水热法绿色合成纳米银及其在水体有机染料中的表面增强拉曼应用

Hydrothermal Green Synthesis of Nano Silver and Its Application in Surface Enhanced Raman of Organic Dyes in Water

工业的发展导致大量染料被排放到水体中,对水环境造成严重污染,危害整个生态系统,因此开发便携快速的检测技术至关重要。表面增强拉曼光谱技术具有单分子水平检测灵敏度高、检测周期短、分子指纹特异性等优点,在水体有机染料检测领域的应用受到广泛关注,但是该技术依赖于高增强能力和高信号重现性的可靠底物,而底物的合成大多使用有毒有害原料,会带来潜在的环境风险。无毒化学品、对环境无污染的溶剂和可再生材料的利用是绿色合成策略中值得重点考虑的因素。采用水热法绿色合成纳米银并用于表面增强拉曼技术,检测水体中的有机染料。首先采用了一种简单、快速、绿色合成的方法,以海藻酸钠为还原剂和稳定剂,水为反应介质,通过水热还原硝酸银实现了纳米银水溶胶的制备,得到本实验的可靠底物。用紫外-可见分光光度法和透射电子显微镜分析了纳米银的结构和表面形貌,结果表明,制得的纳米银水溶胶粒径较大,分布较宽,分散良好且呈球形,颗粒平均直径为46 nm。将三种染料(亚甲基蓝、罗丹明B和碱性品红)配置成不同浓度梯度的溶液,然后与制备好的银胶混合用于表面增强拉曼检测。检测染料溶液的拉曼光谱,查阅文献分配指认特征峰;染料纯溶液在1×10^-3 mol·L^-1浓度时能检测出拉曼特征峰,但在1×10^-4 mol·L^-1及更低浓度时已无特征峰;检测银胶的拉曼光谱,其并没有拉曼光谱峰,表明银胶对混合液的拉曼光谱并没有背景影响;银胶混合液的拉曼光谱特征峰位在低浓度梯度仍比较明显。结果表明,通过该方法绿色合成的纳米银对三种染料均有较好的拉曼增强作用,灵敏度能达到10^(-6) mol·L^-1。随着人们对环境保护的重视,以绿色方法合成的纳米银作为可靠基底的表面增强拉曼技术将在染料废水检测领域具有更广阔的应用前景。

The development of industry has caused a large number of dyes to be discharged into water bodies,causing serious pollution to the water environment and harming the entire ecosystem.Therefore,it is important to develop portable and rapid detection technology.Surface-enhanced Raman spectroscopy has the advantages of high single-molecule level detection sensitivity,short detection cycle,and molecular fingerprint specificity.Its application in the field of water organic dye detection has received widespread attention,but this technology relies on reliable substrates with high enhancement and high signal reproducibility,but the synthesis of substrates mostly uses toxic and hazardous materials,posing potential environmental risks.The use of non-toxic chemicals,non-polluting solvents and renewable materials are important considerations in green synthesis strategies.In summary,this paper adopts a hydrothermal method to green synthesize nano-silver and use it in surface-enhanced Raman technology to detect organic dyes in water.First,a simple,fast,and green synthesis method was adopted,using sodium alginate as the reducing agent and stabilizer,and water as the reaction medium.The nano-silver hydrosol was prepared by hydrothermal reduction of silver nitrate,and a reliable substrate for this experiment was obtained.The structure and surface morphology of nano-silver were analyzed by UV-visible spectrophotometry and transmission electron microscopy.The results showed that the prepared nano-silver hydrosol had a large particle size,a wide distribution,a good dispersion and a spherical shape,and an average particle diameter 46 nm.Three dyes(methylene blue,rhodamine B,and basic fuchsin)were formulated into solutions of different concentration gradients and then mixed with the prepared silver gum for surface-enhanced Raman detection.The Raman spectrum of the dye solution was detected,and the characteristic peaks were identified by reference to the literature.Raman characteristic peak can be detected when the concentration of the pure solution is 1×10^-3 mol·L^-1.However,there was no characteristic peak at 1×10^-4 mol·L^-1 concentration or lower.The detection of the Raman spectra of the silver gum showed that there was no Raman peak,indicating that the silver gum had no background effect on the Raman spectra of the mixture.The Raman spectral characteristic peak position of the silver gum mixture is still relatively obvious at low concentration gradients.These results show that the Nano-silver synthesized by this method has a good Raman enhancement effect on the three dyes,and the sensitivity can reach 10^-6 mol·L^-1.With the emphasis on environmental protection,the surface-enhanced Raman technology using Nano-silver synthesized by green method as a reliable substrate will have a broader application prospect in the field of dye wastewater detection.