Acrylamide Hydrogels as an Alkali-Dosifier to Synthesize Zinc Powder Nanomaterials and the Effect on Microstructure

Zinc-based materials such as layered double hydroxides (LDHs), zinc hydroxide nitrate (ZnHxN), and zinc oxide (ZnO) are currently useful for different applications. Their performance depends greatly on their microstructure, especially since these are materials in the form of powders. Precipitation with bases, such as NaOH solutions, is one of the most common synthesis methods and the rate of addition and concentration of the base influence the particle size, morphology, phase, and number of phases. In this work we used hydrogels that were swollen with NaOH solutions and used as base dosers in zinc salt solutions. One acrylamide hydrogel was synthesized in water (HG-W) and another in a water/ethanol (HG-W/EtOH) solution. The obtained products were LDH, ZnHxN and ZnO. In LDHs, the particle sizes ranged from 69 nm to 889 nm and were inversely proportional to the mass of the hydrogel used. Regarding ZnO particles, sizes from 75 to 141 nm were obtained using HG-W, which was minimally influenced by the mass of the hydrogel. HG-W/EtOH produced ZnHxN and ZnO. Of all the materials, only the ZnO obtained with HG-W, with a particle size of 75 nm, was active in the transesterification of coconut oil, producing methyl esters, compounds in demand as biofuels.