Systematic design of hydrophobic deep eutectic solvents by VEGA, COSMO-RS, and experiments for efficient removal of Saxitoxin and brevetoxin from water.

Harmful algal blooms (HABs) and their associated neurotoxins, Brevetoxin (PbTx3) and Saxitoxin (STX), pose significant environmental, economic, and public health challenges. This study investigated the design of hydrophobic deep eutectic solvents (HDES) as a green and sustainable alternative for the simultaneous removal of PbTx3 and STX from contaminated water. An initial systematic screening of 8556 potential HDES combinations was conducted using Virtual models for property Evaluation of chemicals within a Global Architecture (VEGA) evaluations and quantum chemical modeling via the Conductor-like Screening Model for Real Solvents (COSMO-RS). Key properties such as activity coefficients, intermolecular interactions, and solid-liquid equilibria were analyzed to identify optimal HDES formulations. Menthol-based HDES combined with citric, lactic, or hexanoic acids demonstrated superior performance due to their balanced hydrogen bonding and van der Waals interaction capabilities. Experimental validation confirmed the computational predictions, with these solvents achieving over 94 % removal efficiency for both toxins in individual solutions. However, competitive adsorption in mixed toxin solutions resulted in a significant reduction in STX removal efficiency. The study underscores the role of HDES in addressing dual-toxin challenges and highlights their potential as environmentally friendly alternatives to conventional toxic solvents. By leveraging green chemistry principles, this research contributes to advancing sustainable solutions for water purification and the mitigation of harmful algal blooms.