Robust PDMS-based porous sponge with enhanced recyclability for selective separation of oil-water mixture

Ideal adsorption material with large adsorption capacity, strong mechanical strength and satisfied reusability plays crucial role in efficient industrial wastewater treatment and oil-water separation. Herein, porous reduced graphene oxide/poly(ethyleneimine)/polydimethylsiloxane (rGO/PEI/PDMS) sponge with robust structure was proposed under mild conditions. Owing to the enhanced interfacial interaction between rGO and PDMS when employing PEI as adhesion layer, the rGO layer was tightly stacked onto the surface of porous channels within PDMS skeleton. Compared to the pristine PDMS sponge, the water contact angle, maximum adsorption capacity towards chloroform and compressive strength at 60% strain of the champion rGO/PEI/PDMS sponge were effectively increased from 101°, 7.38 g/g and 35.82 kPa to 135°, 16.38 g/g and 111.78 kPa, respectively. The porous rGO/PEI/PDMS sponge also demonstrated good adsorption capacities towards various substrates, including organic solvents (carbon tetrachloride, chloroform, dichloromethane , dimethylformamide , n-hexane, petroleum ether, and toluene) and oils (pump oil, silicone oil soybean oil). The rGO/PEI/PDMS sponge was further assessed as oil/water separation material, displaying high efficiency and good selectivity to the representatives of both heavy and light oils. More importantly, the resultant sponge delivered excellent recyclability without obvious attenuation of adsorption capacity at least 60 cycles. This work proposed a perspective for rational designing and fabricating efficient adsorbent with robust structure and durability in practical application.