Fabrication of graphene-rapped melamine sponge and its photothermal adsorption on viscous oil spill

Abstract

Graphene oxide melamine sponges (GOMSs) were prepared by impregnating melamine sponge (MS) with graphene oxide (GO) dispersion. Thereafter, reduced graphene oxide melamine sponges (HGOMSs) were obtained by one-step heat treatment of GOMSs, and the effects of heat treatment and GO load on sponge structure, hydrophobicity/ lipophilicity, photothermal properties, mechanical properties and light-aided adsorption performances were evaluated. The results show that heat treatment under 400 °C is an optimum choice. A small amount of graphene could effectively wrap on the melamine sponge skeleton and closely combined with the sponge. This effectively wrapped structure can not only improve the photothermal and mechanical properties of the sponge, but also retain the rich pore structure of the sponge to provide sufficient space for oil adsorption. HGOMS prepared under 400 °C with 1 mg·ml−1 of GO concentration shows an average light absorption rate of 84.4% in the full solar spectral range. Under 1 sun illumination in air, the surface can quickly rise to 99.4 °C, and the bottom surface is 72.8 °C, showing excellent photothermal conversion performance. The saturated adsorption capacity on heavy oil reached 103.2 g·g−1 under 1 sun illumination. The material was reused through mechanical extrusion method. After 10 times of adsorption- extrusion operations, its saturated adsorption capacity still retained more than 80% of the first time. These characteristics make HGOMS an energy efficient and reusable adsorbent for oil spill.