Synthesis of the hybrid composite 2,4-D/LDH (herbicide/layered double hydroxides): influence of pH on the synthesis

Hybrid composites based on the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) encapsulated in Layered Double Hydroxide (LDH) have been synthesized by direct method at three different pH values (7, 9, and 11). It was found that with a decrease in pH, the formation of the 2,4-D/LDH hybrid composite was favored. At pH 9 and 11, the predominant phases were ZnO and Zn-Al-LDH. At pH 7, 2,4-D was inserted into the LDH structure, increasing basal spacing from 7.8 Å, the value without the herbicide, to 19.2 Å, the basal spacing of LDH with herbicide. Infrared spectroscopy confirmed the presence of 2,4-D mainly in sample synthesized at pH 7. The morphology of the particles in the sample synthesized at pH 7 was different. pH influenced the thermal and textural properties of the samples. Our results have significant implications for understanding 2,4-D/LDH hybrid composite synthesis and properties.