Clay-gelatin/hydroxypropyl cellulose composite films for methylene blue adsorption

Obtaining new materials with high water resistance, biodegradability, and adsorption properties is strategic for removing dyes from an aqueous system. In this context, films of biopolymers such as gelatin and hydroxypropyl cellulose (HPC), when combined with clay, offer advantageous properties for environmental remediation. However, despite these benefits, there are no reports of obtaining gelatin/HPC/clay composite materials specifically for adsorbing contaminants in aqueous media. Therefore, composite films consisting of gelatin, HPC, and 0, 2.5, or 5.0 % (w/w) of Montmorillonite clay Cloisite Na+ (NaMt) were obtained using propylene glycol (PG) as plasticizing. The adsorption efficiency of Methylene blue (MB) was evaluated for both crosslinked and non-crosslinked films with and without glutaraldehyde (GA). The results indicated that crosslinking gelatin/HPC films with clay particles resulted in a more compact, smooth, and homogeneous surface, leading to increased water resistance, and improved thermal stability of the films. Additionally, MB adsorption was enhanced, with a maximum adsorption capacity of 11.2 mg g−1 of dye adsorption observed for the crosslinked film of gelatin/HPC with 5.0 % (w/w) clay, corresponding to 89.1 % (w/w) of MB removal from the aqueous phase. This performance was superior to that of films without the crosslinking process. Hence, incorporating clay particles and the crosslinking process played an important role in enhancing MB adsorption on gelatin/HPC surfaces, suggesting that specific interactions between MB molecules and composite films can modulate and broaden the possibilities of removing dyes in wastewater treatment applications.