Dye wastewater has caused great harm to the environment, which is an urgent problem to be solved. As typical three-dimensional porous materials, aerogels have attracted great interest in dye wastewater treatment. In this work, spherical attapulgite/silica (ATP/SiO2) gels were initially prepared by easily scalable sol-gel dripping methods and then dried to aerogels with three drying techniques, namely, supercritical CO2 drying (SCD), freeze-drying (FD), and ambient pressure drying (APD). The effect of the drying techniques and heat-treated temperature on the physical characteristic, morphological properties, microstructure, and chemical structure of the spherical ATP/SiO2 aerogels were investigated. The macroscopic morphology of the spherical ATP/SiO2 aerogels was homogeneous and integrated without local cracking. The average pore diameter and specific surface area of the spherical ATP/SiO2 aerogels prepared by the three drying techniques were in the range of 6.8-8.6 nm and 218.5-267.4 m2/g, respectively. The heat treatment temperature had a significant effect on the pore structure and the wetting properties of the aerogels. The 600 °C heat-treated aerogels were subjected to adsorption tests in methylene blue (MB) solution (60 mg/g, 100 mL), which exhibited a great adsorption capacity of 102.50 mg/g. Therefore, the resulting spherical ATP/SiO2 aerogels possessed multipath preparation and exhibited an efficient adsorption performance, with the potential to be applied as an adsorbent for dye wastewater.
Keywords: adsorption performance; drying techniques; heat treatment; spherical ATP/SiO2 aerogels.