Nano-fluoro dispersion functionalized superhydrophobic degummed & waste silk fabric for sustained recovery of petroleum oils & organic solvents from wastewater

Superwettable and chemically stable waste silk fabric and degummed silk were used in this study for treatment of oily wastewater and oil/solvent recovery. Silk functionalized with a nano-fluoro dispersion showed a superhydrophobic and oleophilic nature. The functionalized silk demonstrated superoleophilicity towards petroleum oils and organic solvents, and exhibited filtration efficiencies of more than 95%, and up to 70% till 25 re-usable cycles. Furthermore, the functionalized silk materials demonstrated high permeation flux of 584 L.m-2.h-1 (for Diesel) for continuous oil-water separation operation. The pH based study in highly acidic and alkaline mediums (pH from 1 to 13) showed excellent stability of nano-fluoro coated silk. Thermogravimetric analysis showed thermal stability up to 250 degrees C, and 400 degrees C, for functionalized waste silk, and degummed silk, respectively. FESEM analysis revealed randomly oriented spindle shaped nano particles anchored on the silk surface exhibiting hierarchical patterns, as required for the superhydrophobic Cassie-Baxter state. The rate absorption study showed close curve fitting for pseudo second order kinetics (R2 = 0.999), which indicated physical absorption process. BET analysis confirmed the porous nature, while the elemental XPS and EDX analysis confirmed strong bonding and uniform coating of fluoro nanoparticles on silk surface. The results demonstrated that nano-fluoro dispersion functionalized silk can be successfully employed for effective oil/solvent-water filtration, oil/solventspill cleanups, and treatment of oily wastewater for protection of water resources.

Automated summary

In this study, superwettable and chemically stable waste silk fabric and degummed silk were used for treatment of oily wastewater and oil/solvent recovery. The silk functionalized with a nano-fluoro dispersion showed superhydrophobic and oleophilic properties, demonstrating high filtration efficiencies and permeation flux for oil-water separation. The functionalized silk also exhibited excellent stability in acidic and alkaline mediums, along with thermal stability. The results indicate that nano-fluoro dispersion functionalized silk can be successfully employed for effective oil/solvent-water filtration and treatment of oily wastewater.