Modified Moringa oleifera Lam. Seed husks as low-cost biosorbent for atrazine removal

Atrazine is an herbicide which is widely applied in sugarcane and corn crops. Its frequent use has resulted in environmental impacts, and its traces have been verified in surface and groundwater. Thus, it is necessary to remove this pollutant, and an alternative is the adsorption due to its universal nature, low-cost and ease of operation. Therefore, the objective of the present work was to study the adsorption capacity of atrazine by modified Moringa oleifera Lam. seed husks, a low-cost adsorbent. The biosorbent was subjected to c hemical and thermal treatment and was characterised by structural, morphological and textural analysis, which showed porous and heterogeneous characteristics, with a specific surface area of 5.77 m² g^-1. The kinetic study demonstrated equilibrium at 1200 min, with an adsorption capacity of 1.90 mg g^-1 and the best fit was for the pseudo-second-order model. The isotherms were obtained at 298, 308 and 318 K. The Freundlich, Temkin and Langmuir models were applied to the experimental data, the latter being the best. The values of the thermodynamic parameters indicated that the biosorption was spontaneous, endothermic and reversible. The highest adsorption capacity obtained was 10.32 mg g^-1, which was higher than several values found in the literature. The biosorbent was regenerated over three cycles, indicating its potential of atrazine removal from surface water.