Carbon Felt Monoliths Coated with a Highly Hydrophobic Mesoporous Carbon Phase for the Continuous Oil Sorption/Filtration from Water

The recovery of oils and organic compounds is a key challenge in wastewater purification processes. Herein we describe a straightforward and easy-to-scale-up strategy for the fabrication of lightweight and highly hydrophobic composites with superior mechanical strength, through the coating of commercial carbon felt (CF) with a thin mesoporous carbon phase (MC). Composites (CF@MC) are prepared by dip-coating method starting from CF foams to be soaked in a water/ethanol solution of food-grade components (sucrose and citric acid) before undergoing two successive thermal treatments. CF@MC composites exhibit an extremely high efficiency and complete reusability in the recovery of oils and organic compounds from wastewaters. They have been successfully employed as classical absorbents under batch conditions or filters under continuum separation mode. Noteworthy, the inherent electrical conductivity/resistivity of CF@MC foams has allowed their application to the recovery of water floating waxy organic residues. Indeed, absorbents can be heated up by the passage of a direct electrical current (DC) thus allowing semi-solid organic pollutants to be melted and absorbed by the hydrophobic composite without sorbents fouling or deactivation. The outlined synthetic strategy towards cheap and scalable lightweight hydrophobic materials for wastewater cleaning and environmental remediation from oil spilling, is a highly attractive technology that offers concrete hints to the exploitation of these composites on an industrial level.