氨基酸共聚物的合成及其与金属离子络合性能的研究

发布时间：2018-08-07 20:31

【摘要】：近年来,水资源危机日益严重,工业循环冷却水系统补给水的水源逐步被再生水替代,该措施在一定程度上缓解了用水紧缺状况,但再生水引起的循环冷却系统结垢问题,以及污水外排造成了环境污染问题日趋严重。因此,需要合成一种高效且环境友好的水处理药剂。本文在聚天冬氨酸改性的基础上研发出了一种新型的水处理药剂,用于解决系统中存在的问题。首先,以天冬氨酸和苹果酸为原料,采用微波加热的方式,合成了天冬氨酸-苹果酸共聚物(PAMA)。研究了原料配比、微波功率、微波时间等对共聚物的络合性能及产率的影响,得到了最优合成工艺条件:以KH2PO4为催化剂,N-N二甲基甲酰胺(DMF)为有机溶剂,当n(Asp)/n(Asp+MA)=0.5,n(Cat)/n(Asp+MA)=0.10,V(DMF)=6mL,微波功率为1000W,微波时间3.5min时,合成的共聚物产率达到98.91%,络合量达到500mg/g。利用红外光谱和核磁共振表征了天冬氨酸-苹果酸共聚物的结构。其次,对天冬氨酸-苹果酸共聚物的可生物降解性进行了研究,结果表明:PAMA是一种易生物降解的药剂;在一定范围内,分子量越小,苹果酸含量越高,PAMA可生物降解性越好;苹果酸和天冬氨酸的可生物降解性能接近,而PAMA的降解效果较其两个单体差一些;加入Al~(3+)和Mn~(2+)对PAMA的可生物降解性能没有产生负面影响,甚至在Mn~(2+)的存在下,PAMA的可生物降解性能有所提升;而加入Zn~(2+)和Cu~(2+)对PAMA的可生物降解性能均产生了负面影响,并且Cu~(2+)的负面影响最严重;PAMA的降解效果优于ATMP和HEDP,但是较PASP和PBTCA的效果要差一些。之后,对天冬氨酸-苹果酸共聚物的络合性能进行研究,针对CaCO_3和CaSO4两种垢型,考察了阻垢剂投加量、pH值、金属离子浓度、恒温温度、恒温时间不同时,PAMA对二者Ca~(2+)的络合性能的影响,结果表明:PAMA适用于温度较高,水力停留时间较长的循环冷却水系统;溶液中加入金属离子后,PAMA的络合性能降低,在金属离子超过一定浓度以后,络合性能几乎完全丧失。因此,在循环冷却系统中应严格控制金属离子的含量。最后,利用XRD和SEM对天冬氨酸-苹果酸共聚物的络合机理进行探讨,结果表明:加入PAMA后,晶体结构由方解石转变为球霰石,晶型由规则坚硬的六面体变为不规则结构松散的体形。
[Abstract]:In recent years, the crisis of water resources is becoming more and more serious, the source of recharge water of industrial circulating cooling water system is replaced by reclaimed water gradually, this measure alleviates the shortage of water to some extent, but the scale problem of circulating cooling system caused by reclaimed water. The problem of environmental pollution caused by sewage efflux is becoming more and more serious. Therefore, it is necessary to synthesize an efficient and environmentally friendly water treatment agent. Based on the modification of polyaspartic acid, a new water treatment agent was developed to solve the problems in the system. Firstly, aspartic acid-malic acid copolymer (PAMA). Was synthesized by microwave heating using aspartic acid and malic acid as raw materials. The effects of raw material ratio, microwave power and microwave time on the complexation properties and yield of copolymers were studied. The optimum synthetic conditions were obtained as follows: using KH2PO4 as catalyst and N-N dimethylformamide (DMF) as organic solvent. When n (Asp) / n (Asp MA) 0.5n (Cat) / n (Asp MA) 0.10V (DMF) 6mL, microwave power 1000W, microwave time 3.5min, the yield of the synthesized copolymers is 98.91 and the complexation amount is 500mg / g. The structure of aspartic acid-malic acid copolymer was characterized by IR and NMR. Secondly, the biodegradability of aspartic acid-malic acid copolymers was studied. The results showed that: (1) PAMA is a biodegradable agent, and the lower the molecular weight is, the higher the malic acid content is, the better the biodegradability of PAMA is. The biodegradability of malic acid and aspartic acid was similar, but the degradation effect of PAMA was worse than that of its two monomers, and the addition of Al3 and Mn2 had no negative effect on the biodegradability of PAMA. Even in the presence of Mn2, the biodegradability of PAMA was improved, but the addition of Zn2 and Cu2 had a negative effect on the biodegradability of PAMA. The degradation effect of Cu2 was more serious than that of ATMP and PBTCA, but it was worse than that of PASP and PBTCA. After that, the complexing properties of aspartic acid-malic acid copolymer were studied. The pH value, concentration of metal ions, constant temperature of scale inhibitor were investigated for two kinds of scale types: CaCO_3 and CaSO4. The effect of PAMA on the complexation property of Ca2 was studied at different time of constant temperature. The results showed that the ratio of PAMA to PAMA was suitable for circulating cooling water system with high temperature and long HRT, and the complexation property of PAMA was decreased when metal ions were added into the solution. When metal ions exceed a certain concentration, the complexation property is almost completely lost. Therefore, the content of metal ions should be strictly controlled in the circulating cooling system. Finally, the complexation mechanism of aspartic acid-malic acid copolymers was investigated by XRD and SEM. The results showed that the crystal structure of the copolymers changed from calcite to vermicelli after the addition of PAMA. The crystal form changes from the regular hard hexahedron to the irregular structure loose body shape.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O631.3;X703

【参考文献】