High-performance quaternary ammonium-functionalized chitosan/graphene oxide composite aerogel for remelt syrup decolorization in sugar refining
High-performance quaternary ammonium-functionalized chitosan/graphene oxide composite aerogel for remelt syrup decolorization in sugar refining
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DOI：
10.1016/j.cej.2021.132575
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发表时间：
2022-01
影响因子：
15.1
通讯作者：
Yao Xiao;Hai-qin Lu;Changrong Shi;Fu Lei;D. Rackemann;Kai Li;Wen Li;William O. S. Doherty
中科院分区：
文献类型：
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作者：
Yao Xiao;Hai-qin Lu;Changrong Shi;Fu Lei;D. Rackemann;Kai Li;Wen Li;William O. S. Doherty
回熔糖浆脱色是制糖过程中最关键的一步，它直接影响到精制糖的质量。吸附法是一种有效的糖浆脱色方法。季铵功能化壳聚糖/氧化石墨烯复合气凝胶（GO-QACSA）是一种有效的吸附剂，可用于去除高分子量还原糖碱性降解产物（HRSADPs）。GO-QACSA去除HRSADP的优势可以归因于其良好连接的三维网络状多孔结构，无毒，高亲水性和丰富的季铵基团。GO-QACSA对HRSADP的平衡吸附容量为364.09 mg/g，去除率> 90%。GO-QACSA表现出超快的吸附速率。回收实验表明，GO-QACSA具有良好的可再生性和可重复使用性。研究了HRSADP在GO-QACSA表面的吸附作用机理，结果表明，HRSADP通过季铵盐与羧酸根之间形成的共价键吸附在GO-QACSA表面。平均而言，一个HRSADP分子中的2-3个羧酸根离子与GO-QACSA的季铵阳离子键合。基于最佳拟合平衡等温线，建立了4个唯象数学模型，即外传质阻力（EMTR）、内传质阻力（IMTR）、EMTR-IMTR组合模型和活性位吸附（AAS）模型。这些模型可为系统的吸附传质行为提供新的认识。
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.