Preparation of caffeic acid-polyethyleneimine modified sponge for emulsion separation and dye adsorption

Water pollution has become a serious problem in aquatic ecology due to the oil spills and the consistent release of industrial pollutants, such as dyes. Herein, we report a simple method to fabricate superwetting caffeic acid (CA)-polyethyleneimine (PEI)-modified melamine sponges (CA-PEI-MS) for oil-in-water emulsion separation and dye adsorption. The as-fabricated CA-PEI-MS exhibited superhydrophilicity with an approximately zero water contact angel (WCA) and underwater superoleophobicity with an underwater oil contact angel (UWOCA) greater than 150 degrees. The compressed CA-PEI-MS showed an excellent oil-in-water emulsion separation performance with a separation efficiency greater than 97% and a water flux of up to 25,480 L h(-1) m(-2) bar(-1). The recyclability test was used to study the stability of the compressed CA-PEI-MS, after washing with acetone; the flux did not show any significant change during the 12-cycle separation test. The separation efficiency in every cycle was greater than 97%. Due to the availability of rich positive charged amino groups, the as fabricated CA-PEI-MS exhibited adsorption ability towards negatively charged dyes such as, rose bengal (RB) and direct red (DR) with 96% adsorption efficiency. Therefore, the as designed low-cost and eco-friendly preparation of CA-PEI-MS has a great potential for practical application as it shows high separation performances and excellent efficiency. (c) 2020 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Automated summary

The study presents a simple method to fabricate superwetting CA-PEI-MS for efficient oil-in-water emulsion separation and dye adsorption. The material shows excellent water treatment performance and dye adsorption ability, indicating great potential for practical applications.