Preparation of amino functionalized magnetic oyster shell powder adsorbent for selective removal of anionic dyes and...

A kind of new magnetic oyster shell (OS) composite (OS-Fe₃O₄@SiO₂@NH₂@PEI) was synthesized and used as an adsorbent to remove carmine (CM), sunset yellow (SY) and Pb (II) from water. Firstly, Fe₃O₄ magnetic nanoparticles were introduced on the surface of waste oyster shell powder, then amino silanization was used to improve the stability of the material, and finally polyethylenimide (PEI) was grafted by Schiff base reaction. The composite was characterized by FT-IR, SEM, EDS, XPS, VSM, BET, TEM and zeta potential. The effects of adsorbent dosage and initial solution pH on the three samples were investigated by adsorption experiments. The adsorption kinetics and isotherms were investigated in depth under the best experimental conditions. The composite adsorbent not only selectively removed anionic azo dyes, but also had good recycling. In addition, OS-Fe₃O₄@SiO₂@NH₂@PEI still had good performance in mixed samples. These results indicated that OS-Fe₃O₄@SiO₂@NH₂@PEI was successfully used for the removal of a wide range of anionic dyes and heavy metal ions from the environment, and provided a new strategy for recycling waste.