Mass transfer kinetics during the extraction of m-cresol from model coal tar using betaine/glycerol deep eutectic solvents

Efficient Extraction of Phenols from Coal Tar and Preparation of Phenolic Resin-Based Porous Carbon for Advanced Supercapacitor Application

Developing simple and efficient extraction methods for phenolic substances from coal tar, which facilitate their direct transformation into high-performance electrode materials, holds considerable practical significance. In this study, amide-zinc chloride deep eutectic solvents are employed for efficient phenol extraction. The optimal phenol extraction process is subsequently investigated, and it is found that the robust hydrogen bonding interactions between solvents and phenols significantly enhance extraction efficiency. Notably, without the need for back-extraction, formaldehyde and tetraethyl orthosilicate are added to obtain phenolic resin, which can subsequently be directly carbonized to fabricate hydrangea-like porous carbon. The carbonization mechanism of the phenolic resin is studied, and the templating and activating roles of tetraethyl orthosilicate and zinc chloride assist in the formation of this unique structure. Furthermore, the flexible supercapacitor assembled using the prepared porous carbon and gel electrolyte achieves a high energy density of 31.0 Wh kg-1 and demonstrates broad temperature applicability ranging from -25 to 100 °C. This work directly converts the extracted phenolic compounds into phenolic resin and shows potential for fabricating porous carbon materials with diverse structures and enhanced capacitive performance.

Multiscale Screening of Deep Eutectic Solvents for Efficient Extraction of m-Cresol from Model Coal Tar

Screening of suitable deep eutectic solvents (DESs) as extractants is vitally important in an extraction process. In this study, a multiscale method combining conductor-like screening model for real solvents (COSMO-RS) calculation, experimental validation, and process simulation is presented. This method was applied to screen DESs for extracting m-cresol from cumene. First, the COSMO-RS model was performed to calculate the phase equilibrium of different ternary systems at different feed compositions, thereby prescreening DESs by investigating the effects of DES structures on the extraction performance. Then, the prescreened DESs were studied by extraction experiments to further validate their extraction performance. The extraction mechanism was investigated through FT-IR characterization. Afterward, continuous process simulation by Aspen Plus was employed to identify more promising DESs. The COSMO-RS calculation and experimental results showed that both choline chloride (ChCl)/ethylene glycol (EG) (1:2) and ChCl/glycerol (Gly) (1:2) demonstrated a high extraction performance, which were selected as two suitable DESs. Considering the mass purity and recovery ratio of m-cresol and cumene products in industrial applications, as well as the extractant dosage and equipment costs, ChCl/Gly (1:2) is considered a more promising DES in industrial application.