## 4 Conclusions  
In the present study, novel polymer supported nanocomposite TiO\({}_{2}\) films, based on poly(L-lactic acid), a well-known bioplastic, have been synthesized and successfully applied for the photocatalytic degradation of a mixture of nine antibiotics which are commonly found at environmental samples. Characterization techniques such as FTIR, WAXD, TGA and DSC further confirmed their successful preparation. Among all prepared catalysts, PLLA-GO-50 wt% TiO\({}_{2}\) composite film showed better photocatalytic activity towards the treatment of the antibiotic mixture. The application was evaluated, comparing its efficiency during the treatment of ultrapure water and a wastewater effluent. Effective degradation of the target compounds was observed in both cases although slower kinetics was obtained for wastewater effluents due to the complexity of the matrix. After photocatalysis, the acute toxicity of antibiotics decreased suggesting that the formed TPs possessed similar or lower acute toxicity to aquatic organisms (_Daphnia magna_) and, therefore, applying the photocatalysis as a post-treatment technique would be beneficial for the elimination of antibiotics.  
In conclusion, the reusability of the photocatalyst was assessed for four consecutive cycles. The findings revealed that the PLLA-GO-50 wt% TiO\({}_{2}\) composite film can be easily reused without losing efficiency and avoiding the need of additional post-treatment recovery. Thus, the proposed bioplastic materials provide new possibilities in the investigation of immobilized TiO\({}_{2}\) graphene composites on polymer films and promote their practical application in water and wastewater purification addressing various environmental issues.  
Conceptualization; N.M.E., A.O., M.P. and D.L.; methodology: N.M.E., A.O., M.P. and D.L.; software: N.M.E., A.O., M.P. and D.L.; validation: N.M.E., A.O., M.P. and D.L.; formal analysis: N.M.E., A.O., M.P. and D.L.; investigation: N.M.E., A.O., M.P. and D.L.; writing--original draft preparation: N.M.E., A.O., M.P. and D.L.; writing--review and editing: N.M.E., A.O., M.P. and D.L.; visualization: N.M.E., A.O., M.P. and D.L.; supervision: [PERSON]; All authors have read and agreed to the published version of the manuscript.  
This research was funded in the context of the project \"Antineoplastic and Antibiotic drugs in Aquatic Environment: Photocatalytic Degradation, Identification of Transformation Products, Toxicity Assessment and Antibiotic Resistance\" (MIS: 5004700) under the call for proposals \"Supporting researchers with emphasis on new researchers\" (EDULLL 34). The project is co-financed by Greece and the European Union (European Social Fund-ESF) by the Operational Programme Human Resources Development, Education and Lifelong Learning 2014-2020.  
The authors would like to specially acknowledge [PERSON] and [PERSON] from Dep. of Chemistry of Aristotle University of Thessaloniki for their helpful advice on various technical issues regarding the preparation of the materials and their photocatalytic application, respectively, as well as MSc. [PERSON] and MSc. [PERSON] for their continuous encouragement during the implementation of this project.  
The authors declare no conflict of interest.