Application of Sugar Cane Bagasse Hydrochar for Fipronil and Atrazine Removal from Water

Pesticides are persistent environmental pollutants that pose risks to human health and ecosystems while also contributing to the contamination of waterways. Conventional water treatment technologies are often ineffective in removing pesticides. Therefore, several treatments have been developed to prevent these compounds from being present in the finished water. In this context, a hydrochar synthesized via hydrothermal carbonization of sugar cane bagasse and vinasse was evaluated to remove atrazine (ATZ) and fipronil (FIP) from water. Kinetic data for ATZ and FIP were successfully fitted using the Elovich (<i>R</i> ² = 0.937) and PFO models (<i>R</i> ² = 0.791), respectively. The adsorption equilibrium was reached at 48 h for ATZ and 1 h for FIP. The Langmuir, Freundlich, and Sips isotherms accurately described the experimental data for both pesticides (<i>R</i> ² > 0.93), with maximum adsorption capacities of 273.3 μg g^-1 for ATZ and 34.6 μg g^-1 for FIP. The adsorption decreased with increasing pH, while ATZ adsorption was only slightly affected. The adsorption mechanism was mainly driven by hydrophobic interaction, hydrogen bonding, and π-π interactions. This study demonstrates the potential of sugar cane-derived hydrochar as a low-cost adsorbent for removing ATZ and FIP from water. Further studies are recommended to improve the hydrochar's affinity for these pesticides.