Alginate–based aerogel fibers with a sheath–core structure for highly efficient methylene blue adsorption via directed freezing wet–spinning

Developing adsorbent materials based on biomass that can be easily recycled and reused to remove water pollutants has received widespread attention. A novel method for the preparation of calcium alginate/poly (vinyl alcohol)/boric acid (as–synthesized Ca-APB) aerogel fibers for highly efficient adsorption of methylene blue by directed freezing wet–spinning was presented in this paper. The Ca-APB-0.5 aerogel fibers exhibited a hierarchical structure consisting of a honeycomb micron pore structure with mesopores walls, with a maximum adsorption capacity of 508.99 mg/g in 5 h at 293 K. Meanwhile, the experimental data for Ca-APB-0.5 aerogel fibers showed the best fit to the Freundlich model and pseudo–second–order model. Moreover, the adsorption capacity was investigated for three consecutive cycles, with 469.37, 457.19, and 439.77 mg/g in the first, second, and third cycles, respectively. This paper proves that the hierarchical structure of alginate-based aerogel fiber is an effective dye adsorption material with high efficiency, reusability, and eco-friendliness.