水中痕量重金属汞离子(Hg2+)对人类健康会构成严重威胁,因此快速高灵敏检测水中痕量Hg2+具有重要科学意义和实际应用价值.为实现这一目标,研究运用银纳米线(silver nanowires,AgNWs)作为表面增强拉曼散射(Surface-Enhanced Raman Scattering,SERS)基底来快速高灵敏检测水中痕量Hg2+.用旋涂法制备了均匀分布的AgNWs基SERS基底,并用罗丹明6G(Rhodamine 6G,R6G)作为拉曼信标分子,以间接检测水中痕量Hg2+.通过研究SERS活性、稳定性、重现性、选择性、AgNWs直径及pH值对其SERS活性的影响,用时域有限差分法(Finite Difference Time Domain,FDTD)模拟了 AgNWs表面电场分布情况.结果显示,AgNWs基SERS基底具有良好的活性、优异的信号再现性、稳定性和选择性,SERS活性随着直径的增大而增强,对Hg2+的检测限(Detection Of Limit,LOD)达 10-11 mol/L,远低于美国环境保护署(The U.S.Environmental Protection Agency,EPA)的饮用水Hg2+浓度标准(10-8 mol/L).在低浓度范围内,SERS特征峰强度(R2=0.9919)有良好的线性关系.FDTD模拟结果为试验结果提供了有力的理论支撑,可为水中检测痕量Hg2+提供新策略,在环境监测中具有广阔的应用前景.
Abstract
The presence of trace heavy metal mercury ions(Hg2+)in water poses a great threat to human health.Therefore,the rapid and sensitive detection of trace Hg2+in water holds great scientific significance and practical application value.To achieve this goal,we investigated the rapid and highly sensitive detection of trace Hg2+in water using five silver nanowires(AgNWs)with diameters of 60 nm,65 nm,71 nm,76 nm,and 85 nm,which were chosen as Surface-Enhanced Raman Scattering(SERS)substrates.Uniformly distributed AgNWs SERS substrates were prepared using the spin coating method,which was then modified with Rhodamine 6G(R6G)for indirect detection of trace Hg2+in water.The activity,stability,reproducibility,and selectivity of the AgNWs-based SERS were investigated.The effects of pH and AgNWs diameter on SERS activity were also studied.To simulate actual wastewater containing mercury ions,simulated wastewater was prepared.The mercury ions in the simulated wastewater were measured using AgNWs SERS substrate.Furthermore,the surface electric field distribution of AgNWs was simulated by using the Finite Difference Time Domain(FDTD)method.The results show that AgNWs exhibited good activity as SERS substrates with excellent signal reproducibility,stability,and selectivity.In a certain range,the SERS activity increases with the increase of pH.When pH reaches 7,the activity tends to be stable.Similarly,SERS activity increased with increasing diameter.The detection limit(LOD)for Hg2+was found to be 10-11 mol/L,far below the US Environmental Protection Agency's(EPA)Hg2+content standard for drinking water(10-8 mol/L).In addition,in the low concentration range,the SERS characteristic peak intensity(R2=0.9919)demonstrated a good linear relationship.The FDTD simulation results well explain our experimental results.This method provides a new strategy for detecting trace Hg2+in water and has broad application prospects in environmental monitoring.
basic disciplines of environmental science and technology/Surface-Enhanced Raman Scattering(SERS)/silver nanowires(AgNWS)/Rhodamine 6G/mercury ion/finite difference time domain
维普
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