PG-PEI-Ag NPs-Decorated Membrane for Pretreatment of Laboratory Wastewater: Simultaneous Removal of Water-Insoluble Organic Solvents and Water-Soluble Anionic Organic Pollutants.

Generally, waste liquid in laboratory can be roughly classified into organic wastewater and inorganic wastewater. However, in some experiments, organic phase and water phase are inevitably mixed together, leaving the postclassification and disposal intractable. Traditionally, we used methods like distillation and extraction to separate these two phases, however, always consuming significant amounts of labor and time and meanwhile having an unsatisfactory separation efficiency. Here, we proposed an improved processing method with a propyl gallate (PG)-polyethyleneimine (PEI)-Ag nanoparticles (NPs)-decorated membrane, possessing the special wettability designed for organic and water phase separation. Accordingly, various kinds of organic solvents/water mixtures were tested, where the PG-PEI-Ag NPs-decorated membrane was used like a common filter paper, fixed onto the funnel of the waste liquid barrel. Afterward, the two phase mixtures were poured onto the membrane; as a result, the organic phase was blocked above while the water phase was left below. All kinds of organic solvents/water mixtures showed higher than 99.90% removal efficiency. Besides, the membrane can remove water-soluble anionic organic molecules through electrostatic interaction. Thus, along the phase separation, anionic organic molecules in water can be removed simultaneously. This pretreatment of lab wastewater with the PG-PEI-Ag NPs-decorated membrane is simple and efficient, relieving the pressure of postcollection and disposal to some extent.