Preparation of graphene aerogels and their photothermal adsorption performance on heavy oil

Given that heavy oil has a high viscosity and is difficult to quickly and effectively adsorb and recover, the problem of offshore oil spill cleaning warrants consideration. In order to drastically reduce the viscosity of heavy oil and achieve effective adsorption and recovery, graphene aerogels appeared as a photothermal adsorbent. Graphene aerogels (RGA) were prepared using graphene oxide (GO) as the raw material, polyvinylpyrrolidone (PVP) as the crosslinking agent, and an ice template method was used. To make high-temperature reduced graphene aerogel (HGA), the prepared RGA was reduced under 800 °C furtherly. Influence of hydrothermal pre-reduction time, crosslinker dosage, and high temperature reduction on the modeling effect of the materials were examined. The functional group structure and micro morphology of the produced graphene aerogels were identified through FT-IR, XRD, XPS, Raman, and SEM. The produced graphene aerogels have complex pore structures. Hydrothermal reduction can remove oxygen-containing functional groups from GO substantially. High temperature treating can further remove oxygen-containing functional groups, correct flaws, and open the pores of the aerogel, but it is unfavourable for the material's mechanical performance. RGA shows high absorbance on visible and ultraviolet light. Effective oil–water separation is possible under the sunlight. The temperature gradients of RGA and HGA are 34.5 and 37.0 K⋅cm −1 , respectively. The saturation adsorption capacities reached 90.20 and 146.03 times of their own masses, respectively, and the rates of adsorption on heavy oil is 4.6 times and 3 times that without light.