Pollution

Pollution

Water Pollution Treatment Using Eco-Friendly ZnO–Chitosan Bio-Composites

Document Type : Original Research Paper

Authors
Alyaa A Zidan 1
Mohamed Abdelaziz Okbah 1
Salah Abdelmoula Mohamed Abokhder 2
Nouria El Hadi Ali Aboshaala 3
Elham M Moaalem 4, 5
1 National Institute of Oceanography and Fisheries, Cairo, Egypt
2 Department of Environment, Faculty of Natural Resources Engineering, University of Zawia, Libya
3 Department of Geology, Faculty of science, University of Zawia, Libya
4 Department of Oceanography, Faculty of Science, University of Alexandria, Alexandria 21511, Egypt
5 Faculty of Marine Science, Hodeidah University, Yemen
10.22059/poll.2026.415226.3348
Abstract
Natural organic matter, particularly humic acid (HA), is a major water contaminant due to its complex structure, strong metal-binding ability, and role as a precursor of toxic disinfection by-products formed during chlorination. This study developed a green and biodegradable ZnO–chitosan bio-composite (ZnO@Cs BC) for efficient HA removal from aqueous solutions. The composite was synthesized by dispersing ZnO within a chitosan matrix and characterized using FTIR, XRD, SEM/EDX, and TGA-DSC, confirming successful ZnO incorporation and enhanced structural and thermal stability compared with pristine chitosan. Batch adsorption experiments evaluated the effects of pH (3–11), contact time (10–180 min), adsorbent dosage (0.05–1.0 g), initial HA concentration (5–100 mg L⁻¹), and temperature (20–60 °C). The ZnO@Cs BC achieved over 90% HA removal across a broad pH range and a maximum removal efficiency of 99.8% under optimum conditions (pH 7, 25 °C, 120 min, 0.05 g adsorbent, and 5 mg L⁻¹ HA). Adsorption kinetics followed the pseudo-second-order model (R² ≈ 1), indicating chemisorption, while equilibrium data were best described by the Langmuir isotherm (R² = 0.99), with a maximum adsorption capacity of 4.535 mg g⁻¹. Thermodynamic analysis confirmed that adsorption was spontaneous (ΔG° < 0) and endothermic (ΔH° > 0). The composite retained approximately 85% of its adsorption capacity after five regeneration cycles, demonstrating excellent reusability. These results highlight ZnO@Cs BC as an effective, sustainable, and cost-efficient adsorbent for removing HA from water.
Keywords
Humic Acid
Chitosan Composite
Zno Nanoparticles
Adsorption Isotherm
Natural Organic Matter
Subjects
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Pollution
Volume 12, Issue 4
Autumn 2026
Pages 1119-1134