Jason Yi Juang Yeo, Manel Bergaoui, Asma Nakhli, Deni Shidqi Khaerudini, Felycia Edi Soetaredjo, Suryadi Ismadji, Jaka Sunarso, Naif Mohammed Al-Hada, Bandar Ali Al-Asbahi, Mohamed Khalfaoui
The wide compatibility of bentonite with diverse organic and synthetic modifiers has led to extensive research into specialized bentonite-based composite adsorbents, which has demonstrated enhanced adsorption performance for persistent and complex pollutants such as amoxicillin (AMO) and ampicillin (AMP). In this study, we have synthesized the bentonite-alginate composite (BA) and presented the experimental adsorption isotherms of AMO and AMP onto BA at 30 to 50 °C. The results were then analyzed using statistical physics-based isotherms, density functional theory (DFT), and molecular dynamics alongside the conventional isotherm model fitting (e.g., Freundlich, Langmuir, Toth, Hill, and Dubinin-Radushkevich) to further investigate the adsorption mechanism on the molecular level. The experiments revealed that the alginate was mainly incorporated on the surface of the bentonite particles, whereas the adsorption capacity of BA was recorded at 42.328 to 59.938 mg g-1 for AMO and 54.013 to 68.913 mg g-1 for AMP within the specified temperature range. The isotherms fitting study indicated that both BA-AMO and BA-AMP systems exhibited Langmuir-type adsorption behavior. The statistical physics model suggested that the antibiotic molecules were implied to be agglomerated, with the adsorption being spontaneous and endothermic. Density functional theory calculations showed that AMP exhibited a higher overall affinity to BA compared to AMO, which correlates with the higher adsorption capacity of BA for AMP. Molecular dynamic simulations revealed that the adsorption mechanisms of BA with AMO and AMP involved van der Waals and electrostatic forces at the bentonite silicate layers, as well as hydrogen bonding between alginate and antibiotics. These findings highlighted the enhancement of bentonite's adsorption affinity for AMO and AMP through surface modification with alginate, thereby improving its effectiveness as an adsorbent for antibiotic contaminants in aqueous environments. © 2025 Elsevier B.V.
Research Centre for Sustainable Technologies, Faculty of Engineering, Computing and Science, Swinburne University of Technology, Jalan Simpang Tiga, Sarawak, Kuching, 93350, Malaysia; Research Group in Materials Science, Microelectronics and Nanotechnologies, Department of Technology, Higher Institute of Computer Sciences and Mathematics of Monastir, University of Monastir, Monastir, 5000, Tunisia; Laboratory of Physical Chemistry of Materials, Department of Physics, Faculty of Sciences, University of Monastir, Monastir, 5000, Tunisia; CRMN, Center for Research in Microelectronics and Nanotechnology of Sousse, Sousse, Sahloul, Tunisia; Research Center for Advanced Materials, National Research and Innovation Agency (BRIN), Bld. 440 Kawasan Puspiptek Serpong, Banten, South Tangerang, 15314, Indonesia; Department of Chemical Engineering, Widya Mandala Surabaya Catholic University, Kalijudan 37, Surabaya, 60114, Indonesia; Shandong Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou, 253023, China; Department of Physics & Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh, 11451, Saudi Arabia