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

Dynamic biosorption of methyl orange on raw and Zn²⁺-modified Posidonia oceanica: optimization and modeling

Rania Hrichi, Ridha Touati, and Aida Kesraoui

Laboratory of Energy and Materials (LABEM), Higher School of Sciences and Technology of Hammam Sousse, University of Sousse, Sousse, Tunisia

E-mail: aida.kesraoui@gmail.com

Received: 16 August 2025  Accepted: 13 December 2025

Abstract:

This study evaluates the dynamic biosorption performance of raw Posidonia Oceanica (P.O) fibers and chemically modified P.O fibers incorporating 4% Zn (P.O-4% Zn) for the removal of methyl orange (MO) dye from aqueous solutions. Fixed-bed column experiments were conducted to investigate breakthrough behavior, adsorption capacity, and regeneration efficiency under continuous flow conditions. Comprehensive characterization using FTIR, SEM, EDX, Boehm titration, and pH_pzc analyses elucidated the structural and chemical modifications induced by Zn incorporation. The modified P.O-4% Zn material exhibited enhanced adsorption capacity, extended breakthrough time, and improved stability over multiple biosorption-regeneration cycles compared to raw P.O fibers. Dynamic modeling using Thomas, Yoon–Nelson, and Clark models accurately described the adsorption kinetics and column performance, while the Weibull model proved less applicable. The incorporation of Zn²⁺ ions via microwave-assisted synthesis improved surface functionality and metal-fiber interactions, contributing to the superior performance of the hybrid biosorbent. These findings highlight the potential of Zn -modified P.O fibers as cost-effective, sustainable, and efficient biosorbents for industrial wastewater treatment, particularly for textile dye removal.

Keywords: Microwave-assisted synthesis; Dynamic biosorption; Posidonia oceanica; Zinc incorporation; Hybrid biosorbent

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-025-04604-5

Chemical Papers 80 (5) 4985–5004 (2026)