Polymer-derived ceramic aerogels as sorbent materials for the removal of organic dyes from aqueous solutions

Polymer-derived SiC and SiOC aerogels have been synthesized and characterized both from the microstructural point of view and as sorbent materials for removing organic dyes (Methylene Blue, MB, and Rhodamine B, RB) from water solutions. Their adsorbent behavior has been compared with a polymer-derived SiC foam and a commercial mesoporous silica. The aerogels can efficiently remove MB and RB from water solution and their capacity is higher compared to the SiC foams due to the higher surface area. The SiOC aerogel remains monolithic after the water treatment (allowing for an easy removal without the need of a filtration step) and its maximum capacity for removing MB is 42.2 mg/g, which is higher compared to the studied mesoporous silica and many C-based porous adsorbents reported in the literature. The reason for this high adsorption capacity has been related to the unique structure of the polymer-derived SiOC, which consists of an amorphous silicon oxycarbide network and a free carbon phase.