Cotton Fabrics Modified Using a Graft Copolymer From Commercial Precursors for Oil/Water Emulsion Separation
Graft copolymers of poly(ethylenimine) (PEI) and poly(dimethylsiloxane) (PDMS) were synthesized and used to coat cotton fabrics with the use of poly(ethylene glycol) diglycidyl ether as a crosslinker. The copolymer was applied to the fabrics via a CHCl3 solution, and secured on the surface by a network of epoxy-amine bonds between the PEI and crosslinker units. The coated fabrics were used to separate and recover oil from surfactant-stabilised, oil-in-water emulsions. The composition of the graft copolymer and obtained coating solutions was varied to determine the effects on separation performance and repeatability. Optimal oil flux and recovery was obtained from coatings composed of high molecular-weight PEI which contained a high percentage of grafted PDMS units. Highly-crosslinked coatings demonstrated repeatable and consistent separation performance, and were able to recover the vast majority of emulsified oil from hexadecane-in-water emulsions stabilized by sodium dodecyl sulfate (SDS). The de-emulsification properties of the optimized coatings may facilitate their use in wastewater remediation or oil recovery from contaminated environments.