Fabrication porous adsorbents templated from aqueous foams using astragalus membranaceus and attapulgite as stabilizer for efficient removal of cationic dyes

The water-based foam stabilized by the natural surfactant applied in the fabrication of porous materials has attracted extensive attention,as the advantages of cleanness,convenience and low cost.Particularly,the development of a green preparation method has became themain research focus and frontier.In thiswork,a green liquid foamwith high stability was prepared by synergistic stabilization of natural plant astragalus membranaceus(AMS)and attapulgite(APT),and then a novel porous material with sufficient hierarchical pore structure was templated from the foam via a simple free radical polymerization of acrylamide(AM).The characterization results revealed that the amphiphilic molecules from AMS adsorbed onto thewater-air interface and formed a protective shell to prevent the bubble breakup,and APT gathered in the plateau border and formed a three-dimensional network structure,which greatly slowed down the drainage rate.The porous material polyacrylamide/astragalus membranaceus/attapulgite(PAM/AMS/APT)showed the excellent adsorption performance for cationic dyes of Methyl Violet(MV)and Methylene Blue(MB)in water,and the maximum adsorption capacity could reach to 709.13 and 703.30 mg/g,respectively.Furthermore,the polymer material enabled to regenerate and cycle via a convenient calcination process,and the adsorption capacitywas still higher than 200 mg/g after five cycles.In short,this research provided a new idea for the green preparation of porous materials and the treatment of water pollution.