Preparation of a β-CD@Fe3O4/KHA/CMC/AM/MAH hydrogel and its slow-release herbicidal properties against glyphosate

Abstract

This study employed β-cyclodextrin (β-CD) for the hydrophilic modification of iron tetraoxide (Fe₃O₄) magnetic materials. Subsequently, potassium humate (KHA) and carboxymethyl cellulose (CMC) were used as raw materials. A β-CD@Fe₃O₄/KHA/CMC/AM/MAH hydrogel with magnetic properties which can be easily recycled was synthesized for the slow release of glyphosate (GLY). FTIR, XRD, TG and VSM analyses demonstrated that the hydrogel possesses good thermal stability and magnetic properties with a saturation magnetization strength of 29.77 emu g⁻¹. The equilibrium solubility of the hydrogel in pH = 7.4 and pH = 8.5 buffer was 24.58 g g⁻¹ and 25.83 g g⁻¹, respectively. The maximum release of GLY was recorded at 63.31% and 67.78%, with the drug release behavior under different loading gels following the Fickian diffusion mechanism. A pot planting experiment indicated that the water content of plants treated with the β-CD@Fe₃O₄/KHA/CMC/AM/MAH drug-loaded gel decreased by 51.69%. Additionally, soluble protein levels decreased to 2.69 mg g⁻¹, chlorophyll content decreased to 0.486 mg g⁻¹, SOD levels decreased to 43.81 U g⁻¹, and MDA increased to 4.02 μmol g⁻¹, effectively inhibiting the growth of grass and providing a theoretical basis for achieving slow drug release.