Removal of Metribuzin and Bentazon by LDH-HA Modified Material: Kinetic and Equilibrium Study

Abstract

ABSTRACT This study investigates the adsorption behavior of herbicides Metribuzin and Bentazon using a soil model incorporating Layered Double Hydroxide (LDH) and humic acid. Mg3AlCl-LDH, synthesized at pH 10, was combined with humic acid to produce two distinct materials: Mg3–5%HA and Mg3–10%HA. These materials were characterized using FTIR, XRD, and SEM techniques. The research confirms that humic acid adsorbs onto the LDH surface without altering its structure, resulting in negatively charged materials. While both materials fully adsorb Metribuzin at 20 mg/L, their adsorption capacities diverge at higher concentrations, with Mg3–10%HA exhibiting a higher capacity than Mg3–5%HA. In contrast, Bentazon’s adsorption is unaffected by humic acid content, displaying identical adsorption capacities in both materials at different concentrations. Both herbicides exhibit rapid adsorption kinetics, reaching equilibrium in 15 minutes. The Avrami model accurately predicts equilibrium adsorption capacities, with Metribuzin primarily adsorbed through electrostatic attraction and hydrogen bonding, while Bentazon’s adsorption is limited due to electrostatic repulsion. The adsorption of both herbicides by Mg3-HA materials is not influenced by pH variations, likely due to the surface charge of the materials. Metribuzin retention in soil containing LDH and humic acid is effective, increasing with higher humic acid concentrations, whereas Bentazon demonstrates greater mobility and resistance. These findings provide valuable insights for developing efficient water decontamination techniques, with implications for environmental protection and public health. Policymakers, researchers, and professionals in water management and pollution control should consider these findings to enhance current practices and technologies.