Sandwich-like construction of a new aminated chitosan Schiff base for efficient removal of Congo red

Abstract Herein, a novel sandwich-like α-ketoglutaric acid Schiff base-aminated chitosan composite (α-kGl-AmCsSB) was fabricated by reacting α-ketoglutaric acid and aminated chitosan. The as-fabricated α-kGl-AmCsSB was inspected by diversified characterization tools to determine its morphology, surface charge, and chemical composition as well as define the linkage pathway between α-kGl and AmCs. The SEM images demonstrated a spongy network of AmCs with interconnected pores structure which turned to a quite rough surface due to the linkage of α-kGl to the free amine groups of AmCs. Notably, the XPS and FTIR spectra suggested the linkage of α-kGl to the amine group of AmCs. The experimental results implied the superior adsorption efficiency of Congo red (CR) onto α-kGl-AmCsSB since the maximum adsorption capacity (qmax) reached 434.78 mg/g at 25 °C and pH 3. Based on kinetics data, the adsorption of CR on α-kGl-AmCsSB followed pseudo-second-order model. Furthermore, D-R model infers that the CR adsorption onto α-kGl-AmCsSB occurred via physical interactions since the E value < 8 kJ/mol. The recyclability test was implemented for five cycles with R% > 72%. More importantly, the adsorption mechanism of CR onto α-kGl-AmCsSB was proposed and discussed. Ultimately, the novel sandwich-like α-kGl-AmCsSB exhibited advanced adsorption performance toward CR along with excellent reusability. Based on these results, we recommend more modifications on α-kGl-AmCsSB for exploiting its remarkable advantages and applying it on a large scale.