Facile synthesis of chitin nanocrystals decorated on 3D cellulose aerogels as a new multi-functional material for waste water treatment with enhanced anti-bacterial and anti-oxidant properties

Abstract

We report the fabrication and application of multi-functional hybrid bio-aerogels based on cellulose nanofibers (CNFs) and chitin nanocrystals (CNCs) developed through an environmentally friendly freeze-drying process. Herein, an organic non-solvent approach such as acid hydrolysis was used to extract CNFs and CNCs from corn husks and shrimp shells respectively followed by characterisation using IR spectroscopy and electron microscopy. The usual wire-like and a rare semi-square morphology was detected for the CNFs and CNCs respectively during electron microscopic analysis. Aerogels with two different quantities of CNCs on the CNFs were prepared (AR1 and AR2) and compared with reference to the neat CNF aerogel (neat AR). Interestingly, for AR2, under an electron microscope, a maple seed like morphology was observed compared to the neat AR and AR1. Their ability in water treatment was determined by conducting adsorption experiments using methylene blue and Rhodamine 6G, and it was found that AR2 had an enhanced removal percentage and adsorption capacity. To address their economic viability, we conducted several rounds of studies and evaluated the reusability of AR2. The antibacterial and antioxidant activities of the aerogels were studied using a disc diffusion method against four bacterial species, including S. aureus, E. coli, S. typhimurium and B. cereus, and the best conditions for the determination of minimal inhibitory concentration were carefully discussed. The prepared material having a higher CNC content (AR2) shows multi-functional behaviour and from further studies it is anticipated that they may be produced on an industrial scale for commercial applications in the future.