Solar photocatalysis using post-consumer alkaline batteries for degrading contaminants of emerging concern in surface water

The goal of this study was to explore the use of post-consumer alkaline batteries' electrolytic paste as photocatalysts in solar processes for degrading contaminants of emerging concern (CECs) in surface water. Two types of alkaline batteries were used: Super Hyper UM-3SHSL8P6 (SH) and Alkaline LR6XAB/4B192 (AK), which were calcined at 500 degrees C for 4 h. The materials underwent various characterization tests, including SEM, XRF, BET, DRS, TGA, DRX, and pH at the Isoelectric Point (pI). The initial pH and catalysts dose conditions that result in the highest efficiency of methylene blue degradation were achieved through central composite design (CCD), i.e., 11.2, a dose of 1.5 g L-1 for AK and 1.6 g L-1 for SH. After 2 h of exposure to natural solar radiation, SH and AK achieved 72.6% and 96.6% removal efficiency in degrading the methylene blue model substance, respectively. This optimal condition was validated experimentally and statistically. In recycling tests, the photocatalysts maintained their efficiency until the third cycle with no statistically significant differences. The toxicity test with Lactuca sativa (lettuce) seeds showed that the treated water was not toxic. The AK catalyst was tested in the presence of three pharmaceutical drugs (ciprofloxacin, acetaminophen, and carbamazepine) in surface water at optimal pH 11.2 and natural pH (similar to 7), resulting in an overall removal of approximately 41.3% and 30.6%, respectively. Overall, our findings demonstrate that post-consumer alkaline batteries' electrolytic paste can be a viable option for solar heterogeneous photocatalysis under well-adjusted conditions.