Thiophene-silane coupling agent for enhancing the dispersibility of graphene and its adsorption capacity for Mo(VI)

Uniform dispersion of graphene is a prerequisite for the preparation of high-performance graphene-based composites. In this study, a new type of coupling agent which contains a thiophene center and two silanol groups (TPSi) is synthesized via amino-epoxy ring-opening reaction. The molecule shows good ability for dispersing graphene in water based on its amphiphilic feature. Dynamic light scattering (DLS) reveals that the concentration of graphene reaches 3 mg mL −1 at the weight ratio of TPSi-to-graphene of 1:1. It also stabilizes graphene well when diminishing the weight ratio to 0.5:1. By freeze-drying the dispersion, TPSi/graphene composite is prepared and it shows good adsorption performance for Mo(VI) in water. The maximum capacity can reach to 134.87 mg g −1 at pH 3 according to the Langmuir isotherm model. The composite also exhibits fast adsorption kinetics that equilibrium could be achieved within 2 h. TPSi plays a key role for the uniform distribution of graphene and improves the adsorption capability of graphene-based composite for Mo(VI) ions.