【作者】 张雪梅；

【导师】 张杰； 兰剑平；

【作者基本信息】 重庆工商大学 ， 材料与化工（专业学位）， 2024， 硕士

【摘要】 废旧印刷电路板（WPCBs）是电子设备中最关键和最宝贵的部件之一,含有大量金属材料,金属资源中铜占90%左右,是克服金属匮乏的潜在二次资源。但同时,WPCBs中含有大量的砷、汞、镉、铅及其他多种持久降解和生物累积性的有毒物质,对自然环境造成了不可忽视的污染。小肽是一种分子量在1000 Da以下的小分子活性肽,由2～3个氨基酸组成,结构中含有的羧基、巯基、氨基等,与金属铜离子有极强的亲和能力,可实现多位点的螯合并生成小肽螯合铜。小肽螯合铜作为新一代高效绿色微量元素营养剂,广泛应用于水溶肥、叶面肥、植物营养调节剂、螯合型复合肥以及杀菌剂。本研究从WPCBs中回收金属铜对环境保护和资源再利用意义重大,对于实现利用WPCBs制备小肽螯合铜具有深远的实际意义,符合国家发展循环经济和绿色化工的需求。初步研究如下:（1）本研究建立了电感耦合等离子体检测方法,金属元素检测浓度在0～30mg/L范围内与强度呈良好的线性关系,满足相关系数达0.99及以上的要求。利用王水加浓硫酸浸取体系测定WPCBs粉末中的金属总含量,其中1.0 g WPCBs粉末中Cu含量高达340.5 mg。水浴机械搅拌、磁力搅拌、超声、超声协同常规搅拌四种浸出方式对比发现超声协同常规搅拌对铜浸取最高效;构建超声场强化螯合反应系统,对比氨基酸与小肽浸取WPCBs中铜的浸取效果,发现3.0 h时小肽类浸取效果高出氨基酸类7.41±0.3%～33.60±0.6%;过氧化氢、氧气、空气三种氧化剂对比分析发现,过氧化氢氧化剂浸取效果相较于另外两种高出75%左右,更有助于提高铜浸取效率;金属之间的竞争机制对比得出谷胱甘肽（GSH）对金属铜的选择性比镍、铅、铝高67.92±0.2%左右。上述研究表明,以过氧化氢为氧化剂,将机械搅拌安装于超声设备上构建超声场强化螯合反应系统,采用超声场强化小肽螯合WPCBs中铜的工艺最佳。（2）在超声场强化螯合反应系统下,浸出参数中初始小肽浓度、温度、初始过氧化氢体积分数对铜浸出效果有显著影响。GSH、甘氨酰甘氨酸（GG）、甘氨酰-L-谷氨酰胺（GLG）对铜的最大浸出率分别达到95.4±0.5%、92.5±0.3%、87.4±0.2%,差异是由小肽官能团不同引起的。超声场处理对铜的浸出量比未进行超声场处理的高出2.1～3.9倍。通过铜浸取动力学研究可得铜浸出过程同时受到扩散和化学反应的控制,且GSH、GG、GLG浸出铜的活化能分别为19.8KJ/mol、28.8 KJ/mol、25.8 KJ/mol,进一步论证了这一点。此外,通过小肽螯合铜配位系数测定分析可得谷胱甘肽螯合铜（CC-GSH）、甘氨酰甘氨酸螯合铜（CC-GG）、甘氨酰-L-谷氨酰胺螯合铜（CC-GLG）的配位数分别为2、1、1,配位作用体现在小肽中的羰基和氨基可能提供了电子与Cu²⁺配位形成配位键,从而形成了稳定的小肽螯合铜螯合物。（3）基于溶剂置换结晶技术获得小肽螯合铜晶体,并对小肽螯合铜晶体进行表征分析。红外检测（FT-IR）结果表明羧基、羰基、氨基、巯基等活性基团是小肽与Cu²⁺络合的主要原因;扫描电镜（SEM）和X射线衍射仪（XRD）结果表明GSH与Cu²⁺的结合能力最强,GLG的结合能力最差;X射线能谱仪（EDS）结果表明CC-GSH、CC-GG、CC-GLG的实际元素组成与理论是一致的。小肽螯合铜有效性研究表明CC-GSH、CC-GG、CC-GLG对浸种的发芽势和发芽率有明显的提升效果,对苗高有微小提升,其中水稻和高粱的发芽势和发芽率达到了100%,相较于空白组和普通铜肥组高出33.3%,水稻和玉米苗高高出1 cm以上。效益分析表明以小肽为浸出剂,不仅对环境无污染还能制备出更具有经济价值的小肽螯合铜,且可判定出GSH、GG为最理想的绿色无污染潜在浸出剂。更多还原

【Abstract】 Waste Printed Circuit Boards（WPCBs）are one of the most critical and valuable components of electronic equipment,containing a large number of metal materials,with copper accounting for about 90%of the metal resources,making them a potential secondary resource for overcoming metal scarcity.However,WPCBs contain a large amount of arsenic,mercury,cadmium,lead and bioaccumulative toxic substances,which cause non-negligible pollution to the natural environment.Small peptides are a kind of small molecule active peptide with molecular weight below 1000 Da,which are composed of 2 to 3 amino acids.The carboxyl group,sulfhydryl group,and amino group of small peptides have a strong affinity with copper ions,which can realize multi-site chelation and generate copper-chelating small peptides（CCPs）.CCPs are a new generation of high-efficiency green trace element nutrients,which are widely used in fertilizers,plant nutrient regulators,feeds,and fungicides.The study on copper recovery from WPCBs is significant for environmental protection and resource reuse.Moreover,it has far-reaching practical significance in realizing the preparation of CCPs from WPCBs.The preliminary study is as follows:（1）In this study,an inductively coupled plasma detection method was established,and the detected concentration of metal elements showed a good linear relationship with the intensity in the range of 0-30 mg/L,which satisfied the requirement of a correlation coefficient of 0.99 and above.The leaching system of aqua regia plus concentrated sulfuric acid was utilized to determine the total metal content in WPCBs powder,in which the Cu content in 1.0 g WPCBs powder was as high as 340.5 mg.The comparison of mechanical stirring in a water bath,magnetic stirring,ultrasonic,and ultrasonic combined with conventional stirring,revealed that ultrasonic combined with conventional stirring was the most efficient for copper leaching.The ultrasonic field enhanced chelating reaction system was constructed to compare the effect of amino acids and small peptides chelating copper in WPCBs,and it was found that the effect of small peptides leaching was higher than that of amino acids by 7.41±0.3%-33.60±0.6%at 3.0 h.Comparative analysis of the three oxidants,hydrogen peroxide,oxygen and air,revealed that the leaching effect of hydrogen peroxide oxidant was about 75%higher than that of the other two oxidants,which was more helpful to improve the copper leaching.The comparison of the competition mechanism between metals showed that the selectivity of glutathione（GSH）for copper metal was about 67.92±0.2%higher than that of nickel,lead and aluminum.The above study showed that the optimal leaching process for copper chelation in WPCBs was to use hydrogen peroxide as an oxidizing agent,install mechanical stirring on the ultrasonic equipment to construct an ultrasonic field-enhanced chelation reaction system,and use ultrasonic field-enhanced small peptides chelating process to chelate copper in WPCBs.（2）Under the ultrasonic field-enhanced chelation reaction system,the leaching parameters including initial small peptide concentration,temperature,and initial hydrogen peroxide volume fraction had a significant effect on the copper leaching.The maximum leaching of GSH,glycylglycine（GG）,and glycyl-L-glutamine（GLG）on copper were 95.4±0.5%,92.5±0.3%,and 87.4±0.2%,respectively,which were caused by the differences in the functional groups of the small peptides.The leaching of copper by the ultrasonic field was 2.1-3.9 times higher than that without ultrasonic field treatment.The kinetic study of copper leaching yielded that the copper leaching process was controlled by both diffusion and chemical reactions.In addition,it was further supported by the fact that the activation energies for copper leaching by GSH,GG,and GLG were19.8 KJ/mol,28.8 KJ/mol,and 25.8 KJ/mol,respectively.It is worth noting that the coordination numbers of copper-chelating GSH（CC-GSH）,copper-chelating GG（CC-GG）,and copper-chelating GLG（CC-GLG）can be obtained as 2,1,and 1,respectively.The carbonyl and amino groups in the small peptides may have provided the electrons to coordinate with Cu²⁺to form coordination bonds,resulting in the formation of stable small peptides chelated copper.（3）CCPs were obtained based on solvent displacement crystallization technique and characterized and analyzed.The results of infrared detection（FT-IR）showed that the active groups such as carboxyl,carbonyl,amino,and sulfhydryl were the main reasons for the complexation of small peptides with Cu²⁺.Scanning electron microscopy（SEM）and X-ray diffractometer（XRD）results showed that GSH had the strongest binding ability to Cu²⁺,and GLG had the worst binding ability.X-ray energy spectrometry（EDS）results showed that the actual elemental compositions of CC-GSH,CC-GG,and CC-GLG were in agreement with the theory.The effectiveness of small peptides chelated copper showed that CC-GSH,CC-GG and CC-GLG had obvious effect on the germination potential and germination rate of the dipped seeds,and had a slight increase in seedling height.Among them,the germination potential and germination rate of rice and sorghum reached 100%,which was 33.3%higher compared to the blank and ordinary copper fertilizer groups,and the seedling height of rice and maize was more than 1 cm higher.Benefit analysis shows that the use of small peptides as a leaching agent is not only non-polluting to the environment but also able to prepare small peptides of chelated copper with a more economic value.Moreover,GSH and GG can be determined as the most ideal green and non-polluting potential leaching agent.更多还原