Influence of GO reinforcement on keratin based smart hydrogel and its application for emerging pollutants removal

Abstract

In this work, the influence of graphene oxide (GO) reinforcement on keratin based smart hydrogel and its application for the emerging pollutant ciprofloxacin removal was studied. Firstly, the obtained material was characterized by Infrared Spectroscopy, Scanning Electronic Microscopy, Small angle X-ray Scattering and Swelling and Rheological behavior. The results showed that the keratin hydrogel and those nanocomposites containing GO present stimuli responsive behavior by changing the swelling along with the pH. Keratin hydrogels and the ones containing 0.5% of GO showed a similar behavior where swelling decreased between pH 6 and 5. The introduction of GO at 2% changed this inflection point at a value between pH 7 and 6. Also, the swelling of the shrunk hydrogels was higher when containing 2% GO. This effect was probably due to the steric hindrance generated by the nanosheets and their functional groups, partially interfering with keratin chains interaction. The antibiotic was adsorbed in the different active sites in the hydrogel provided by the keratin and the GO structures. After that, the composite adsorption isotherms against ciprofloxacin (CPX) and its kinetics were studied. The ability of the material to expand at high pH allowed a better desorption of the CPX. Thus, reusability presented a better performance when basic washings were used.