Exfoliation of graphite as flexible SERS substrate with high dye adsorption capacity for Rhodamine 6G

Adsorption is one of the most important processes in wastewater treatment, especially for dye removal. In addition to adsorption, there must be a vigilant technique, such as Surface Enhanced Raman spectroscopy (SERS), for detection of low concentration of dye molecules to detect water foiling. Herein, we report a simple, low cost, rapid and efficient technique for the production of exfoliated graphite (EG) under microwave irradiation at 800 W in 1 min, as excellent adsorption material for Rhodamine 6G (R6G) dye. The effect of adsorption process parameters such as pH, contact time, isotherm models (Langmuir and Freundlich) and kinetic models (pseudo-first and pseudo-second-order) on dye removal under aqueous solutions, were investigated. The maximum adsorption capacity for R6G dye is 212.72 (±5.3) mg/g. Meanwhile compressing of EG, into a flexible graphite sheet (FGS) demonstrates responsive SERS for R6G molecules up to detection limit of 10−7 mol/L. However, with silver nanoparticle incorporation, the detection limit increases up to 10−12 mol/L. Performance of flexible sheet checked over a month by rubbing sheet through paper and cloth doesn’t have any impact on the synthesis of exfoliated graphite. Aging factor of the sheet also shows reproducible SERS spectra after a month. These are the highest reported values till today, for adsorption of R6G dye on Exfoliated graphite, with reasonable SERS detection.