Preparation of a composite material based on self-assembly of biomass carbon dots and sodium alginate hydrogel and its green, efficient and visual adsorption performance for Pb2+
Preparation of a composite material based on self-assembly of biomass carbon dots and sodium alginate hydrogel and its green, efficient and visual adsorption performance for Pb2+
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DOI：
10.1016/j.jece.2021.106921
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发表时间：
2021-12
影响因子：
7.7
通讯作者：
Siyi Zhang;Kamile Arkin;Yuxin Zheng;Jicheng Ma;Yuyang Bei;Di Liu;Q. Shang
中科院分区：
文献类型：
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作者：
Siyi Zhang;Kamile Arkin;Yuxin Zheng;Jicheng Ma;Yuyang Bei;Di Liu;Q. Shang
本文以带正电的生物质碳点（PEI-CDs）和阴离子聚电解质海藻酸钠（SA）为原料，通过静电自组装制备了一种环保、可见且易于回收的球形吸附剂（SA@PEI-CDs， SA：海藻酸钠，PEI：聚乙烯亚胺，CDs：碳点）。SA@PEI-CDs能高效优先吸附Pb2+。与赤色SA相比，SA@PEI-CDs的吸附量从206.93 mg/g提高到380.39 mg/g (pH=4)，提高了83.82%。经过5次循环后，仍能保持原有吸附量的85.67%。由碳点衍生的吸附剂的蓝色荧光猝灭表明吸附过程已经达到饱和。吸附等温线模型、动力学和热力学参数的研究表明，吸附过程遵循基于化学吸附的Freundlich等温线模型，是一个熵增加的吸热自发反应。可能的吸附机理是静电吸引、离子交换以及-NH2、-OH、-COOH与Pb2+的配位作用。此外，在净水器模型中，极易回收的球形吸附剂也被用于模拟污水样品的多层吸附和分离。对于5 / 3种重金属离子浓度超过标准100倍的模拟水样，使用吸附剂SA@PEI-CDs连续吸附2 ~ 3次后，重金属含量迅速下降，远低于优质水的极限值。Pb2+离子浓度分别从1.0 mg/L降至0.002540 mg/L和0.003611 mg/L。
In this paper, an environmentally friendly, visible and easy-to-recycle spherical adsorbent (SA@PEI-CDs, SA: sodium alginate, PEI: polyethyleneimine, CDs: carbon dots) has been prepared from functionalized positively charged biomass carbons dots (PEI-CDs) and anionic polyelectrolyte sodium alginate (SA) through electrostatic self-assembly. SA@PEI-CDs can efficiently and preferentially adsorb Pb2+. Compared to bare SA, the adsorption capacity of SA@PEI-CDs increased from 206.93 mg/g to 380.39 mg/g (at pH=4), which enhanced 83.82%. It can still maintain 85.67% of the original adsorption capacity after five cycles. The quenching of the blue fluorescence of the adsorbent derived from carbon dots indicates that the adsorption process has reached saturation. The investigation about the adsorption isotherm models, kinetics and thermodynamic parameters reveals that the adsorption process follows Freundlich isotherm model based on chemical adsorption, which is an endothermic spontaneous reaction with an increase in entropy. The possible adsorption mechanism is electrostatic attraction, ion exchange, and together with the coordination of -NH2, -OH, -COOH with Pb2+. In addition, the extremely easy-to-recycle spherical adsorbent is also used in the multi-layer adsorption and separation of simulated sewage samples in the water purifier model. For simulated water samples whose concentration of five/three types of heavy metal ions exceeds 100 times the standard, after using adsorbent SA@PEI-CDs for two or three consecutive adsorptions, the content of heavy metals decreases rapidly, which is far below the limit value of high-quality water. The Pb2+ion concentration decreased from 1.0 mg/L to 0.002540 mg/L and 0.003611 mg/L, respectively.