Enrofloxacin (ENR), a widely used fluoroquinolone antibiotic, has emerged as a persistent environmental contaminant that contributes to the spread of antimicrobial resistance. Photocatalytic degradation offers a promising approach for its removal from aqueous environments. This study aims to evaluate the photocatalytic performance of a composite material based on coconut shell hydrochar@O-doped g-C₃N₄ (Hydrochar@OCN) for ENR degradation under various operational and environmental conditions. The effects of water matrices (deionized, rain, river, lake, and spring water), solution pH (2, 4, 7, 10, 12), catalyst dosage (1, 1.5, 2, 2.5, 3 g/L), hydrochar@OCN composition (hydrochar, OCN, 1%, 10%, 20%), and initial ENR concentration (3, 5, 7, 9, 10 mg/L) were systematically investigated. The experiments were conducted for 90 minutes, consisting of a 30-minute dark adsorption stage to reach adsorption equilibrium, followed by 60 minutes of LED irradiation to initiate photocatalytic degradation. The results revealed that ENR removal efficiency strongly depended on the operating parameters in 60 minutes. The deionized water matrix with hydrochar loading of 10% in OCN, and neutral pH (pH 7) yielded the highest removal photocatalytic activity (70.29%). While the lake water reaches 47.48%, river (53.26%), rainwater (61.23%), and spring water (61.23%). The optimal conditions were achieved at a catalyst dosage of 3 g/L, with a degradation efficiency of 94.20%, and at an initial ENR concentration of 3 mg/L, with a degradation efficiency of 94.93%. The photocatalytic degradation followed pseudo-first-order kinetics with a rate constant of k = 0.086 g mg-1 min-1, demonstrating the superior activity of the optimized composite