Surface Modified Graphene for Heavy Metal Ions Adsorption

In this study, the adsorption capacity of graphene sheets before and after modification with 1-pyrenebutyric acid (PBA) via the – stacking interaction for heavy metal ions such as Cu²⁺, Cd²⁺ and Pb²⁺ was explored. The adsorption capacities and efficiency for heavy metal ions at different pH and contact time were also investigated. The results showed that PBA modified graphene were better adsorbent for heavy metal ions than graphene. Graphene exhibited the adsorption capacity of up to 77.3 mg/g for Cu²⁺, 78.5 mg/g for Cd²⁺ and 99.3 mg/g for Pb²⁺, while graphene/PBA exhibited the higher adsorption capacity of up to 92.3 mg/g for Cu²⁺, 85.8 mg/g for Cd²⁺ and 124.2 mg/g for Pb²⁺ at pH of 5. The adsorption isotherms study revealed that the adsorption of graphene and graphene/PBA toward Cu²⁺ was well described by Langmuir isotherm model. The adsorption kinetics of Cu²⁺ onto graphene and graphene/PBA illustrated that the adsorption data fit the pseudosecond-order models. These graphene sheets were characterized by transmission electron microscope (TEM), scanning electron microscope (SEM), dynamic light scattering (DLS) and FT-IR spectrum.