Effective separation of petroleum oil-water mixtures via flexible and re-usable hydrophobic soot-coated melamine sponge

Abstract

Superhydrophobic materials like carbon-coated sponges have been attracting attention due to their wide applicability in several industries. One of the main applications of such materials is the efficient removal of various water pollutants such as oil by adsorption. Herein, a flexible, porous, and hydrophilic melamine sponge was coated by superhydrophobic soot that was produced by incomplete combustion of the propane-butane mixture. Characterization of the soot and the sponge was performed via several methods such as spectroscopy, microscopy, and thermogravimetry. The product was tested in the petroleum oil removal process. The superhydmphobic sponge repelled water well and at the same time perfectly sorbed oil products. The wetting edge angle of soot coated sponge was found between 145 and 150 degrees. The sponge showed an excellent adsorption capacity of 24 g oil/g for the selective separation of oil from water. The entrapped oil was released simply by squeezing the sponge for cyclic use and about 95.5 wt% of the oil was adsorbed and the soot-coated sponge still maintained this capacity after 19 cycles. Hence, this novel soot-coated hydrophobic sponge is considered a promising candidate for oil-polluted water treatment.