Effect of Voltage Variation on the Synthesis and Properties of Electrochemically Exfoliated Graphene from Dry-Cell Battery Waste for Chromium Ions Adsorption

Electrochemical synthesis can produce graphene-like materials containing structural defects, known as electrochemically exfoliated graphene (EEG), due to the presence of oxygen functional groups. These defects provide active sites for the adsorption of chromium ions. This study aims to determine the effect of voltage variation on the electrochemical exfoliation of graphite, specifically to identify the optimal voltage for producing EEG materials with the highest chromium adsorption capacity. We exfoliated graphite rods from dry-cell waste in a 0.2 M sulfuric acid solution at 5, 10, 15, and 20 V. The EEG was characterized with FTIR and Raman spectroscopy. The adsorption capacity was measured by AAS using 0.1 g of adsorbent in 10 mL of a 50 ppm Cr(VI) solution at pH 2 for 1 h. FTIR confirmed samples are reduced graphene oxide, showing hydroxyl, epoxy, carbonyl, carboxyl, and sulfonate groups. Raman spectroscopy revealed that EEG_15V was the most graphene-like, with the highest I2D/ID ratio. EEG_15V had the greatest Cr(VI) adsorption capacity at 5.27 mg/g.