Purification of creosol applying green heterogeneous extraction technology

BACKGROUND Cresol is an important industrial raw material, which is mainly derived from lignocellulosic biomass. High-purity creosol can significantly improve the quality of its downstream product. The extraction of creosol with ultra-high purity (>99.5%) and low cost has attracted extensive attention in recent years. A new and simple green heterogeneous extraction technology for separating ultra-high-purity creosol is proposed in this paper. RESULTS When a certain amount of creosol is gradually dripped into Ca 2+ solution, the chemicals in three reaction stages are successively monitored by in situ Fourier transform infrared spectroscopy. The molar ratio of creosol and Ca 2+ in the end-product of this reaction reaches four. Three different chemical bonds in three reaction stages are successively monitored: ion bond, coordination bond formed by ionic compound, and coordination bond formed by creosol molecule. This collected end-product can be decomposed easily. The vapors released in this decomposed process is determined to be high-purity creosol. Meanwhile, the molar ratio of creosol to Ca 2+ in the residual solid after decomposition of the end-product reduces to two. CONCLUSION Based on the reaction mechanism between Ca 2+ and creosol, a new route for the separation and purification of creosol was proposed in this study. The creosol extraction rate reached 91.5% when excessive Ca 2+ solution was added to the creosol solution. The purity of creosol reaches up to 99.7% when the end-product of the reaction between Ca 2+ and creosol is decomposed at 170 °C. © 2022 Society of Chemical Industry (SCI).