Synthesis and Characterization of Metal Modified Hydrogels of Poly (Acrylic Acid-co-Acrylamide) and Poly (Metharcrylic Acid)

Abstract

In this work, the synthesis of hydrogels of poly (acrylic acid-co-acryl amide), poly (methacrylic acid), and poly (acrylic acid) was carried out using free radical polymerization, followed by the incorporation of metal nanoparticies (NPs) of silver, copper, nickel, and cobalt within the hydrogel matrix. To obtain metal NPs the metal ions were reduced by sodium borohydride (NaBH4). The synthesis ofthe hydrogels and metal modified hydrogels was confirmed using Fourier transform infrared (FTIR) spectroscopic and X-ray diffraction (XRD) analyses. The XRD patterns displayed the amorphous nature of the pure hydrogels and the induced crystalline character in metal-modified hydrogels. FTIR spectra helped in the identification of various functional groups in bare and metal modified hydrogels. The particulate nature of prepared hydrogels was confirmed with the assistance of dynamic light scattering (DLS) and their hydrodynamic radii were calculated. The materials' thermal properties were investigated by employing differential scanning calorimetry (DSC). The synthesized hydrogels were tested for their adsorptive and catalytic properties against some harmful dyes (Rhodamine B, Congo Red, Disperse Red 54, Reactive Black 8, and Reactive Red 195) in an aqueous medium under optimum conditions. The parameters such as pH, amount of catalyst, temperature, and amount of reducing agent were investigated. Thermodynamic and kinetic studies of the degradation process were carried out as well. The maximum degradation efficiency for the mentioned dyes was observed at 10 mg loading of catalyst in the presence of 10 mg of sodium borohydride at room temperature. Composite reusability up to five times was studied. The consequence of the concentration of adsorbate and the amount of adsorbent on adsorption of the above-mentioned dyes was investigated. The prepared hydrogel systems were used against certain strains of bacteria and fungi to assess their biological activity. It was found that the metal-modified hydrogels possess a high potential to be used as adsorbents and catalysts for removing harmful dyes from aqueous medium and in the biomedical fields as antibacterial and antifungal agents.