ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Tunisian natural chert as an eco-friendly adsorbent for trimethoprim removal from water

Samia Ahmadi, Najah Mahjoubi, Nawel Tlili, Hervé Gallard, and Elimame Elaloui

Laboratoire d’Application des Matériaux à l’Environnement, à l’Eau et à l’Énergie LAMEEE (LAM3E), Département de chimie, Faculté des Sciences de Gafsa, Université de Gafsa, Gafsa, Tunisia

E-mail: samiaahmadi1998@gmail.com

Received: 23 September 2025  Accepted: 1 April 2026

Abstract:

The presence of pharmaceutical antibiotics in aquatic environments has become an emerging environmental concern due to their persistence and potential ecological and human health risks. In this context, this study investigates the potential of natural chert sourced from Jebel el Ali (Kef Ensour) in the Gafsa region of Tunisia as a sustainable, environmentally friendly, and cost-effective adsorbent for removing the pharmaceutical antibiotic trimethoprim from an aqueous medium. Batch experiments were performed to evaluate the impact of key operational parameters on adsorption performance, including contact time (0–180 min), adsorbent dosage (0.2–8 g/L), temperature (10–40 °C), and pH between pH (6–9). The results showed that adsorption increased as the pH decreased from 8.6 to 6.1. The linear isotherm model provided the best fit to experimental data, with an adsorption constant of 1.07 L/g at pH 7.2 in 10 mM phosphate buffer. The adsorption behavior followed pseudo-second-order kinetics and was well described by the Freundlich isotherm model, indicating multilayer adsorption on a heterogeneous surface. Thermodynamic parameters (∆G°, ∆H°, and ∆S°) indicated that the process was exothermic and spontaneous. Overall, this work shows the potential of natural chert as a promising and sustainable adsorbent, offering an environmentally friendly approach for wastewater treatment.

Keywords: Adsorption; Tunisian chert; Pharmaceutical compound; Antibiotic; Wastewater treatment; Low-cost adsorbent

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-026-04874-7

Chemical Papers 80 (7) 8069–8080 (2026)