In situ crosslinking of poly (vinyl alcohol)/graphene oxide-glutamic acid nano-composite hydrogel as microbial carrier: Intercalation structure and its wastewater treatment performance

Poly (vinyl alcohol) (PVA)/graphene oxide (GO) nano-composite hydrogels were prepared through in situ chemical cross-linking by incorporation with glutamic acid (Glu) as a compatibilizer. Through covalent and hydrogen bonding interaction, much more PVA molecules were grafted onto GO surface, while GO was exfoliated and uniformly distributed in the PVA matrix with increasing average layer thickness. Addition of GO-Glu hybrid could improve the storage modulus and the effective crosslinking density (v(e)) of the composite hydrogels, and the network structure with GO as crosslinking point formed. Moreover, the specific surface area and the biocompatibility of PVA hydrogel were improved significantly by compositing with GO-Glu, resulting in a remarkable increase of loading capacity of microorganism. And therefore the COD removal rate could be improved when the hydrogel was applied in wastewater treatment.