Laboratory scale study on rheological behavior, morphological and structural properties of crosslinked polyacrylamide composite hydrogels embedded with date seed powder

Incorporation of biofillers in polymeric hydrogels has continued to receive great attention in recent times because of their excellent properties. In this study, polyacrylamide (PAM) and polyethyleneimine (PEI) were used to develop novel composite hydrogels filled with date seed powder (DSP) via chemical crosslinking technique. Pristine PAM/PEI hydrogel and PAM/PEI-DSP hydrogels at various DSP loadings were fabricated and subjected to gelation at 40°C for 24 h. The impact of various DSP loadings on the hydrogel samples developed was investigated using hybrid rheometer, SEM, XRD, and FTIR instruments, respectively. Rheological measurements confirmed the viscoelastic responses of the neat PAM/PEI hydrogel and the PAM/PEI-DSP hydrogels reinforced with various DSP contents (0.8, 2.4, and 4 wt %). The dynamic strain, dynamic frequency and time sweep tests demonstrated that PAM/PEI-DSP hydrogels were slightly more elastic than the virgin PAM/PEI hydrogel. The SEM characterization revealed the surface micrographs of the neat PAM/PEI hydrogel and the PAM/PEI-DSP hydrogels at different DSP loadings to be smooth, homogeneous, and dense. Besides, the SEM micrographs supported the incorporation of DSP in the PAM/PEI-DSP hydrogel samples. XRD analysis showed that the structures of neat PAM/PEI hydrogel and PAM/PEI-DSP hydrogels filled with various DSP contents were predominantly amorphous while FTIR results confirmed the functional groups and evidence of crosslinking in the neat PAM/PEI hydrogel and the PAM/PEI-DSP hydrogels embedded with different DSP contents. It is believed that these new hydrogels have huge development potentials and promising future in wastewater treatment and removal of heavy metal ions in aqueous solutions.