Construction of chitosan/polyacrylate/graphene oxide composite physical hydrogel by semi-dissolution/acidification/sol-gel transition method and its simultaneous cationic and anionic dye adsorption properties

•Controllable and stable physical hydrogel based on chitosan was prepared.•Compositing of polyacrylate improved the swelling and adsorption properties.•Graphene oxide enhanced mechanical and adsorption properties of the hydrogel.•The products showed properties of adjustable polyampholyte hydrogel.•The composite hydrogel could simultaneously adsorb cationic and anionic dye. In the current study, a novel CTS/PAA/GO composite polyampholyte physical hydrogel was prepared by the SD-A-SGT method to achieve desired adsorption properties for printing and dyeing wastewater treatment. The hydrogels exhibited controllable and stable structure. The linear PAA significantly improved the swelling and adsorption properties of the hydrogel, and the composition of GO enhanced its mechanical and adsorption properties. The batch adsorption experiments revealed the ability to simultaneously absorb the cationic model dye, MB, and anionic model dye, FY3, with the similar equilibrium adsorption capacities of 296.5±31.7 mg·g−1 and 280.3±23.9 mg·g−1, respectively. The factors affecting the dye adsorption performance, including the hydrogel composition, initial dye concentration and dye solution pH, were investigated. The dye adsorption kinetics was studied and the adsorption mechanisms were proposed. The unique structure and properties of the hydrogel make it a great candidate adsorbent for wastewater treatments.