Adsorption of 17β-estradiol by graphene oxide: Effect of heteroaggregation with inorganic nanoparticles

Increasingly applications of graphene nanomaterials have resulted in their release into the water environments where lot kinds of chemicals and inorganic nanoparticles co-exist. In this work, the influences of two common inorganic nanoparticles (INPs), namely SiO2 and Al2O3, on the adsorption of 17β-estradiol (E2) onto graphene oxide (GO) were examined by using batch adsorption experiments in combination with microscopic, spectroscopic, and computational methods. Results exhibited that the presence of INPs significantly inhibited the adsorption and increased the time to reach adsorption equilibrium for the adsorption of E2 onto GO. Besides, the impact of Al2O3 was greater than that of SiO2 due to the enhanced electrostatic attraction between positively charged Al2O3 and negatively charged GO. Derjaguin-Landau-Verwey-Overbeek calculation revealed that GO tended to first homoaggregate and then heteroaggregate with SiO2. However, oppositely charged Al2O3 and GO were likely to heteroaggregation rather than homoaggregation. This was also demonstrated by the zeta potential measurement, and scanning electron microscope. These observations highlighted the significant influence of INPs on the adsorption of contaminants onto GO, and also provided new insights into the fate and transport of GO and pollutants in natural water environments.