Biomass-based soft hydrogel for triple use: Adsorbent for metal removal, template for metal nanoparticle synthesis, and a reactor for nitrophenol and methylene blue reduction

A biomass-based hydrogel prepared from polymerization of Enteromorpha with acrylic acid (p(EP-g-AA)), was tested for application as a green and effective soft reactor for three purposes. First, swelling property of the p(EP-g-AA) hydrogel was tested and its use as an adsorbent for Cu(II) removal was studied. Then, these hydrogel networks were used as a template for in-situ copper nanoparticle synthesis. Both TEM and SEM images confirmed the formation of Cu particles sizing smaller than 100 nm. EDS mapping showed a homogeneous dispersion of the nanoparticles within the hydrogel structure. XRD patterns of the nanoparticles correspond to metallic Cu establishing a hexagonal crystallinity. Finally, the hydrogel-metal nanoparticle (p(EP-g-AA)-Cu) were employed as a catalyst for reduction of two organic contaminants, p-nitrophenol (4-NP) and methylene blue (MB). Reusability and stability studies demonstrated that the p(EP-g-AA)-Cu catalyst still maintained 80-90% of catalytic activity after 5 times use and 30 days storage. (C) 2018 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.