Synthesis of a new porous Graphene Oxide Framework (GOF) for high-performance ultrasonic-assisted removal of cadmium and lead ions from aqueous solution

A novel chelating adsorbent was successfully synthesized by cross-linking of 4, 4', 4"-s-triazine-1, 3, 5-triyltri-p-aminobenzoic acid as a linker with nanosheets of graphene oxide to provide a 3-dimensional framework. Therefore, the adsorption process Cd2+ and Pb2+ on the adsorbent was investigated by employing an ultrasonic bath. The optimum condition containing the small amount of adsorbent (10 mg) for both metals at pH=8 for Cd2+ and pH=5 for Pb2+, and a short time of two minutes caused gaining an absorption capacity at a high level. The presence of nitrogen-functionalized groups in the porous graphene oxide framework (GOF) contributed to the absorption of lead and cadmium ions. To define the kinetic process the kinetic models of pseudo-first-order and pseudo-second-order were used. The experimental adsorption datum was properly-suited to the kinetic model of the pseudo-second-order (R2=0.99). It indicated that adsorbing ions of heavy metals onto GOF happens through a chemical process and adsorption isotherms of Cd2+ and Pb2+ ions were in high-grade accordance with the Longmuir model. Eventually, because of the rapid adsorption kinetics, high capacity for removing, perfect stability, and being reusable, this GOF can be used as a remediation adsorbent with high-performing heavy metals removal from aqueous solutions.