Preparation of high-performance chitosan adsorbent by cross-linking for adsorption of Reactive Red 2 (RR2) dye wastewater

In this study, high-performance adsorbents were developed by modifying chitosan (CS) with polyethylene glycol (PEG) and formaldehyde. The prepared chitosan beads were tested for adsorption in Reactive Red 2 (RR2) dye wastewater. All the prepared samples were characterized by FI-IR, DSC, XRD, and SEM. The effects of different pH, temperature, PEG molecular weight, and PEG content on the adsorption performance of RR2 were investigated. The results showed that the adsorption equilibrium of RR2 dye was consistent with the Langmuir model and the pseudo-second-order kinetic model. The negative values of (Delta G(0)) suggested that this adsorption process was spontaneous. At 30 degrees C, when the ratio of CS and PEG (MPEG=4000) was 1:1, the maximum adsorption capacity of PEGylated chitosan beads (CS/4000 P-1) was 2334.8 mg.g(-1). This high adsorption performance is mainly attributed to the protonation of NH3+ groups on the surface of CS/4000 P-1 which enhances its electropositivity. In addition, the CS/4000-1 pore structure is enriched to further improve the adsorption performance. For the regeneration investigation, HCl regent was found to have a fine regeneration effect, and the beads showed the pH-dependent swelling behavior.