Recent Advances, Emerging Trends, and Technology Readiness Level of ZrO2-Based Nanomaterials for the Photocatalytic Degradation of Pharmaceutical Pollutants

Abstract

Photo-enhanced advanced oxidation processes have attracted considerable attention for the removal of pharmaceutical pollutants from water. However, the development of efficient and sustainable photocatalysts remains a key challenge. This review examines recent advances in ZrO₂-based nanomaterials (ZOBNs) for photocatalytic pharmaceutical degradation, with emphasis on degradation performance, reusability, and technological readiness level (TRL). The analysis reveals that ZOBN composites, particularly heterojunction-engineered systems, performed better compared with pristine ZrO₂, with many of the reported ZOBN systems achieving >75% degradation efficiencies under optimized operating conditions. Enhanced performance is primarily associated with improved charge separation, defect engineering, oxygen-vacancy generation, and interfacial charge–transfer processes. Biosynthesized ZOBNs, ternary composites, and assisted photocatalytic systems were identified as promising material classes for improving degradation efficiency and stability. Reusability studies further indicate that many ZOBNs can retain up to 70% of their photocatalytic activity over 3–7 cycles, supporting their potential for practical application. Nevertheless, the technology remains at an early stage of development (TRL 1–4), and challenges related to real pharmaceutical effluent treatment, long-term stability, catalyst leaching, scale-up, and techno-economic feasibility continue to limit industrial implementation. Finally, key research priorities are proposed to facilitate the transition of ZOBN-based photocatalytic systems from laboratory investigations toward commercial wastewater treatment applications.