Surface-Enhanced Raman Spectroscopy for Rapid and Cost-Effective Quantification of Amines in Sour Water

Abstract

Organic amines are corrosion control agents that increase pH and scavenge corrosive contaminants. Their presence in sour water can lead to the formation of heat-stable salts, resulting in potentially corrosive deposits. The measurement and monitoring of amines in sour water requires chromatographic techniques, with corresponding complexity, training, and expense. A rapid, field-deployable method to measure amines in refinery process waters would speed testing time, increase the temporal data resolution, and allow for immediate response and process adjustment. We present a new approach to amine measurement using Surface-Enhanced Raman Spectroscopy. By mixing a pH-adjusted sample with gold nanoparticles, a strong amine signal is obtained with a potential for sub-100-ppb detection. An optimized approach for ppm-level detection reports 27.8Ϯ3.9-ppm and 76.4Ϯ5.1-ppm for~25-ppm and~75-ppm samples, respectively, with more than one-hundred tests per sample over a three-month period. This method is at least as accurate, sensitive, and repeatable as ion chromatography, yet can be performed in the field in under five minutes.

Quantification of Amines in Refinery Process Water via Surface-Enhanced Raman Spectroscopy

“…Raman spectroscopy can be amplified by the use of noble-metal nanoparticles. − These nanoparticles act as antennae, increasing the efficiency of Raman scattering by 3–9 orders of magnitude. This signal enhancement allows the detection of a wide variety of molecules down to trace concentrations. ,− Coined “surface-enhanced Raman spectroscopy” (SERS), this effect was first discovered in the 1970s and was conclusively demonstrated to be sensitive enough to observe the vibrations of a single molecule. ,, …”

Quantitative Analysis of Triazine-Based H2S Scavengers via Raman Spectroscopy

“…The intensity of the observed spectrum is linearly related to the concentration in solution . We use this relationship coupled with an internal standard to produce a fast, laboratory-quality test for MEA-triazine quantification in fresh scavenger solutions, which is an approach that has been used successfully for analyte quantitation in other complex sample matrices. , In recent years, because of the miniaturization of lasers, electronics, and microprocessors, Raman spectrometers have decreased in size, and cost, thereby increasing portability and convenience. This Research Note details the application of cutting-edge Raman techniques to create a rapid and accurate MEA-triazine monitoring system.…”

Rapid Quantification of 4,4′-Methylenedianiline by Surface-Enhanced Raman Spectroscopy

“…This signal enhancement allows detection of a wide variety of molecules down to trace concentrations. Surface-enhanced Raman spectroscopy (SERS) was first discovered in the 1970s, and within 30 years, it was conclusively demonstrated to be sensitive enough to observe the vibrations of a single molecule. − Recently, SERS has been used to detect and quantify amines such as ethanolamine and methylamine in aqueous solutions …”

“…8−10 Recently, SERS has been used to detect and quantify amines such as ethanolamine and methylamine in aqueous solutions. 11 Reported herein is a relatively rapid method for the quantification of 4,4′-MDA in aqueous grease extracts; furthermore, we will describe differentiation of 4,4′-, 3,3′-, and 2,4′-MDA molecules in an extracted sample. The 4,4′-MDA and 2,4′-MDA are impurities in the manufacturing of grease, derived from the corresponding 4,4′-and 2,4′methylene diphenyl diisocyanate (MDI) starting materials.…”