AccScience Publishing / AJWEP / Online First / DOI: 10.36922/AJWEP026030011
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ORIGINAL RESEARCH ARTICLE

The environmental significance of Citrullus lanatus seed husk in biosorption of Pb2+, Ni2+, and Co2+ from municipal wastewaters

Sufyan Mohammed Shartooh*
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1 Biology Department, College of Science, University of Anbar, Ramadi, Anbar Province, Iraq
AJWEP, 026030011 https://doi.org/10.36922/AJWEP026030011
Received: 15 January 2026 | Revised: 5 March 2026 | Accepted: 10 March 2026 | Published online: 14 April 2026
© 2026 by the Author(s). This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International License ( https://creativecommons.org/licenses/by/4.0/ )
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Abstract

Heavy metal contamination in municipal wastewater poses a serious threat to aquatic ecosystems and human health. This study evaluated the potential of Citrullus lanatus seed husk biomass as a low-cost and sustainable biosorbent for removing lead (Pb2+), nickel (Ni2+), and cobalt (Co2+) ions from wastewater. Batch experiments were conducted to optimize key operational parameters, including pH, temperature, retention time, biosorbent dosage, and particle size. Maximum biosorption efficiencies were achieved at pH near 7, 30–40 °C, and 30 min retention time, with a biosorbent dosage of 5 g/L and a particle size of 0.106 mm. Pb2+ exhibited the highest removal efficiency (up to 95.88%), followed by Ni2+ and Co2+. Fourier transform infrared spectroscopy and scanning electron microscopy analyses confirmed the involvement of hydroxyl and carboxyl functional groups in the adsorption process. Biosorption behavior fits both the Langmuir and the Freundlich isotherm models, indicating favorable and heterogeneous adsorption. Municipal wastewater samples showed unacceptable heavy-metal levels after conventional treatment, whereas post-biosorption levels were reduced to below detectable limits. These findings highlight C. lanatus seed husk as an effective, sustainable, and economically feasible biosorbent for enhancing tertiary wastewater treatment and protecting aquatic ecosystems.

Graphical abstract
Keywords
Citrullus lanatus
Heavy metals
Biosorption
Wastewater
Adsorption kinetics
Adsorption isotherms
Funding
None.
Conflict of interest
The author declares no conflicts of interest.
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Asian Journal of Water, Environment and Pollution, Electronic ISSN: 1875-8568 Print ISSN: 0972-9860, Published by AccScience Publishing
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