【作者】 孙咏红；

【导师】 项文化；

【作者基本信息】 中南林业科技大学 ， 生态学， 2010， 博士

【摘要】 过去的二十世纪,化学为人类创造了巨大的物质财富和生存革命,也让人类付出了资源枯竭和环境污染的沉重代价,忽视自然规律和生态系统自我调节能力利用化学的过程产生了系列生态问题。“从源头根除污染”的绿色化学应运而生,依照绿色化学建立的标准、原则和方法体系,设计更安全和更环保的化学品,开发可最大限度利用能源、资源,并且无毒、无害、无污染排放的化学反应和化工过程正在成为化学工作者努力的方向和追求的目标。本研究从绿色化学的理念出发,以目前公认的绿色阻垢剂聚环氧琥珀酸(Polyepoxysuccinic acid PESA)为对象,从阻垢剂的绿色化学设计与性能研究入手,通过实验及理论分析,对PESA的合成工艺及在反渗透(RO)水处理中的应用进行较为全面和深入的研究。依据绿色化学的原则,研究具有原子经济性、对人类和环境友好的PESA的合成方法。选择无磷无氮、不含对环境有害成分的化合物马来酸酐作为单体,用水溶液作反应介质,在合成过程中不使用有机溶剂,而采用简单的无机化合物,用过氧化氢作氧化剂、钨酸钠作催化剂、固体氢氧化钠作引发剂,通过单因素试验和正交设计试验对一步法合成PESA工艺的水解、环氧化反应、聚合反应条件进行优化,以实现目标产物高性能、能源消耗最小化和反应过程无废化。优化的环氧化条件为：反应温度70℃；反应时间55分钟；氧化剂H202(30%)用量为马来酸酐质量的35%；催化剂Na2WO4用量为马来酸酐质量的2.4%。聚合反应条件为：引发剂NaOH用量为马来酸酐质量的0.34%；聚合温度80℃；聚合时间2h；聚合反应体系的pH=7±0.5。按上述优化条件合成的PESA,马来酸酐单体的转化率为89.1%；目的产物中羧基含量为21.45%；对CaCO3的阻垢率大于96%。按HG/T 3823-2006《聚环氧琥珀酸(盐)》的技术要求对产品进行检验和表征的结果全部达标；参照国际标准OECD301B测定的10天生物降解率大于77%。采用静态和动态的方法研究了PESA作为反渗透阻垢剂的有效性和可行性。模拟反渗透浓水水质,在阳离子质量浓度分别为40mg/L、100mg/L、200mg/L的试验水中加入10m/LPESA,试验结果表明,PESA对易沉积在反渗透膜上的碳酸钙、硫酸钙、硫酸钡、硫酸锶的平均阻垢率可达到90%以上,具有多元阻垢性能。模拟海水和城市自来水的反渗透系统,采用加药全循环的方式,考查PESA的动态阻垢性能,经过10个周期的实验,反渗透膜透水率和脱盐率的变化均未超过5%。且与反渗透预处理中常用的铁盐及铝盐混凝剂有着良好的相容性。用JSM-6360LV型扫描电镜对加入阻垢剂PESA的碳酸钙垢晶体进行扫描分析的结果显示,PESA可以使碳酸钙(CaCO3)的晶格发生畸变,破坏CaCO3晶体原有的规则致密结构,从而抑制了CaCO3垢的形成,结合PESA可显著提高微溶盐的相对过饱和度,足见PESA对成垢离子具有分散、络合增溶、晶格畸变等多种阻垢作用。本文还对阻垢剂的评价方法进行了试验研究,采用电导法评定PESA的阻垢性能,通过电导率滴定难溶盐的相对过饱和度,分析评价阻垢剂的阻垢效果。对比试验的结果显示,电导滴定法与碳酸钙沉积法的试验结果一致,但重现性优于碳酸钙沉积法。与碳酸钙沉积法相比,电导法能够快速、准确地评定阻垢剂的阻垢性能,具有简单方便、重现性好等优点。更多还原

【Abstract】 In the 20th century, chemistry created enormous material wealth and brought great revolutions for human survival. At the same time, human beings had paid huge prices of resources depletion and environmental pollution, as a consequence of ignorimg natural law and the limited self-regulation capacity of ecosystem. This curel realtity challenged the idea of traditional chemistry. "Eliminating the pollution from the source"-the concept of green chemistry was proposed and embraced by more and more chemists. Producing safer and more eco-fridenly chemical producs following the standards and protacals of green chemistry, developing energy-saving, non-toxic, pollution free chemical industry has become the goal for many chemists. This paper aims to study the widely recognized green scale inhibitor, Polyepoxysuccinic acid. From the property and the green chemistry design of the scale inhibitor, using both experiments and theoretical analysis, we carefully studied the synthesis and application of PESA in the reverse osmosis process.We employed synthetic method for PESA which is of atomic economy and environmental friendly on in term of the theory of green chemicals. Maleic anhydride without nitrogen and phosphorus pollution was chosen as the monomer, and water as the reaction medium without any organic solvents, the inorganic compound H2O2 as oxidant, Na2WO4 as catalyst, and solid NaOH as initiating agent. The optimal conditions of hydrolysis, epoxidation and polymerization of the synthetic process were identified through simple factor experiment and orthogonal experiment. In this case, the PESA product with high performances, less energy consumption and no waste has been realized. The optimal conditions of the epoxidation are that the reaction temperature is 70℃reaction time is 55 min, with 35% dosage of oxidizing agent H2O2 (30%),2.4% dosage of maleic anhydride and catalyst Na2WO4 and the dosage of maleic anhydride. The condition of polymerization is that the dosage of initiating agent is 0.34% maleic anhydride with polymerization temperature of 80℃, polymerization time of 2h, and pH of 7+/-0.5.The PESA was obtained under the optimal conditions above with the maleic anhydride monomer converting ratio of 89.1% and carboxyl content of 21.45%. The scale inhibition ratio of CaCO3 is above 96%. After tests and measurement, the products could meet all requirement of The Sector Standard of The Technical requirements of PSEA (HG/T 3823-2006), According to the standard method OECD301B, the biograduation ratio of PESA is above 77%. The effectiveness and applicability of PESA as a RO scale inhibitor were studied using both static and dynamic methods. 10mg/L PESA was added into the synthesized RO water with cation concentration of 40mg/L, 100mg/L and 200mg/L, respectively. According to the results, PESA showed multi-inhibitory performances with the average scale inhibition ratio of 90% to CaCO3, CaSO4, BaSO4 and SrSO4 which could easily deposit on the RO membrane.The dynamic scale inhibition performance of PESA in the RO system of both sea water and tap water was investigated under the full recycle operation mode. After ten cycles of experiments, the variations in water permeability and desalination ratios are within 5% after PESA treatment. In addition PESA is well compatible with with Fe and Al coagulants commonly used in RO system.Analysis of JSM-6360LV SEM images of CaCO3 crystals treated with PESA suggested that PESA could induce CaCO3 crystal deformation, damaging the crystal structure, thus prevent the growth of CaCO3 scale. Reacting with PESA can greatly increase the relative degree of super saturation of slightly soluble salts. We recognized that PESA had a verity of anti-scaling effects like separation, promotion in solubility by complexion, and crystal deformation on scale causing ions.We also compared the methods for evaluating scale inhibitors. Through conductometric titration, the relative saturation level of the slightly soluble salts was obtained which is used to evaluate the performance of scale inhibitor. The results show that Titration method gave essentially the same results as the precipitation of CaCO3, but was more repeatable. Compared with CaCO3 precipitation, conductometric titration can access the performance of the scale inhibitor more quickly and accurately, is easier to apply and more repeatable.更多还原