Durable Carboxylated Porous Polymer Foam as a High-Performance Adsorbent for Dye and Heavy Metal Ion Removal

PolyHIPEs are porous emulsion-templated polymers synthesized within high internal phase emulsions (HIPEs), which are generally used as adsorbents due to their excellent porosity and large specific surface area. However, most reported polyHIPEs-based adsorbents showed inferior adsorption performance due to their hydrophobic nature and limited stability. Herein, we prepared a novel carboxylated porous polymer foam (CPPF) by covalently grafting iminodiacetic acid onto glycidyl methacrylate (GMA)-based PolyHIPEs. CPPF has a large specific surface area of 25.07 m2/g and abundant surface hydrophilic carboxyl groups, which give it a lower potential than porous foam without carboxylation treatment (stable at −32 mV when the pH is higher than or equal to 5). The strong electronegativity on the CPPF surface gives it highly effective adsorption of electropositive contaminants. Notably, the CPPF can effectively adsorb various dyes (methylene blue, malachite green, and methyl violet) and heavy metals (Cu2+ and Cr3+) with adsorption capacities over 500 and 30 mg/g, respectively, which are superior to most reported adsorbents under similar conditions. Furthermore, the CPPF demonstrates great stability and recyclability with removal efficiency higher than 97% after five consecutive adsorption/desorption cycles, indicating its great potential for diverse environmental engineering applications.