Synthesis, characterization and control release properties of single metal zinc layered hydroxide-2napthoxyacetic acid (BNOA) nanocomposite / Hasnatul Fitriah Abd Rahim

The utilization of nanocarriers in the development of environmentally friendly herbicides has led to the creation of controlled release formulations. These formulations offer precise concentration and timed-release properties. To achieve this, zinc chloride (ZnCl2) and zinc nitrate hexahydrate (Zn (NO3)2.6H2O) were used as precursors to synthesize zinc layered hydroxide-chloride (ZLC) or zinc layered hydroxide-nitrate (ZLN). These compounds were then intercalated with 2-napthoxyacetic acid (BNOA), an herbicide, resulting in nanocomposites called Zinc layered hydroxide-2napthoxyacetic acid (ZLCB) and (ZLNB) through ion exchange. The formation of these nanocomposites was analysed using Powder X-Ray Diffraction (PXRD), which revealed an increase in the basal spacing from 7.9Å to 27.3Å in ZLCB and from 9.8Å to 28.2Å in ZLNB, indicating successful intercalation of the anions into the interlayer of the host material. Fourier Transform Infrared Spectroscopy (FTIR) confirmed the presence of BNOA anions within the interlayers of ZLCB and ZLNB by detecting the formation of COO- ions (carboxylate ions) a new peak at approximately 1611 cm-1 and 1616 cm-1 respectively. The surface area of ZLCB and ZLNB also increased from 6.61 m2g-1 to 27.47 m2g-1 and from 9.16 m2g-1 to 28.08 m2g-1 respectively, indicating the successful insertion of BNOA into the interlayers of ZLC and ZLN. Additionally, the loading percentage of BNOA, estimated using a CHNS analyser, was found to be 83.9% for ZLCB and 41.80% for ZLNB. The controlled release properties demonstrated that the release of BNOA in various aqueous solutions followed the order of Na3PO4 > Na2SO4 > NaCl and confirmed pseudo-second order kinetic models for both nanocomposites.