Hybrid Nanocatalysts Coupled with Advanced Oxidation and Reduction Processes for Emerging Organic Pollutants, Focusing on Design Evidence, Reactor Configurations, and Sustainability Metrics

Emerging organic pollutants, principally antibiotics, synthetic dyes and per- and polyfluoroalkyl substances (PFAS), persist in aquatic systems because of chemical stability, incomplete metabolic transformation and limited removal in conventional biological and physical treatment. Hybrid nanocatalysts coupled with advanced oxidation processes (AOPs) and, for PFAS, advanced reduction processes (ARPs) are the principal research responses. Four architectures dominate the recent literature: hollow nanostructures that improve photon utilization and shorten carrier diffusion paths; metal-free floatable composites that ease recovery and surface oxygenation; carbon-nanostructure heterojunctions; and nanomaterial-reinforced membranes that combine rejection with catalytic degradation. These materials are most often paired with visible-light or solar photocatalysis and with peroxymonosulfate (PMS) activation. Laboratory parent-compound removals commonly exceed 80–95% in synthetic single-solute solutions, yet total organic carbon (TOC) mineralization, reusability after documented regeneration, and energy or cost metrics remain sparsely reported. Electrical energy per order (EE/O) for laboratory photocatalysis is frequently greater than 100 kWh m−3 order−1, whereas optimized ultraviolet/hydrogen peroxide (UV/H2O2) systems can approach 0.06 kWh m−3 order−1 at full scale. Reported PMS treatment costs for real chemical-industry wastewater span 0.43–4.66 € kg−1 chemical oxygen demand (COD) under the tariff assumed by the source study. Reactor evidence is dominated by short-duration batch slurry vessels and laboratory membrane modules; continuous-flow and multi-month operational data are scarce. This review maps design evidence, performance data and process configurations in the peer-reviewed literature from 2010 to 2026. It integrates a bibliometric reading of publication trends and keyword evolution, distinguishes parent-compound removal from TOC mineralization and from fluoride release, and identifies the experimental and sustainability gaps that currently limit confident extrapolation to engineered treatment systems.