Understanding Microcystin-LR separation by hydrophobic deep eutectic solvents with COSMO simulation and experimental findings

Abstract

Microcystin-LR (MCLR) is considered the most toxic compound in the large family of Microcystin. This study evaluates MCLR separation by hydrophobic deep eutectic solvents (HDESs) for the separation of Microcystin-LR from solutions. Conductor-like Screening MOdel (COSMO) was utilized to evaluate 528 type V HDES by computing the σ-surfaces, σ-profiles, σ-potentials, ln(activity coefficients), and excess enthalpy of adsorption. According to the adsorption thermodynamic, the HDES based on tetrabutylammonium bromide (TBAB) exhibits significantly higher affinity towards MCLR, with the ln(activity coefficient) being as low as −14.3, indicating strong separation capability. Excess enthalpy results reveals that the interactions between HDES and MCLR are predominantly governed by Vander Waals interactions, which exhibit >10 times higher enthalpic release compared to that of hydrogen bonding. The experimental results show that 79.85 ± 0.75 % MCLR removal can be achieved by TBAB: acetic acid (1:1 ratio). Finally, Virtual models for property Evaluation of chemicals within a Global Architecture (VEGA) analysis was performed on the best performing HDES (TBAB:acetic acid, TBAB: arginine, and TBAB: glutamic acid) to evaluate human and environmental toxicity endpoints, i.e., mutagenicity, carcinogenicity, acute toxicity, and bioconcentration factor (BCF). The results show that the HDES exhibit low toxicity and negligible environmental concerns.