[Preparation of Functional Attapulgite Composite and Its Adsorption Behaviors for Congo Red]

Heavy metal ion wastewater poses a serious threat to human health and the environment. The adsorption method is an important method to remove heavy metal ions from heavy metal wastewater. Magnetic attapulgite (ATP) composite nanomaterials with excellent adsorption properties were prepared by grafting the Fe₃O₄ nanoparticles and using 3-aminopropyl triethoxy silane (APTES) modification. The prepared ATP-Fe₃O₄-APTES materials were used as adsorbents and applied to the treatment of heavy metal ion wastewater. The structure and surface properties of the materials were characterized by FT-IR, XRD, SEM, TEM, and BET characterization, Zeta potential, and VSM. The effects of pH, adsorption time, adsorption temperature, and initial concentration of Pb²⁺ on the adsorption properties of the ATP-Fe₃O₄-PEI materials were investigated. The results show that the maximum adsorption capacity of the materials for Pb²⁺ was 129.32 mg·g^-1 under optimum conditions. The adsorption process conformed to the pseudo second order kinetic model and Langmuir adsorption isotherm, which indicates that the adsorption of Pb²⁺ is a monolayer chemical adsorption and a spontaneous endothermic process. The driving force of adsorption mainly comes from the coordination between the amino group (-NH₂) on the ATP-Fe₃O₄-APTES surface and Pb²⁺. These results indicate that the functionalized magnetic attapulgite adsorbent has good adsorption properties for heavy metal ions and is expected to be used in the treatment of heavy metal ion wastewater.