Adsorption and Photo(electro)catalysis for Micropollutant Degradation at the Outlet of Wastewater Treatment Plants: Bibliometric Analysis and Challenges to Implementation

Micropollutants (MPs), which include both natural and manmade substances, are becoming more prevalent in aquatic habitats as a result of the insufficient removal of these compounds in wastewater treatment plants (WWTPs). Advanced remediation techniques are required due to their persistence and potential ecotoxicological hazards. Although adsorption and photo(electro)catalysis exhibit potential in laboratory-scale investigations, the effects of their use in actual WWTP systems are still poorly understood. However, before large-scale application can be implemented, a number of issues need to be resolved, including material limitations, reactor design and optimization, and actual wastewater complexities. This study critically evaluates the application of adsorption and photo(electro)catalysis to actual wastewater, as well as recent advancements in adsorption and photo(electro)catalytic systems for the removal of micropollutants. We also explore the particular difficulties and strategies involved in the large-scale use of adsorption and photo(electro)catalysis in the treatment of wastewater. Emerging trends such as nanocomposites, metal–organic frameworks (MOFs), heterojunctions, and single-atom catalysts (SACs) are highlighted by the bibliometric analysis. We also evaluate MPs’ ecological effects in aquatic environments and the incorporation of artificial intelligence (AI) for process optimization. A strategy for transferring nanotechnologies from laboratory-scale research to wastewater treatment implementation is presented in this paper. In this strategy, implementation is proposed based on actual wastewater conditions, focusing on the development of adsorbents and catalysts, reactor design and optimization, synergy between adsorption and catalysis, life cycle analysis, and cost–benefit studies.