Solar-heated graphene sponge for high-efficiency clean-up of viscous crude oil spill

A solar-driven self-heated sponge was developed as a novel sorbent to achieve fast collection of crude oil from spills by taking advantage of light-to-heat conversion to significantly reduce oil viscosity. The sorbent was fabricated via facile dip-coating reduced graphene oxide on a commercial melamine sponge. The photothermal effect of sorbent on absorption of crude oil was investigated through infrared thermal imaging, permeating behavior of crude oil droplet and absorption-recovery of crude oil. The results indicated that the graphene sponge revealed an outstanding light-to-heat conversion capability and stability with almost full absorption (similar to 98%) of sunlight. The surface temperature spontaneously increased to as high as 89 degrees C under one sun simulated irradiation (1.0 kW/m(2)) at room temperature (30 degrees C), which subsequently reduced the in situ viscosity of the crude oil by over two orders of magnitude. As a result, the absorption time was reduced by approximately 86% for a solar-heating sponge under one sun illumination compared with that of the sponge without light illumination. In addition, the consecutive recovery rate for pumping-driven crude oil clean-up from seawater under one sun illumination was 12 times faster than that of the sponge without light illumination. The proposed solar responsive sorbent design represents a sustainable approach to address the problem of remediation of viscous crude oil spills. (C) 2019 Elsevier Ltd. All rights reserved.