Versatile CO2-responsive Sponges Decorated with ZIF-8 for Bidirectional Separation of Oil/Water and Controllable Removal of Dyes

The complex wastewater containing water-soluble dyesand water-insolubleoils has given rise to significant environmental concerns that demandurgent remediation. Herein, a novel "smart" multifunctionalsponge (ZIF-8@PMS) stepwise decorated with ZIF-8 nanoparticles andCO(2)-responsive copolymer (poly(2-(diethylamino) ethyl methacrylate-co-3-(trimethoxysilyl)propyl acrylate-co-stearyl methacrylate) was successfully prepared for CO2 controllable oil/water separation and dyes removal. The resultsrevealed that the sponge coated with CO2-responsive copolymerfor three cycles (ZIF-8@PMS-3) exhibited optimal comprehensive properties.The ZIF-8@PMS-3 had excellent compressive-resilient characteristicsand chemical stability. As expected, it displayed tunable wettabilityand charged state under the regulation of CO2. Based onthese features, ZIF-8@PMS-3 presented highly efficient removal ofoil and dyes, even for the dye-containing oil/water emulsions, viaa synergistic combination of adsorption and separation methods. Theadsorption capacity for oil and various organic solvents ranged from21.3 to 50 g g(-1). The maximum adsorption capacitiestoward anionic dyes: methyl orange with 1205.89 mg g(-1) and methyl blue with 880.00 mg g(-1) in the presenceof CO2 through electrostatic interaction. In the absenceof CO2, it achieved maximum adsorption capacities for cationicdyes, including malachite green with 1246.15 mg g(-1) and rhodamine B with 203 mg g(-1), primarily drivenby & pi;-& pi; interactions. According to distinct adsorptionmechanisms, ZIF-8@PMS-3 could selectively adsorb either anionic orcationic dyes by exploiting CO2 as a trigger. Furthermore,the separation efficiencies for both types of oil/water emulsionssurpassed 99.9%, with respective fluxes of 1566.99 L m(-2) h(-1) (water-in-oil emulsion) and 310.37 L m(-2) h(-1) (oil-in-water emulsion). Additionally,the as-prepared sponges exhibited remarkable antibacterial propertiesand exceptional recyclability. Therefore, the ZIF-8@PMS-3 holds substantialpromise for potential applications in practical industrial wastewatertreatment.