Dual-Responsive Graphene Oxide/Poly(NIPAM-co-AA) Hydrogel as an Adsorbent for Rhodamine B and Imidacloprid

A dual-responsive hydrogel based on graphene oxide (GO) was prepared by in situ radical copolymerization of N-isopropyl acrylamide (NIPAM) as a temperature-sensitive component and acrylic acid (AA) as a pH-sensitive unit. The resulting hydrogels (GO/poly(NIPAM-co-AA) (PNA) were systematically characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy. With the change of AA content, the lower critical solution temperature of hydrogels changed from 26.91 to 24.38 °C. The swelling ratio under alkaline condition was higher than that under acidic condition. The adsorption of rhodamine B (RB) followed Langmuir isotherm model and pseudo-second-order model, and nearly 93% of RB could be released within 10 h at pH 4.01 and 60 °C. With imidacloprid as the model drug, the higher cumulative release rate of the GO/PNA hydrogel was obviously observed at pH = 4.01 than at pH = 9.18. On the basis of their good adsorption–desorption, loading-releasing, and regeneration ability, the GO/PNA hydrogel as a multifunctional adsorbent might have broad application prospects in environmental protection and biomedical engineering.