Optimization of Vermiculite Modification Conditions as TiO₂ Carrier Material for Removal of Norfloxacin in Aqueous Environment

Abstract:

Antibiotic contamination in water environment remains a serious issue in Vietnam, primarily caused by untreated and/or ineffectively wastewater from hospitals, pharmaceutical factories, and antibiotic overuse in aquaculture and livestock. High levels of antibiotic residues, often in µg/L range, have been detected in major rivers, fostering the spread of antibiotic-resistant bacteria and genes. Despite the implementation of Vietnam’s National Action Plan on Antimicrobial Resistance (2020–2025), weak wastewater treatment infrastructure continues to limit effective control. The use of vermiculite (Ver) and TiO₂ carrier enhances the removal efficiency of norfloxacin (NOR) from water by improving adsorption capacity and photocatalytic activity. Ver provides a large surface area support for contaminant capture, while TiO₂ facilitates photocatalytic degradation of NOR under UV or visible light irradiation. In this study, Ver was acid modified using HNO₃, H₂SO₄ and HCl with concentration ranging from 1 to 3M. The soaking time ranged from 1 to 7 days. Modified Ver was used as a TiO₂ carrier by sol-gel method to enhance the efficiency of both photocatalytic and adsorption processes. The properties of the TiO₂/modified Ver material were evaluated using SEM, XRD, and Zeta potential analysis. With increasing soaking time, SEM images reveal that the modified Ver surface becomes more cracked and porous compared to the smooth surface of the original Ver. However, no significant difference was observed with changing soaking time. Additionally, the Ver surface modified with HNO₃ found more uniform porosity and cracks compared to the other used acids. The XRD spectra of TiO₂/modified Ver using HNO₃ 3M showed the strongest and clearest anatase TiO₂ peak compared to the other samples. The TiO₂/modified Ver (soaked for 1 day in HNO₃ 3.0M) also showed better adhesion and a more uniform TiO₂ coating. The Zeta potential of this modified material was the lowest and negative, indicating the strongest reduction in TiO₂ particles electrostatic interaction, resulting in the most stable dispersion and a more uniform surface. The removal efficiency of norfloxacin by Ver was only 20% whereas TiO₂/modified Ver material using H₂SO₄ 3M, HNO₃ 3M and HCl 3M achieved of 74, 60 and 45%, respectively, under fluorescent light with an initial norfloxacin concentration of 20 ppm and a material dose of 2.0g/L after 6.0 hours. The treatment efficiency reached the highest 99% with flow rate 1mL/min.

• Periodical: Engineering Headway (Volume 40)
• Pages: 3-14
• DOI: https://doi.org/10.4028/p-Bdq8Hm
• Online since: July 2026
• Authors: Nguyen Thi Hue, Chu Viet Hai, Tran Van An, Le Quang Vinh, Luu Van Huyen, Dang Thi Ngoc Thuy, Nguyen Thi Ha*
• Keywords: Carrier Material, Modified Vermiculite, Norfloxacin, Photocatalyst, TiO₂

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