Rapid dipping preparation of robust Zn(OH)2@STA nanosheet coating on cotton fabric for multifunctional high efficient oil-water separation

Abstract

A simple, cost-effective, eco-friendly and rapid dipping technique is developed to fabricate the robust superhydrophobic and superoleophilic Zn(OH)2@STA nanosheet coating on cotton fabric surface. When the precursor solution including solvent of anhydrous ethanol and the stearic acid (STA) is dipped onto the cotton fabric surface, with the solvent evaporation of anhydrous ethanol, the precipitated STA from solvent is directly modified on each Zn(OH)2 nanosheet which is formed through chemical reaction in precursor solution, and then the Zn(OH)2@STA nanosheets are closely packed cotton fabric surface, which endows the coating large porosity and is beneficial for the oil-water separation. Meantime, the strong adhesion between the nanosheet coating and fabric is achieved by the esterification reaction of the STA and hydroxyl groups on the cotton fabric surface, which has been verified by a series of mechanical stability test. In various harsh environments, the coating also exhibits the excellent thermal and light irradiation stability, corrosion resistances of acid/alkali and NaCl solution, self-cleaning ability in muddy water and the fire resistance. Finally, in the oil-water separation, the coating on cotton fabric can not only effectively realize the oil-water separation by adsorption oil both floating on water surface and in water, but also can be used for oil filtration in water with efficiency of about 99.8 % and the oil flux of 1515 L/(m2⋅h).