Mesoporous degradable chitosan-based monoliths: synthesis and applications toward water purification†

The sustainable synthesis of porous polymer monoliths has significant advantages over powdered porous polymers and is capable of adsorbing multiple types of pollutants efficiently from water. They are important as an easily affordable material for water purification. Herein, we report the synthesis of mesoporous chitosan, PEG monoliths, via the crosslinking of chitosan with PEG-diacrylate macro-crosslinkers using aza-Michael reactions in water. The surface area and pore volume are tuned by varying the crosslinking density and length of the macro-crosslinker. The materials show very good thermal and chemical stability against organic and aqueous (within pH 2–9) solvents. The monolith is capable of removing a wide range of both organic and inorganic pollutants, such as anionic dyes, metal ions, iodine, and pharmaceuticals, from contaminated water. The reusability of the monolith after it is regeneration by releasing the adsorbed pollutant is important for its affordable practical application. In addition, the monolith can be completely degraded in a strong alkaline solution to quantitatively recycle the chitosan derivative.