## 8 Conclusions and Outlooks  
In conclusion, a wide variety of copper-based catalysts can be considered for PMS activation, with particular attention to emerging materials such as MOFs, LDHs, and DESs. These materials offer promising avenues for the development of advanced catalysts, as they provide enhanced stability, increased surface area, and tunable properties. These characteristics make them excellent candidates for improving the efficiency and selectivity of catalytic processes in environmental applications. As demonstrated throughout this study, the activation of PMS by copper-based catalysts has yielded promising results in the treatment of persistent pollutants in wastewater. Cu-based catalysts exhibit remarkable versatility in both radical and non-radical pathways, offering significant advantages across various environmental conditions. Their ability to efficiently generate ROS, such as sulfate radicals and hydroxyl radicals, as well as singlet oxygen through non-radical pathways, underscores their potential in diverse applications. Furthermore, the use of these catalysts provides an economically viable and environmentally sustainable solution for water treatment. Utilizing these catalysts in heterogeneous forms, which reduces secondary pollution from copper ion leaching, further enhances their practical applicability. Additionally, water treated through PMS-based degradation processes, particularly with Cu catalysts, is generally found to be non-toxic, reinforcing the effectiveness of these methods. However, as with any treatment process, when residual toxicity remains, it may be necessary to integrate additional treatment systems with the PMS-based processes to ensure the elimination of any lingering toxic compounds. Despite the high effectiveness of Cu-based catalysts, challenges such as metal leaching and the need for optimized catalyst design must be addressed. Certain limitations still exist, and further research is required to unlock the full potential of these catalysts. The main outlooks for future work include the following:  
* Future research directions: Continued research should focus on enhancing the stability and reusability of Cu-based catalysts, particularly through innovative catalyst design and the exploration of new materials such as bimetallic MOFs and advanced LDHs. Further investigation into the mechanisms of PMS activation, especially under real-world conditions, will be critical for optimizing these systems. * Real applications: The translation of laboratory findings into large-scale industrial applications remains a key objective. This includes scaling up the synthesis of Cu-based catalysts and integrating them into existing wastewater treatment infrastructure. The potential for coupling Cu-based catalysts with other AOPs offers exciting opportunities for developing more efficient and comprehensive treatment systems. * Sustainability considerations: As environmental regulations become more stringent, the demand for sustainable water treatment technologies will continue to grow. Cu-based catalysts, with their low toxicity and high efficiency, are well-positioned to meet this demand. Future developments should prioritize minimizing the environmental footprint of these catalysts, ensuring they contribute to a circular economy by enabling the recovery and reuse of resources. In summary, Cu-based catalysts represent a promising and versatile tool in the fight against water pollution. Their ability to activate PMS and degrade a wide range of organic pollutants positions them as a key component of modern wastewater treatment strategies. However, achieving their full potential will require ongoing research, innovation, and a commitment to sustainability. By addressing current challenges and exploring new avenuesfor catalyst development, Cu-based systems can play a pivotal role in creating cleaner and safer water resources for the future. Conceptualization, B.B. and M.A.S. ; resources, M.A.S.