Clean Water and Sanitation (SDG 6), Climate Action (SDG 13)
Chitosan-based ionotropic hydrogels for effective remediation of polyethylene terephthalate microplastics Tejesvi Patel 1 , Roselyn Lata 1 , Joachim Emeka Arikibe 2 , David Rohindra 1* 1 School of Agriculture, Geography, Environment, Oceans and Natural Sciences, The University of the South Pacific, Private Mail Bag, Suva, Fiji. 2 Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Via F. Marzolo 5, 35131, Padova (PD), Italy. E-mail: david.rohinda@usp.ac.fj Microplastics(MP), defined as plastic particles smaller than 5mm, are ubiquitous in the environment and poses a growing health concern. [1] WHO has highlighted the potential risks of MP ingestion, particularly through drinking water. MPs small size makes removal challenging using conventional wastewater treatment processes. [2] The ingestion of MP can result in physical, chemical and biological changes in an organism by causing physical damage to the intestinal and respiratory tract of the organism, which affects its growth and development. [3, 4] Addressing MP pollution aligns with SDG 6 which emphasizes improving water quality and reducing pollutants. In this study, biodegradable chitosan(CHI) is modified with iron(Fe-CHI) and aluminium(Al-CHI) salts to form cationotropic hydrogels for PET-MP removal. Al-CHI demonstrated higher swelling, conductivity, and MP removal efficiency compared to Fe-CHI beads, particularly at low pH, where adsorption was most effective. Variations in adsorption performance with pH were attributed to the protonation of CHI and the formation of cationic and anionic species of the metal ions. Zeta potential analysis showed MP and bead instability at low pH, with improved stability at neutral and higher pH. Both Fe-CHI and Al- CHI beads exhibited re-adsorption efficiencies exceeding 70% across three cycles, demonstrating their potential for sustainable and effective MP remediation. Key words: Water pollution, Adsorption, Metal Doping, Zeta potential References 1. C. Lim, N. Kim, J. Lee and Y. Yoon, “Potential of Adsorption of Diverse Environmental Contaminants onto Microplastics,” Water , vol. 14, no. 24, p. 4086, 2022. 2. C. Rolsky, V. Kelkar, E. Driver and R. U. Halden, “Municipal sewage sludge as a source of microplastics in the environment.,” Current Opinion in Environmental Science & Health , vol. 14, pp. 16-22, 2020. 3. F. Shahul Hamid, M. S. Bhatti, N. Anuar, N. Anuar, P. Mohan and A. Periathamby, “Worldwide distribution and abundance of microplastic: how dire is the situation?.,” Waste Management & Research , vol. 36, no. 10, pp. 873-897, 2018. 4. C. Guo, L. Wang, D. Lang, Q. Qian, W. Wang, R. Wu and J. Wang, “UV and chemical aging alter the adsorption behavior of microplastics for tetracycline,” Environmental Pollution , vol. 318, p. 120859, 2023.
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