▎ 摘　　要

The decolorization of remelt syrup is the most critical step in the sugar refining process as it directly affects the quality of refined sugar. Adsorption is a useful method that can be applied to decolorize the syrup. A quaternary ammonium-functionalized chitosan/graphene oxide composite aerogel (GO-QACSA) was developed as an effective adsorbent for the removal of high-molecular-weight reducing sugar alkaline degradation products (HRSADPs), the main class of colorants in remelt syrup. The advantages of GO-QACSA to remove HRSADPs can be attributed to its well-connected 3-D network-like porous structure, nontoxicity, high hydrophilicity, and the richness of quaternary ammonium groups. The equilibrium adsorption capacity of GO-QACSA for HRSADPs reached 364.09 mg/g and the removal rate was > 90%. GO-QACSA exhibited an ultra-fast adsorption rate. Recycling experiments indicated that GO-QACSA exhibited good renewability and reusability. The interaction mechanism for the adsorption of HRSADP on GO-QACSA was studied, and the results revealed that two layers of HRSADPs adhered to the surface of GO-QACSA via electrovalent bonds formed between the quaternary ammonium and carboxylate groups. On average, 2-3 carboxylate ions in one HRSADP molecule bonded with the quaternary ammonium cations of GO-QACSA. Four phenomenological mathematical models, namely, External mass transfer resistance (EMTR), Internal mass transfer resistance (IMTR), combined EMTR-IMTR, and Adsorption on active sites (AAS), were presented based on the best-fit equilibrium isotherms. These models could be used to provide new insights into the adsorption mass transfer behaviors of the system.