Infrared Spectroscopy Reveals Sorption Mechanism of Organic Compounds on Mineral Composite Material

The purification of wastewater contaminated with organic compounds poses a significant global challenge. To address this issue, researchers have been exploring novel methods for pollutant removal. A recent study conducted by scientists from GH University of Science and Technology in Kraków, Poland, focused on the application of a mineral sorbent composite based on lignite and bentonite for the removal of surfactants, dyes, and pharmaceuticals (1). The study, published in the Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy journal, utilized infrared (IR) spectroscopy to investigate the sorption mechanisms involved in immobilizing the organic compounds onto the mineral composite sorbents (1).

To conduct the experiment, the researchers first prepped lignite-bentonite (BL) composite sorbents (1). Then, they examined their sorption capabilities for several dyes, which included rhodamine B (RB) and Remazol brilliant blue R (RBBR) (1). The researchers also examined the sorption capabilities for a couple pharmaceuticals, including ibuprofen (IB) and sulfathoxazole (STX) along with the surfactant sodium dodecylbenzenesulfonate (SDBS) (1). Infrared (IR) spectroscopy provided an important function in this study, as it was used to elucidate the sorption mechanism (1).

IR spectroscopy analysis of the sorbent spectra revealed distinctive bands associated with the adsorption of RB, RBBR, IB, STX, and SDBS onto the BL sorbent (1). The results indicated that the sorption process primarily involved physical interactions such as electrostatic forces, hydrogen bonding, and dispersion interactions (1). As the lignite component predominated in the composite, the sorption capacity and mechanism aligned more closely with lignite's sorption properties rather than those of bentonite (1). In the case of RB absorption on bentonite, X-ray diffraction (XRD) analysis was used to reveal the involvement of ion-exchange processes (1).

The sorption mechanisms observed were complex because of the diverse sorption properties of the mineral composite and the varying chemical properties of the tested organic compounds (1). The spectroscopic studies revealed important insight into the interactions between the organic compounds and the mineral materials (1).

This study has several positive ramifications for removing organic compounds from wastewater using mineral composite sorbents. By understanding the sorption mechanisms involved in this process, researchers in future studies can build on the findings presented here to create and implement more environmentally friendly and sustainable purification methods to decontaminate water (1). Ultimately, the results in this study could pave the way for improving human health by providing a blueprint to researchers on how they can improve current water purification methods.

Reference

(1) Solińska, A.; Marchewka, J.; Sitarz, M.; Bajda, T. Infrared spectroscopy: the key to elucidating the sorption mechanism of surfactants, dyes and pharmaceuticals on mineral composite material. Spectrochimica Acta Part A: Mol. Biomol. Spectrosc. 2023, 299, 122758. DOI: 10.1016/j.saa.2023.122758