Adsorption Capacity of Tetracycline in Solution by Cu-BTC@Carboxyl-Functionalized Carbon Nanotubes@Copper Alginate Composite Aerogel Beads

Abstract

In order to remove tetracycline (TC) from sewage more effectively, the adsorption performance of TC on alginate composite aerogel beads containing carbon nanomaterials was studied systematically. Carboxylated functionalized carbon nanotubes (F-CNTs)@Cu-based metal-organic framework (Cu-BTC) carbon nanomaterial composites (F-C) were prepared by a hydrothermal method, and the F-C powders were coated and fixed by macromolecular polymer copper alginate (CA). Then, F-CNTs@Cu-BTC@CA composite aerogel beads (F-C-CA) were prepared by a vacuum freeze-drying method. The new composite was characterized by BET, SEM, FTIR, and TGA, and its physical and chemical properties were analyzed. The results of batch adsorption experiments showed that F-C-CA aerogel beads had excellent adsorption capacity for TC. At 303 K, 10 mg F-C-CA aerogel beads adsorbed 20 mL 100 mg·L−1 TC solution; the removal rate reached 94% after 48 h. After kinetic analysis, the adsorption process of F-C-CA on TC was found to be more coherent with the pseudo-second-order kinetic model (chemisorption process). The isotherm fitting analysis indicated that the adsorption behavior was more suitable to the Langmuir model (monolayer adsorption), and the fitted maximum adsorption was 297 mg·g−1.