsorption capacity reported in the current literature. In 5mg/L the initial concentration of boric acid, the adsorption amount of PAA-g-PG24 nano fiber membrane of boric acid is 0.82mmol/g, and the time of adsorption equilibrium thermodynamics with Langmuir adsorption model and pseudo first order kinetic model for 15min.PAA-g-PG24 nano fiber membrane adsorption process. After 10 cycles, PAA-g-PG24 nano fiber membrane remained at RE 93.9%, showed good evidence The use of ring performance. Finally, in order to simplify the process of the film was prepared by phase inversion method, the specific function of the removal of boron adsorption resin (BSR) and polysulfone (PSF) blends, PSF/BSR mixed matrix membranes were prepared by non solvent phase. Mixed matrix membrane has faster adsorption rate than the polymer resin, which makes the the membrane of boric acid solution with low concentration the more adsorption advantage. When processing the 10mL concentration of 5mg/L boric acid solution, PSF/BSR4 blend membrane flux is 25 L/m2 - H, the boron removal rate was 97.6%, after 10 cycles, the recovery rate can be maintained at 95.9%.

【学位授予单位】：天津工业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TQ051.893

【相似文献】