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REVIEW article

Front. Environ. Chem.

Sec. Sorption Technologies

Volume 6 - 2025 | doi: 10.3389/fenvc.2025.1526366

This article is part of the Research Topic Advances in the synthesis and utilization of waste-derived materials for water purification View all 4 articles

Adsorption of heavy metals onto food wastes: A review

Provisionally accepted
  • 1 Maseno University, Maseno, Kenya
  • 2 University of Malawi, Zomba, Malawi, Malawi
  • 3 Kaimosi Friends University College, Kaimosi, Kenya

The final, formatted version of the article will be published soon.

    There has been an increase in the production of food waste materials worldwide due to rapid population growth. The ineffective and sometimes unscientific and ad-hoc disposal of these food waste materials has led to environmental pollution. Studies have reported the occurrence of heavy metals in water resources poses serious health threats to the environment and human health. Heavy metals are documented to be recalcitrant to conventional water treatment facilities since they are non-biodegradable. The use of food waste-based adsorbents provides an alternative solution for the adsorption of heavy metals in water resources, with concomitant benefit of valorization of otherwise waste materials. Therefore, this study examined the applications of food waste-based adsorbents for the removal of heavy metal ions. The study adopted a literature-based approach which involved reviewing published papers from selected science databases. The results indicate that these bioadsorbents have great removal efficiencies for different heavy metals with, rice husks and sugarcane bagasse demonstrating special sorption properties, especially for chromium and lead metal ions, respectively. The adsorption data were mostly best described by the Langmuir and Freundlich isotherm models, suggesting a monolayer coverage with similar sites and a heterogeneous surface, respectively. Further, the kinetic studies indicated that the adsorption processes largely followed a pseudo second-order model, showing chemisorption-mediated ratelimiting steps. However, regardless of these encouraging results attained, the use of food wastebased adsorbents has limitations such as variation in the composition and the structure. This leads to inconsistencies in adsorption efficiencies, regenerations and reuse, and reduced removal capacities. There is also the possibility of leaching of heavy metals from the adsorbents which may in-turn cause secondary pollution. Sustainability investigations such as life cycle assessment, costbenefit analysis, pilot-scale studies and optimization studies present areas for future research.

    Keywords: food wastes, heavy metals, Adsorption, wastewater, Waste Management

    Received: 11 Nov 2024; Accepted: 01 Apr 2025.

    Copyright: © 2025 Nyairo, Njewa and Shikuku. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Wilfrida Nyairo, Maseno University, Maseno, Kenya

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

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