A universal strategy for efficient separation from single emulsion separation to oil-in-water and water-in-oil mixed emulsions

To realize efficient treatment of oily wastewater, various super-wetting materials have been developed. Oily wastewater is often complex and may contain both oil-in-water and water-in-oil emulsions. However, most of the current studies focus on the treatment of single emulsions, and there are fewer studies on the simultaneous separation of oil-in-water and water-in-oil emulsions. In this paper, by removing hemicellulose and lignin from bamboo processing waste powder (BPWP), the treated bamboo powder (TBP) containing mainly cellulose was obtained. TBP has superoleophobicity underwater and superhydrophilicity underoil, which can separate not only various oil-in-water emulsions stabilized by surfactants, but also water-in-oil emulsions stabilized by different surfactants, and the separation efficiency is higher than 99 %. The separation efficiencies of TBP for different water-in-oil emulsions were all higher than 99 %. On this basis, we have established an intelligent device that makes full use of underwater super-hydrophobic and under-oil super-hydrophilic properties to realize the purification of water and de-watering and recycling of floating oil in complex oil-water systems. This work provides a very promising direction for industrial application in practical oily wastewater treatment and fuel recovery.