Supramolecular hydrogel based on cyclodextrin modified GO as a potent natural organic matter absorbent

[Display omitted] •The nanocomposite hydrogel with porous structure synthesized successfully.•α-CD molecules attached to the surface of graphene oxide by ene-click reaction.•The gel structure of supramolecular hydrogel collapsed upon addition of adamantane.•The obtained nanocomposite hydrogel presented a good ability for water purification. New nanocomposite hydrogel was synthesized using biocompatible and biodegradable material. Firstly α-cyclodextrin functionalized with mercaptoacetic acid (MAA) and then attached to the surface of graphene oxide (GO) by ene-click reaction. Also starch (St) functionalized with myristic acid (MA) by esterification reaction. In the next step host-guest interactions formed between α-CD cavities and MA molecules. Due to this interaction graphene oxide nanosheets crosslinked to each other and a stable nanocomposite hydrogel formed successfully. These new synthesized nanomaterials were characterized by spectroscopic methods such as IR spectroscopy, UV–vis spectroscopy, X-ray diffraction (XRD) technique, scanning electron microscopy, thermogravimetric analysis (TGA) and Raman spectroscopy. FE-SEM analysis confirmed that prepared nanocomposite hydrogel has a well-defined and interconnected 3D porous network with pore sizes in the range of submicrometer to several micrometers. This nanocomposite hydrogel has beneficial application in different fields such as water purification. This newly synthesized nanomaterial is sensitive to external stimuli. We illustrated that addition of adamantane to the system as an external stimulus, result in destroying host-guest interactions between α-CD and St-MA because adamantane is a strong competitor for α-CD cavity in comparison with MA molecule. This also confirms that host-guest complex formation between α-CD and MA is the driving force for hydrogel formation. The obtained supramolecular hydrogel was used for water purification and the results showed that this product has a good ability for removal of organic materials such as humic acid (HA) from contaminated water.