Insight into the highly efficient adsorption towards cationic methylene blue dye with a superabsorbent polymer modified by esterified starch

Abstract

A superabsorbent polymer (SAP) is developed utilizing a synthesized starch phosphate carbamate (SPC) and acrylamide (AM) via radical polymerization and utilized for the adsorption removal of methylene blue (MB). A series of characterization measurements including FT-IR, XRD, EDS, and XPS are conducted to confirm the formation of the SPC-based SAP (SPC-SAP). Due to the rough surface and abundant irregular pores confirmed in SEM, this SPC-SAP shows a prominent adsorption capability toward MB, yielding a maximum adsorption capacity as high as 62.52 mg/g in optimal conditions. The MB adsorption process by the SPC-SAP simultaneously satisfies the Langmuir model and the pseudo-second-order model of intraparticle diffusion with a spontaneous process. In comparison with natural starch based SAP (NS-SAP), the enhancement of MB adsorption by SPC-SAP can mainly be attributed to the improvement of the hydrogen-bonding and electrostatic interaction between SPC-SAP and MB due to the existence of abundant -NH2, -PO4- groups in SPC. Additionally, the SPC-SAP exhibits a better biodegradability in soil. In a conclusion, this work developed a biocompatible and stable SPC-SAP and provided a novel strategy for organic dye pollutants removal.