Porous 3D network rectorite/chitosan gels: Preparation and adsorption properties

• Porous rectorite gels were prepared by crosslinking chitosan with glutaraldehyde.
• RCG gels were calcined to remove polymer components.
• RCG and CRCG gels were characterized, and were used to adsorb liquids.
• CRCG gels were used to study MB adsorption including kinetic and isotherm study.

Ultra-light porous 3D network rectorite (Rec) gels were prepared by crosslinking chitosan with glutaraldehyde in a simple process of aqueous gel precursor freezing, solvent exchange, and ethanol drying instead of expensive supercritical drying technology. The porous structures of Rec gels were composed of randomly oriented Rec layers. Rec gels with densities of 28.8 to 79.6 mg/cm3 withheld liquids such as water up to 13–26 times, DMSO 12–35 times, and soybean oil 9–20 times the weight of the gel. However, the crosslinked chitosan components, which were used to consolidate the porous 3D network, delayed methylene blue (MB) adsorption of Rec gels. After calcination at 500 °C most of the polymer was burnt away from gels, though the porous structure was maintained and could still contain liquid. The process for MB dye adsorption by the obtained gel was studied. The kinetic adsorption fit the pseudo second-order well, and the isotherm data followed the Langmuir models. The maximum adsorption capacity reached 162.6 mg/g. The calcined REC gels could effectively remove the cationic dye from aqueous solutions.