Preparation of Novel Magnetic Sodium Alginate-Ferric(Ⅲ) Gel Beads and Their Super-Efficient Removal of Direct Dyes from Water

Lv Ting; Li Beigang

摘要

Novel magnetic sodium alginate-based biopolymer Fe3O4@SA-Fe was successfully prepared by the cross-linking reaction of sodium alginate (SA) and Fe(III) ions and adding magnetic ferric oxide (Fe3O4), and characterized by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), UV-visible diffuse reflectance spectroscopy (UV-Vis DRS), Fourier Transform-Infrared (FTIR), X-ray Photoelectron Spectroscopy (XPS) and Vibrating Sample Magnetometer (VSM), respectively. The effects of preparation and adsorption conditions on the adsorbent were investigated by adsorbing Congo red (CR) and Direct red 23 (DR 23) dyes. The results showed that the synthesized Fe3O4@SA-Fe polymer gel beads exhibited super-high adsorption property and good stability when the mass concentrations of SA, Fe(III) ions and Fe3O4 are 16, 12.5 and 7 g/L at room temperature respectively. The adsorption rates of two dyes by Fe3O4@SA-Fe were very fast at 298 K, and the time required to reach the equilibrium was very short, which was 30 min for CR and 60 min for DR 23. Moreover, the dye removal efficiencies were over 99.4% and 95.2% in a wide pH range of 2.0 similar to 9.0 for CR and 2.0 similar to 10.0 for DR 23, respectively. The adsorption process could be accurately described by the pseudo-second-order rate model, which were mostly controlled by intra-particle diffusion. The fitting results of isothermic data by Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models revealed that the equilibrium data completely obeyed the Langmuir model and the obtained maximum adsorption capacities of CR and DR 23 were 3333 and 1429 mg/g at 298 K, respectively. FTIR, UV-Vis and XPS analysis indicated that the electrostatic adsorption, hydrogen bonding and ligand exchange promoted the interaction between dye molecules and Fe3O4@SA-Fe. A green magnetic biosorbent Fe3O4@SA-Fe gel beads with simple preparation method and high-cost performance can be used for super-efficient purification of high-concentration dye effluent and quickly separated from the aqueous phase and recovered, which would have a good application prospect.

机译：通过藻酸钠（SA）和Fe（III）离子和加入磁性氧化铁（Fe3O4）的交联反应成功制备了新型磁性藻酸钠的生物聚合物Fe3O4 -Fe，并通过扫描电子显微镜（SEM ），能量分散光谱（EDS），UV可见漫射反射光谱（UV-VIS DRS），傅里叶变换 - 红外（FTIR），X射线光电子能谱（XPS）和振动样品磁力计（VSM）。通过吸附刚果红色（Cr）和直接红色23（DR 23）染料，研究了制备和吸附条件对吸附剂的影响。结果表明，当SA，Fe（III）离子和Fe3O4的质量浓度分别为16,12.5和7g / L时，合成的Fe3O4 @ SA-Fe 2 4 @ SA-Fe聚合物凝胶珠呈超高吸附性能和良好的稳定性。 Fe3O4 @ SA-Fe的两种染料的吸附率在298k时非常快，并且达到平衡所需的时间非常短，这对于Cr和23号DR 60分钟为30分钟。此外，染料去除效率为30分钟。此外，染料去除效率在2.0的宽pH范围内超过99.4％，95.2％，同样为CR和2.0的9.0，分别与DR 23的10.0相似。可以通过伪二阶速率模型来精确描述吸附过程，其主要由粒子扩散控制。 Langmuir，Freundlich和dubinin-Radushkevich（DR）模型的等温数据的拟合结果表明，平衡数据完全遵循Langmuir模型和Cr和Dr 23的最大吸附容量为3333和1429mg / g，为298 k，分别。 FTIR，UV-Vis和XPS分析表明，静电吸附，氢键和配体交换促进染料分子和Fe3O4 @ -Fe之间的相互作用。具有简单制备方法和高成本性能的绿色磁性生物生物生物凝胶Fe3O4 @ SA-Fe凝胶珠子可用于高浓度染料流出物的超高效净化，从水相快速分离并回收，这将具有良好的应用展望。

Preparation of Novel Magnetic Sodium Alginate-Ferric(Ⅲ) Gel Beads and Their Super-Efficient Removal of Direct Dyes from Water

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