Polyelectrolytes with abundant ionizable groups always possess excellent adsorption capacity for metal ions. However, these polymer chains are limited for direct application, resulting from lacking a fixed shape. In this paper, polypropylene (PP) fibers decorated with high-density polyacrylic acid (PAA) brushes were prepared using modified ultraviolet-induced graft technology and used as an efficient adsorbent for recovering rare-earth elements from wastewater. The preparation conditions for the degree of grafting were optimized with the response surface methodology mode. After grafting, apparent expansion happened to the fibers, and scanning electron microscopy images indicated that the fiber diameter increased from 48 to 175 μm along with the increase of the degree of grafting. By means of attaching one end of PAA chains onto the PP substrate, the free end would be exposed to the surrounding medium, which leads to a huge number of highly accessible adsorption sites and further guaranteed us with a fast adsorption–desorption rate and larger adsorption capacity. Adsorption could reach above 85% of the maximum adsorption capacity, with a magnitude of 435.19 mg·g^–1 within 5 min toward a model rare-earth element Ce³⁺. Isotherm and kinetic analyses were also undertaken. Moreover, the recycling experiment suggested that the adsorbent taken with almost 100% desorption efficiency could be reproduced robustly for several cycles. In addition, the modified PP fiber can be considered as potential column packing because it exhibits higher adsorption capacity and desorption efficiency than commercial D113 and DL001 resins.

中文翻译：

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采用RSM模型优化的高密度聚丙烯丙烯酸刷式接枝聚丙烯纤维，具有超快和稳定的吸附-解吸性能，可回收宝贵的稀土离子

具有丰富的可电离基团的聚电解质始终具有对金属离子的出色吸附能力。然而，由于缺乏固定的形状，这些聚合物链被限制用于直接施用。本文采用改进的紫外线诱导接枝技术制备了装饰有高密度聚丙烯酸（PAA）刷的聚丙烯（PP）纤维，并将其用作从废水中回收稀土元素的有效吸附剂。用响应面法优化了接枝度的制备条件。接枝后，纤维发生了明显的膨胀，扫描电子显微镜图像表明，随着接枝度的增加，纤维直径从48μm增加到175μm。通过将PAA链的一端连接到PP基材上，自由端将暴露于周围的介质中，从而导致大量高度可访问的吸附位点，并进一步为我们提供了快速的吸附-解吸速率和更大的吸附容量。吸附量可达到最大吸附量的85％以上，幅度为435.19 mg·g5分钟内向模型稀土元素Ce ^3+注入–1。还进行了等温线和动力学分析。此外，循环利用实验表明，以几乎100％的解吸效率吸收的吸附剂可以稳定地再生数个循环。另外，由于改性PP纤维比商用D113和DL001树脂具有更高的吸附能力和解吸效率，因此可以认为是潜在的柱填料。