Adsorptive removal of aqueous MB molecules by spent lithium-ion battery cathode scrap

This study describes the application of cathode scrap obtained from spent lithium-ion batteries (LIBs) in the adsorptive removal of aqueous MB dye molecules. The physicochemical properties of the cathode scrap are thoroughly examined. High-resolution microscopic images display aggregation of small-sized particles in cathode scrap. Thermogravimetric analysis confirms the presence of stable metallic compounds (89% by weight) in cathode scrap above 600 °C. Surface charge analysis proves that negative surface charge of cathode scrap increases with the rising pH of the solution. The high negative surface charge facilitates adsorption of positively charged MB molecules onto negatively charged cathode scrap. The maximum quantity of MB adsorbed, as determined by the Langmuir model, is 80.42 mg/g at pH 12. Further, the material may be regenerated efficiently post-adsorption study without requiring any expensive solvent. Reusability studies demonstrate that the material maintains its activity even after five test cycles. The slight reduction in activity observed after each cycle may be attributed to the loss of some active sites into the solution during repeated use. The data clearly confirm that cathode scrap has the potential to remove various pollutants from wastewater with proper optimization of the pretreatment conditions.