高强度高容量聚乙烯醇离子交换纤维的制备与应用

【作者】 逯阳；

【导师】 张华；

【作者基本信息】 天津工业大学 ， 材料学， 2005， 硕士

【摘要】 离子交换纤维是一种纤维状离子交换材料。它与离子交换树脂相比,具有更大的比表面积,交换与洗脱速度更快,可以以各种形式应用,如纤维、纱线、织物、非织造布等,适用于各种方式的离子交换过程。可用于电子纯水、医药用水制备、生物制剂制备、工业污水处理、有毒和恶臭气体吸附、催化剂载体、贵重金属回收、海洋稀有金属采集等,是一种有着广阔发展前景的新型功能材料。但是,现有离子交换纤维普遍存在着强度低、交换容量小等缺点。本文以高强高模聚乙烯醇纤维为原料,通过缩苯甲醛化、半碳化处理使纤维进一步交联,以满足以后使用的要求,然后分别进行磺化处理和巯化反应,制备了以高强聚乙烯醇纤维为基体的阳离子交换纤维和螯合纤维。本文对聚乙烯醇离子交换纤维的制备工艺及其在处理含重金属离子废水中的应用进行了较深入研究,得到了高强度、高交换容量的螯合纤维,克服了以往离子交换纤维机械性能和交换容量难以兼顾的缺点,具有较高的实用价值。研究结果表明: 1、纤维缩苯甲醛化反应的最佳条件为:苯甲醛、硫酸、氯化锌的浓度分别为190g/L、73.6g/L、60g/L,浴比1:50,65℃反应90min,纤维的最大缩苯甲醛度可达到12.2%;纤维的缩醛化温度不能超过70℃,否则纤维会在反应过程中溶解;改变氯化锌的浓度,对缩醛度没有明显影响。 2、半碳化处理对聚乙烯醇阳离子交换纤维制备的影响很大。最佳半碳化温度为200℃,半碳化时间应多于60min,否则强度无法保证:阳离子交换纤维交换容量的大小与半碳化及磺化时间有关,半碳化60min、磺化8h的纤维交换容量最大。 3、巯基聚乙烯醇螯合纤维的最佳制备工艺为:缩苯甲醛并半碳化处理90min后的纤维2g,依次加入巯基乙酸20mL、乙酸酐18mL、36%乙酸10mL、浓硫酸0.2mL和去离子水5mL,于30℃恒温烘箱中放置96h。 4、本实验制得的聚乙烯醇阳离子交换纤维,对水溶液中Na⁺有较好的交换性,交换容量最高可达2.55mmol/g,且经多次使用后交换柱中没有发现残渣,有效地避免了二次污染,说明该纤维在水处理过程中有很强的实用性。 5、本实验制得的巯基纤维在水溶液中对部分重金属离子具有良好的吸附性,吸附容量较高,对Cu²⁺、Zn²⁺、Pb²⁺的最大吸附量均在1mmol/g左右,且可多次反复使用,适合于工业废水中有害离子的滤除。其强度达到4.04CN/dtex,接近普通聚乙烯醇纤维的强度,具有较高的实用性。更多还原

【Abstract】 Ion-exchange fiber is a fiber-form ion-exchange material. It has bigger specific surface area and faster rate of exchange and elution than that of ion-exchange resin. It can be applied in many kinds of forms, such as: fiber, yarn, fabric, non-woven etc., and can be applied to various processes of exchange. Ion-exchange fiber can be applied to the preparations of electronic pure water, medical water and biological agent, the purification of industrial sewage, adsorption of poisonous and mephitic gases, the carrier of catalysts, the recovery of heavy metals and rare-earth elements and so on. It is a new type ion-exchange material with promising prospects. At the same time, existing ion-exchange fibers generally have some defects, i.e. low strength and small exchange capacity etc. In this paper, we used high strength and high modulus polyvinyl alcohol fiber as the stuff, and fabricated ion-exchange fiber with high cross-linkage through treatments of benzalation and semi-carbonization so as to it can be suitable for the needs of application. We sulphonated the fiber to gain cation-exchange fiber and mercaptoethylated the fiber to gain mercapto-polyvinyl alcohol chelating fiber respectively. We throughout studied the technology of making ion-exchange fiber and the application of adsorption of heavy metal ions in wastewater. We gained the chelating fiber of high strength and high exchange capacity, and overcome the shortcoming of the incompatibility of mechanistic property and exchange capability of the former fiber, and it has high practicability. The conclusions are showed as follows:1. The optimal reactive condition of benzalation is: [CH₃CH₂OH]=392g/L, [BD]=130g/L, [ZnCl₂]=60g/L and [H₂SO₄]=73.6g/L, the bath ratio=1:50, at 65℃ for 90min, here the maximal degree of acetalization is 12.2%; The temperature of benzalation will not exceed 70 ℃, otherwise the fiber will be dissolved in the solution; The change of the concentration of ZnCl₂ has no influence on degree of acetalization.2. The treatment of semi-carbonization has heavy influence on making polyvinyl alcohol ion-exchange fiber. The temperature of semi-carbonization should be controlled at 200℃ and the period is no more than 60min at the same time, otherwise the strength of the fiber will be not enough; the exchange capability of the cation-exchange fiber are related with the period of semi-carbonization and sulfonation, when the period of semi-carbonization andsulfonation is 60min and 8h, the fiber has the maximal exchange capability.3. The optimal technology of making the mercapto-polyvinyl alcohol fiber is: 2g of the fiber that had been benzaldehyde-acetalized and semi-carbonized entered the C2H4O2S 20mL, （CH3CO）2O 18 mL, CH3COOH（36%） lOmL, H2SO4 0.2 mL and H2O 5mL for 90min, placed them in the oven at 30"C for 96h.4. The polyvinyl alcohol cation-exchange fiber has good adsorption property for Na+ in aqueous solution. Its maximal exchange capacity can reach 2.55mmol/g. No residues were left in the exchange-column when the fibers were used for several times. It can effectively avoid the repeated pollution. It was proved that this fiber had good practicability at water treatment.5. The mercapto-polyvinyl alcohol chelating fiber has good adsorptions of heavy metal ions in aqueous solution, the maximal adsorption capacities for metal ions of Cu2+, Zn2+, Pb2+ are all about lmmol/g, and it can be used timeless. This fiber is suitable for leaching the deleterious ions. The strength of this fiber is 4.04CN/dtex, the strength is close to the strength of ordinary polyvinyl alcohol fiber, and has good practicability.更多还原