壳聚糖-果胶凝胶珠吸附剂的改性及其去除藻蓝蛋白中Pb（II）的应用

刘玉环; 关瑞; 曹雷鹏; 周悦; 黄正花; 薛命雄; 周佳文

doi:10.13386/j.issn1002-0306.2023020098

壳聚糖-果胶凝胶珠吸附剂的改性及其去除藻蓝蛋白中Pb（II）的应用

Modification of Chitosan-Pectin Beads Adsorbent and Its Application for the Removal of Pb (II) from C-phycocyanin

摘要

摘要: 壳聚糖-果胶凝胶珠（Chitosan-pectin gel beads，CPB）吸附去除食品中重金属具有较高的潜力，为提高其稳定性、再生利用性及吸附能力，本文采用明胶（Gel）和羧甲基纤维素钠（CMC）对CPB进行改性，利用扫描电镜（SEM）、比表面积与孔隙度分析（BET）、傅里叶变换红外光谱（FTIR）、热重分析（TG）、Zeta电位仪、X射线光电子能谱（XPS）及等技术表征其结构特性，优化吸附解析条件，并评估其对藻蓝蛋白中Pb（II）的实际去除效果。结果显示，与CPB和Gel-CPB相比，CMC改性的CPB（CMC-CPB）热稳定性高、表面粗糙多孔、比表面积大（20.28±1.35 m²/g）及Zeta电位低，对金属离子吸附能力强，且解析再生利用率高。FTIR图谱分析显示改性前后CPB官能团结构未发生明显变化，其主要结构官能团为羧基、羟基和氨基。TG分析表明改性前后的CMC-CPB的热稳定性显著高于CPB和Gel-CPB（P<0.05）。XPS光谱分析表明三种吸附剂成功吸附了Pb（II），其中CMC-CPB对Pb（II）的吸收峰最强。三种吸附剂（CPB、Gel-CPB和CMC-CPB）去除Pb（II）的最佳pH和温度分别为6.0和60 ℃，对Pb（II）的吸附过程均符合Langmuir吸附等温模型（R²=0.9543~0.9811）和准二级动力学模型（R²=0.9963~0.9991），该吸附属于单分子层化学吸附，即-COO、-OH、-CO-NH与Pb（II）之间的络合作用。根据Langmuir模型曲线评估，CMC-CPB对Pb（II）的最大吸附容量q_max为69.37 mg/g，显著高于Gel-CPB和CPB（P<0.05）。综合在藻蓝蛋白中的应用效果，CMC-CPB低成本高效安全地去除藻类和藻蓝蛋白食品中Pb（II）具有更广阔的前景。

Abstract: Chitosan-pectin gel beads (CPB) have high potential for removing heavy metals from food. This study aimed to improve their stability, recyclability, and adsorption capacity by modified CPB with gelatin (Gel) and carboxymethyl cellulose sodium (CMC). The structural characteristics of the modified CPBs were characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG), Zeta potential, scanning electron microscopy (SEM), pore size distribution analysis (BET), X-ray photoelectron spectroscopy (XPS), specific surface area analysis. The adsorption-resolution conditions of modified CPB were optimized, and their actual removal efficiency for Pb(II) in C-phycocyanin was evaluated. Results showed that CMC-modified CPB (CMC-CPB) had higher thermal stability, rougher and more porous surface, larger specific surface area (20.28±1.35 m²/g), lower zeta potential, stronger metal ion adsorption capacity, and higher regeneration efficiency compared with CPB and Gel-CPB. FTIR showed the functional group of CPB had significant difference after modification, and the main group in CPB were carboxyl, hydroxyl, and amino groups. TG analysis presented the thermal stability of CMC-CPB was higher than that of CPB and Gel-CPB. XPS analysis showed CMC-CPB had the strongest absorption peak for Pb(II). The optimal pH and temperature for the three adsorbents (CPB, Gel-CPB, and CMC-CPB) to remove Pb(II) were 6.0 and 60 ℃, respectively. The Pb(II) adsorption process of all three adsorbents fit the Langmuir isotherm model (R²=0.9543~0.9811) and the pseudo-second-order kinetic model (R²=0.9963~0.9991), and the adsorption process belonged to the monolayer chemical adsorption, involving the complexation of -COO, -OH, -CO-NH, and Pb(II). Based on the Langmuir model curve, the maximum adsorption capacity (q_max) of CMC-CPB for Pb(II) was 69.37 mg/g, significantly higher than that of Gel-CPB and CPB (P<0.05). Combing application effect of three adsorbents in C-phycocyanin, CMC-CPB showed a great prospect to efficiently remove Pb(II) in food of algae and C-phycocyanin at low-cost and environment friendly.