Hemicelluloses-based magnetic aerogel as an efficient adsorbent for Congo red

Abstract

A renewable, efficient, and low-cost material is essential for adsorbing water pollution, such as dyes and heavy metal ions pollution. Here in, we demonstrate an aerogel to remove the dyes from water based on hemicellulose. The dialdehyde hemicelluloses (DAH) were synthesized by oxidation of hemicellulose extracted from straw with NaIO4. The hydrogels were prepared based on the dialdehyde hemicellulose and chitosan-Fe3O4 composite by the Schiff's base reaction, which were processed with vacuum freeze-drying technique to obtain aerogels. It was found that hydroxyl groups at C2 and C3 of hemicellulose were oxidized to aldehyde groups after modification, and the content of aldehyde group was 5.57 mmol/g. The maximum compress strength of aerogel was 0.37 MPa, and the maximum absorption capacity of Congo red dye was 137.74 mg/g. Aerogels with Fe3O4 exhibited magnetism which enables the aerogels to easily recycle. Meanwhile, the thermal stability, mechanical properties of the aerogels and its adsorption property to Congo red dye could be improved directly by the addition of Fe3O4.