Polymer-Decorated Filter Material for Wastewater Treatment: In Situ Ultrafast Oil/Water Emulsion Separation and Azo Dye Adsorption

Aiming to realize the wastewater treatment of various pollutants simultaneously, a dual-functional poly(ether amine)-polydopamine (PEA-PDA)-modified filter material was fabricated in this work for in situ separation of stable oil-in-water emulsion and adsorption of anionic azo dyes. PEA and PDA could be copolymerized via the Michael addition reaction on a polyurethane sponge substrate firmly. The as-prepared filter shows superhydrophilic and underwater superoleophobic wettability. After being squeezed in a glass tube, the material could separate different kinds of stabilized oil-in-water emulsions with high flux and efficiency. Besides, the PEA-PDA copolymer endows the material with the ability to adsorb large amounts of anionic azo dyes during the separation of emulsions with good adsorption capacity. Moreover, adsorbed dyes in the filter material could be easily desorbed in base aqueous solution and the whole process is conducted under gravity without external aid. This dual-functional material shows great potential for the application in industrial field because of its ability for the complex wastewater treatment.

Nature-Inspired Strategy toward Superhydrophobic Fabrics for Versatile Oil/Water Separation

Phytic acid, which is a naturally occurring component that is widely found in many plants, can strongly bond toxic mineral elements in the human body, because of its six phosphate groups. Some of the metal ions present the property of bonding with phytic acid to form insoluble coordination complexes aggregations, even at room temperature. Herein, a superhydrophobic cotton fabric was prepared using a novel and facile nature-inspired strategy that introduced phytic acid metal complex aggregations to generate rough hierarchical structures on a fabric surface, followed by PDMS modification. This superhydrophobic surface can be constructed not only on cotton fabric, but also on filter paper, polyethylene terephthalate (PET) fabric, and sponge. Ag^I, Fe^III, Ce^III, Zr^IV, and Sn^IV are very commendatory ions in our study. Taking phytic acid-Fe^III-based superhydrophobic fabric as an example, it showed excellent resistance to ultraviolet (UV) irradiation, high temperature, and organic solvent immersion, and it has good resistance to mechanical wear and abrasion. The superhydrophobic/superoleophilic fabric was successfully used to separate oil/water mixtures with separation efficiencies as high as 99.5%. We envision that these superantiwetting fabrics, modified with phytic acid-metal complexes and PDMS, are environmentally friendly, low cost, sustainable, and easy to scale up, and thereby exhibit great potentials in practical applications.