Superhydrophobic melamine sponge-sorbent fabricated using WS2, halloysite nanotube, octyltriethoxysilane, tetraethoxysilane, and polydimethylsiloxane for the selective uptake of oil from water

Abstract

Here, a novel coating formulation was developed using WS2, halloysite nanotube (HNT), octyltriethoxysilane (OTES), tetraethoxysilane (TEOS), and polydimethylsiloxane (PDMS) to fabricate a new melamine sponge (MS)-based superhydrophobic sorbent material for the treatment of wastewater polluted with oily substances and organic solvents. The innovative aspect of this study lies in the alteration of WS2 particle size within the sorbent material and the chemical modification of HNT with silane compounds through the formation of reactive -OH groups on the cylindrical outer surface of clay mineral by chemical activation. The effect of nano- and micro-WS2 particle sizes on the wettability of sorbent material was investigated systematically. Successful coating of MS with the developed coating formulation was confirmed using SEM, mapping, EDS, and FTIR analyses. Sorbent material showed remarkable superhydrophobicity (WCA: 170.3°), excellent thermal and mechanical stability, good chemical durability, high sorption capacity (34.0–73.8 g/g), good reusability, outstanding oil-water separation ability (>99.8 %) and flux (11,774 L/(m2.h)), and efficient separation ability for water-in-oil emulsions (up to 99.6 %). The results of this study exhibit that MS/WS2/HNT/OTES-TEOS/PDMS sorbent material is of a great potential for the selective and effective removal of oily substance and organic solvent spills from water.