In the quest for innovative solutions to industrial oil/water emulsion separation challenges, this study introduces a unique chitosan/poly(vinyl alcohol)/s-triazine (CPT) hydrogel and its hydrogel-coated mesh (CPTM), meticulously designed at the nanoscale for advanced separation. Featuring a sophisticated double-network, dual cross-linked nano-architecture, the CPTM exhibits unparalleled superhydrophilicity and underwater superoleophobicity, achieving separation efficiency exceeding 99.4% even under corrosive conditions such as acidic, alkaline, and saline environments. This high efficiency is particularly notable for emulsions, where micro/nanosized droplets are stabilized and notoriously difficult to separate, marking a significant advancement over existing solutions. The incorporation of trifunctional s-triazine enhances the hydrogel's mechanical stability and imparts potent antibacterial properties, effectively reducing biofouling risks and extending the material's lifespan. The hydrogel's self-healing and self-cleaning capabilities further ensure its durability and reusability, maintaining performance over 50 separation cycles and underscoring its practical applicability. This research not only advances the field of oil/water emulsion separation technology but also opens scalable, energy-efficient avenues for the development of environmentally friendly and sustainable materials. The multifunctional capabilities of the CPTM, including superior separation efficiency, robust mechanical strength, antibacterial activity, biofilm inhibition, and sustained performance, hold great promise for widespread applications in the petroleum industry and environmental conservation efforts. By emphasizing the pivotal role of nanoscale engineering in developing advanced materials, this study paves the way for future innovations in addressing environmental challenges.