Anionic hydrogel fabricated with metal nanoparticles: highly efficient and easily recyclable catalysts

Herein, we synthesized poly(methacrylic acid) [p(MAAc] hydrogels by an effective and simple free radical polymerization process and then silver, cobalt, and their bimetallic nanoparticles (NPs) were synthesized by using p(MAAc) as a template. Upon loading of Ag (I) and Co (II) ions by p(MAAc) hydrogels from their corresponding aqueous salt solutions, these metal ions loaded hydrogels were then treated with sodium borohydride, a reducing agent to obtain corresponding metal nanoparticles (NPs) within the hydrogel network. Hydrogels and metal nanoparticle containing composite hydrogels were analyzed in detail by Transmission Electron Microscopy, X-ray Diffraction, Fourier Transform Infra-red spectroscopy, UV-Vis Spectrophotometry and Thermal Gravimetric Analysis techniques. Synthesized p(MAAc)-M hydrogel composites were utilized as catalysts for degradation of some harmful organic residual dyes like Eosin Y (EY), methyl orange (MO) along with reduction studies of some nitro aromatic compounds including 2-nitrophenol (2-NP), 4-nitrophenol (4-NP), 4-nitroaniline (4-NA) to their respective amino phenolic compounds from contaminated water. Above all, we also report simultaneous degradation studies of a dye EY and a nitro compound, 4-NP catalyzed by p(MAAc)-Ag composite hydrogel. The parameters such as nature of metal, catalyst amounts, temperature, water samples from different resources, and reusability of prepared hydrogel-metal nanoparticle nanocomposite catalysts were also investigated.

Automated summary

Poly(methacrylic acid) hydrogels were synthesized using a free radical polymerization process as templates for the synthesis of silver, cobalt, and bimetallic nanoparticles. The loaded metal ions in the hydrogels were treated with a reducing agent to obtain corresponding metal nanoparticles, which were used as catalysts for degrading organic dyes and nitro compounds in contaminated water. Various parameters of the catalysts and their reusability were investigated.