## 4 Conclusions  
Composite materials based on poly(acrylonitrile-co-acrylic acid) and red mud were prepared in the form of beads and used for pesticide removal in synthetic wastewater using adsorption/oxidation processes. The composite beads were primarily investigated for structure, composition, thermal stability, morphology, and porosity to identify at least one viable system of beads with potential application in wastewater treatment. In this respect, FTIR spectra indicated an exciting interaction of RM with the copolymer backbone as a function of copolymer composition. At the same time, the thermogravimetry assays allowed for the evaluation of the influence of RM upon the stability and homogeneity of the  
Figure 5: FTIR spectra of (**A**) 3-RM, 3-RM before and after adsorption (3-RM-Ads)/oxidation (3-RM-Ox) processes; (**B**) 3-RM after reconditioning from the two procedures (3-RM-R-Ads after adsorption and 3-RM-R-Ox after oxidation).  
composite beads, by comparing the initial RM content with the calculated amount of RM from TGA in the analyzed samples. The morphology and porosity of beads depended on the composition of the copolymer, but also on the homogenous distribution of RM. Thus, the composite beads based on copolymers with higher acrylic acid content (20%) exhibited less extended pore structures with poor surface communication and smaller pore surface areas due to their higher hydrophilicity. Nevertheless, this same system was the only one prone to absorb the target pesticide, 2,4-DCFA, as revealed by the TOC measurements in the adsorption trial. The adsorbent/oxidizing character was better highlighted by the following oxidation processes, which pointed out that RM contributed to a specific retention of 2,4-DCFA relative to the TOC values registered for the reference beads, up to 22.81%. Although the study may need further optimization and evaluation, the results obtained in this study show that RM can be repurposed for developing adsorbents for wastewater purification using low-cost precursors and methods, which for the industry may represent a fair trade-off vs. other performant carbon-based adsorbents that require complex preparation methods and pose a risk for CO2 pollution due to preliminary carbonization procedures [78; 84; 85]. Future studies regarding the synthesis optimization of the composite beads in terms of the maximum amount of RM that can be integrated in the precursor solution, as well as reuse studies for multiple adsorption/oxidation cycles, will bring this potential option closer to the industry.  
Conceptualization, T.S. and A.S.; Formal analysis, T.S., A.M., S.-V.D., A.Z. and A.-M.G.; Investigation, E.A.O., R.-A.M., A.M., S.-V.D., A.Z., A.-M.G. and M.-V.D.; Methodology, T.S., E.A.O., R.-A.M., M.-V.D., A.-L.C. and T.-V.I.; Supervision, A.S. and T.-V.I.; Validation, A.Z., A.-L.C., A.S. and T.-V.I.; Writing--original draft, T.S. and T.-V.I. All authors have read and agreed to the published version of the manuscript.  
The authors from ICECHIM acknowledge the funding from UEFISCDI and the European Commission for ctr. 57/2024 \"WATER-BIGFIL\" within the WATER4 ALL 2022 JOINT TRANSNATIONAL CALL and the support of the Ministry of Research, Innovation, and Digitalization for the study through the institutional project 2N/03.01.2023 (PN 23.06.01.01. AQUAMAT).  
Not applicable.  
All the data are available from the corresponding author, [PERSON], [EMAIL_ADDRESS].  
The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.