Junaid Ur Rehman Abbasi0000-0002-0690-310XKah Hon LeongLan Ching SimChaomeng DaiAzrina Abd Aziz0000-0002-2507-3690Sumathi SethupathiShaliza Ibrahim2025-09-112025-09-112025-05-0210.1007/s11356-025-36461-whttps://dspace-cris.utar.edu.my/handle/123456789/11315Carbamazepine (CBZ), as an emerging contaminant, falls under the category known as pharmaceuticals and personal care products (PPCPs). It has adverse effects on both humans and the environment, leading to issues such as defects in the central nervous and digestive systems of humans. Traditional treatment methods have limited effectiveness in degrading CBZ due to its chemical properties, leading to its increased accumulation of CBZ in water bodies, especially during the recent pandemic (COVID-19). The focus of this research is on utilizing g-C3N4/Bi2O2CO3 with different weight percentages, namely 30% GCN/BOC, 40% GCN/BOC, and 50% GCN/BOC, through a physical mixing approach to degrade CBZ. The proposed photocatalyst underwent thorough analysis through various characterization techniques, including FESEM-EDX, HRTEM, XRD, FTIR, and UV–Vis DRS. FTIR analysis revealed the presence of Bi–O–Bi, CO32−, C–N, and C = N functional groups in g-C3N4/Bi2O2CO3. The bandgap energy, determined by UV–Vis DRS analysis, is 3.44 eV for pure Bi2O2CO3 and 2.84 eV for the optimal ratio of g-C3N4/Bi2O2CO3. Additionally, the photocatalytic degradation experiment showed that the composite with 40% g-C3N4/Bi2O2CO3 exhibited the highest removal efficiency, achieving a rate of 98% within 180 min under sunlight irradiation. Therefore, the use of the coupled photocatalyst g-C3N4/Bi2O2CO3 demonstrated significant potential as a photocatalyst for degrading CBZ when exposed to sunlight. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.en-USBand gap energyCarbamazepineDegradationPharmaceuticals and personal care products (PPCPs)PhotocatalystPhotocatalytic activityPhotodegradationAdverse effectEmerging contaminantPharmaceutical and personal care productPharmaceutical and personal care productsPhoto-catalytic removalPropertyTreatment methodsUV-vis-DRSWeatheringjournal-article