Methylene Blue\nRemoved from Aqueous Solution by Encapsulation\nof Bentonite Aerogel Beads with Cobalt Alginate

Abstract

It can be difficult to remove dark methylene blue (MB)\nfrom water\neffectively. The use of sodium alginate and bentonite (Ben) as the\nmatrix produced a displacement reaction that occurred in cobalt chloride,\nwhich allowed Ben to be successfully encapsulated in cobalt alginate\n(CA). Finally, a vacuum freeze-drying method was used to prepare a\nlow-cost composite of CA/Ben aerogel for adsorbing MB in aqueous solutions.\nIn addition to scanning electron microscopy, thermogravimetric analysis,\nand Fourier transform infrared spectroscopy, the composites were also\ncharacterized and analyzed. Different adsorption experiments were\nconducted in order to determine the effects of dosage, pH, adsorption\ntime, and temperature on the adsorption performance of the adsorbent.\nAccording to the results of the experiment, the adsorption capacity\nof CA/Ben aerogel was 258.92 mg·g^–1, and the\npseudo-first-order kinetic model and Freundlich isotherm model can\nfully explain the adsorption process of MB on this aerogel. The composite\nmaterial reported in this paper is easily recycled, and the removal\nrate reaches 65% after four times of recycling. Moreover, compared\nwith other adsorbents, the composite material of the invention is\nhighly environmentally friendly and has a simple preparation process.\nA large-scale application of this technology is the removal of dyes\nfrom water on a large scale.