Sustainable Conversion of Waste Carbon Brush and Fly Ash into a Novel Nanocomposite for Selective Adsorption of Cationic Dyes

The motto of this research is “WASTE CAN REMEDIATE WASTE”. In this light, to the best of our knowledge, this is the first independent study that reports on the extraction and utilization of graphite materials from waste carbon brushes to produce a composite for pollutant adsorption. First, waste carbon brushes were used for the synthesis of graphene oxide (GOFCB). The second component, silica (Si), was obtained from fly ash, another desecrated material. These components were integrated into a composite comprising a natural biopolymer, carboxy methyl cellulose (CMC), to boost its effectiveness as a selective adsorbent (GO-Si-CMC) for hazardous cationic dyes. The waste-derived GO-Si-CMC nanocomposite was an efficient adsorbent for removing toxic methylene blue from both single and mixed dye systems. It possessed a maximum adsorption capacity of 657.9 mg·g–1 and an optimum methylene blue (MB) removal of 99.8% from a cationic–anionic mixed dye system at pH 8, initial concentration of 20 mg·L–1, adsorbent dosage of 30 mg L–1, and temperature of 313 K. The adsorption process obeyed Langmuir isotherm and pseudo second-order kinetics. The selective adsorption of MB reported herein was further optimized by response surface methodology (RSM) for understanding the impact of inter-parameter interactions. Results obtained for physico-chemical characterization of the adsorbent described the mechanism of selective dye uptake, and GO-Si-CMC has the potential to remove a wide range of effluents.