Detection and classification of volatile fatty acids using surface‐enhanced Raman scattering and density functional theory calculations

Abstract

Volatile fatty acids of acetic, butyric, lactic, and propionic acids play an important role in the methane fermentation process. Particularly significant amount of propionic acid presence in the process will influence the methane fermentation efficiency. Herein, zigzag‐aligned silver nanorods were designed as surface‐enhanced Raman scattering (SERS)‐active substrates to establish the classification of volatile fatty acids against the traditional poor sensitive and time‐consuming titration and gas chromatography methods. SERS and chemometric method of principal component analysis is used for the detection and classification of volatile fatty acids. Density functional theory calculations were performed to understand the Raman vibrations and compare with experimental observations and to aid in the assignments of spectral lines. For the first time, the authors have used SERS technique to classify the acids. The findings suggest that this method is of great potential in the field of methane fermentation from industrial waste.

Hydrophilic and Hydrophobic Nanostructured Copper Surfaces for Efficient Pool Boiling Heat Transfer with Water, Water/Butanol Mixtures and Novec 649

“…These values were used to identify possible changes in the chemical composition of the surface due to transition between copper species. Since the exposure of copper (and similar materials capable of acting as catalysts) to n-butanol at elevated temperatures, which can appear during boiling, may cause oxidation and conversion to other hydrocarbon species (such as n-butyraldehyde) [85][86][87][88], the spectra of possible reaction products were also reviewed [89][90][91][92] to determine whether such species might have reacted with or formed on the surface. Surface properties were also evaluated through wettability measurements.…”

Functionalized MXene/Halide Perovskite Heterojunctions for Perovskite Solar Cells Stable Under Real Outdoor Conditions

“…After functionalization of the d‐MXene with the H3pp molecule, the peaks at 148 cm −1 , 613 cm −1 , and 245 cm −1 have been quenched and a new peak at 301 cm −1 is observed which is attributed to the in‐plane oxygen vibration modes from the termination groups (T x ) of MXene naosheets [ 38 ] while preserving the peak at 963 cm −1 . [ 37,39 ] These results demonstrate that after addition of the H3pp molecule, the Ti and C vibration modes are strongly weakened and the oxygen termination group are strengthened due to the presence of a P─O bonding in H3pp by its attachment to the MXene nanosheets surfaces.…”

Elaboration and Characterization of Natural Deep Eutectic Solvents (NADESs): Application in the Extraction of Phenolic Compounds from pitaya

“…Characteristic bands were identified in the spectrum of the pure lactic acid in the region between 2834 cm −1 and 3051 cm −1 , referring to the different vibration modes of CH 3 groups and the C=O group (stretching) in 1730 cm −1 [ 51 ]. An intense torsion band of the cluster was also detected for NH 3 + (1323 cm −1 ), which is typical of pure glycine and other less intense bands, such as the elongation of C-C (893 cm −1 ) and CCN (1037 cm −1 ) groups [ 52 , 53 ].…”