In-situ synthesis of bi-modal hydrophobic silica nanoparticles for oil-water separation

We report the synthesis of hydrophobic silica nanoparticles of different mean sizes ranging in diameter from 48 to 260nm for the preparation of superhydrophobic composites. The nanoparticles were synthesized by adding methanol into aqueous solution of sodium silicate followed by the addition of trimethylchlorosilane. The different mean sizes of nanoparticles were achieved by varying the concentration of sodium silicate solution in methanol. It was found that nanoparticles with bi-modal distribution demonstrated superior hydrophobic properties owing to their hierarchical structure. The nanoparticles with bi-modal size distribution were deposited on cotton fabric and fibers to prepare superhydrophobic composites using an immersion technique. The prepared composites were used for the separation of four oil-water mixtures; the composites containing fabric separated oil-water mixtures via filtration while composites containing fibers separated oil-water mixture by absorption. (C) 2016 Elsevier B.V. All rights reserved.