Novel approach for azole fungicides extraction from aqueous environments using terpenes and eutectic solvents

The presence of azole fungicides in aquatic environments is a significant issue due to their toxicity and persistence related to a low removal of these compounds by conventional processes in wastewater treatment plants. A growing environmental public concern is reflected in the inclusion of these compounds in the 2020 and 2022 European Surface Water Watch Lists. Therefore, it is necessary to develop efficient processes that allow their removal sustainably. This work applies liquid-liquid extraction using terpenes as green solvents and terpenebased eutectic solvents to remove azole fungicides from aqueous streams imazalil, metconozale, penconazole, prochloraz, and tebuconazole. First, an initial screening was performed by molecular simulation using the COSMO-RS method. The selected solvents were applied in the individual extraction of azole fungicides, and selecting the solvents thymol+octanoic acid and carvacrol. These solvents have been tested in studies with surface water matrix on the effect of temperature, initial concentration, and pH on extraction performance. From these results, it has been shown that carvacrol is the solvent that is least affected by these variables and obtains extraction yields higher than 97.88%, with a Solvent/Feed ratio up to 0.050, outperforming the conventional solvent methyl isobutyl ketone. This solvent has been used in solvent reuse cycles obtaining a reduction of less than 1% in three extraction cycles. Therefore, carvacrol is presented as a sustainable solvent for the extraction of azole fungicides from aqueous environments.

Automated summary

This study explores the use of green solvents and terpene-based eutectic solvents for the removal of azole fungicides from aqueous environments. The solvent carvacrol is found to have the best extraction performance, achieving an extraction efficiency of over 97.88%. Moreover, it can be reused multiple times with minimal loss of extraction effectiveness. Carvacrol is thus proposed as a sustainable solvent for the extraction of azole fungicides.