(142b) Adsorption of Microcystin-LR on Model Hydrochar Studied Using Molecular Simulations

Microcystin-LR (MC-LR), the most well-known variant of the microcystin family, is a toxin that is produced by cyanobacteria during algal blooms. It is hepatoxic and can affect various human organs, such as the stomach, kidney, and brain, with the liver as a primary target. According to the World Health Organization, the maximum permissible limit of MC-LR in drinking water is 1 µg/L. Traditional water treatment processes such as chlorination and oxidization are costly for MC-LR treatment, and therefore, it is necessary to look cheaper ways of eliminating it from water supply. One solution is to use pyrolyzed hydrochar produced via hydrothermal carbonization for MC-LR adsorption from water. In this work, we have employed advanced molecular dynamics (MD) simulations in full atomistic detail to understand the adsorption behavior of MC-LR on hydrochar surfaces of different surface functional groups (ammonium, phosphate, and a charge neutral surface). Based on the surface charge, we note stark differences in the free energy of adsorption of MC-LR as well as the adsorbed orientation of the MC-LR molecule. We have identified key interactions that promote strong adsorption of MC-LR on hydrochar surfaces.