Recovery of high‐purity‐4‐chloroguaiacol from bleaching wastewater by a heterogeneous extraction method

Abstract

AbstractBACKGROUNDDuring the pulping and bleaching processes, 4‐chloroguaiacol accounts for a large proportion of chlorine containing pollutants. In this study, a heterogeneous extraction method for extracting 4‐chloroguaiacol from the bleaching wastewater by using the intermediate as the solid phase extraction agent is proposed.RESULTSThe solid intermediate with the molar ratio of 4‐chloroguaiacol to calcium 2:1 is firstly prepared. It is used for reacting with the crude 4‐chloroguaiacol in the bleaching wastewater to generate the end solid complex with the molar ratio of 4‐chloroguaiacol to calcium 4:1. It is verified to be that the high‐purity 4‐chloroguaiacol can be released from the simple thermal decomposition of the end solid complex.CONCLUSIONAt an optimum extraction condition including 30 °C reaction temperature, the pH value of 7, using the deionized water as the solvent, the extraction yield and the purity of 4‐chloroguaiacol reached 89.2% and 97.8%. Furthermore, after 15 cycle extraction times, the extraction rate of 4‐chloroguaiacol can still reach 86.3%. The extraction yield and the purity of 4‐chloroguaiacol reached 68.15% and 99.56% when the guaiacol content was lower than 25 mg/L at the bleaching wastewater. © 2023 Society of Chemical Industry (SCI).