【作者】 夏仙兵；

【导师】 蔡邦肖；

【作者基本信息】 浙江工商大学 ， 食品科学， 2010， 硕士

【摘要】 纳滤(NF)是介于反渗透(RO)与超滤(UF)之间的一种压力驱动型膜分离技术,是20世纪70年代末期开始发展起来的一种高新技术。根据NF膜的特点和性能,NF膜技术的主要应用是水软化、水净化、相对分子质量在百级的物质的分离、分级和浓缩等。随着社会发展的需求不断增加,NF在饮用水净化、水质软化,抗生素、多糖、多肽等化工和生物工程产物的分级和浓缩,脱色和去异味,以及废水处理和资源回收等方面都有越来越明显的作用。海带工业废水中甘露醇(M)的含量较高,约1.0 wt%。显然,开发海带加工过程中的M回收利用技术,具有重大的经济效益。以海藻资源综合利用为背景,进一步发展海带食品和海带化工系列产品生产的节能减排工艺和资源高效利用技术,已列为国家科技支撑计划项目。由于废水成分复杂,污染物浓度高,经预处理工艺去除悬浮物、蛋白、糖胶等大分子有机物后,仍残留含量较高的无机盐类杂质,其中主要的无机盐为氯化钠(NaCl).传统方法脱除NaCl难度较大,普遍存在着能耗高、环境污染大的问题。本文面向海带加工废水中M的提取技术的开发,在选用的两种聚酰胺(PA)卷式NF膜组件、设计制作的总膜面积为6.8 m2的成套化中试装置上,以去除NaCl为主要杂质成分,进行中M混合物水溶液中M的纯化实验。实验设计膜分离用的废水为以M、NaCl为海带废水中的主要成分,进行了M水溶液以及M-NaCl-水混合物的膜性能及其工艺参数的大量实验。结果表明,影响NF膜分离的主要工艺参数是料液中的M浓度和NaCl浓度以及操作压力(P)和操作温度(T)；比较两支NF膜组件的渗透性和选择性,1#优于2#。NF分离单组分M水溶液体系时,渗透通量(J)较高,M截留率(RM)大于80%。NF分离M-NaCl混合物水溶液体系时,RM值稳定在75-80%,J值稳定在13 L/m2·h；当初始料液中NaCl浓度(Cf,NaCl)分别为0.2 wt%和0.8 wt%时,NaCl透过率(SNaCl)分别约达50%和70%。提出的优先渗透和空间位阻的集成效应传质现象解释了M-NaCl水溶液体系的NF膜分离机理。基于NF膜对M-NaCl水混合物的集成效应传质机理及其分离效果的初步研究结果,进一步利用已优选出的1#NF膜组件,组合NF膜过程与DF操作模式,提出了能够达到脱盐和浓缩目的的预浓缩(CⅠ)-连续恒容渗滤(CCVD)-后浓缩(CⅡ)组合工艺过程,即膜渗滤(MDF)法。着重研究了主要工艺参数,即截留液中的M和NaCl的浓度,预浓缩因子(CF),CCVD操作时间(t),渗滤溶剂(去离子水)消耗量(VW)及组合工艺的净化因子(PF)对MDF的影响。结果表明,在CCVD操作前进行适当的预浓缩是必要的,在CF为2.0-2.5之间,料液中的NaCl去除率约90%,M质量浓度约为初始料液浓度的3倍,PF达40。DF过程耗用的去离子水量小。本文在相关理论研究及本实验料液体系特点的基础上,推导出下列计算公式,以期预测MDF工艺过程中M、NaCl质量浓度及渗滤溶剂消耗量的变化：浓缩阶段：(?)渗滤阶段：(?)(?)研究获得的这种新型的去除NaCl和浓缩M的双重效果的NF工艺可行,技术合理。实验结果为建设海带加工中M的NF膜纯化和浓缩工程应用提供了理论基础。更多还原

【Abstract】 Nanofiltration (NF) is a new type of pressure-driven membrane technology located between reverse osmosis (RO) and ultrafiltration (UF), and developed in the late 1970s as a new kind of high technology. Based on NF membrane performance, NF technology has been mainly used in water softening, water purification, and separation, grading & concentration of the substance with Mw 100-1000, and so on. With the fast-growing demands of social development, NF technology become more and more obvious effects in the application of drinking water purification, water softening, grading & concentration, decolorization & removing foreign taste from the products of chemical industry and bioengineering, such as antibiotics, polysaccharoses, polypeptides, and wastewater treatment & resource recovery.The mannitol (M) concentration is about 1.0 wt%, and is relatively high in kelp process industry. Obviously, development of recycling technology in the kelp process is significant economic benefit. Based on the background of comprehensive utilization of kelp resources, developping the technologies of energy saving and efficient utilization of nature resource in the production of kelp food and a series of chemical products from kelp has been listed as National Key Technology R&D Program. Because of the complexity of wastewater constituents, there is still residual high inorganic salts impurity after removed suspended substance, protein, glucide and other macromolecules organic by pretreatment process, especially, the main salt is NaCl. It is difficult to reject NaCl by conventional process, and is common to be high energy consumption, serious environmental pollution. Present dissertation face to the development of extraction technology of mannitol in kelp processing wastewater. For the purpose of removing the main impurity NaCl, the purification experiments of M in mixtures solution were studied by means of a setup pilot scale device equipped two kinds of polyamide (PA) spiral wound NF membrane modules with total effective area of 6.8 m2. The experiments were designed M & NaCl as the main impurity in kelp wastewater, and studied the membrane performance and process parameters in M aqueous solution and M-NaCl mixtrues solution. The results show that effect parameters on NF membrane separation performances were mainly the concentrations of M and NaCl in the feed, operation pressure (P) and temperature (T). The 1# membrane module was preferred the 2# membrane module in terms of permeate flux (J) and selectivity. The J was higher, and the M retention (RM) was more than 80% when separating M aqueous solution system. The RM of 75-80% and J of 13 L/m2-h were stable when separating M-NaCl mixture aqueous solution system. The NaCl penetration (SNacl) was about 50% and 70%, when NaCl concentration (Cf,NaCl) in the initial feed was 0.2 wt% and 0.8 wt%, respectively. The transport model of integrate effect considered preference penetration and space hinder was developed and successfully used to interpret the mechanisms of NF membrane separation of M-NaCl mixture aqueous solution system.In present dissertation, with the preferable 1# NF membrane, this work combined the NF process and DF operation mode, and brought forward the combined process of Pre-concentration (CⅠ)-Continuous Constant Volume Diafiltration (CCVD)-Post-concentration (CⅡ) to meet the need of desalination and concentration of M, namely MDF technique. The effects of main process parameters namely the concentration of M and NaCl in the retention, the pre-concentration factor (CF), the operation time (t) of (CCVD), the consumption of diafiltration solvent (deionized water) (Vw), and purification factor (PF) of membrane diafiltration (MDF) were discussed. The experimental results showed that the suitable process of pre-concentration before CCVD was necessary, and the rejection of NaCl in the feed was about 90%, the concentration of mannitol rose to about 3 times of initial feed concentration, PF come up to 40, the consumption of deionized water was lower when CF was between 2.0 and 2.5. In order to predict M/NaCl concentration and consumption of diafiltration solvent (deionized water) in MDF technological process, present dissertation deduced the following formula based on the related theories research and the characteristics of M/NaCl solution system:Concentration stage:(?)Diafiltration stage:(?) Vw(?) This work reveals the feasibility of new double effect NF process of NaCl penetration and M retention. The result provides the theoretical basis for constructing the engineering application of purification and concentration of M in kelp processing by means of NF membrane.更多还原