Fabrication of Iron Oxide/Chromium Oxide/rGO Core–Shell Nanospheres for Efficient Photocatalytic Degradation of Ciprofloxacin: Insights into Mechanisms and Intermediates

Global interest is growing in the continuous improvement of wastewater treatment strategies, especially for emerging contaminants. The complexity involved in treating water pollutants via photocatalysis remains a significant challenge. Here, α-Fe 2 O 3 /Fe 3 O 4 /Cr 2 O 3 /rGO (FO-CrO-rGO) core–shell nanospheres were synthesized for ciprofloxacin (CIP) photocatalytic degradation under solar light illumination. The synthesized material’s crystallinity, morphology, and optical properties were investigated. The morphology of the prepared materials reveals the formation of rGO nanosheets around the FO-CrO core–shell nanospheres, facilitating heterojunction formation and contributing to effective CIP degradation. The BET surface area of the FO-CrO-rGO nanospheres was found to be 41.4 m 2 /g with mesopores in nature predominantly. The synthesized photocatalysts demonstrated effective photocatalytic performance, achieving degradation efficiencies of 92.1 ± 1.2% in 120 min for CIP under solar light exposure. The increased photocatalytic performance resulted from their narrow band gap, better visible light absorption, and efficient charge separation and migration. Their reusability and stability were systematically tested over five cycles, demonstrating their potential for effective photocatalytic activity. Due to their magnetic nature, the FO-CrO-rGO nanospheres could be efficiently recovered after photocatalytic treatment. The intermediates were identified, and the pathways involved in CIP degradation were proposed using LC-MS.