Infrared Spectrum Characteristics and Quantification of OH Groups in Coal

Abstract

The KBr pellet press method for detecting the infrared spectrum of coal is one of the commonly used methods for analyzing the types and content of functional groups in coal. However, KBr crystalline water or moisture has a significant impact on the peak position, peak shape, and peak area of the organic O–H based stretching vibration wave in coal. In this paper, the theoretical characteristics of infrared spectra of phenols and alcohols have been simulated and analyzed using the Gaussian 16 series of programs. Four infrared spectral analysis techniques, in situ infrared, KBr pellet press, dry KBr pellet press, and paste methods, have been used to detect the infrared spectra of coal. The results show that the stretching vibration peaks of free O–H radicals without hydrogen bonding are located between 3700 and 3600 cm–1. After the O–H form hydrogen bonds with each other, the O–H stretching vibration frequency moves toward the low frequency direction, and the lower the wavenumber, the more O–H content. The conventional KBr gasket manufacturing process will absorb moisture in the air to interfere with the hydroxyl absorption peak of coal, and the experimental process requires absolute drying. The relative content of hydroxyl in coal can be compared and analyzed based on the peak position, peak shape, and peak area of the hydroxyl stretching vibration wave. Quantitative analysis of hydroxyl groups in coal also requires combination of elemental analysis and X-ray photoelectron spectroscopy.

Evaluating a polymicrobial biofilm model for structural components by co-culturing Komagataeibacter hansenii produced bacterial cellulose with Pseudomonas aeruginosa PAO1

“…The broad bands between 3650 and 3000 cm −1 correspond to O–H stretching vibrations which was related to hydrogen bonding in the cellulose network. The broadened absorption peak near 3400 cm −1 belongs to O–H groups and water [ 29 ]. Attenuation of these bands in the co-cultured biofilms, suggests that EPS secreted following PAO1 colonization have formed H-bonds with the cellulose O–H groups, thereby aggregating the cellulose microfibrils [ 30 ].…”

Proficient Engineering of NiO/Cu2S/rGO heterojunction photocatalysts: fabrication, dye degradation, and mechanism pathways towards environmental remediation

“…Peaks at 1400 and 1200 cm −1 were attributed to the (C–O and CO, respectively) carboxylate stretching vibrational groups. 39 The spectral bands processed under 850 cm −1 correspond to the metal–sulfide or metal–oxygen–metal and metal–oxygen (M = Ni, Cu). The ternary composite projects the availability of the characteristic bands corresponding to rGO, NiO, and Cu 2 S, thereby authorizing the presence of all element counterparts and confirming the hybrid formation.…”

Optimization of Plasma Activated Water Extraction of Pleurotus ostreatus Polysaccharides on Its Physiochemical and Biological Activity Using Response Surface Methodology

“…It is crucial to note that all of the samples' FTIR spectra exhibited similarity, with no discernible emergence of new peaks after plasma-treated. The presence of several absorption peaks suggests that the peak at 3700-3590 cm −1 is attributed to the free -OH group from alcohol and phenol [65]. The absorption peaks at 3305-3202 cm −1 and around 2900 cm −1 were attributed to O-H bond stretching in glycosidic bonds and C-H bond stretching on the benzene ring in the polysaccharides, respectively [22,66].…”