Cross-linked graphene with chitosan nanocomposites for efficient photocatalytic degradation of bromothymol blue, bromophenol blue dye molecules.

The pervasive occurrence of various organic contaminants, primarily dye molecules, in water bodies was caused by multiple dye industrial wastes, which recently sparked great scientific concern and public awareness due to their potential to spread these contaminants' resistant genes and pose a risk to humans. Cross-linking graphene in chitosan resulted in nanocomposites with varied morphology, increased surface area, and improved photocatalytic removal of bromothymol blue and bromophenol blue. The degradation capacity of photocatalysts at various concentrations (25 and 50 mg) was 96.2 % (170 min) and 99.2 % (80 min) with bromothymol blue, revealing a two-fold variation based on the Gr/Cts NCs concentrations. Similar to bromophenol blue dye molecules, which showed a two-fold enhancement of degradation based on graphene/chitosan nanocomposites concentration, bromophenol blue dye molecules were 95.3 % and 98.6 % at 240 and 120 min time intervals. The bromophenol blue and bromothymol blue dyes degraded according to the Langmuir adsorption model. Furthermore, the minimal cytotoxicity of graphene/chitosan nanocomposites to the human lung epithelial cell line and the human macrophage-like cell line indicates that the material is safe. This study reveals that the degrading properties of graphene/chitosan nanocomposites significantly improve as the concentration increases.